Systems and methods for implementing a regional air traffic network using hybrid electric aircraft

Abstract

A system, apparatus, and method are provided for overcoming the disadvantages of current air transportation systems that may be used for regional travel by providing a more cost-effective and convenient regional air transportation system. [Solution] In some embodiments, the air transportation system, operation method, and related aircraft of the present invention include a series of highly efficient plug-in hybrid-electric powertrains (specifically optimized for aircraft operating at regional distances), a forward-compatible, range-optimized aircraft design that enables earlier availability of electric air services as integrated transportation systems and related technologies are developed, and a platform for semi-automated optimization and control of powertrains and semi-automated optimization of flight path determination for regional-distance hybrid-electric aircraft flights.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 043990, entitled "System and Methods for Implementing Regional Air Transit Network Using Hybrid-Electric Aircraft," filed August 29, 2014, the entirety of which (including any appendices) is incorporated by reference herein for all purposes. [Background technology]

[0002]

[0002] Transportation devices and systems are important parts of the infrastructure used to enable commerce and the movement of people between places. As such, they are a fundamental service for economic growth, social development, and effective governance of regions. Transportation devices and systems are used to move goods between distribution points, allow face-to-face meetings and discussions, and generally foster the growth of relationships. Furthermore, as new modes of transportation are developed, travel times and cargo carrying capacities change dramatically, allowing new and often faster ways of communication and delivery of goods and services. Over the years, several basic types of transportation systems have been developed in this regard. However, typically each has its own focus, advantages, and disadvantages compared to other transportation modes.

[0003] For example, in the United States today, 100 years after the first powered flight, most (>97%) local long-distance trips (i.e., 50-500 miles) are made by private automobile. In countries with extensive rail systems, 10-15% of trips may have been replaced by rail, but well over 80% of trips are still made by automobile. This may not be in the best interest of society as a whole, as it is inefficient and impedes mobility (relatively long door-to-door times), pollutes, and puts a strain on existing highway infrastructure. However, current commercial air services that cover this distance are often relatively costly and inconvenient. One reason for this inefficiency is the relatively short distances flown, which means that a relatively large proportion (>70%) of the total travel time is spent on the ground (this "ground" time includes travel time to and from the airport, time through the terminal, time at the gate, or time taxiing on the runway). As a result, air transport is generally not the preferred mode of transportation in such situations, and currently air transport accounts for less than 1% of such local trips.

[0004]

[0004] Air transport services for people and cargo are nearly doubling every 15 years, enabling unprecedented global mobility and distribution of cargo. In contrast, even assuming that nearly all (94%) long-distance travel is regional, the relatively low-value planning (and therefore use) of aviation over regional distances may be considered a notable failure. In this sense, there is a demonstrated need for a desirable form of regional air transport, but no desirable system to satisfy this need.

[0005]

[0005] The failure to develop an effective and efficient form of regional air transportation has led to decades of stagnation in door-to-door travel times in the United States and has been a major factor limiting mobility improvements. It is highly undesirable that mobility restrictions affect business and tourism travel, employment promotion and employment opportunities, educational choices, and other factors that are favorable for social growth and prosperity. In some perspective, the viability of regional air transportation has actually been steadily declining since the 1960s as airlines have moved to larger aircraft and longer distances to meet competitive pressures and to lower costs per passenger mile of transportation. Thus, current economic forces are constantly shifting current methods of providing air transportation away from the types of systems and methods described herein.

[0006]

[0006] As described below, conventional approaches to providing air transportation services for regional travel are not sufficiently convenient or effective to encourage widespread use by potential customers. Embodiments of the present invention are directed to solving these and other problems, individually and collectively. Summary of the Invention

[0007]

[0007] As used herein, the terms "invention," "the invention," "this invention," and "the present invention" are intended to refer to all subject matter broadly described in this document and the claims. Statements containing these terms should be understood as not limiting the subject matter described herein or limiting the meaning or scope of the claims. The embodiments of the invention covered by this patent are defined by the claims and not by this Summary. This Summary is a high level summary of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This Summary is not intended to identify key, necessary, or essential features of the claimed subject matter, nor is it intended to be used in isolation to define the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification of this patent, any or all drawings, and each claim.

[0008]

[0008] As recognized by the inventors, the failure of modern air services to address the needs of regional air transportation is a direct result of the use of conventional aircraft technology. It is well known to those skilled in the art that optimizing conventional aircraft for regional operations results in design and performance bottlenecks that adversely affect efficiency. For example, gas turbines (jet and turboprop engines) suffer significant efficiency losses at lower altitudes and slower speeds, and further efficiency losses when scaled to smaller dimensions. In addition, short runway operations incur sizing penalties of wings and / or engines larger than optimal dimensions for efficient cruise performance. As a result, large aircraft over long distances offer the lowest operating costs per passenger mile, with costs increasing rapidly for distances less than 500 miles and aircraft with passenger numbers less than 100 seats (or the equivalent of 25,000 pounds of cargo weight). It should be noted that, given their relatively less efficiency in ground or go-around modes, scaled-down gas turbines are more costly for short-haul operations (for shorter hauls, ground or go-around time is significant and accounts for a relatively larger percentage of the total travel time) compared to longer-haul operations.

[0009]

[0009] This inefficient cost relationship shapes many aspects of today's airline service. Competitive pressures are driving airlines to larger aircraft and longer flights. This leads to fewer flights from fewer hubs that can capture sufficient passenger capacity to support larger aircraft. For example, the United States has approximately 13,500 airports, yet 70% of air traffic is concentrated in 29 hubs and 96% in 138 hubs. Fewer flights from fewer and increasingly congested hubs, which leads to longer ground travel times, in turn results in a relatively low utilization of air transport for regional travel purposes. More recently, airlines' increased emphasis on "capacity discipline" has led airlines to seek to focus on fewer hub airport requirements, exacerbating the problem.

[0010]

[0010] Embodiments of the present invention are directed to systems, apparatus, and methods for overcoming the disadvantages of current air transportation systems that may be used for regional travel by providing a more cost-effective and convenient regional air transportation system. In some embodiments, the air transportation systems, methods of operation, and associated aircraft of the present invention include one or more of the following elements, functionality, or features: 1. A range of highly efficient plug-in hybrid-electric powertrains specifically optimized for aircraft operating within the regional scope; and 2. Forward-compatible, range-optimized aircraft designs that enable earlier adoption of electric air services as an integrated transportation system and associated technologies have been developed; 3. A platform for semi-automatic optimization and control of powertrains, and semi-automatic optimization of flight path determination for regional distance hybrid electric aircraft flights.

[0011]

[0011] In one embodiment, the present invention is directed to a hybrid electric aircraft, the aircraft comprising: a source of energy, including a source of stored electrical energy and a source of generated energy provided by a generator; a powertrain operable to receive input energy from a source of energy and responsively operate one or more electric motors; one or more propulsors, each propulsor coupled to at least one of the one or more electric motors; an electronic processor programmed with a first set of instructions, which when executed provide one or more functions or processes for managing the operation of an aircraft, the functions or processes including: determining a status of the amount of stored electrical energy and the amount of generator fuel currently available to the aircraft; determining the amount of stored electrical energy and the amount of generator fuel required to enable the aircraft to reach its intended destination; determining an amount of energy that can be generated by sources of power generation energy currently available to the aircraft; Determine how to optimally extract energy from sources of stored electrical energy and generated energy; and said electronic processor including functions or processes for determining powertrain reconfiguration and revised control strategies for continued flight in the event of a powertrain component failure or abnormal operation; an electronic processor programmed with a second set of instructions, which when executed provide one or more functions or processes for planning a flight for an aircraft, the functions or processes including: accessing data regarding the total amount of stored electrical energy and generator fuel currently available to the aircraft; determining whether the amount of stored electrical energy and generator fuel currently available to the aircraft is sufficient to enable the aircraft to reach its intended destination, including considering a first mode of aircraft operation in which the stored electrical energy is used exclusively and considering a second mode of aircraft operation in which a combination of stored electrical energy and generated electrical energy is used; If the amount of stored electrical energy and generator fuel currently available to the aircraft is sufficient to enable the aircraft to reach its intended destination, planning a route to the intended destination; planning how to optimally draw energy from sources of stored electrical energy and generator energy over a planned route to the intended destination if the amount of stored electrical energy and generator fuel currently available to the aircraft is sufficient to enable the aircraft to reach its intended destination; planning a route to an intermediate destination when the amount of stored electrical energy and generator fuel currently available to the aircraft is insufficient to enable the aircraft to reach its intended destination; determining one or more possible energy and / or fuel suppliers; determining whether the available stored energy and generator fuel is sufficient to reach at least one of the suppliers; creating a route to at least one supplier; and planning how to optimally extract energy over the route. and a communication element(s) operable to enable data transfer from the aircraft to a remote data processing platform or operator and to receive data from a remote data processing platform or operator to exchange data related to one or more of route planning or recharging and refueling sources.

[0012]

[0012] In another embodiment, the present invention is directed to a regional air transportation system including a plurality of hybrid electric aircraft of the present invention and a plurality of aircraft takeoff or landing locations, each takeoff or landing location including a recharging and refueling platform operable to provide recharging services for a source of stored electric energy and fuel for a source of generated energy, and a data processing system or platform operable to provide route planning data to one or more of the plurality of hybrid electric aircraft.

[0013] In yet another embodiment, the present invention is directed to a non-transitory computer readable medium having a set of instructions thereon which, when executed by a programmed electronic processing element, cause an apparatus housing the electronic processing element to: determining a status of an amount of stored electric energy and an amount of generator fuel currently available to the hybrid electric aircraft; determining an amount of stored electric energy and an amount of generator fuel required to enable the hybrid electric aircraft to reach its intended destination; causing the hybrid electric aircraft to determine an amount of energy that can be generated by a currently available source of generated energy; Determine how to optimally extract energy from sources of stored and generated electrical energy; and In the event of failure or abnormal operation of a component within the powertrain, powertrain reconfiguration and revised control strategies are determined for continued flight.

[0014]

[0014] Other objects and advantages of the present invention will become apparent to those skilled in the art upon review of the detailed description of the invention and the accompanying drawings.

[0015]

[0015] Embodiments of the present invention according to the present disclosure will be described with reference to the drawings. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of the transport system 100 of the present invention. [Diagram 2] 2 is a diagram illustrating certain basic components, elements, data flows, and processes that may be present in an implementation of an embodiment of the transportation system 200 of the present invention. [Diagram 3] 3 is a diagram further illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of the transport system 300 of the present invention. [Figure 3a] 1 is a flowchart or flow diagram illustrating a process, method, act, or function for determining required recharging and refueling services at a destination airport, which may be used in implementing embodiments of the systems and methods of the present invention. [Figure 3b] 1 is a flowchart or flow diagram illustrating a process, method, act, or function for determining in-flight recharging and refueling services to a destination airport, which may be used in implementing embodiments of the systems and methods of the present invention. [Figure 4]4 is a diagram further illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of the transport system 400 of the present invention. [Diagram 5] 5 is a diagram illustrating an embodiment of a range-optimized hybrid electric airplane 500 of the present invention that may be used in the implementation of the regional air transportation system of the present invention. [Figure 6] 6 is a diagram illustrating a variable pitch ducted electric fan integrated propulsion system 600 that may be used in an embodiment of an electric hybrid aircraft that is part of the air transportation system of the present invention. [Figure 7] 7 is a diagram illustrating a powertrain 700 and its associated elements that may be used in an embodiment of an electric hybrid aircraft used as part of the air transportation system of the present invention. [Figure 8] 8 is a schematic diagram of a series of hybrid drive configurations 800 for an exemplary aircraft that may be used in implementing embodiments of the transportation system of the present invention. [Figure 9] 9 is a diagram illustrating an exemplary user interface 900 for use by a pilot of an embodiment of the aircraft of the present invention. [Figure 10] FIG. 1 is a schematic diagram illustrating basic functional elements or modules of a Powertrain Optimization and Control System (POCS) that may be used in an embodiment of an electric hybrid aircraft that may be used as part of the air transportation system of the present invention. [Figure 11] 1 is a schematic diagram illustrating basic functional elements or modules of a POCS that may be accessed and used to control or modify processes on an aircraft in an embodiment of the air transportation system of the present invention. [Figure 12] An interface configuration for an exemplary powertrain 1200 is shown that is coupled to an on-board POCS by several interfaces / connectors 1202 for the purposes of sensing performance parameters and returning control signals to the powertrain or its control system components. [Figure 13]1 is a diagram illustrating an example flight path optimization for an aircraft that may be generated by a flight path optimization platform (FPOP) and used at least in part to control aircraft operations in a regional air transportation system embodiment of the present invention. [Figure 14] FIG. 1 is a flowchart or flow diagram illustrating certain inputs, functions, and outputs of a flight path optimization platform (FPOP) that may be used to determine or revise a flight path for an electric hybrid aircraft that may be used as part of the air transportation system of the present invention. [Figure 15] 1 is a flowchart or flow diagram illustrating a hybrid electric airplane design process that may be used in implementing an embodiment of the air transportation system of the present invention. [Figure 16] 1 is a schematic diagram of an example hybrid electric aircraft designed according to the principles and processes described herein. [Figure 17] 1 is a diagram illustrating the efficiency of certain aircraft and propulsor configurations as a function of flight altitude and required power. [Figure 18] 1 is a diagram illustrating several regional zones and associated airports or landing areas that may be used as part of implementing an embodiment of the regional air transportation system of the present invention. [Figure 19] 19 is a schematic diagram illustrating elements or components that may be present in a computing device or system 1900 configured to implement a method, process, function, or operation according to an embodiment of the invention.

[0017] It should be noted that the same numbers are used throughout the disclosure and figures to reference similar components and features. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018]

[0037] While the subject matter of embodiments of the present invention is described herein with specificity to meet statutory requirements, this description is not necessarily intended to limit the scope of the claims. The claimed subject matter may be embodied in other ways, may include different elements or steps, and may be used in conjunction with other existing or future technologies. This description should not be construed as implying any particular order or arrangement between the various steps or elements, unless the order of arrangement of the individual steps or elements is explicitly described.

[0019]

[0038] Embodiments of the present invention will be described more fully hereinafter with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, exemplary embodiments in which the invention may be practiced. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather these embodiments are provided so that this disclosure will satisfy statutory requirements and will convey the scope of the invention to those skilled in the art.

[0020]

[0039] In particular, the present invention may be embodied, in whole or in part, as a system, as one or more methods, as one or more elements of an aircraft or transport system, as one or more elements or functional modules of an aircraft (flight) control system or a regional aircraft transport system control system, or as one or more devices. An embodiment of the present invention may take the form of hardware implementing the embodiment, software implementing the embodiment, or an embodiment combining software and hardware aspects. For example, in some embodiments, one or more of the operations, functions, processes, or methods described herein for use in aircraft flight control or transport system flight control (or other forms of control) may be performed by one or more suitable processing elements (such as processors, microprocessors, CPUs, controllers, etc.) that are part of a customer device, a server, or other form of computing or data processing device / platform, which may be programmed with a set of executable instructions (e.g., software instructions), which may be stored in a suitable data storage element. In some embodiments, one or more of the operations, functions, processes, or methods described herein may be performed by specialized forms of hardware, such as programmable gate arrays, application specific integrated circuits (ASICs), or the like. Therefore, the following detailed description is not to be taken in a limiting sense.

[0021]

[0040] Before describing several embodiments of the aircraft and associated regional air transportation network of the present invention, it is noted that the following abbreviations or terms may be used herein and are intended to have at least the indicated meaning with respect to concepts, processes, or elements: ADS-B: Automatic Dependent Surveillance-Broadcast – Air-to-air and air-to-ground communications and data enabling NextGen air traffic control. ATC: Air Traffic Control - refers to both the controllers assigned to aircraft and the flight paths. ·BPF: Blade passing frequency, given in Hz for ducted fans. Calculated by dividing the rotational frequency (Hz) by the number of blades. Conventional Aircraft Engine: a combustion engine currently used to provide propulsion for aircraft, including, but not limited to, reciprocating or rotary internal combustion engines, gas turbines, turboprops, turbojets, turbofans, and ramjets. COT: Cost of Time - in this context it refers to the cost of time per passenger or payload. For example, a business jet has a very high cost of time per passenger, while the COT for cargo is much lower. A measure of the "value" of a quantity of time for a particular passenger, piece of cargo, etc. (and thus a pricing factor). DOC: Calculated as the sum of direct operating costs, energy (fuel and / or electricity), amortization of energy storage units, and maintenance reserves for the airframe and range extension generators or engines. Ducted Blower: A multi-blade aerodynamic propulsor positioned within an axial flow duct. The duct is shaped to maximize the efficiency of the blower. FMS: Flight Management System, an embedded computer system that controls an aircraft through the autopilot and autothrottle interfaces. The FMS is typically programmed before takeoff and can fly the aircraft to its destination with little or no pilot intervention. I: Indirect costs of operation on a time basis, including aircraft depreciation, crew costs, insurance, etc. · Mach Number: The ratio of a vehicle's travel speed to the speed of sound. Range extension generators: may consist of an internal combustion engine, each driving one or more motor-generators, or may consist of a unit that converts stored chemical energy directly into electricity (e.g. a hydrogen fuel cell). Rechargeable Energy Storage Unit: consists of a battery pack, supercapacitor, or other medium (or a combination thereof) for storing electrical energy, coupled to a battery management system(s) that manages the operation and safety of the pack. Each pack may comprise multiple, individually removable battery modules and may operate some or all of these modules in a stationary state. Also referred to as "Energy Storage Unit". Solidity: A measure of the area of ​​the propeller disk occupied by the blades. It is defined as the ratio of the total chord of the blower disk at a given radius to the circumference at that radius. STOL: Short Takeoff and Landing - not a strict definition, but implies a significantly shorter runway length and steeper approach angle than a similarly sized non-STOL equipped aircraft. · TDI: Turbo Diesel Injection - compression ignition engine with boosted intake manifold pressure.

[0022]

[0041] In some embodiments, the transportation network of the present invention may be defined by an optimized demand and supply mechanism for airports (and associated ground transportation options), aircraft, and regional electric air transportation services. This combination of technologies, processes, devices, and control methods may be used to provide multiple benefits to users. Regional electric air transportation offers significantly shorter door-to-door travel times and costs per mile than alternative travel modes (i.e., highways, high-speed rail, and conventional air). As a result, the system of the present invention facilitates and supports four large-scale applications: A. Commercial Scheduled Flights: Regional electric aviation can provide twice the door-to-door speed of conventional aviation at roughly half the cost, along with convenience and comfort. Unlike today's highly centralized aviation network, where large aircraft fly long distances to a diminishing set of high-demand hubs, the regional electric aviation network of the present invention is (much) more distributed. Smaller aircraft flying lower serve a multitude of community airports. More options of schedules and destinations, along with less trafficked routes, will result in a much more personalized travel experience than available from aviation today. Regional electric aviation will serve two major groups of demand: point-to-point flights and feeder flights. Point-to-point flights typically serve a pair of destinations within a region, avoiding conventional aircraft and hub airports. Feeder flights transport passengers from their local regional airport to a more distant conventional hub for connection to a long-haul flight outside the region. Conversely, feeder flights transport passengers arriving on long-haul flights to their local regional airport. Both dramatically reduce door-to-door travel times not only for local areas but also for long-distance trips by avoiding congested hubs and reducing ground traffic. B. Business and On-Demand: The value proposition of regional electric air transportation systems for business and on-demand travel is also strong. Electric planes offer comfortable travel over regional ranges at a cost 80-90 percent lower than business jets. In addition, quiet STOL (short take-off and landing) capability opens up access at all times to a large selection of smaller airports, allowing door-to-door times comparable to faster business jets that require longer runways and also cause noise pollution and other issues. Furthermore, the disruptive low cost of electric air transportation extends the demand for this form of travel, while pooling technology multiplies the options for use. In addition to the air taxi, charter, and fractional ownership modes available today, this capability can also be offered on a pooled or on-demand basis. For example, in pooled flights, vacant seats on an existing flight are offered to other passengers, often at a lower rate. On-demand flights, on the other hand, schedule based on the number of passengers. These include on-demand markets that allow passenger demand for flights and allow flights to be scheduled based on a combination of demand and historical demand patterns. C. Cargo: Even though regional transportation infrastructure has been stagnant for the past few decades, the demand for urgent delivery of goods has increased many fold, driven by the rapid growth of online commerce. Electric air transport offers a disruptive alternative by offering door-to-door speeds 4-5 times faster than ground at comparable or lower costs. This is made possible via cargo flights (manned, remote pilot controlled, or autonomous) from airports at or near regional logistics hubs to airports at or near local depots. As an example, urgent delivery of goods to a home or business is made possible by electric air transport cargo flights between a regional distribution center and a local supply depot. An electric airplane is loaded with packages at the distribution center that are routed to one or more local supply depots. Once loaded, the aircraft takes off from adjacent or nearby airfields for regional flights to airfields adjacent or near each of the local supply depots to which the cargo is destined. Delivery from the local depot to the final destination may use existing modes (e.g., delivery trucks) or one of several emerging platforms (e.g., autonomous vehicles, delivery drones). As another example, rapid delivery of goods to the point of use is enabled by electric air transport flights from a corresponding production site (e.g., manufacturing facility, farm) or logistics hub (e.g., warehouse, transportation terminal). The electric aircraft is loaded at the production site or logistics hub and takes off from a nearby airfield for a rapid flight to the airfield near the point of use. D. Military: Despite the tremendous advances in military technology over the past few decades, the development of platforms for the transport of troops or cargo over regional distances has largely stalled and remains largely restricted to ground convoys or to much less cost-effective conventional or rotorcraft. In much the same way as cargo, electric aircraft could transform regional military logistics by allowing parts of the supply convoy to be shifted from ground to electric aircraft. This would reduce exposure to enemy attack and increase the speed of the supply chain by a significant factor (estimated at 5x or greater) at a cost comparable to or less than ground transport. As an example, electric air transport flights could enable rapid supply from a theater logistics hub to a forward base. At the logistics hub, electric aircraft could be loaded with troops and cargo and routed to one or more forward bases. Once loaded, the aircraft would take off from a nearby airfield for a regional flight to an airfield nearby each of the destination forward bases. Delivery could also be made without touching down at the forward base, using a parachute or other mechanism to safely direct the cargo to the base. Other opportunities include replacing conventional aircraft or rotorcraft in tactical transport missions due to faster travel, increased stealth, and significantly lower cost. E. Manned and Unmanned: Given the rapid and continuing development of autonomous vehicles and remotely piloted drones, the four applications of regional electric air transportation services described above may include not only traditional piloted aircraft, but also aircraft designed with increasing degrees of autonomy. These include piloted aircraft with remote pilot backup control, unmanned aircraft controlled by a remote pilot, and semi-autonomous aircraft with remote pilot backup control.

[0023]

[0042] In one embodiment, the regional air transportation network of the present invention may include four classes of airports, most of which have runways (or pads for VTOL aircraft) greater than 1,500 feet, and which are differentiated based on their respective roles within the regional network and the extent to which they are equipped to support high-frequency hybrid electric flight. Regional Tier I, Tier II, and Tier III airports. These are the first nodes of the regional network. Tier I airports are best equipped for high frequency electric flight and offer rapid recharging and swapping stations, as well as all-weather and night operation capabilities. Some of the Tier I airports may also be used for scheduled flights of conventional aircraft. Tier II airports include rapid recharging and swapping stations, while Tier III airports have basic recharging capabilities on the tarmac. Unlike conventional hub airports, regional airports offer fewer or lesser ground services (e.g., baggage, security, etc.), assuming relatively lower traffic and smaller aircraft. This allows for quicker transit through the airport, further reducing door-to-door travel times. Large hub airports in mainline regions. Some of the large commercial hub airports located in regions that have support for small to medium sized hybrid electric aircraft. These may include dedicated short runways, non-intrusive flight corridors, relatively quick recharging and swapping stations, and rapid passenger transfers from regional electric aircraft flights to conventional aircraft flights and from conventional aircraft flights to regional electric aircraft flights. Assuming most regional electric flights are "non-sterile", the hub airport may also include access facilities for this traffic to sterile areas of the airport (e.g. baggage and security services for arriving regional passengers). Regional Service Hubs. Airports within a region that are equipped to service and accommodate electric aircraft. These are typically part of a regional Tier I or Tier II airport and typically include parking areas, maintenance facilities, and operations centers. Cargo airports. Airports that allow regional transportation between network hubs or distribution centers of goods and local delivery depots. These are equipped for high frequency electric flight like the Tier I, Tier II, and Tier III airports mentioned above and can include shared cargo and passenger facilities. These cargo airports are typically located near the origination point of goods (e.g., network hub, distribution center) or the delivery point of goods (e.g., local delivery depot).

[0024]

[0043] In some embodiments, the hybrid-electric range-optimized aircraft and associated regional air transportation networks of the present invention may provide a relatively quieter, cost-effective, energy-efficient, and more convenient mode of transportation while providing multiple associated social and economic benefits. Such benefits include a reduced need to rely on automobiles for local transportation, which is expected to provide less pollution and traffic congestion. The aircraft and systems of the present invention may also save passengers time, leading to increased productivity, encouraging greater rural development and housing supply, supporting decentralized living and working patterns, and creating new markets for connective transportation services.

[0025]

[0044] To allow for the realization of the opportunities offered by a more effective and efficient regional air transportation system, the inventors have recognized a need for enabling devices, systems, data processing methods, and technologies. These include, but are not limited to, hybrid electric aircraft with efficient, quiet, short takeoff capabilities, and associated and appropriately optimized technologies for regional operations "close" to communities and urban agglomerations. Further, there is a need for a regional transportation network consisting of such aircraft, supporting airports, and appropriate demand and supply matching mechanisms. Elements of embodiments of the present invention are designed to address these and other needs. In particular, embodiments of the systems and methods of the present invention may include one or more of the following: A series of highly efficient plug-in hybrid electric powertrains optimized for regional range. The powertrain may be designed to minimize the energy required for rapid cruise over a given percentage of the distance that represents the majority of the flight by sizing the powertrain slower for longer ranges. This allows the generators to be scaled down by reducing the power output below that required for standard cruise, so that the energy storage units are used continuously during the flight and are fully depleted (less than the FAA required reserve). This also allows for a relatively high energy storage mass fraction in the range of 12-20% of the total aircraft weight. This higher ratio of electrical storage to power output compared to conventional hybrid designs (and often with power generation optimized for cruise mode) is one key to the 65-80% lower DOC (than conventional aircraft) achieved by the inventive design. Further reductions are possible with propulsor regenerative braking and all-electric ground operation. Range-optimized aircraft designs enable the early benefits of electric aviation. Efforts to design commercial electric aircraft to date have focused on comparable size, speed, and range capabilities to conventional aircraft. Assuming a scaling of energy required for flight with distance times speed squared, this results in designs that are either "modestly electric" and incorporate only a small percentage of energy storage, or more electric but require advanced electric technology. This results in the prospect that electric aviation will achieve limited savings in the near term and that significant technologies will take decades or longer to mature. In contrast, by tailoring the aircraft of the present invention to regional ranges and reducing speed, altitude, and size, the "range-optimized" designs of the present invention can achieve significantly lower DOC based on technology that will be available in a significantly shorter time frame. This can speed up time to market by many years. · Degree of built-in “future proofing” (e.g., prevention of relatively early technological or business-related obsolescence) via forward compatible powertrain propulsion coupled with a modular, forward compatible airframe. As with rapidly improving electric vehicle technology, a key barrier to early adoption of electric airplanes driven by technological innovation is obsolescence. This potential inhibitor to adoption of electric airplanes and related transportation systems is countered by modularization, i.e., forward compatible design of powertrain, propulsion, and airframe that allows technology upgrades via simple module replacement. This allows for early introduction of hybrid electric airplanes that achieve continuous improvements in DOC via upgrades to keep up with improvements in energy storage technology and / or operational efficiency. Another key enabler is the Powertrain Optimization and Control System (referred to herein as “POCS”) of the hybrid aircraft of the present invention. This platform adjusts the operation of the modular powertrain based on the characteristics of the onboard energy storage units and generators to achieve optimal performance. As a result, technology upgrades are easily adapted to flight objectives, speed, efficiency, noise, and payloads are transformed to control the powertrain in a manner that best utilizes the onboard modules without the need for detailed operator or pilot intervention. ·Quiet operation with Short Take-Off and Landing (STOL) capability allows for "close" flying and improves community acceptance. Quiet STOL capability dramatically improves the ability of aircraft to fly "close" to communities and settlements, thereby realizing a radical change in reducing door-to-door travel times. STOL avoids congested hubs and allows for operation to smaller community airports (over 13,000 in the U.S.). Quiet operation improves community acceptance that is often a limitation to such flights. The system and aircraft of the present invention utilizes quiet electric ducted controllable pitch fans (referred to herein as "eFans") for propulsion to reduce runway requirements and lower noise levels, thereby enabling operation at the majority of existing airports. The blower design proposed in the present invention is aerodynamically and acoustically optimized for the moderate speeds and altitudes of range-optimized aircraft. This includes the use of a low pressure ratio variable pitch blower, allowing propeller blade pitch to be adapted to flight mode for greater efficiency, and the use of regenerative braking instead of spoilers, which typically result in noise. The blower is positioned in the center of the duct and driven by one or more high density electric motors connected to the blower directly or through an optional elliptical gear reducer. The high torque at low RPM of the electric motor coupled with the high stable thrust of the ducted blower results in good STOL performance. The combination of low blower tip speed, acoustic design of the fan stator and duct, and acoustic treatment of the duct results in a significantly lower noise profile. As an added benefit, the increased safety and "jet-like" appearance of the ducted blower is expected to translate into strong consumer appeal compared to open propeller aircraft often used for regional operations. The aircraft and powertrain also include other features intended to reduce cabin and environmental noise. A distributed regional hybrid electric air transportation network for passengers and cargo that enables efficient large scale operation of the electric airplanes of the present invention. Today's air services require passengers (or those transporting cargo) to tailor their travel to the flight patterns of larger, cost-competitive aircraft. In contrast, and as recognized by the inventors, hybrid electric technology allows the opposite, allowing aircraft and flight patterns to be tailored to the needs of passenger travel. This is implemented through a distributed regional electric air transportation network that operates from a relatively large number of neighborhood and community airports and operates smaller electric airplanes optimized for individual routes. The topology of this network will be significantly different from traditional long-haul air transportation networks and systems, resulting in unique requirements for the components and processes used to implement and operate this network. These are described herein and include requirements for demand supply matching mechanisms for airports (including ground transportation options) and aircraft. With respect to airports, in one embodiment this includes four classes of airports, all with runways (or VTOL pads) over 1,500 feet, and differentiated based on their role in the regional network and the extent to which the airports are equipped to enable high frequency electric flight. For aircraft, in one embodiment this includes hybrid electric airplanes designed for "fuel-saving" operation in the air and for low-service community airports on the ground. These elements work together and their use is optimized using next-generation regional capacity management to improve aircraft seat utilization and utilization. · Development and use of aircraft powertrain fault-tolerant designs for aviation-grade safety, a key requirement for large-scale applications of hybrid electric powertrains. In one embodiment, this is addressed by designing the powertrain for a relatively high degree of redundancy, as well as supporting optimization and control systems ("POCS" systems), to ensure continued safe flight when a failure occurs. This may include features that provide redundancy in the event of failure of a power source, converter, sensor, or motor, among other elements or processes. Other safety features may include those used to prepare the powertrain prior to a crash to ensure the platform and module response to impacts in a manner that minimizes risk to aircraft occupants. Use of a powertrain designed for semi-automated optimization and control, a key factor to enable pilot acceptance and high frequency operation at optimal efficiency. The key to pilot acceptance of a hybrid electric airplane is a control platform with a simple pilot interface that mimics the operation of a conventional aircraft. This platform, an example of which is illustrated in FIG. 9 and described further herein, should optimize the operation of the powertrain modules across the incorporated powertrain (e.g., generator operation during flight) and for each module (e.g., motor RPM and torque for maximum efficiency) to meet the pilot's objectives for the flight. Additionally, the control platform (i.e., POCS) should support safe operation of the powertrain through appropriate fault isolation and recovery mechanisms. Other functions of the control platform may include streamlined powertrain preparation and pre-flight inspection, assisted diagnostics and post-flight maintenance, and simple calibration after replacement of a power module. Many of these functions or requirements are enabled through the Powertrain Optimization and Control System (POCS), which serves as a single control platform for the noted powertrain and its modules. · An automated optimization method for generating and modifying flight paths for regional hybrid electric flights. Note that, unlike long-distance flights with conventional jets, determining optimal paths for one or more regional hybrid electric flights (typically flying at altitudes <30,000 feet) is more complex with clearly defined optimal altitudes and speeds. For example, different operational characteristics of various power sources based on the extent to which generators are required during the flight result in changes in optimal flight altitudes. Therefore, to determine the optimal path, it is necessary to consider the power source operating characteristics along with the physical conditions during the flight (e.g., terrain, weather, and flight distance) and the pilot's flight preferences (e.g., high speed or economical). In some embodiments, this is made possible via a flight path optimization platform (referred to herein as "FPOP" and described with reference to Figures 13 and 14) that works with the flight management system (FMS) and POCS to define optimal flight paths and refine these as conditions released with the flight.

[0026]

[0045] 1 is a schematic diagram illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of the transportation system of the present invention. As described herein, the transportation system of the present invention, as well as related apparatus and processes, may include a decentralized air traffic network for regional transportation based on small to medium (6-90 seat) hybrid and electric aircraft (with VTOL / STOL capability) that are used to supplement the current traditional long-range air transportation system concentrated in a few hub airports.

[0027]

[0046] The air traffic network is adapted for high frequency operation of electric aircraft to multiple regional airports currently not adequately served by conventional aviation, and with low impact operation to major hub airports. This offers airlines, public transportation, air taxis, charter operators, and cargo operators profitable, scheduled or reschedulable, and on-demand flights across the region, with a cost structure competitive with long-haul aviation. The transportation network of the present invention offers significantly shorter door-to-door travel times and lower total costs per mile than alternative regional travel modes (i.e., highways, rail or high-speed rail, and conventional airways). In some embodiments, this is accomplished through convenient, high frequency, "close by" flights to multiple regional airports near communities and settlements using the quiet, range-optimized hybrid electric aircraft of the present invention.

[0028]

[0047] As shown in the figure, an embodiment of a transportation network 100 of the present invention may include one or more regional subnetworks 102. Each subnetwork 102 may belong to a region of a country, a state, or other geographic region. Each subnetwork 102 typically includes multiple cities and one or more regional or hub airports 104 from which one or more of the aircraft 106 of the present invention operate. Each regional or hub airport 104 may include elements and services to support aircraft scheduling and "refueling," where refueling refers to recharging or replacing stored energy units, and adding fuel for range-extending generators (as suggested in the figure by "Recharging and Refueling Services" 108). Management of scheduling, refueling, and other services (such as record keeping) may be performed by one or more service platforms 110. Such platforms may include those used to access and process diagnostic information regarding flights, operate refueling stations, and schedule refueling operations. In some embodiments, the service platform 110 may include processes capable of matching supply and demand for flight scheduling, making parts available in an efficient manner, or performing other desired matching or optimization processes related to managing the network and its components.

[0029]

[0048] 2 is a diagram illustrating certain basic components, elements, data flows, and processes that may be present in an implementation of an embodiment of the transportation system of the present invention. As shown, such a system 200 may include an implementation of a hybrid electric regional aircraft 202 of the present invention. The aircraft 202 includes an embodiment of a hybrid powertrain 203 described herein, a powertrain optimization and control system (POCS) 204, a flight path optimization platform (FPOP) 205, a flight management system (FMS) 206, and communications capabilities 207 for the transfer of messages and data to other components or processes of the system 200. The regional air transport operator 210 may include a set of processes for use in flight planning and other scheduling or management activities associated with one or more airports and their associated aircraft operations. The communications capabilities 207 may be used to transfer data regarding the aircraft payload, flight path, and energy state (among other parameters) to the regional air transport operator 210. Data obtained from and / or processed by one or more of the aircraft 202 and transport operators 210 may be used to assist in flight scheduling via a regional capacity management platform or process 212, to assist in managing and scheduling the "refueling" process via a recharging-refueling platform 214, or to assist in monitoring the operation of the aircraft during and after flight (for purposes of pilot logging and diagnosing any issues) via a POCS online process or platform 216.

[0030]

[0049] As suggested by the diagram, demand for regional air transportation services may be driven by various types of reservations, as well as aircraft, parts, and pilot availability. Such information 218 is typically used by a regional capacity management platform or process 212 to determine the appropriate number and type of flights to make available to customers. Similarly, fuel / energy / power service providers may use information regarding flight scheduling, fuel needs, available fuel (e.g., charged modules), and sales / payments 220 to schedule and pay for refueling operations via a recharge-refuel platform 214. Aircraft manufacturers 222 typically provide information regarding the structure and operation of the aircraft and its systems to a POCS online process or platform 216 for use in assisting pilots or processes to operate the aircraft and diagnose problems.

[0031]

[0050] FIG. 3 is a diagram further illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of the transportation system 300 of the present invention. As suggested by the diagram, the aircraft and pilot 318 may utilize one or more systems, platforms, modules, or processes (as suggested by “FMS”, “FPOP”, “POCS”, “RRP on site”) as part of scheduling or operating the aircraft. The recharging and refueling platform on site 314 (the “RRP on site”) assists the pilot by determining the optimal recharging and refueling services required during the flight or at the destination by utilizing one or more systems, platforms, modules, or processes (as suggested by “Recharging and Refueling Assistant”, “Service Provider Database”, “Preferences”). Alternatively, the recharging and refueling decisions may be made by the regional air transport operator 302 based on information provided by the aircraft and pilot 318. The recharging and refueling platform on site 314 assists them as well as shown. Information about recharging and refueling services requested by the pilot or operator, as well as schedules proposed by the service provider, is exchanged between the recharging-refueling platform online 316 and the aircraft and pilots 318 or regional air transport operators 302 via suitable interfaces 308. The recharging-refueling platform online 316 may utilize one or more systems, platforms, modules, or processes (as suggested by "Service Scheduling," "Service Calendar and Log," "Supplier Database," "Payment Platform," "Platform Mapping," etc.) as part of providing recharging and refueling schedules, processing payments for such services, etc. Similarly, data may be exchanged between the recharging-refueling platform online 316 and the airport fuel service provider 306.

[0032]

[0051] As shown, airports / airfields served by the regional electric air transportation system of the present invention may provide various levels of rapid swap and recharging infrastructure to enable high frequency electric flight. Recharging stations operate to enable standard and rapid charging of aircraft energy storage units in situ, while swapping stations operate to swap out discharged or partially discharged energy storage units and replace them with charged ones. The aircraft of the present invention includes bays to house standard and extended energy storage units, which may each be modular to allow removal of individual modules with standard or extended packs. As a result, swapping may include replacing existing modules with smaller or larger numbers based on operator requirements (such as upcoming flight speed, range, payload, and cost).

[0033]

[0052] It should be noted that the speed, range, payload, and operating costs of an aircraft are determined to a large extent by the energy storage capacity installed. As a result, the ability to add or remove modules that provide energy allows the performance to be tailored to the needs of a particular flight. For example, on flights with less than the design payload, the operator can reduce operating costs and / or increase the electric range by adding an energy storage unit with a weight up to the design payload minus the actual payload, and reducing the reduced fuel required. Conversely, the operator can accommodate a higher than design payload by removing an energy storage unit with a weight greater than the payload excess, and adding the additional fuel required for the flight. This capability allows the operator to reduce costs on legs where the aircraft is underloaded and to accommodate overloaded flights. Additionally, the transportation network may be supported by software and communication platform 312 that allows the pilot or regional air transport operator to determine energy needs and communicate these to a fuel service provider at the destination airport or at an airport(s) en route to the destination, to enable efficient module replacement and recharging.

[0034]

[0053] As mentioned, a block diagram of an embodiment of the recharging-refueling platform 304 is shown in Figure 3. Aspects of its operation are illustrated by Figure 3a, which is a flow chart or diagram of an exemplary process for determining required recharging or refueling services at a destination, and in Figure 3b for determining such services en route to the destination. These processes or operations are performed by a "Recharging and Refueling Assistant" module or process of the on-site aspect 314 of the platform 304 based on pilot or operator requests.

[0035]

[0054] The process or process flow illustrated in Figures 3a and 3b depends on several factors, including the payload and energy requirements of the route leg, the energy storage capacity and charge remaining on board, and the turnaround time and cost to determine the swap and recharge requirements. These parameters and data are typically communicated to the airport fuel service provider 306 along with the flight details, ETA, and turnaround time, allowing the provider 306 to schedule the service and arrange for the swap or recharge to be performed quickly and properly. To assist the pilot with recharging and refueling at the destination airport, the platform 304 determines the additional energy required for the next flight (e.g., flight segment) and generates viable options based on the capabilities of the preferred service provider at the airport.

[0036]

[0055] Such options may include one or more of: matching the stored energy capacity to the payload, adding stored energy units to flights with low payload to improve energy efficiency, or removing units on flights where additional payload is needed. Options may also include replacement or recharging for the stored energy units based on one or more of the cost, turnaround time, or impact on the operational life of the stored energy units. The options are presented to the pilot along with the cost and time required, and the pilot's selection of the desired option is transmitted to the provider 306 for scheduling service. Similarly, to assist the pilot in receiving service en route to the destination, the platform 304 determines the range of the aircraft, assuming the remaining on-board energy and additional energy required for the next leg. This may be done to generate viable pilot options based on the service providers within the range of the aircraft along with the cost and time impact of each selection. Note that the platform 304 may be used to assist in recharging and refueling planning for a single flight, for consecutive flights, or for flights with multiple legs. Successive services for a trip with multiple steps are selected by the pilot based on guidance from the platform and transmitted to the service provider. En route, recharging and refueling needs and schedules are periodically refreshed based on the progress of the flight and transmitted to the service provider whenever they differ significantly or meet specific regulations or conditions.

[0037]

[0056] The recharging and refueling platform 304 also provides support for billing, payment, and account management so that such transactions are conducted efficiently and using standard transaction authentication, authorization, and processing techniques. The energy storage units may be owned by the aircraft operator, in which case replacement units would be pre-deployed based on flight patterns much like replacement parts are today. The energy storage packs could also be owned by a service provider or a third party and rented out as a service to aircraft operators. The service provider stores and recharges the spare packs, and replaces them with discharged packs as needed.

[0038]

[0057] The recharging-refueling platform 304 consists of a set of on-site functional modules 314 implemented on-board the aircraft or at the premises of the regional air transport operator, and a set of online functional modules 316 accessible via the Internet or other suitable communication network. It should be noted that although the services provided by the operator of such a platform are referred to herein as recharging / refueling, they may also include the exchange of energy sources, and that the exchange may involve adding more or decreasing the total number of battery packs depending on the operational needs. The recharging-refueling platform connects and allows communication between the hybrid-electric airplanes, the regional air transport operators, and the airport fuel service providers to enable efficient refueling operations. Elements of the platform may include one or more of the following: · The online 320 and on-site 321 service supplier database is a regularly updated listing of airports, fuel service suppliers at each airport, their service capabilities, service schedules, prices, and other logistical details (e.g., affiliation, available payment methods, etc.). Typically, an up-to-date comprehensive version of this database is maintained in the online platform 316. A shortened version of the database (e.g., tailored for local / regional use) is located as part of the on-site aspect 314 of the platform 304 so that the on-site recharging and refueling assistant module / process 322 can function without dependency or connectivity to the online platform 316. However, it should be noted that one or more of the distributed on-sites may maintain a copy of the comprehensive version of the database as a backup. This redundancy may be useful in providing recharging and refueling data to pilots and local facilities in the event of an interruption in the services provided by the central data repository, or to provide assistance to pilots who are significantly off-course. The shortened version may be periodically updated from the online database, provided that safe access is appropriately available and the updates can be performed without having undesirable impacts on operations. Preference data (elements, processes, or modules 324 and 325) is a record of adapted settings for an aircraft or operator. These may include default units, currency and time zones, preferred fuel service providers and customary prices, communication and transaction processes, and standard fueling protocols for a particular route. These are stored on-site 324 as well as in the online platform 325. Recharging and Refueling Assistant 322 enables the pilot or operator to determine the optimal fueling required to support one or more flights and to select among available suppliers at the airport or within the aircraft. The function or process leverages the on-site supplier database 321 and the recharging-refueling platform 304 preference data 324, as well as a set of modules or functions (whose functions or operations are described in more detail herein) accessible on the aircraft or by the operator, such as POCS and FPOP. The service schedule module 326 receives specific fuel service requests and attempts to schedule these with the requested supplier. If the requested time slot is available, the module returns a confirmation and records a booking for this aircraft on the service calendar 328. If this time is not available, the module returns an alternative available time. The supplier may leave their schedule to the recharging-refueling platform and / or may manage their own schedule. If the platform has control, the module 326 creates a schedule of the service on the supplier's calendar and sends a notification to the supplier. If the supplier has control, the module 326 notifies the supplier of the service request and waits for confirmation or communicates details of an alternative availability. · The service calendar and log module 328 maintains a record of all services scheduled by aircraft and supplier. For each past service, the module may track the disposition, whether the service was performed, billing for services performed, details of completed payments, outstanding customer feedback, etc. The module 328 enables service providers to define future available service slots, allow the platform to hold reservations or control on their behalf, update their calendar to reflect reservations made outside the platform, etc. · Accounting Module 330 is a record-keeping and transaction module that allows suppliers to issue invoices and customers to make payments. This module leverages standard payment platforms 332 (e.g., EDI, credit cards, EFT, etc.) currently used by pilots and operators.

[0039]

[0058] A further aspect of the system 300 of the present invention is an airport fuel service provider 306. This represents an operator or manager of an airport or airfield that is part of the transportation system of the present invention. Such an operator or manager may provide a set of services that allow aircraft to efficiently recharge or replace energy storage units, take on additional fuel for range extension generators, process payments for these services, etc. The provider of regional airport or airfield services 306 communicates and transfers data with the recharging-refueling platform 304 via a suitable interface 310.

[0040]

[0059] Returning to FIG. 3a, which is a flow chart or diagram of an exemplary process for determining recharging or refueling services required at a destination, in one embodiment, the POCS (described in more detail with reference to FIGS. 11 and 12) may be used to determine the available energy / fuel for the aircraft, the estimated time of arrival, and the post-arrival energy / fuel situation (step or step 350). Next, based on input from the pilot or flight scheduling process, information or data regarding the next leg or segment of the flight may be received (step or step 352). The FPOP process (described in more detail with reference to FIG. 14) is used to determine the total energy required for the next leg or segment (step or step 354). Next, the maximum available stored energy capacity for the next leg or segment is determined (step or step 356).

[0041]

[0060] The preference data (described with reference to FIG. 3) may then be considered to determine the allocation between storage (e.g., battery) and generation (e.g., based on fuel usage) of the total energy required for the next leg or segment. If such preferences exist (as suggested by the “Yes” branch of step or step 358), such preferences or conditions / constraints are used to determine the recharging and / or refueling requirements (step or step 360). If such preferences do not exist (or are not applicable for some reason as suggested by the “No” branch of step or step 358), a recharging and / or refueling option is determined based on availability, price, etc. (step or step 362). As suggested by the figure, this determination includes consideration of data contained in the airport service provider database. The determined recharging and / or refueling options are presented to the pilot, and the pilot's decision(s) may be received (step or step 364).

[0042]

[0061] Based on the preferences and / or pilot decision(s), the recharging and / or refueling requirements are communicated (step or step 366) to an appropriate service provider 367. This may include information regarding the flight, the aircraft, available and required energy, the configuration of the energy sources, etc. After receipt and processing, the service provider 367 may provide a confirmation of the recharging and / or refueling order and any related information to the pilot (step or step 368).

[0043]

[0062] Returning to Figure 3b, which is a flow chart or diagram of an exemplary process for determining in-flight recharging or refueling services to a destination, in one embodiment, POCS (described in more detail with reference to Figures 11 and 12) may be used to determine the available energy / fuel for the aircraft, the estimated time of arrival, and the post-arrival energy / fuel situation (step or step 380). The FPOP process (described in more detail with reference to Figure 14) is then used to estimate the remaining range of the aircraft and determine the total energy required for the next leg or segment (step or step 382). An airport service provider database may be used as an information source and data source regarding airfields with suitable recharging and / or refueling facilities (step or step 384).

[0044]

[0063] The preference data (described with reference to FIG. 3 ) may then be considered to determine the allocation between storage (e.g., battery) and generation (e.g., based on fuel usage) of the total energy required for the next leg or segment. If such preferences exist (as suggested by the “Yes” branch of step or stage 386), such preferences or conditions / constraints are used to determine the recharging and / or refueling requirements (step or stage 388). If such preferences do not exist (or are not applicable for some reason as suggested by the “No” branch of step or stage 386), a recharging and / or refueling option may be determined based on a consideration of the impact of one or more recharging / refueling service options on the flight (as suggested by step or stage 390). This may include consideration of the required turnaround time and any expected flight delays, costs, airfield charges, etc. Based on the determined options and application of any associated rules, conditions, or constraints, a portion of the possible options may be determined and presented to the pilot (as suggested by steps or stages 392 and 394), and the pilot's decision(s) are received.

[0045]

[0064] An FPOP module or process may be used to determine the aircraft's estimated time of arrival, stored energy, and available fuel (step or process 396). Based on the preferences and / or pilot decision(s), charging and / or refueling requirements are communicated to an appropriate service provider 397 (step or process 398). This may include information regarding the flight, the aircraft, available and required energy, energy source configuration, etc. After receipt and processing, the service provider 397 may provide confirmation of the recharging and / or refueling order and any related information to the pilot (step or process 399).

[0046]

[0065] 4 is a diagram further illustrating certain basic components, elements, and processes that may be present in an implementation of an embodiment of a transportation system 400 of the present invention. With reference to FIG. 4, in some embodiments, the transportation system of the present invention includes a hybrid electric regional aircraft 402, a regional Tier I or Tier II airport 404, a regional air transportation operator 406, an airport fuel service provider 408, and a recharging-refueling platform 410.

[0047]

[0066] As suggested by the figure, an embodiment of the aircraft 402 of the present invention may be equipped with several modular energy storage units, with a standard unit 412 sized for use in flights at the design payload and an extended unit 413 for increased electric range sized for use in flights below the design payload. These packs may be located in locations such as on the wings, in pods suspended from the wings, under the fuselage, etc. for easy replacement when on the ground using quick release mechanisms 414. The aircraft 402 control includes a powertrain optimization and control system ("POCS", described in more detail herein) 416, a flight management system (FMS) 417, and a secure data link 418. The POCS 416 and FMS 417 may be embodied in the form of a set of computer / software instructions executed on electronic processing elements, a CPU, a state machine, etc. Among other functions, the POCS 416 tracks on-board energy storage capacity and remaining energy, the FMS 417 estimates arrival time at the destination airport, and the data link is used to communicate with the operator and fuel service provider.

[0048]

[0067] The regional Tier I or Tier II airport 404 is equipped with a swap, refueling and recharging station 420 that allows for rapid turnaround of hybrid electric flights. This includes equipment for automated or semi-automated removal and swapping of energy storage units, transport of packs to and from storage, and storage and recharging facilities for the energy storage units. The airport 404 may include a solar farm 422 for on-site power generation, and on-site stationary storage 424 connected to a power grid 426. Power for recharging the energy storage units may be drawn in an optimal manner across the solar farm, stationary storage, and power grid depending on requirements, costs, availability, etc.

[0049]

[0068] The recharging-refueling platform 410 may connect facilities across the aviation network to help organize efficient recharging and exchange. The platform works with pilots or air transport operators to identify / select suppliers and services based on operational needs. These requests are communicated to suppliers who identify and schedule services and ensure stations are ready for aircraft arrival. Certain operations or functions that may be performed by the platform 410 are described herein with reference to Figures 2 and 3. The regional air transport operator 406 may operate to schedule and administer services for passengers, pilots, and aircraft. Certain operations or functions that may be performed by the platform 406 are described herein with reference to Figures 2 and 3. The airport fuel service supplier 408 may operate to schedule and administer the provision of recharging and exchange operations for stored energy units (such as elements 412 and 413 in the figure) or to add fuel to range-extending generators onboard aircraft. Certain operations or functions that may be performed by the platform 406 are described herein with reference to Figures 2 and 3.

[0050]

[0069] 5 is a diagram illustrating an example of a range-optimized hybrid electric airplane 500 of the present invention that may be used in the implementation of a regional air transportation system of the present invention. In some embodiments, such aircraft and / or air transportation systems may have one or more of the following characteristics or qualities, where the regional hybrid-electric airplane is designed for optimal transportation of passengers or cargo over regional ranges, typically up to 500-1000 miles. The aircraft is designed for "fuel-saving" operation in flight and on the ground using one or more of the elements or processes described herein to enable air service to small, service-limited airports. This "fuel-saving" operation in flight is enabled by one or more of the following features of the aircraft: - Lower energy and cost: aircraft and powertrains are optimized for regional flights, e.g. speed, range and ceiling are lower than long-distance passenger aircraft. A Powertrain Optimization and Control (POCS or similar) platform is used to optimize energy usage during flight between one or more energy / power sources. - Lower ATC load: on-board ADS-B including data link to air traffic control if desired. - Fewer pilots: Fly-by-wire capability including auto-landing (if desired). Comprehensive FMS with operator upload. High levels of automation including provision for remote pilot or fully autonomous flight. - All-weather operations: Pressurized for medium-altitude flight (e.g., 25,000 feet) to allow for weather and terrain avoidance. - Minimal runway requirements. Balanced runway takeoff less than 5,000 feet. Capable of landing on soft runways. Additionally, "fuel-saving" ground operation is enabled by the following features on the aircraft and at the airport: - Rapid refueling and repair: Capability of rapid on-board recharging or replacement of on-board energy storage units (e.g. batteries) alongside the aircraft. Automatic or manual transmission over data link of refueling, recharging and maintenance requirements prior to landing. - Rapid check-in and loading: To reduce the overhead space typical in small to mid-size aircraft, cabins are designed with bins near the doors that allow passengers to board with airline standard carry-on baggage. At the same time, reconfigurable barriers may be used to separate passengers from secure holding facilities for oversized and checked-in baggage. A simple check-in platform (e.g., smartphone, tablet, PC) at the planeside may allow rapid identity and ticket verification, as well as fee collection. Even in offline mode and without network access, the design will support operations through pre-downloading of passenger and cargo manifests, and delaying payment execution until the next collection by the network. - Flight Preparation: Comprehensive FMS with optional operator uploads. Automated system checks performed by POCS or other systems. On-board aircraft surveillance platform with data link. To help maximize aircraft seat utilization and utilisation, regional air transportation networks may be supported with next generation capacity management capabilities such as: - Higher seat utilization: Regional booking platform with links to GDS for traditional aviation. The booking platform works to match customer demand with available flights in real time, including offering fixed and demand-based schedules (including near real-time capacity), as well as on-demand and charter operations. Operators work with the platform through private ARS (for larger operators) or through a variety of hosted privately labeled ARS products (typically used by smaller operators), resulting in higher aircraft utilization. A virtual "pool" of electric aircraft may be created, allowing owners and operators to offer and rent aircraft for short (hours) or medium term (days to weeks). The platform allows pooled aircraft to be listed, including availability and rental period. The platform includes streamlined processes for locating available aircraft based on requirements, and for negotiating terms and contracts, payment processing and remittance payments, and aircraft pick-up or return. Similar virtual pools for spare parts and pilots / crew allow for quick turnaround and schedule flexibility.

[0051]

[0070] Returning to FIG. 5 , the following table(s) provide a description of the basic elements of the aircraft illustrated in the figure, but also note the differences in construction, materials, and requirements between the aircraft of the present invention and conventional aircraft. [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5]

[0052]

[0071] With respect to the embodiment of the aircraft of the present invention shown in Figure 5, it should be noted that this embodiment is a conceptual design for a range-optimized regional passenger aircraft. Electricity for the propulsion motors 522 is provided by a range-optimized series hybrid-electric powertrain (described further herein with reference to Figures 7 and 8) consisting of an energy storage unit 510 and range extension generators 526-527 (only the left side is shown). Energy storage units (battery packs in this case) are located in the wings, including a standard pack 510 and an extended pack 511 for use with flights below the design payload. In other embodiments, the energy storage units may be located in pods 512 under the wings and at various locations in the fuselage. In the embodiment shown, the battery packs 513 are located below the passenger cabin in the forward fuselage. Fuel for the range extension generators is stored in wing-to-body fairing tanks 519. · The propulsion motor 522 in this embodiment is embedded within a ducted blower 523 for increased static thrust, enabling short takeoff and landing fields, high go-around speeds, and quiet operation. Additional noise reduction is achieved by positioning the fan between the V-tail 531 and above the fuselage for noise shielding to the ground. The generator 527 is embedded within the soundproof aerodynamic nacelle 521. Power to the traction motors is delivered by an electrical distribution system 525 that sources energy from any combination of stored energy units 510, 511, 512, 513 and range extension generators 526, 527. Optimal sourcing of energy from the storage units and generators is managed by a Powertrain Optimization and Control System 534 (POCS, described further herein with reference to Figures 9 and 10). The aircraft is a "plug-in" hybrid electric aircraft, designed to recharge stored electrical energy via ground-based charging stations via plug-in points 528 or by replacing a fully or partially discharged storage unit with a charged one. A charging mechanism is included on-board that connects to mains or a fast charging station, allowing for slow or fast recharging in situ. The storage units are also equipped with quick release mechanisms that allow for rapid replacement of storage units or their modules. Limited recharging of the storage units by on-board generators during low power navigation, either in flight or on the ground, is also possible. All or most of the aircraft subsystems are electric and powered by the hybrid-electric powertrain. These may include the flight control system, landing gear, environmental control system, anti-icing, fuel pumps, taxiing motors, and lighting. The aircraft may be equipped with a variety of flight modes ranging from traditionally piloted, to remotely assisted piloted, to remotely piloted, to fully autonomous with remote assistance. As a result, the cockpit of the aircraft 533 may be configured for no pilot, one pilot, or two pilots and may include capabilities allowing for remote pilot control of the aircraft as well as control by an autopilot unit.

[0053]

[0072] Embodiments of the hybrid electric regional transport aircraft 500 optimized for the scope of the present invention show an optimized forward-compatible hybrid electric aircraft for regional passenger or cargo operations, either manned or unmanned, and relatively quieter. In some embodiments, such an aircraft uses a propulsion system driven by one or more electric motors that deliver thrust via a propeller or other suitable mechanism, such as a ducted fan (such as the "eFan" of the present invention described in more detail with reference to FIG. 6). The aircraft is designed to operate efficiently in regional operations with distances < 1,000 miles, with cruise speed and altitude optimized for this range (< M0.7, < 30,000 feet), burning typically 60 - 80% less fuel than conventional aircraft. The aircraft is smaller than a conventional jet (< 100 seats) to accommodate lower passenger numbers on regional routes and is designed for shorter runway operations (< 5,000 feet) to open access to a number of smaller community airports, and also operates with lower cabin and environmental noise (< 70 EPNdB in both external and cabin) to be more understandable to passengers and communities.

[0054]

[0073] FIG. 6 is a schematic diagram illustrating a propulsion system 600 incorporating a variable pitch electric ducted fan that may be used in an embodiment of an electric hybrid aircraft that is part of the air transportation system of the present invention. · Propulsion system 600 utilizes the quiet electric ducted fan propulsor (referred to herein as "eFan") of the present invention, which enables a significant quiet STOL capability. Quiet STOL dramatically improves the ability of aircraft to fly "close" to communities and settlements, thereby realizing a radical change in reducing door-to-door travel times for passengers or cargo. STOL allows operation to smaller community airports (over 13,000 in the U.S.), thereby avoiding congested hubs and also reducing passenger travel times. Quiet and efficient reverse thrust may be used instead of ground support equipment for ground operations, reducing the need for personnel and infrastructure that may not be available at smaller airports. Quiet operation also translates to greater community acceptance, which is often a limitation to such flights. As described herein, we propose a novel range-optimized design of a regional hybrid electric aircraft with emphasis on high efficiency at cruise and high static thrust for STOL with intermediate speed and highly optimized aerodynamics and acoustics. This is made possible by the use of a low pressure ratio (1.02-1.10) controllable pitch blower, allowing propeller blade pitch to be adapted to the flight mode, and including reverse thrust, regenerative braking, and feathering. The eFan is driven by one or more high power density electric motors positioned at the center of the duct and connected to the blower directly or through an optional gearbox. Liquid or air cooling of the motors is fully integrated within the duct. The gearbox is fault tolerant and designed for continued safe operation in the event of motor, sensor or communications failure, which preserves thrust output or allows for graceful degradation. Additionally, by allowing for graceful degradation of thrust, the variable pitch electric blower enables additional safety and efficiency benefits not readily available with conventional propulsion systems and methods. The available high torque, fast response speed of thrust variations may be applied to secondary flight controls, increasing efficiency and augmenting flight controls or replacing flight controls entirely (e.g., in the event of failure of the primary controls). · In normal operation, propulsor control is via the pilot or autopilot commanding % power, % reverse power, or % regenerative braking, which is translated by the POCS system into appropriate propeller(s) blade pitch angle, motor(s) RPM, and torque (or regenerative RPM and torque) and transmitted to the motor and controllable pitch controllers. In backup mode, the POCS automation is bypassed and the pilot commands the motor and controllable pitch controllers directly. The POCS system converts % total power into RPM, torque, and propeller blade pitch angles based on power plan, % power, flight mode, altitude, and speed. Commands may be synchronized for multiple propulsors so all ganged propulsors operate at identical settings. Similarly, the POCS system converts the % regenerative braking or % reverse power so that the propeller blade pitch angle is matched with the motor set to the appropriate level of regenerative RPM and torque. In the event of an emergency shutdown, the POCS system (or the pilot directly via a backup mode) commands the propeller blades to a feathered position and stops the motors from moving. The combination of low blower tip speeds, blower-stator and duct acoustic design, and duct acoustic treatments provide significantly lower noise characteristics, while the high torque at low RPM of the electric motor coupled with the high static thrust of the ducted blower results in good STOL performance. As an added benefit, the increased safety and "jet-like" appearance of the ducted blower is expected to translate into stronger consumer appeal compared to open propeller aircraft often used for regional flying. The propulsors are designed for forward compatibility, targeting optimal efficiency over a 30% higher speed range, with a structure designed to accommodate the higher torque and gyroscopic loading of future motors. Range-optimized design is tailored for high cruise efficiency at intermediate speeds and altitudes (Mach number <0.7, altitude <30,000 ft) typical of regional operations. · Forward compatible designs through the selection of mass flow design points span the cruise range including future maximum speeds and altitudes. This range extends from 30 to 250 miles per hour at equivalent airspeeds where Mach number is <0.7. Blower cruise pressure ratios are 1.02-1.10, much lower compared to high speed jet engines for installed high net efficiency, especially for go-arounds and lower altitude, slower speed cruise operations. Inlet and exhaust areas are selected to avoid separation and distortion over this range of mass flow conditions. · Variable pitch blower disk and blades 601 allow high efficiency over the target speed range.

[0055]

[0074] In some embodiments, the eFan design consists of the following: -The blower disc has multiple blower blades (6-20 blades) and the disc solidity is greater than 60%. -Blower blades are designed for low pressure ratios and high efficiency at 3000-4000 RPM operation. This involves an increase in aerodynamic loads with an increase in span and corresponding chord. The blower tip may be of spherical cross section to allow for pitch variations in matching duct wall curvature while maintaining the small tip clearance required for high efficiency. - Blower blades are designed for optimum efficiency over target cruise speeds, extending into future maximum speeds and altitudes. Includes designs for static thrust, reverse thrust, and regenerative braking via variable pitch capabilities. -Blower blades are mechanically pitched over a wide range of angles. Blower pitch angle is measured such that 0° is the blade tip chord plane along the plane of rotation. - The blower blades are variable pitch with angle changing at speeds >100° / sec. -The variable pitch mechanism accommodates a normal operating range between a minimum of 15° for fine pitch at takeoff and a maximum of 50° for high speed, low RPM cruise. -The maximum positive angle is up to 80° relative to the lowest drag "feathered" position where the blade is aligned with the incoming flow. -The minimum angle may be up to -40°, allowing reverse thrust while maintaining continuous motor and blower rotation.

[0056]

[0075] As shown in FIG. 6, the blower blades 601 are attached to a mechanical hub with a mechanism 610 at the root 611 for electromechanical change of blade angle (pitch) from a negative angle, which provides reverse thrust to enhance runway braking, to a fully streamlined angle for lowest drag if the propulsor is stopped in flight. The entire mechanism rotates along with the blower disk and electric drive motor. Blade pitch change signals are transmitted across the rotation boundary. The mechanism drives all of the blades simultaneously through mechanical links. The design includes a non-return directional brake to lock the feedback torque from the mechanism during periods of no pitch change.

[0057]

[0076] The eFan may be installed in an aerodynamically curved flow duct 603 to achieve the noise reduction and static thrust required for quiet STOL operation. In one embodiment, the duct axial length is 50-125% of the diameter, and the blower is located at 40-60% of the duct length. The duct is supported by multiple stators 602 located aft of the blower disk. The duct inlet lip curve 604 is designed with a continuously varying radius for high efficiency at cruise, no separation at low speed and high power, and reduced forward blower sound transmission. The duct inlet lip curve 604 forward of the blower promotes laminar flow while minimizing separation. The duct curve aft of the blower is gentle enough to avoid flow separation within the normal operating envelope. The duct exit area minimizes jet noise by expanding the flow aft of the blower and reducing the flow to near freestream levels. The outer curved surface 603 of the duct is designed to maximize natural laminar flow for low drag. The interior cross section of the duct may include radial recesses or other features aligned with the blower that allow for the small tip clearance required for high efficiency.

[0058]

[0077] The eFan 600 of the present invention may be characterized by one or more of the following: Designed for low noise operation, 15-25 EPNdB quieter than conventional aircraft, achieved through one or more of the following features: · The blades in ducted blowers are shorter than those of open propellers of comparable thrust, resulting in quieter operation due to reduced tip speeds, targeted at 500-600 ft / sec, with an upper limit of 800 ft / sec, and attenuation of axial noise components due to ducting and duct insulation. Additionally, the blades are optimized for low noise, including leading edge tip sweep angle, trailing edge shape, blade tip and root shape, and blade tip to duct gap shape with varying pitch. Rotor-stator noise reduction through stator design and placement for lower noise. The number of stators is optimized for noise and is determined by the number of blower blades and blade RPM to ensure that the primary and secondary BPFs fall below 2500Hz. (BPF=Blade Passing Frequency) Stator spacing behind the blades is optimized for noise reduction, i.e. 1.5 to 2.5 chords behind the blower. Stator twist and platform are designed to eliminate swirl and reduce turbulent vortex noise. The use of controllable pitch blades reduces wake strength, which is the main cause of rotor stator noise, especially during takeoff. The duct is designed to attenuate noise, including optimized axial location of the blower within the duct, duct cross-section design, inlet lip curvature and outlet shape to minimize blower sound transmission, and acoustic treatment of critical areas of the duct inlet, center fairing, and outlet. The duct may be used as a variable drag air brake to replace conventional spoilers, which are a significant source of aircraft noise. ·It is designed for energy recovery and aircraft speed control via regenerative braking with the goal of improving overall efficiency, eliminating the need for air brake mechanisms that typically result in noise. Regeneration, and therefore airspeed control, is made possible by adjusting the electrical loads placed on the fully variable and controllable pitch propellers and motors. The pilot may request % regenerative braking by moving into a guarded range below standard flight idle using standard power lever angles. The POCS system achieves % regenerative braking by controlling the propeller blade pitch angle and motor regenerative power to achieve a target level of aerodynamic drag measured via motor power. · It is designed for reduced stopping distances, especially on surfaces with reduced braking effort, and reverse thrust for ground operations requiring reversal (e.g. standard gate "push back"), reducing the need for airport operating infrastructure. Reverse thrust may be possible through a controllable pitch blower where the blade pitch is at a negative angle, or by reversing the direction of motor rotation. Reverse rotation is a unique capability of electric blowers and is not available in conventional aircraft engines without complex gearing arrangements. ·It is designed for secondary or primary control of an aircraft. High constant torque, fast millisecond motor response, and fast blower pitch rate response allow for rapid thrust output changes in a ducted blower. This actuated or redirected thrust generates a moment about the aircraft's center of gravity that may be utilized to provide primary or secondary aircraft control. In the event of a primary control failure, the control system may be reconfigured to utilize the thrust moment to regain some degree of lost control authority. - Operating thrust. In one implementation, thrust from one or more propulsors may be varied to provide a moment about the center of gravity. Depending on the location of the motors and the number of propulsors, this may produce a pitching moment or a yaw moment. -Vectored Thrust. In more active implementations, thrust from one or more propulsors may be redirected through the use of exhaust louvers, propulsor gimbals, or other means of generating pitch, yaw, or roll moments. Ducted blowers may be designed for lift augmentation, either directly, through louvers, gimbaled mountings, or other means to generate a thrust vector that redirects thrust from one or more propulsors, to offset aircraft weight (i.e., lift), or indirectly, by channeling the exhaust flow over an aerodynamic surface to create suction (lift) and / or flow deflection (e.g., Coanda surfaces, such as "blown flaps"). · It is designed for built-in cooling. Electric motors and associated controller-inverter electronics generate significant amounts of waste heat. It is highly desirable to achieve heat removal with minimal added weight and drag. This may be implemented directly into the ducted blower design in the following manner: - Heat exchanger surfaces may be incorporated into the stator and / or into the inner rear surface of the duct. In this way, there are no additional heat sinks and no additional surface area for drag, which is especially important since heat flow varies directly with power and may go down to zero during descent in flight, when negligible cooling losses are desirable. -Motor heat may be removed with a heat exchanger in the leading edge of the nacelle to prevent ice build-up when flying in freezing precipitation, which is substantially more energy efficient than providing power to a hot leading edge using conductive methods. Note that the eFan design is fault tolerant as exemplified by the following features: · The assembly is designed with graceful degradation of thrust upon failure of any one motor system (including motor inverters, controllers, power bus, etc.) to ensure continued safe operation, enabled by POCS (element 1042 in FIG. 10 and / or element 1160 in FIG. 11). The hardware is designed to support graceful degradation of thrust by including the motors being designed to partially or fully adapt to a failure in any one of them, where multiple electric motors may provide power to a single shaft, electrical isolation ensures that a failure of one does not affect the safe operation of the other(s), and individual motors may be designed to operate at peak performance 60-80% higher than their continuous performance for a 5-10 minute recovery period. This may include designing the motors for higher power ratings and introducing mechanisms for active cooling of hot spots so that extended peak operation does not damage the motors. In the event of a loss of motor power due to a motor failure, the POCS will alert the pilot and reallocate power to healthy units to maintain thrust long enough for the pilot to operate safely (element 1144 in FIG. 11). In the event of total propulsor failure, including failure due to physical damage, the blades may be automatically set to "pinwheel" (the blades rotate continuously but no energy is extracted from the flow to minimize drag) or pitched fully in line with the streamlines ("feathered") and the motor braked to prevent rotation. Faults or potential failures may be detected through monitoring of motor power vs. commanded power and by vibration monitoring to detect mechanical damage / failure in the motor. Fault tolerance in case of communication or sensor failure may be achieved through redundant systems. The standard connections of the motor and variable pitch controller to the POCS are supplemented by backup wiring that includes the capability for direct access to the controller without POCS intervention. Similarly, the motor and pitch sensors are supplemented by backup sensors or sensorless control capability. The sensor failure detection capability within the POCS can be switched between these as required.

[0059]

[0078] Returning to FIG. 6, the following table provides a description of the basic elements of the eFan illustrated in the figure, but also note the differences in construction, materials, and requirements between the eFan of the present invention and conventional fans / propulsors. [Table 2-1] [Table 2-2]

[0060]

[0079] 7 is a diagram illustrating a powertrain 700 and its associated elements that may be used in an embodiment of an electric hybrid aircraft used as part of the air transportation system of the present invention. As shown in the figure, in one embodiment, the powertrain 700 and associated elements may include or be characterized by one or more of the following functions, elements, processes, or aspects: A series of hybrid electric powertrains that provide output via one or more electric motors combined with a battery (or other method(s) for storing electrical energy) and a combination of a chemical fuel based engine and generator as an optional range extender. The engines can be piston, turbine, or other forms of heat engines and convert the stored chemical energy into electricity. The powertrains also provide output to other electrical subsystems of the aircraft which can include flight control systems with electrically actuated devices, electrically actuated landing gear, environmental control systems, taxiing motors, anti-icing, fuel pumps, and lighting. · The powertrain comprises a set of modules, e.g., battery pack, engine, generator, power inverter DC / DC converter, fuel system, electric motor, etc., integrated via a powertrain platform with power and control circuitry. Each module is connected via control circuitry to a Powertrain Optimization and Control System (POCS). Module controllers are queried or targeted by the POCS platform and send a range of status and performance information to POCS on demand or continuously. POCS to module controller communication is enabled by APIs, which define the protocols to communicate with POCS and the modules. · The operation of the powertrain is controlled by the POCS in semi-automated mode(s) or fully automated mode(s) based on the pilot's commands. To enable this, each powertrain module is equipped with a controller that communicates with the POCS across module interfaces via API, on demand and / or periodically. Key metrics communicated to the POCS may include on / off, RPM, power, status of each motor; battery capacity, power, status of each battery pack; fuel level and flow; engine on / off, power, status; and status of each converter. Key control commands received from the POCS include on / off, RPM and torque of each motor; power of each battery pack; engine on / off and power. · The powertrain is "plug-in" and designed to recharge stored electrical energy via a ground-based charging station. Limited in-flight recharging may also be possible by the engines during low-power flight and / or by windmilling the propulsors during descent and regenerative braking of the landing gear after touchdown. As described, the energy storage units may be housed in modules and mounted internally or externally to the aircraft (e.g., in the wings) with quick release mechanisms as desired to allow rapid swapping or throwing. Charging and cooling mechanisms are included on board that connect to mains or fast charging stations for in-situ slow or fast recharging.

[0061]

[0080] 7, powertrain 700 includes one or more electric propulsors 701, one or more distribution buses 730, one or more rechargeable energy storage units 710, and, if desired, one or more optional range extension generators 720. Powertrain 700 may also include an element 731 for powering distribution bus 730 from an external source, an element 713 for charging rechargeable storage units 710 from an external source, and an element 732 for distributing power to other electrical systems of the aircraft. It should be noted that elements 713, 731, and 732 may take any suitable form, such as, but not limited to, electrical interfaces, cables, couplings, or controllers. Whatever its form, element 732 typically includes one or more DC-DC converters that convert the power to lower voltage levels typically required by other electrical systems (e.g., environmental control systems, fuel pumps, anti-icing, lighting, as well as backup / fail-safe distribution for essential systems (e.g., flight controls and avionics)).

[0062]

[0081] The powertrain 700 is a plug-in series hybrid designed to power the electric propulsor 701 with energy optimally drawn from the rechargeable energy storage 710 and the range extension generator 720. Typically assuming a lower total cost of energy from the rechargeable energy storage 710, power is drawn from the range extension generator 720 only when the stored energy is insufficient to complete the flight or when the operation requires more power than is available from the rechargeable storage 710. The total cost of energy from a rechargeable energy storage unit is equal to the cost of the energy used to charge the unit, the efficiency of the unit's charging and discharging, and the cost of the unit amortized over its useful life, defined as the number of charge-discharge cycles before performance degrades below a threshold. For example, a cost-effective battery pack can be charged using low-cost electricity from the grid and provides very efficient charging and discharging, with a useful life exceeding 1,000 cycles.

[0063]

[0082] The electric propulsor 701 is either a ducted fan as shown (such as described with reference to FIG. 6) or an open propeller. The propulsor is designed for operation in multiple modes through a variable pitch mechanism 703 as shown, or other means such as an adjustable exhaust plug. Possible operation modes may include, for example, takeoff, cruise, regenerative braking, feathering, and reverse thrust. The blower 702 is mechanically coupled to one or more electric motors 704 with a mechanism or process for isolating the individual motors to allow continued operation in the event of a mechanical or electrical failure. In normal operation, the blower 703 is driven by an electric motor 704 that receives electrical energy from the distribution bus 730 via a motor controller and a DC-AC inverter rectifier 705. However, in regenerative braking, the blower 703 drives the electric motor 704 to generate electrical energy that is delivered to the distribution bus 730 via the DC-AC inverter rectifier 705.

[0064]

[0083] The rechargeable energy storage unit 710 consists of the battery pack 711 shown, supercapacitor, or other media (or combination thereof) for storing electrical energy, and is coupled to a battery management system(s) 712 that manages the operation and safety of the pack. Each pack may comprise multiple individually removable battery modules and may operate some or all of these modules in a stationary state. The storage unit 711 is primarily charged by an external source 713, but may also be charged in flight for limited periods by the electric propulsor 701 during regenerative braking, or by the range extension generator 720 during low power flight. The rechargeable storage unit 710 delivers power to the distribution bus 730 when discharging, or receives power from the distribution bus 730 or the external source 713 when recharging.

[0065]

[0084] The storage units 711 provide for rapid in-situ charging via an external source 713 and also for rapid replacement using a quick release mechanism, allowing manual or automated replacement of an on-board storage unit with a ground-based pre-charged replacement.

[0066]

[0085] The optional range extension generators 720 may consist of internal combustion engines 721 each driving one or more generators 723. Alternatively, they may consist of units that convert stored chemical energy directly into electricity (e.g., hydrogen fuel cells). The internal combustion engines 721 may be conventional, using one of a variety of fuels to initiate and sustain combustion in one or more combustion chambers, e.g., diesel, gasoline, jet-A, etc. The fuel is stored in one or more fuel tanks 722 and pumped to the generators as needed. The engines 721 are typically mechanically connected to the generators 723 with a mechanism or process that isolates the individual generators in the event of a failure. When operating, the engines 721 drive the generators 723 and deliver electrical energy to the distribution bus 730 via an inverter acting as an AC-DC rectifier or active rectifier 724.

[0067]

[0086] 8 is a schematic diagram of a series of hybrid drive configurations 800 for an exemplary aircraft that may be used in implementing embodiments of the transportation system of the present invention. The following features, elements, processes, or aspects should be noted: The powertrain includes two electric propulsors 801, each powered by two electric motors 802, two battery packs 803 as rechargeable storage units, and a single range extension generator. In this embodiment, the generator couples a single internal combustion engine 804 coupled with two motor-generators 805. - In some embodiments, the electric motor 802 is a brushless, electronically controlled, axial flux drive motor with efficiency over 90%, power density over 5kW / kg at continuous power, and peak power over 50% higher than continuous power. Additionally, the motor may be designed to allow direct drive at low RPM (e.g., <4,000). The motor generator 805 is of identical construction to the drive motor and can operate at peak during recovery periods (e.g., battery pack failure). Each motor 802 and generator 805 is coupled to a solid-state converter-controller (such as a rectifier) ​​to provide precise motor control with minimal losses and to protect the motor from voltage fluctuations. In one embodiment, the internal combustion engine 804 is a turbo-diesel piston engine, tuned to operate at maximum efficiency at a fixed RPM, which may match the design RPM of the electric motor to allow for direct drive. Turbocharging allows the engine to deliver a relatively consistent power output from sea level up to 10,000 feet. Power is delivered to each of the propulsors 801 by one of two primary buses 806, each of which is powered by one of two battery packs 803 and one of two motor-generators 805. The primary bus 806 also distributes power to the non-propulsion subsystems of the aircraft 810 via step-down DC-DC converters 807. - A third main bus 808 reroutes power to accommodate failure of any of the electric motors, distribution bus, battery packs, or generators. In the event of failure of the electric motor 802, the main bus 808 reroutes power to the surviving motor, allowing the pilot to request peak thrust for recovery maneuvers. In the event of failure of the primary bus 806, the main buses 808 cooperate to fully replace the lost functionality. In the event of failure of the battery pack 803 or generator 805, the main bus 808 reroutes power from the surviving source to maintain a balanced output from the electric motors. In the event of a failure of the primary bus 806 or one of the step-down DC-DC converters 807, the main bus 808 also reroutes power to the non-propulsion subsystems 810 and avionics 812. - Depicted 810 and 812 are representative of standard circuits used to power the non-propulsion subsystems and avionics onboard an aircraft. The former include systems such as ice protection, fuel pumps, pressurization, cooling, flight controls, and operation at medium voltage (e.g., 270V). The latter operate at low voltage (e.g., 28V) and include most of the critical avionics systems on the aircraft. As shown, these circuits typically include redundant paths and additional power sources for fault tolerance in the event of a failure.

[0068]

[0087] As described with reference to Figure 5, the transportation system of the present invention includes an aircraft design optimized for maximum transportation efficiency over geographic ranges, and in particular, a novel range-optimized hybrid-electric powertrain design. In some embodiments, the goal of this design is to contribute to the following capabilities, which collectively enable a 65-80% lower DOC than conventional aircraft over the targeted geographic ranges: · Dimensioned for maximum transport efficiency over geographic ranges of less than 1,000 miles, the powertrain is designed through three levels or tiers of objectives. (A) Highest efficiency (80+% lower DOC than conventional aircraft) and optimal speed over the electric-only range (B) Intermediate efficiency (60-70% lower DOC than conventional aircraft) and optimal speed over a wider hybrid range (C) Good efficiency (30-60% lower DOC than conventional aircraft) and lower speeds up to a maximum range beyond these as determined by on-board stored energy and fuel minus safety reserves. · The powertrain is sized for optimal speed and altitude for regional sub-range (B) by minimizing the objective function (e.g., "DOC+I+COT" for flight over the sub-range) (may be optimized for lower speeds over regional sub-range (C) based on the relative frequency of travel over range (C) versus range (A) and range (B)). This results in a design for slower speeds, lower altitudes, and shorter ranges than for a conventional jet aircraft. · The rechargeable energy storage and range extension generator combination is sized based on speed and range requirements (A), (B) and (C). A stored energy first design, whereby for flights within range (B) and range (C), the rechargeable energy storage is fully depleted while maintaining the necessary reserve as fuel for the optional range extension generator, or depleted minus the necessary reserve if the range extension generator is not installed. Over the hybrid range (B), the rechargeable energy storage and range extension generator are sized to allow optimum speed, and over the electric-only range (A), the rechargeable energy storage is sized to allow optimum speed. The range extension generator is sized to allow lower speed cruise over range (C), and is therefore scaled down to less than 70% of maximum continuous powertrain output for improved efficiency (much lower than conventional aircraft). Optimization of the energy storage mass (12-20% of the aircraft weight) and reduction in the scale of the range extension generators results in a very low power output, typically less than 70% of the maximum continuous power output of the powertrain (lower than conventional aircraft).

[0069]

[0088] It should be noted that a design process for an embodiment of an aircraft and powertrain optimized for the scope of the present invention is described herein, including a process in which the described three-tier set of speed and range requirements are used to dimension the elements of the hybrid-electric powertrain. The described design for the aircraft and associated elements of the present invention is forward compatible to support anticipated upgrades of operational capabilities or major powertrain modules over the life of the aircraft. Given the rapid innovation of EV technology, this feature ensures that the powertrain remains competitive over time as individual module technologies (e.g., batteries, supercapacitors, electric motors, internal combustion engines, fuel cells) improve. Additionally, this feature allows for a smooth transition of the aircraft from hybrid-electric to all-electric as energy storage technology improves to the point where range-extending generators are no longer necessary.

[0070]

[0089] To provide forward compatibility, the powertrain will be designed by sizing the energy storage unit and generator combination for the speed and range requirements (A), (B), and (C) described above, based on the technology available at the aircraft's launch and expectations of technology that will be available over the next 15 years, including plans for a transition from hybrid-electric to all-electric. This will lead to expectations for on-board rechargeable storage and range-extending generators, and will further determine performance characteristics (speed, electric and hybrid range, and operating costs) over time, resulting in increased electric range and reduced operating costs as technology advances.

[0071]

[0090] Forward compatibility requires limiting the weight of the rechargeable energy storage unit to 12-20% of the aircraft weight, which will roughly level out payload capacity as EV technology advances. A larger weight percentage will lead to designs that are larger and heavier than aircraft with similar payloads in the first few years, but as the payload increases over time. A lower percentage will lead to suboptimal efficiency, assuming much greater use of range-extending generators.

[0072]

[0091] To achieve forward compatibility, the powertrain platform is designed to support modular technology over the design life of the aircraft (typically 15-20 years). This can be achieved by designing the platform based on powertrain operation with future modules, where appropriate, and it is relatively simple and cost-effective to accommodate upgrades required to accommodate future technologies. For example, wiring to the electric motors may be rated up to 30% higher than peak power to support future more powerful motors and higher aircraft speeds. The platform wiring may be designed to be oversized and redistributed for the rechargeable storage unit, and undersized or removed for the range extension generator. Wiring from the energy storage unit may be designed to support a higher capacity pack in the future, and the space used for the range extension generator may be routed for use with the rechargeable storage unit when the generator is removed. Additionally, powertrain modules and elements that are likely to require upgrades (e.g., wiring, harnesses, switches, converters) are designed and located for simple replacement and easy access.

[0073]

[0092] The powertrain platform, and powertrain optimization and control system (POCS described with reference to FIGS. 9-11, and exemplary powertrain configurations illustrated in FIGS. 7-8) are designed to enable a gradual transition from hybrid to all-electric powertrains as storage technology improves. This includes designs on an engineered platform that allows operation with or without a range-extending generator as desired, fuel or rechargeable storage-based reserve, and replacement of the generator with a storage unit over time. Additionally, the powertrain may be characterized by: Modular - A set of interchangeable, near "plug and play" capable modules connected by a hardware and software platform. This allows the powertrain to adapt to rapidly evolving technology through relatively simple upgrades of the modules. Powertrain modules include rechargeable storage units, range extension generators, and electric motors. The powertrain platform includes the Powertrain Optimization and Control System (POCS), electrical wiring, distribution bus, converters, fuel systems, sensors, cooling, shielding, and any additional processes or structures that operate to enable the modules to work together to form the powertrain. · The modular approach is facilitated by the design of the powertrain platform and the interfaces that connect the modules to the platform to be compatible with the range of modular technologies (as discussed above) that are likely to become available over the life of the airframe. This allows compatible modules to be plugged into the powertrain by connecting the modules to interfaces consisting of electrical and control circuits and services such as cooling, shielding, fuel, and structure. For example, a range extension generator plugs into the platform via electrical connectors to the generator rectifier, via POCS connectors to the generator controller, internal combustion engine controller and fuel system controller, and via fuel and cooling services to the generator and engine. In areas where upgrades may be required to accommodate new modules, the powertrain is designed to allow for relatively simple and cost-effective modifications. To orchestrate the operation of the powertrain, the individual module controllers are connected to a Powertrain Optimization and Control System (POCS). The module controllers are queried or targeted by the POCS platform and send a range of status and performance information / data to the POCS on demand or continuously. The POCS to module controller communication is enabled by an API, which defines the protocol for communicating with POCS and the modules. The operation of the powertrain is controlled in semi-automated or fully automated modes by POCS based on the pilot's commands. To enable this, the individual powertrain modules are equipped with controllers that communicate with POCS over module interfaces on demand and periodically via the API. Key metrics communicated to the POCS may include on / off, RPM, power / status of each motor; battery capacity, power / status of each battery pack; fuel level and flow rate; and on / off, power / status of the generator. Key control commands received from the POCS include on / off, RPM and torque of each motor; power of each battery pack; and on / off and power of the generator. · The powertrain is designed to support relatively simple module swaps / replacements. The powertrain platform and interfaces to the platform, electrical, control, and services (cooling, shielding, fuel, structural, etc.) are designed to accommodate a wide variety of modules. These include specifications for corresponding wiring, control or monitoring, and other on-board service capabilities, with each module allowing some sort of "plug and play" pairing. For example, for a battery pack, this would typically include peak and steady state discharge rates, BMS protocols, socket descriptions. POCS also allows for calibration of the powertrain following module changes. This may include FAA certification of the powertrain for use with a range of pre-approved compatible modules. Additionally, in some cases, the powertrain design may include the ability to support relatively simple or cost-effective modifications in areas where new modules may require modifications. Powertrain variants may be implemented, with performance tailored to different markets, and in some cases this may be done by changing the selection of powertrain modules to provide different speeds, ranges, and operating costs for aircraft configurations. For example, an "economy" commuter powertrain might combine a highly efficient turbo-diesel range extender with a medium density battery to provide the best operating costs in its class, but longer flight times for longer range. In contrast, a "performance" business powertrain might combine a less efficient but lighter turbo-shaft range extender with a high density battery to provide the best regional speeds in its class, but moderately higher operating costs. Powertrain operations may provide optimal efficiency over local ranges through maximum use of rechargeable storage units, which may be implemented by targeting full depletion during flight (or lower if within electric range (A)) and switching on range extension generators only when there is insufficient stored energy available to complete the flight. This results in ultra-efficient stored energy flight within the electric-only range (A), and also highly efficient hybrid flight over longer hybrid ranges (B) or total ranges (C). · Safety reserves are maintained across the rechargeable storage units and range extension generators to maximize use of the rechargeable storage units. For example, if the on-board range extension generator output is capable of safely operating the aircraft, the reserve is maintained as fuel for the generators sufficient to operate for a length of time determined by regulation or other means. If the range extension generators are not capable of safely operating the aircraft, the fuel reserve is supplemented with stored energy equivalent to that required to enable operation for the targeted length of time. The powertrain is "plugged in" and the rechargeable storage units are designed to be replenished by ground-based charging stations. This is enabled by an on-board charging platform to connect to mains or fast charging stations for in-situ slow recharging or fast recharging. Rapid swap-out capability of the rechargeable storage units is also included via a release mechanism that allows for the rapid replacement of depleted units with charged units. Each rechargeable storage unit may consist of multiple independently replaceable modules. This allows for increased efficiency in low payload flights by loading additional modules to extend electric-only range, or unloading some modules to increase payload capacity, but at the expense of electric-only range. In the case of batteries, this is made possible by the design of cell modules that plug into bays in the battery pack. Each module may house one or many cells with wiring, sensors, and controllers, along with first level cooling, structural support, and fire protection. Easy installation is made possible by connectors to the battery pack output, sensors, control, and cooling circuits, as well as quick release mechanisms. · The powertrain design provides for energy recovery via regenerative braking of the propulsor. To enable this, the propulsor is equipped with a controllable pitch propeller or varying the degree of air braking through the use of another mechanism (e.g., an adjustable exhaust plug). As a result, the rechargeable energy storage receives energy from the electric motor, which acts as a generator when the air brake is engaged. The powertrain is also designed for selective charging during low power operation by the range extension generator. In this mode, some or all of the electrical energy generated by the range extension generator is directed to the rechargeable energy storage unit.

[0074]

[0093] The powertrain design and configuration of the present invention is built to tolerate graceful degradation for safety and fault tolerance that exceeds stringent aviation requirements (FAA and EASA). This includes the ability to tolerate failures of the power source (energy storage unit, generator), motor (propulsion, generator), converter (inverter, rectifier, DC-DC converter), distribution (bus, wiring), control (sensors, communications), and for safety when the system is moderately or severely affected.

[0075]

[0094] To achieve this, the powertrain is designed for graceful degradation, so that failure of any section only partially impacts powertrain performance, allowing near-normal flight to the nearest airport for repairs. At least three unique aspects of the hybrid powertrain of the present invention make this possible with only modest cost or weight loss. Having multiple power sources creates a simple path to graceful degradation by dimensioning the sources and allowing the aircraft to fly on only a subset of these. · The ability to design a powertrain with multiple partial components, each with a high peak-to-continuous ratio of performance, limits the impact of failure to less than an equivalent percentage of function. Electrical components (e.g., motors, converters, distribution buses, wiring, switches), unlike mechanical or hydraulic components, make this possible with only modest cost or weight loss. Many of these also have high peak-to-continuous ratio performance capabilities (often thermally limited), allowing non-failed components to compensate to some degree for the failure of others during recovery periods. High speed solid state sensors and connectors allow for fault detection and repair within milliseconds as opposed to the microseconds of traditional contactors, or even seconds of mechanical devices. As a result, hybrid powertrain embodiments of the present invention can engage in the redistribution of power to uniquely redundant and non-failed components on physically comparable time scales.

[0076]

[0095] In some embodiments, the design for graceful degradation includes sizing the power source, the rechargeable energy storage unit, and the range extension generators so that the aircraft can operate safely in the event of failure of one or more of these elements. For example, the aircraft may be designed to fly with only the rechargeable storage unit or only the range extension generator to withstand failure of either one. Furthermore, redundancy of the storage unit or generators may be used for additional safety to reduce the possibility of a complete loss of the source. This design of the power source is combined with distribution elements (e.g., buses, switches, and wiring) that are constructed to reroute power in the event of a failure (as illustrated in FIG. 8), and the propulsors receive an equal distribution from the non-failed sources. This rerouting is managed by the Powertrain Optimization and Control System (POCS). A failure of the storage unit or generator is detected by the POCS's fault detection and recovery module, which then optimally redistributes power to maintain safe flight. Furthermore, the POCS also ensures that the storage unit and fuel system hold sufficient reserves to independently meet safety requirements.

[0077]

[0096] Designing for graceful degradation may also include the use of multiple separate components, propulsors, generators, motors, and storage units for fault tolerance to failure of any one. This may include having two or more propulsors or generators powering the powertrain, each powering two or more motors, so that failure of any one component does not equate to total loss of capacity. Individual motors may be designed for a peak performance 60-80% higher than continuous performance during a 5-10 minute recovery period, so that non-failed motors can boost power to compensate for motor failures of others. This peak power capability, combined with engineered distribution (buses, switches, wiring), allows power to be rerouted to non-failed motors to safely peak. Propulsor, generator, motor, or storage unit failures are detected by the POCS's fault detection and recovery module, which then optimally redistributes power to maintain safe flight.

[0078]

[0097] Designing for graceful degradation may also include building redundant distribution elements (e.g., buses, switches, wiring, fault isolation components) so that the powertrain can tolerate failures in individual circuits. This may include the use of multiple buses, each feeding one or more propulsors simultaneously with a backup bus, so that the impact of a bus failure is limited to a portion of the propulsors, and power to the affected propulsors can be rerouted through the redundant bus. This bus structure is combined with wiring and switches so that power from the source is distributed evenly between the primary and backup buses, and power to the propulsors can be routed through either the primary or backup buses. This may also include a fault tolerance scheme for the converters with fault isolation, e.g., redundant converters or redundant phase legs, so that functionality of a failed converter is largely restored. Faults in the distribution system are detected by the POCS's fault detection and recovery module, which then optimally redistributes power to maintain safe flight.

[0079]

[0098] Designing for graceful degradation also includes designing the powertrain control system (POCS) to allow safe flight in the event of failure of one or more sensors. This may include sensor failure detection capabilities in a Fault Detection and Recovery module in the POCS, as well as backup sensors, or sensorless (sensor independent) monitoring to cover critical sensor failure modes. For example, propulsor motor fault tolerant control is managed by a Fault Detection and Recovery module in the POCS that monitors flight conditions to detect and diagnose problems, then redistributes power to healthy motors in an optimal manner to restore full flight capability.

[0080]

[0099] The design(s) of the present invention also include procedures for safety in the event of a crash. For example, a fault detection and recovery module in the POCS initiates emergency isolation of high voltage circuits (e.g., storage units, generators, converters) upon pilot request or when a significant impact is detected. Note that the graceful degradation measures described above are coupled with the distribution structure to reroute power in the event of a fault with minimal impact on performance. For example, Figure 8 shows the architecture for a representative twin-engine propulsor aircraft with two rechargeable storage units and a single range extension generator implemented using redundant primary buses.

[0081]

[0100] 9 is a diagram illustrating an exemplary user interface 900 for use by a pilot of an embodiment of the aircraft of the present invention. The diagram illustrates various operational and status displays that may be used in an embodiment of an electric hybrid aircraft that is part of the air transportation system of the present invention. In one embodiment, the displays are digital and show performance parameters in the same or similar format as those of a conventional aircraft for ease of use. The diagram illustrates an example of a pilot interface for an "In-Flight Optimization and Control" mode of operation and contains the following displays and information: Industry typical color coding is chosen for ease of pilot transition. Green or white items are labels, magenta items are active indications of system status. Triangular "bug" indications indicate current or labeled target indications. Color coding is standard using green / yellow / red for normal / caution / dangerous operating zones. The power indicator (top left) shows the current propulsor power commanded by the power lever in RPM and % of maximum power. These are very similar to conventional gas turbine power indicators. The speed tape shows current airspeed vs. target airspeed (top right) in units, knots indicated airspeed, KIAS utilizing an industry standard vertical airspeed indicator. Unique to this invention, a "speed bug" is shown in the calculated speed, in this example "High" is shown at 213 KIAS, "Optimal" at 196 KIAS and ECON is shown without bug below the current range of the speed tape. -The second column of the indicator shows battery, fuel, and power balance. Battery and fuel are shown with indicators typical of the industry, including color coding for normal, caution, and depleted energy states. When coupled with an active flight plan through POCS, an "energy bug" is enabled that shows the projected energy state upon landing (shown for battery and fuel). The balance between generated power and battery power is shown with a pie chart. This is an indicator unique to hybrid-electric aircraft. The lower quadrants show more detailed data on the powertrain system, organized for the current powertrain components. The example shown utilizes three separate packs of batteries coupled to a turbo-diesel reciprocating generator engine, and the relevant information for each is displayed using a typical indicator format. These lower quadrants may display multiple system information pages, allowing the pilot to scroll between the information. These displays are specific to hybrid-electric powertrain implementations. This cockpit interface to the hybrid electric powertrain has multiple modes, in this example mode selection is via a knob with three positions on the bottom right. The "Flight" mode is the one shown here, additional modes could be a "Calibration" mode which is invoked after every module change, a "Pre-Flight" mode which will initiate and allow the internal systems to self-check the flight and display the status, and a "Diagnostics" mode which displays more detailed information about and can control all the systems being monitored and is primarily used for system configuration, maintenance and repair.

[0082]

[0101] In addition to the representations and associated aircraft functions or systems shown in FIG. 900, an underlying Powertrain Optimization and Control System (POCS) platform may allow control of one or more specific powertrain capabilities, including but not limited to rechargeable energy storage units (e.g., batteries, supercapacitors, and range-extending generators), internal combustion engines, or fuel cells. The POCS provides a unified interface to the powertrain modules to provide installation, flight preparation, flight operations, and diagnostics.

[0083]

[0102] POCS capabilities are important for the early adoption of hybrid-electric airplanes by optimizing operations for highest efficiency across regional flights, by reducing pilot workload through fast and safe fault repair, by easing pilot transition to electric powertrains, and by simplifying modular modifications to alternative or future technologies. POCS embodiments may aid in the adoption of regional air transportation systems based on hybrid-electric airplanes as a result of one or more of the following: ·Enable range-optimized regional flights by optimizing energy sources over the flight path. To maximize efficiency, energy procurement should prioritize lower cost sources (typically energy storage units) over higher cost sources (typically generators) over the course of the flight. For example, flights over longer ranges than electric-only range should deplete lower cost energy storage units to a minimum acceptable level determined by safety or battery life considerations. Furthermore, procurement should optimally utilize both storage units and generators to blend charging throughout the journey while ensuring energy extraction promotes safety and operational life. POCS enables this by determining an optimal energy plan (established by the operator) that minimizes the total cost of flight within system constraints based on flight path and flight mode, departure and arrival energy states, and aircraft characteristics. This defines the hybrid powertrain energy state (e.g., percent state of charge for battery packs, percent fuel capacity for generators) along the route to the destination and guides the real-time flow of power from storage units and generators. POCS enables further optimization by identifying opportunities to upsize the energy storage unit on low payload flights with longer electric-only range. · Optimally control the real-time power flow from the storage units and generators to achieve the target energy plan. The energy plan defines the overall procurement strategy for the flight, but given the need to adapt to unpredictable changes in the flight environment, this is inadequate for real-time control. Furthermore, there is a need to command each of the powertrain modules to deliver the requested power in an optimal manner (e.g., operating the generators on their optimal working curves). POCS enables this in two stages. First, it defines the power flow from the energy storage units and generators in real time in line with the energy plan by determining the optimal procurement for the required power. Second, the settings of the powertrain modules are optimized to deliver the requested power with the highest efficiency, and these are used to command the module controllers. For example, the requested propulsion power is delivered to the propulsion motors (torque, RPM) and propulsors (e.g., blower pitch angle, exhaust plug position) via optimized settings. POCS also manages the energy harvesting during the flight, for example, via regenerative braking of the propulsors or via the generators during low power operation. ·Enable fault-tolerant control of the powertrain: Helps the operator maintain normal or gracefully degraded operation in the event of a failure. Hybrid powertrains are designed with graceful degradation, whereby the powertrain performance is only partially affected by a failure in any area. This is made possible by multiple on-board power sources, by designing with multiple partial components, by use of redundant components and circuits, and by use of high speed solid-state sensors and connectors for rapid detection and repair. POCS builds on this capability by enabling rapid assisted response to failures for continued safe flight. This is done by continuous monitoring of the health of the powertrain with fault detection and identification capabilities. A combination of signals and models is utilized to identify and isolate the fault as quickly and accurately as possible. In the event of a failure, POCS notifies the operator and initiates a repair response. POCS also initiates a powertrain redesign to gracefully adapt to the failure, and a controller redesign to accommodate the potentially redesigned powertrain due to the failure. Powertrain and control redesigns may be initiated by the operator. POCS also helps ensure safety in the event of a crash by isolating high voltage circuits at the pilot's request or when an impact is detected. · Reduce pilot workload and ease pilot transition from conventional to hybrid aircraft by providing a simplified, unified interface to the hybrid powertrain. The key to rapid adoption of hybrid propulsion is to enable pilots to reliably operate the more complex powertrain with minimal incremental training. POCS makes this possible through optimization and control that shields pilots from the added complexity of the powertrain and interfaces with an interface that mimics that of conventional aircraft. Additionally, POCS provides automation to streamline pilot range and maintenance activities such as powertrain calibration, pre-flight preparation, in-flight control, and powertrain diagnostics. · Streamline the installation of new modules to support forward compatibility and modularity. This important hybrid powertrain differentiation is enabled by POCS in two ways. First, POCS provides a range of module alternatives with a standardized control and monitoring interface that allows generator switchover to compensate for payload, upgrade to advanced technology energy storage units, or adding or removing storage modules. Second, POCS enables simple calibration of new modules via upgrades for compatible aircraft and powertrain models, via operator input, or from an online library, coupled with targeted performance testing to fine-tune the model to the installed unit. Similar testing is also performed routinely to ensure model reliability continues with module age versus use.

[0084]

[0103] As described with reference to FIG. 10, POCS provides two interfaces to the operator: "Integrated" and "Modular." Integrated is a simplified user interface to the powertrain that mimics the controls of a conventional aircraft, reducing pilot workload and easing the transition from conventional to hybrid aircraft. Modular is a direct user interface to the individual modules of the powertrain, allowing low level precision control of the powertrain operation. These are described in more detail below. · Integration. Integration from the front end to all POCS capabilities allows the operator to switch between appropriate operational modes (calibration, pre-flight, in-flight control, diagnostics). The display uses similar performance parameters as used in conventional aircraft to ease the pilot's transition to new techniques and capabilities. An example of the pilot interface in "Fly" mode is shown in display 900 in FIG. 9. The display is coupled with cockpit controls similar to those found in conventional aircraft today, which translates operator inputs into optimal settings for the underlying hybrid powertrain based on a defined objective function for flight as follows: -Power Levers - one for each propulsor, controls the power output of the propulsors. The power lever angle (PLA) determines the power output of each propulsor as a percentage of full power and also allows limited duration surges to peak power. The in-flight control module converts the power requested by the power levers to the optimal setting for each propulsor in real time and optimally sources this power from the on-board generators and stored energy units to meet the operator-defined flight objectives within the constraints of the aircraft and powertrain. Some embodiments also provide blower or propeller control levers with feathering extensions ranging from maximum to minimum to control the RPM of each propulsor. Some embodiments may allow control to synchronize multiple propulsors so that all linked propulsors operate at the same setting, or may allow autothrottle operation, whereby the in-flight control module commands the throttles based on the flight path. In these situations, servo motors or similar mechanisms are used to move the throttles based on the current power setting (standard FAA autothrottle operation). -Regenerative Brake Control - one for each propulsor, controls the regenerative power of the propulsors. This is done via dedicated regenerative brake levers, or by extending the range of the power levers to negative power levels, or from zero power to full regenerative power. In either case, the lever angle determines the regenerative power of each propulsor as a percentage of full regenerative power. In flight, the control module translates the regenerative power requested by the levers into the optimal setting for each propulsor in real time. -Reverse Power Control - one for each propulsor, controls the reverse power of the propulsors. This may be done via a dedicated reverse power lever, or by extending the range of the power lever to negative power levels, from zero power to full reverse power. In either case the lever angle determines the reverse power of each propulsor as a percentage of full reverse power. In flight the control module translates in real time the reverse power requested by the levers into the optimal setting for each propulsor. -Low Level Controls - Provided in some embodiments to allow operator manual control of the generators, storage units, and power distribution. These include generator controls for turning the generators on and off, controlling generator output from idle to peak power. Controls can also include power distribution controls for redirecting power flow from on-board sources to the propulsors. In twin-propulsor aircraft with port and starboard propulsors and port and starboard sources, these can provide a choice of split flow (left to left, right to right), directional (split flow plus right to left or left to right), and coupled (port to port). Modular. Provides a direct interface to the individual modules of the powertrain through their on-board controllers. Intended for situations where there is a need to circumvent the flight optimization capabilities of POCS to directly engage a controller (e.g., repairs, emergencies, non-standard operations). The range of modules that may be accessible for a sample hybrid powertrain is shown in FIG. 10 and described in more detail herein.

[0085]

[0104] 10 is a schematic diagram illustrating basic functional elements or modules of a Powertrain Optimization and Control System (POCS) that may be used in an embodiment of an electric hybrid aircraft that may be used as part of the air transportation system of the present invention. Each or combination of the functions, operations, or processes performed by or under the control of the elements or modules illustrated in the figure may be performed by the execution of a set of instructions by a suitably programmed processing element (such as a controller, state system, microcontroller, CPU, microprocessor, etc.).

[0086]

[0105] As shown in the figure, the elements or functional modules of an embodiment of a POCS platform 1000 may include "on-board" components 1002 and "on-line" components 1004. The on-board components, elements, and processes 1002 typically reside on the aircraft being controlled, while the online components, elements, and processes 1004 typically reside on a data processing platform or system located remotely from the aircraft (such as in a control center, in a centralized data processing and scheduling platform, etc.), and which communicate (as needed) with the on-board components 1002 via a suitable communications channel or combination of communications channels (such as wireless technologies that may communicate via the internet linked to a server).

[0087]

[0106] In an exemplary embodiment, the functionality of the POCS platform 1000 is enabled by the following onboard capabilities (components, elements, and processes 1002): Standard Procedures (elements / components 1041), which are a library of preset and operator defined standard operating procedures for the powertrain and its modules. This includes: Flight mode(s): e.g. Optimal, Fast, Economical, Custom. Scans and diagnostics: e.g. initialization scan, energy scan, pre-flight scan, in-flight scan, post-flight scan. Operational Rules Library: defines operational priorities for the powertrain based on safety requirements or operator preferences. These constrain the Hybrid Energy Planner and Hybrid Power Manager. Also includes: - A minimum energy state to ensure adequate safety reserves, e.g., stored energy units at 20% capacity and generator fuel equivalent to 45 minutes of flight. -Energy state upon arrival, e.g. stored energy units depleted to a minimum level of 20% of capacity. Power distribution priority, by flight leg. For example, taxiing on stored energy only, or approaching on stored energy only, and using generator idling for high availability. - Power level settings by flight leg, e.g., 80% of full power for a go-around, or neutral thrust for initial descent. · On-board logs. A database that captures information about key aspects of the powertrain and its performance. These include operator details, on-board modules, operator preferences, life cycle and maintenance records, performance logs, inspection and diagnostic logs, access history logs. The database transmits logs periodically via a secure data link (element / component 1043) to the online log (element / component 1023) and stores only limited history on-board. · A secure data link (element / component 1043). This allows for periodic uploads from the on-board logs to the online log(s) 1023 for a particular powertrain, remote diagnostics and maintenance of the powertrain, and access to the aircraft and powertrain libraries (element / component 1020) for calibration or benchmarking purposes. The data link may include two levels of security, a lower level for communicating log or library data and a higher level for diagnostic and maintenance data. Access to the data link is secure and all access history is logged. It also allows for bidirectional data flow between the POCS and the FPOP / FMS for flight data. Module Interfaces (elements / components 1050). These are connector interfaces to a range of lower level controllers of on-board modules, allowing the controllers to be queried or commanded by the POCS platform, and transmitting a range of status and performance information to POCS on-demand or continuously. Typically, the API specification defines the protocols by which POCS and the modules communicate. Control modules may include variable pitch blower controllers, propulsor motor controllers, battery management systems, engine controllers, fuel system controllers, generator motor controllers, distribution controllers (switches, connectors, and converters), etc. Note that Fig. 12 shows an interface configuration for an exemplary powertrain 1200 that is coupled to an on-board POCS by several interfaces / connectors 1202 for the purposes of sensing performance parameters and returning control signals to the powertrain or its control system components. Similarly, Figs. 10 and 11 show communication and data flow from the POCS optimization module 1130 and the powertrain and control manager 1142 to the powertrain harmonization module interface (element 1050 and element 1150). The system provides the pilot with a secondary direct path (element 1052) to the module controller via the modular operator interface (element / component 1012). The system may include backup connectors to the module controller for redundancy, along with connectors and switches for activating the backup circuits.

[0088]

[0107] The POCS platform 1000 may also provide one or more of the following online capabilities via a secure POCS cloud-based data platform (element / component 1004): · Aircraft and Powertrain Library (element / component 1020). The library of aircraft and module performance models includes operational models for each class, and parameters for modules of the class. The models and parameters are updated periodically via benchmarking and platforming (element / component 1021). The database is designed to be queried by the on-board POCS when initialized, when calibrating a new module, or for periodic refresh. · A benchmark platform (element / component 1021). This is a database of performance benchmarks and may include input capabilities for external benchmarks and uploading raw performance data from online logs for individual powertrains. It also includes statistical data analysis or other data analysis procedures to periodically update the benchmarks. · A diagnostic platform (element / component 1022) capable of enabling remote diagnostics and maintenance of the powertrain over a highly secure data link. · Powertrain Log (element / component 1023), which serves as an archive of on-board logs from the individual powertrains, coupled with comparative performance statistics derived from platform benchmarking, and uploaded periodically via secure data links.

[0089]

[0108] In an exemplary embodiment, an implementation of a POCS platform (such as element 1000 of FIG. 10) may provide the following functionality or capabilities: Calibration (represented by element / component 1025), which adapts the specific modules installed and optimizes and controls platform to allow for upgrades to future technologies, aircraft variants, up / down sizing of energy storage units or generators, and high fidelity modeling of module performance. In some embodiments, this may perform or help perform the following functions / operations: -Scan the powertrain against recent scans to identify changes to on-board modules, authenticate and log in on-board. - Optimization and control parameters for all modified modules are downloaded via data link from the online aircraft and powertrain libraries and injected into the installed model. - Calibrate the model to the performance of the installed module. The operator steps through a series of tests of the module defined by an initialization scan procedure to evaluate actual performance vs. model performance. Identify and flag potential problems. Adjust model parameters to better match actual performance. -Allows operators to define a range of preferences for powertrain optimization and control, display, reporting, monitoring, and diagnostics, including settings tailored to specific operating environments, mission profiles, and trade-offs; stores preferences in an on-board log. Flight preparation (represented by element / component 1026), which performs automated checks to ensure the powertrain has adequate energy to safely complete the planned flight and is in a flight ready state. In some embodiments this may perform or assist in performing the following functions / actions: -Flight acceptable mode by default or optimal, and flight details: atmospheric path or flight time (or distance), payload and uncertainty factors. These can be entered manually or via FPOP. - Calculate and display the energy state based on the energy state scanning procedure. - Determine if additional generator fuel or stored energy is required by using the Hybrid Energy Planner with the given flight details, flight mode, and energy state. Review payload vs. design payload to ensure safe flight and evaluate if there are options to increase the capacity of the stored energy units. -If the on-board energy or payload is changed via additional stored energy units, an increased state of charge or fuel will re-run the hybrid energy planner. -Perform pre-flight testing of the powertrain as defined by the operating procedures, identify problems and activate the fault detection and recovery module. In-flight control (represented by element / component 1027). This allows simplified control of the power delivered by the hybrid powertrain and optimizes powertrain and module performance based on the operator selected flight mode and flight details. The control may be semi-automated or fully automated and optimization may be basic or integrated. In some embodiments this may perform or assist in performing the following functions / operations: - Calculates optimal energy plan, arrival energy state, target speed and range (max, optimal and economical) using hybrid energy planner based on flight details, flight mode and energy state. Flight details are either basic, use flight time (or distance) as input or integrate airpath as input. Displays arrival energy state and target speed. Energy plan describes energy state along with airpath. Stores energy and generator fuel at individual waypoints. -If the arrival energy condition is below the minimum reserve level, it will notify the operator and provide an alternative flight mode, target speed setting to reach the destination. - As conditions change, control the powertrain in real time in parallel with operator input to optimally source and adjust power from storage units and generators to achieve the energy plan. Figure 11 provides a summary of the in-flight control process and functional modules or sub-processes that may be utilized and are described in detail herein. This control process may include the following functions or operations: -Uses a hybrid power manager to determine control strategies in real time to define optimal energy distribution across generators and stored energy units. -The energy distribution is passed to a module optimizer that calculates the optimal settings for the powertrain modules and then transmits these to the low-level module controllers via the module interfaces in POCS. - Periodically refresh the energy plan based on deviations from the previous plan. -Periodic refresh of the energy state via an energy state scanning procedure. - Allows updates to flight modes and flight details, either manually or via FPOP (described with reference to Figure 14), and responds by refreshing the energy plan. -Allows for semi-automated or fully automated operation, where the operator controls the power levers, or where the in-flight control module commands all functions and adjusts the power levels required to achieve the optimum airspeed. -Continuously monitors powertrain performance via module optimizers and evaluates models, safety limits via in-flight scanning procedures. In case of problems, triggers fault detection and recovery modules to coordinate alerts and actions. Diagnostics (represented by element / component 1028), which performs post-flight mission analysis, powertrain diagnostics, and problem resolution. In some embodiments, this may perform or assist in performing the following functions / operations: - Runs mission analysis algorithms against monitored data stored in the on-board log to calculate and display vital flight statistics (e.g. distance, time, average speed), details of total energy used, remaining fuel and stored energy, vital performance statistics (e.g. overall efficiency and efficiency per module), and stores the results in the on-board log. - Updating the operational history of modules or components that require regular maintenance or have a limited life span. - Monitors powertrain health and performance and evaluates models, safety limits via post-flight scan procedures, and in case of problems, initiates fault detection and recovery modules to coordinate alerts and actions. Fault Detection and Recovery (represented by element / component 1042), which performs ongoing monitoring of the powertrain to detect and identify faults, notify the operator, and assist in corrective action. In some embodiments, this may perform or help perform the following functions / operations: -Fault detection and isolation capabilities monitor the health of the powertrain, utilizing a combination of signals and models to identify and isolate faults as quickly and accurately as possible. -If a malfunction occurs, the pilot is notified and a remedial response is initiated via the powertrain warning function. - In the event of a fault, it triggers the powertrain and control managers to determine the necessary action and execute it in coordination with the pilot. -Remedial actions may be initiated by the pilot, who works with the powertrain and control managers to execute them.

[0090]

[0109] In some embodiments, the POCS determines an optimal power plan based on flight details and a given flight mode. The POCS then controls the operation of the powertrain and its modules during flight to align with the power plan by monitoring the performance of the powertrain and its modules, adjusting as necessary. The POCS is designed for semi-automated or fully automated operation, where the pilot retains control of the throttle while the POCS controls all functions. However, the pilot can override the POCS settings.

[0091]

[0110] 11 is a schematic diagram illustrating the basic functional elements or modules of the POCS that may be accessed and used to control or modify processes on board an aircraft in an embodiment of the air transportation system of the present invention. Each or a combination of the functions, operations, or processes performed by or under the control of the elements or modules shown in the figure may be performed by the execution of a set of instructions by a suitably programmed processing element (such as a controller, state system, microcontroller, CPU, microprocessor, etc.).

[0092]

[0111] As shown in the figure, elements or functional modules of an on-board aircraft process 1100 of an embodiment of POCS include the following: Optimization Module (element 1030 in FIG. 10 and / or element 1130 in FIG. 11) Hybrid Energy Planner (element 1132 in Figure 11): -Determine the optimal energy path over the flight / flight trajectory by minimizing a non-linear cost objective (see below) that targets initial and arrival energy states, module performance constraints, and operating rules; a blended charging strategy that typically looks to gradually deplete stored energy units over the path of the flight allows operation at optimal efficiency of each of the on-board power sources. - This is done by decomposing the trip into a flight path consisting of segments with roughly uniform operational requirements (e.g. taxi, takeoff run, uniform speed go-around, cruise, power neutral descent (done as part of flight preparation)). An optimization is then performed to determine the optimal energy plan along the provided flight path. If a detailed atmospheric path is not provided, a standard wear profile is assumed (e.g. linear over the cruise and go-around legs) after budgeting based on benchmark look-up tables for taxi, takeoff, descent and landing. -Optimization is performed through fully dynamic programming (or similar algorithms) or simplified approaches such as using look-up tables or functions to determine optimal power distribution across generators and stored energy units based on flight legs and operating conditions. Power distribution can be described in one of a number of ways, including generator power setting as a percentage of total generator power, or a power ratio equal to the ratio of power drawn from stored energy to the total power required. - The objective function defines the quantities to be minimized over the atmospheric path by the hybrid energy planner. For example, the objective function may include one or several of the following terms with parameters defined by the operator: Objective function = cost of fuel + cost of stored energy + cost of engine maintenance and reserves (amortized) + cost of battery packs (amortized) + cost of passenger and crew time + cost of aircraft + cost of emissions. - The objective function is minimized based on provided departure and arrival energy states, operating rules from an operating rules library, powertrain and module performance constraints from powertrain and module (propulsor, generator, stored energy) models. The optimization process requires a simulation of aircraft and powertrain performance provided by aircraft and powertrain performance models. Hybrid Output Manager (element 1134 in Figure 11): -Determine real-time control strategies to optimize energy distribution, described via variables such as generator power settings or power ratios, across on-board sources to deliver the power required based on the overall energy path for the flight, determined by minimizing nonlinear objectives for the flight segment subject to module performance constraints and operating rules, including the provided energy path. - Optimization may be performed by relatively simple methods such as determining the generator power settings (or power ratios) for individual ranges of flight legs and operating conditions from a look-up table of optimal values, or by more complex methods such as determining the optimal values ​​using one of several algorithms such as Pontryagin's Minimum Principle (PMP) or Equivalent Consumption Minimization Strategy (ECMS). Consistency with the provided energy plan is driven by an outer control loop (e.g. proportional plus integral). - The objective function defines the quantities to be minimized over the atmospheric path by the hybrid energy planner. For example, the objective function may include one or several of the following terms with parameters defined by the operator: Objective function = cost of fuel + cost of stored energy + cost of engine maintenance and reserves (amortized) + cost of battery packs (amortized) + cost of passenger and crew time + cost of aircraft + cost of emissions. - The objective function is minimized based on provided departure and arrival energy states, operating rules from an operating rules library, powertrain and module performance constraints from powertrain and module (propulsor, generator, stored energy) models. The optimization process requires a simulation of aircraft and powertrain performance provided by aircraft and powertrain performance models. Propulsor optimizer (element 1136 in Fig. 11): -Determine real-time control strategies for each of the propulsors based on the requested power, airspeed, and environmental conditions. Convert the requested power into propulsor settings for optimal efficiency. The optimal settings are then used to direct the low-level module controllers (e.g., variable pitch blower controllers, motor controllers) to the POCS platform via the module interfaces (element 1050 in FIG. 10 and / or element 1150 in FIG. 11). The optimal settings may be further modified via detailed control loops for performance improvement. This may include peak search loops to fine-tune the operating point, and smoothing loops to soften sudden changes in settings over intervals determined by comfort ride performance constraints, aircraft structural performance constraints, or powertrain performance constraints. - Optimized settings may include propulsor attitude, e.g., variable pitch blower angle, exhaust plug position, and propulsor motor inverter power (e.g., torque, speed). The optimizer adjusts propulsor settings over a range of aircraft operations including standard thrust, neutral thrust, regenerative braking, reverse thrust, and recovery thrust. -For standard thrust control, the optimizer is driven by the required power, airspeed, and environmental conditions for each propulsor and determines the propulsor settings that maximize the delivered thrust. This is done by performing a stepwise or coupled optimization over the motor and propulsor performance models (element 1040 in FIG. 10 and / or element 1140 in FIG. 11). In a stepwise approach, the motor and propulsor settings are optimized sequentially. For example, the motor settings to maximize efficiency may first be determined by optimization using the motor performance models within the operating constraints defined for the motors. Following this, the propulsor attitude (e.g., blower pitch angle or exhaust plug position) is determined to maximize the propulsor thrust by optimization using the propulsor performance models within the operating constraints defined for the propulsor attitude. These settings are then used to command the operation of the low-level controllers via the module interfaces in the POCS. In some implementations, a lookup table is used to determine a near-optimal value, which may then be followed by an optional optimization step to refine the estimate along the lines of those described above. -For reverse thrust, the optimizer is driven by the reverse power required for each propulsor and determines the propulsor settings that maximize the reverse thrust delivered. This is done by a process similar to that for standard thrust. For staged approach, the motor settings are determined to maximize efficiency by optimization using a motor performance model or by a look-up table of motor performance. The harmonic propulsor attitude is then determined by optimization using a propulsor performance model or by a look-up table of propulsor performance. -For regenerative braking control, the optimizer is driven by the required reverse power for each propulsor, airspeed, and environmental conditions, and determines the propulsor settings that maximize the delivered thrust. This is done by performing a stepwise or coupled optimization over the motor and propulsor performance models. In a stepwise approach, the motor and propulsor settings are optimized sequentially. For example, the motor settings to maximize efficiency may first be determined by optimization using the motor performance models within the operating constraints defined for the motors. Following this, the propulsor attitude (e.g., blower pitch angle or exhaust plug position) is determined to maximize the propulsor reverse thrust by optimization using the propulsor performance models within the operating constraints defined for the propulsor attitude. These settings are then used to command the operation of the low-level controllers via the module interfaces in the POCS. For neutral thrust, the optimizer commands the low level controllers to cut power to the motors and set the propulsor attitude to minimum drag (e.g., set the controllable pitch fans to feathering or pinwheeling, set the exhaust plugs to maximum extension). Conservation Energy Optimizer (element 1138 in Fig. 11): - Monitor the performance and status of the rechargeable storage unit via module interface 1150 in POCS to help ensure operation within the long life range defined by the performance constraints. If the storage unit is outside of its long life range, the optimizer adjusts the Hybrid Energy Planner and Hybrid Power Manager settings to reallocate power to generators, for example, by increasing the effective cost of the storage unit. Generator Optimizer (element 1140 in Fig. 11): -Determine real-time control strategies for each of the generators based on the requested power, airspeed, and environmental conditions. Convert the requested power into generator settings for optimal efficiency. The optimal settings are then used to command low level module controllers (e.g., engine control units, motor controllers, fuel system controllers) via module interfaces 1150 in the POCS platform. The optimal settings may be further modified via detailed control loops for performance improvement. This may include peak search loops to fine-tune the operating point, and smoothing loops to soften sudden changes in settings over intervals determined by comfort ride performance constraints, aircraft structural performance constraints, or powertrain performance constraints. The optimized settings may include the output of the internal combustion engine, such as speed, torque, and generator motor inverter takeoff (e.g., torque, speed). -The optimizer is driven by the required power, airspeed, and environmental conditions for each generator and determines the generator settings that maximize efficiency. This is done by performing a stepwise or coupled optimization over engine and motor performance models (or embedded generator models). In a stepwise approach, the engine and motor settings are optimized sequentially. For example, the engine settings to maximize efficiency may first be determined by optimization using the engine performance model within operating constraints defined for the engine. Following this, the motor settings to maximize efficiency are determined by optimization using the motor performance model within operating constraints defined for the motor. These settings are then used to command the operation of the low level controllers via module interfaces in POCS. In some implementations, a lookup table is used to determine a near-optimal value, which may then be followed by an optional optimization step to refine the estimate along the lines of those described above. - Includes a strategy for routing excess power output (above demand) from the generator to charge a storage unit to isolate the generator during transients or times when the demanded power output is outside the generator's optimum range. Powertrain and Control Manager (element 1142 in FIG. 11): - Driven by input from the pilot or the powertrain and control redesign functions, executes diagnostic or solution processes, reconfigures the powertrain, or modifies the control law. - Receives solution or diagnostic process steps, powertrain reconfiguration commands, control laws from the pilot, and powertrain and control redesign functions. -Resolve conflicting directives and follow safety procedures defined in the Operating Rules function. - Implementing a set of rational changes in the safety sequences by instructing the low level controllers via module interfaces and by modifying the optimization module, aircraft, and powertrain models. For example, in the event of an impending emergency landing, a "safe and isolate" sequence, activated by the pilot just prior to touchdown, would command the powertrain and control redesign functions to shut down or isolate all high voltage or flammable systems in the powertrain to protect passengers and cargo. Alternatively, a fault detection and identification function may activate a sequence based on an assessment of a crash from aircraft state variables. Output Allocator (element 1144 in FIG. 11): -Determine power distribution across on-board propulsors based on pilot commands and powertrain capabilities, which may include: Power allocation for coordinating multiple propulsors, e.g., balanced power to eliminate yaw moment, e.g., a propulsor providing power for zero moment about the aircraft center of gravity, or propulsor power determined by the power setting of a master propulsor. Power allocation consistent with required power to optimally accommodate a propulsor failure while maintaining normal performance or performance for graceful degradation. For example, the allocation may boost power to healthy propulsors to compensate for the failure, while simultaneously limiting yaw moment and ensuring higher than minimum power required to maintain safe flight for that flight leg, and not exceeding propulsor constraints. Power allocation for directional control by distributing power to produce the required yaw moment. Aircraft and powertrain model (element 1040 of FIG. 10 and / or element 1150 of FIG. 11) Aircraft performance model (element 1152 in Figure 11): - The flight tests calibrate a single degree of freedom physics-based performance simulation model that calculates the expected power and go-around or descent rate required for the current phase of flight given aircraft weight, speed, air temperature, and pressure (further description of this aspect is provided in the discussion of the FPOP system). Powertrain and propulsor model(s) (elements 1153 and 1154 in FIG. 11): -Performance models, look-up tables, and performance constraints that allow optimization of propulsor settings based on required power, airspeed, and environmental conditions. These may include one or more of the following: Motor performance models, e.g. describing motor efficiency as a function of motor torque, speed, and voltage. Propulsor performance models, e.g., defining propulsor thrust as a function of blower pitch angle, torque, airspeed, blower speed, and standard braking, reverse braking, or regenerative braking settings. Motor and propulsor performance lookup tables, which define performance relationships at discrete points for use as a replacement for optimization or to generate a starting approximation. Performance constraints, on motor and propulsor settings. For example, blower pitch angle range for standard operation, regenerative braking, and reverse thrust. Generator model (element 1156 in Fig. 11): Performance models, look-up tables, and performance constraints that allow optimization of generator settings based on requested power, airspeed, and environmental conditions. These may include one or more of the following: · Engine performance models, e.g., defining engine efficiency as a function of engine torque, speed, and ambient conditions. Motor performance models, e.g. describing motor efficiency as a function of motor torque, speed, and voltage. Define performance relationships at discrete points to use as a replacement for engine and motor performance look-up tables, performance models, or as a starting approximation. Alternatively, a generator motor for integrated engine motor performance (e.g. describing generator efficiency as a function of torque, speed, voltage, and ambient conditions). As above, the generator motor can be replaced or supplemented by a generator performance look-up table that defines the performance relationships at discrete points. Performance constraints on engine and motor or combined generator settings. For example, engine power may range from full power, boost and peak, motor power may range from full power, boost and peak, with safe periods for boost and peak. Conserved Energy Model (element 1158 in Figure 11): Performance models, look-up tables, and performance constraints to enable optimization of power distribution across rechargeable stored energy units and generators based on requested power output, current state of charge, and environmental conditions. These may include: A decay model for stored energy units, which relates to the state of charge of currently drawn units, for example via common coulomb counting. · A stored energy performance model, which determines the operating efficiency of the unit based on power drawn, state of charge, ambient conditions, and other factors. For example, a Rint-type equivalent circuit model coupled into the model for key parameters (such as open circuit voltage) as a function of state of charge and temperature. · Conservation Energy Performance Lookup Table, defines performance relationships at discrete points for use as a trade-off for optimization or as a starting approximation. Performance constraints on the stored energy unit, including state of charge and limits on the power drawn from the unit. Fault Detection and Fault Recovery (element 1042 in FIG. 10 and / or element 1160 in FIG. 11) Fault detection and fault localization (element 1162 in FIG. 11): -Continuously monitor the health of the powertrain through a combination of signal-based and model-based methods to detect failures of sensors, actuators, components or modules. -Periodic sampling of signals from a range of sources, control signals from POCS to low level controllers, output signals from low level controllers, powertrain and module sensors, and aircraft state variables. -Monitors signals to ensure the powertrain is operating within safe limits defined by performance constraints. If a safe limit is exceeded, monitors the magnitude and duration of the spike to assess the severity of the problem. - Activate a powertrain alert (element 1164) via the cockpit interface (element 1170 in FIG. 11, and more specifically, element 1172 to inform the pilot). -Utilize various methods (e.g. Fourier analysis, limit checking) to detect fault signals. -Comparing powertrain, module and subsystem performance to internal models of components or processes to identify potential faults through methods such as parameter estimation or neural networks. - Determine the location and nature of faults via signals and models using analytical methods and / or heuristic problem solving techniques. Classify faults based on location, type, and severity. -Invoke the powertrain and control redesign function / process (element 1166 in FIG. 11) to initiate corrective action. For purposes of aircraft and transportation system management, it is noted that the Powertrain Configuration and Control Law Library includes the following information, data, or processes: -A resolution process that describes the process steps to be followed to resolve a powertrain fault. -Each powertrain configuration describes the configuration, e.g., switches, connectors, contactors, that must be collectively configured to implement the process steps that perform the safe reconfiguration and the structure along with the control laws that operate the reconfigured powertrain. -Each control law describes optimization and control procedures for a powertrain, including objective functions, operating laws, powertrain and module performance constraints, and aircraft and powertrain performance models. Powertrain and control redesign (element 1166 in Figure 11): - Combining predefined designs with in-flight synthesis to determine the powertrain and control redesigns required to accommodate an activated fault while maintaining normal or gracefully degraded performance. - Determine if corrective action is necessary based on the location, type, and severity of the fault. -Selecting a solution process, powertrain configuration, and control law to optimally accommodate a fault via an expert system (or other decision process) that combines lookups in a library of predefined solution processes, powertrain configurations, and control laws with synthesis to tailor the response to specific conditions. For example, Isolation of a faulty module or circuit. For example, in case of a short switch failure in a converter, a fast acting fuse connected to the switch can be used, and when the fault occurs, the fuse will isolate the switch and solve the problem. Redistribution of power to accommodate failures. For example, in a powertrain with left and right twin propulsors, each powered by a stored energy unit and generator, a propulsor or source failure may require the ability to transfer power from one side to the other to optimize power output. In the case of a left propulsor failure, a left-to-right transfer would help compensate by allowing the right side to boost. Similarly, a left-to-right transfer would help accommodate a failure of the right power source, so that both are equally powered. Activation of redundant modules or circuits. For example, in a powertrain with left and right twin propulsors, each powered by a bus, failure of either bus can be accommodated by a single redundant bus. The redundant bus can also be used to create paths for left and right transfers. -Isolation of high voltage circuits. - Initiate notification and corrective action by initiating Powertrain Alarm (element 1164 in FIG. 11) and Powertrain and Control Manager (element 1142 in FIG. 11) functions, actions, or processes.

[0093]

[0112] 14 is a flow chart or diagram illustrating certain inputs, functions, and outputs of a flight path optimization platform (FPOP) that may be used to determine or revise a flight path for an electric hybrid aircraft, which may be used as part of the air transportation system of the present invention. Each or combination of the functions, operations, or processes performed by or under the control of the elements or modules shown in the figure may be performed by the execution of a set of instructions by a suitably programmed processing element (such as a controller, state system, microcontroller, CPU, microprocessor, etc.).

[0094]

[0113] An implementation of the flight path optimization platform may be used to determine optimal flight path(s) for a hybrid electric aircraft, including defining speed and altitude, and energy planning for each of a series of flight segments while simultaneously satisfying performance and cost targets defined by the flight mode. The FPOP determines an optimal path over one or more flight routes, and in so doing takes into account aircraft and powertrain characteristics, weather conditions, ATC restrictions, hazards, etc.

[0095]

[0114] It should be noted that flight planning for a regional hybrid electric airplane with multiple power sources requires a more complex set of tradeoffs than a manned conventional aircraft over long ranges. For example, for a hybrid electric airplane, the optimal flight altitude is determined by a combination of speed vs. efficiency goals, flight distance, air weather, aircraft aerodynamics, available energy and power, and relative stored energy vs. generator usage. In contrast, flight altitudes designed for long-distance commercial passenger or cargo flights may be set by one or more of FAA requirements, policies, and general aircraft characteristics. This is a much simpler form of determination of the segment(s) of a traditional long-distance flight. Due to the complexity of the flight planning process required for the aircraft and regional air transportation system of the present invention, FPOP is used to perform the optimization process required to determine the optimal flight path both before and during the flight (as conditions change).

[0096]

[0115] In addition to the initial flight path planning, the FPOP may also be utilized periodically during flight to update the flight path to the destination (taking into account changes in winds, ATC routing settings, etc.) and may also provide an alternate destination or flight path in the event of a failure in the powertrain or other in-flight emergency. During flight, periodically identify all airports within range taking into account the aircraft's current energy state. The results may be displayed to the pilot in any format including range rings on a map, highlighting the airports on the map, a simple textual list, etc. · In the event of any emergency, provide immediate flight routing to the nearest acceptable alternate airport. In case of a partial failure within the powertrain, the FPOP identifies alternative destinations available for the degraded state of the powertrain. Examples of partial failures would include failure of one or more energy storage units, power generation modules, traction motors, etc.

[0097]

[0116] In some embodiments or implementations of the FPOP platform or data processing system, the optimization process may be performed at two levels. Level 1: Simple rules based calculations using standard libraries to set altitude and speed based on flight mode and distance. Level 2: Optimization over a range of feasible alternative altitudes and speeds built on the output of Level 1.

[0098]

[0117] In some embodiments, the FPOP platform may include or be configured to access one or more of the following functions, operations, or processes: Route Generation (element or process 1404 in FIG. 14). This defines a Level 1 flight path for each flight route. This module builds a 3D flight path defined by waypoints (latitude, longitude, and altitude) connected by flight segments (e.g., cruise, go-around, descent) with speed and energy plans assigned to each segment. A cruise may consist of one or more segments as required by altitude constraints and ATC routing. For Level 2 optimization, a Route Alternative Creation Rules module (1413) is used to build alternative flight paths for each route. For each flight path, a speed rules library is used to determine target speeds for each leg, and weather and hazard indices by interpolating over the provided conditions. In general, the route generation process or element utilizes a core sequence drawn from a library of performance heuristics and airspace constraints such as: The route creation sequence first sets the cruise altitude(s) and flight speed heuristically. Go-around and descent distances are calculated to set intermediate waypoints, and airspace constraints are calculated as waypoints with altitude constraints. Finally, power ratios (range extension generator states) are set for each segment. Route Heuristics (element 1407 in FIG. 14) A library of altitude, speed, and energy source utilization based on a database from detailed flight route optimization. For a given range, weight, and flight mode, returns optimal go-around and descent rates, cruise altitude and speed, and range extension generator utilization times for a simple flight profile with no wind. The heuristics may be created using the process described herein. Airspace Constraints. (Element 1410 of FIG. 14) Impose constraints along the flight route as start and end waypoints (latitude, longitude, and altitude), utilizing a navigation database of airspace and terrain combined with the flight route to determine minimum or maximum altitude constraints. · Go-around, Descent Library. (Element 1409 of FIG. 14) A library that returns the time and distance to go-around or descend at current weight and speed between two altitudes provided by route heuristics. The library may contain table lookups with smoothing or accumulated performance calculations with interpolation. Environmental Assessment. (Element or process 1412 in FIG. 14) Determines if environmental conditions warrant a level of route optimization beyond the baseline heuristic route. Weather and caution data is applied to the route of flight; any cautions, high winds, or significant changes in winds along the flight path may necessitate L2 route refinement. Alternate Flight Path Generator (element or process 1413 in FIG. 14): Constructs a set of alternate flight paths by varying segment altitudes from the original flight path. Uses a breakpoint generator to further split existing flight segments with additional waypoints if compensated, then creates a set of all possible paths. The maximum number of paths (on the order of 10) is limited by altitude constraints (min, max) and airspace regulations that require cruising at incremental altitudes (e.g., over the US, Eastbound flight cruising at odd multiples of one thousand feet, i.e. 9000 feet, 13000 feet, etc.). Breakpoint Creator (element or process 1414 in FIG. 14). This routine compares existing cruise segments against caution and weather indicator data (elements 1403 and 1405). Typically, waypoints are inserted at the boundaries of any hazards and also anywhere there is a significant wind speed change. Each additional waypoint increases the degrees of freedom available to the optimizer. A flight path optimizer (element or process 1408 of FIG. 14 ), which varies cruise speed(s) and power ratio over the flight path to minimize an objective function while meeting constraints. The optimization is performed for current aircraft states, which may include weight, stored energy, and available range extension generator fuel, as well as environmental conditions, which may include wind, precipitation, temperature, etc. Results of the optimization process may include an optimized flight path, atmospheric path, energy plan, and objective function values. The flight path optimizer may include one or more of the following processes, operations, functions, elements, etc. · Objective function. Set by flight mode, the objective function will affect cruise speed and energy utilization strategy. Exemplary objective functions that "bracket" the performance space would typically be maximum speed (minimum time), or minimum energy. A more global objective function would include one or several of the following terms, with parameters defined by the operator: Objective function = Cost of fuel + Cost of stored energy + Cost of engine maintenance and reserves (amortized) + Cost of battery packs (amortized) + Cost of passenger and crew hours + Cost of aircraft + Cost of emissions. Optimization variables. The optimizer varies the cruise speed(s) and power ratio. For example, depending on the flight range, maximum speed optimization will result in a high level of range extension generator usage, while minimum energy optimization will result in a level of range extension generator usage, with short enough flights resulting in no range extension generator usage at all. Optimization constraints. May include one or several constraints on the powertrain for performance and safety, including maximum discharge rate of stored energy, minimum state of charge at any point during the flight, minimum energy reserve at the end of the flight (note that optimization occurs on a defined flight path, and any altitude constraints are satisfied by the flight path generator). · Optimization process. The optimization space is non-linear and may contain generator state discontinuities, both of which preclude closed-form solutions. Optimization requires modeling of aircraft and powertrain performance over a defined flight path using the current aircraft configuration and in a time-dependent manner in the expected flight environment. The performance model results in time-integrated sums that are used to calculate the objective functions (e.g. fuel consumed and energy stored). Flight modeling may be accomplished using dynamic programming (e.g., flight simulation (described in more detail below) that includes representative aircraft and powertrain models) or by simplified methods such as reduced order models (as long as the discrete, time-integrated characteristics are properly modeled). The methods described herein utilize a flight simulator process with representative aircraft and powertrain models and also incorporate current operating environment effects. Optimization algorithms. Flight profiles with a single cruise speed variable may be optimized using gradient descent or Newton's method. Multi-segment flights with power ratio discontinuities may require more sophisticated nonlinear algorithms (such as NPSOL). Constraint Checking (element or process 1406 in FIG. 14) checks the optimized trajectory results against the required end-of-flight energy reserve or other constraints that may be used to shape the optimization space. Any trajectories that could not be optimized to meet the constraints are discarded at this point and become invisible. Route Evaluation (element or process 1402 of FIG. 14). This sorts all valid routes by an objective function and returns the default route (originally requested) and the optimized route (i.e., the route with the lowest objective function) along with all relevant information. Flight Simulation Models and Modules. Flight simulation models may be utilized by the flight path optimizer (element or process 1408 of FIG. 14) and are flight test calibrated, single degree of freedom, physics-based performance simulation models that calculate the expected power required for the current phase of flight given aircraft weight, speed, air temperature and pressure, and go-around or descent rate. The models utilize aircraft and powertrain models at time steps and empirical routines to continuously calculate performance in the presence of expected weather along the flight path. The results are integral sums over time, distance, and energy. The integral distance sum is the atmospheric path. These models may include one or more of the following: Flight Modules. Performance is calculated for each flight segment by the corresponding flight module (e.g. takeoff, go-around, cruise, descent, landing, etc.). The modules are initialized with aircraft and segment information and return the integrated performance for the complete flight segment. The table provides the input and output details for each module, and the modules use aircraft and powertrain models to calculate the aircraft performance. · Aircraft model. The model is initialized with aircraft states (altitude, speed, power level, weight, rotation rate, etc.) and operating environment (altitude, air temperature, pressure, density) and may return the corresponding instantaneous performance (energy use, fuel burn, acceleration, go-around or descent rate, etc.). The model is based on the force and moment equations (C L , C D , C Di , C M , F, and N Z W), and a comprehensive table lookup for determining instantaneous aircraft performance, where: C L -C L =N Z Standard calculation of W / q / S. C D -Drag corrected for test drag, lifted through the Reynolds based skin friction method using form drag factors. Additional factors for cooling drag, flap and landing gear drag (if required), protrusion and interference drag. C Di -Standard C L 2 / (πARe), e is provided by table lookup, C L A function of the flap setting. Trim drag is added incrementally to the wing as lift, and C Di is calculated from HT. C M - Calculated from pitch moment, aircraft weight, CG, and neutral point (speed dependent, from table lookup). F-Thrust, both available and required thrust. Powertrain and propulsor models are called to determine available SHP and converted to thrust using an aerodynamic propulsor model (table lookup of efficiency vs. speed). Required thrust is calculated to balance drag (non-max thrust cases) and used for energy / fuel burn. N Z W - Load factor, due to accelerated flight (turn rate or pitch rate), expressed as a fraction of (g). · Powertrain model. Represents the physics of a hybrid electric powertrain module and propulsor. In response to thrust requirements from the aircraft, the powertrain module distributes power between the range extension generators and the energy storage unit and returns available thrust, range extension generator state(s), fuel burn rate, and storage discharge rate. The aircraft simulation tracks range extension generator operating hours, total fuel burned, and kWh used of storage. Additional information about the powertrain model is provided in the Powertrain section (e.g., elements 1153 and 1154 of FIG. 11).

[0099]

[0118] As described, the FPOP flow chart or flow control diagram shows the sequence of steps in an exemplary implementation of the FPOP process. These typically include: 1. FPOP starts with POCS (1409) and the data required for trajectory generation / optimization may be collected from several sources. a. Pilot-entered flight mode information (1410) is provided by the POCS, which also includes energy state requirements (e.g., level of reserve required upon landing). b. The GPS / FMS provides the original pilot-entered flight route to be optimized (1412), and there may be more than one flight route option (e.g., multiple circular routes, or over terrain). c. Weather information (1414) is uploaded over the data link (ADS-B in). d. The aircraft data bus provides current operational or environmental parameters (1416), including temperature, air pressure, and, if an in-flight update, aircraft position and speed. 2. Data Pre-Processing (1420) converts the wide area weather information into weather indicators (1403) that are interpolated along the flight route (based on latitude, longitude, and available altitude). Similarly, sources of caution (e.g., icing or precipitation) are pre-processed to check for their possible effect on the intended route of flight, and the data is provided to Caution Factors (1405). 3. The FPOP platform is invoked with a fully assembled set of input data (step or stage 1401). 4. The Flight Path Generator (1404) creates a 3D flight path from the provided 2D flight track. The generated path is defined by a set of waypoints (defined by latitude, longitude, and altitude) that are connected per segment (go-around, cruise, descent) with speeds specified for each segment. A library of Route / Performance Heuristics (1407) provides optimal go-around rates, cruise altitudes, and descent rates. The heuristics are calibrated for the aircraft's current weight and energy state. b. The go-around and descent library (1409) uses rates (from heuristics) that provide go-around and descent distances to determine intermediate waypoint locations. c. Intermediate waypoints may be added to conform to airspace constraints (1410), including constraints due to terrain. d. Waypoints are connected with flight segments and speed and range extension generator states are assigned heuristically to every segment. 5. Environmental Assessment (1412) reviews the flight path using a combination of weather and hazard data to determine whether the path is favorable in terms of optimization under real-world conditions. If further optimization is not required or would not be advantageous, the route is provided to the trajectory optimizer (1408). b. If further optimization is potentially advantageous, an Alternate Flight Path Generator (1413) is invoked. i. The breakpoint creator (1414) may add additional intermediate waypoints to the cruise segment based on caution and / or airborne wind sources, which provides more freedom in the optimization space. ii. The altitude of each cruise segment varies from a maximum (set by performance limits) to a minimum (set by constraints). Speed ​​and energy resource utilization are again set by using heuristics. iii. The full set of possible routes is provided to a trajectory optimizer (1408). 6. The trajectory optimizer (1408) varies the cruise speed and power ratio over the trajectory to minimize the objective function within any specified constraints. For each trajectory, the optimizer creates an atmospheric trajectory, an energy plan, and an objective function. Note that if a feasible energy plan cannot be found, the trajectory may be discarded. 7. All feasible routes are sorted by the objective function and the optimal route is identified and returned. The final output (1430) is the flight path and trajectory, the energy plan, the required reserve energy, the arrival energy, and the value of the identified objective function. Flight Simulation Module (Note that these are examples of possible implementations) [Table 3-1] [Table 3-2]

[0100]

[0119] It should be noted that flight path optimization (such as that performed by FPOP and described herein) depends on parameters that affect aircraft efficiency and cost, which vary significantly between conventional and hybrid platforms, as shown in the table below. [Table 4-1] [Table 4-2]

[0101]

[0120] In some embodiments, an optimization process may be performed to generate routes or other heuristics for the FPOP flight path generator, as described herein. Below is a table containing information regarding the differences between optimization processes that may be implemented for the hybrid electric regional air transportation system of the present invention and those that may be used for conventional aircraft and transportation systems. [Table 5-1] [Table 5-2] [Table 5-3]

[0102]

[0121] FIG. 13 is a diagram illustrating an exemplary flight path optimization for an aircraft that may be generated by a flight path optimization platform (FPOP) and used at least in part to control aircraft operations in a regional air transportation system embodiment of the present invention. As shown in the figure, a flight path 1300 may be assembled from one or more segments (such as those identified in the figure by "A", "A.1", "B", "C", "D", etc.), each of which may require a specific configuration of the aircraft and control system to perform properly (e.g., subject to constraints imposed on the aircraft operation (e.g., by distance traveled, fuel (energy) level, fuel consumption, total weight, etc.)). The figure shows an example of a graphical representation of the flight path optimization process in cross section, and therefore only the altitude profile as a function of distance. In this example, the default flight path 1300 is a single origin, single destination route that is broken into multiple segments by the route generation module / function of FPOP.

[0103]

[0122] The initial path (shown by the dashed line) generated by the FPOP module's path generation process is based on the origin (A), destination (D), and altitude constraints for terrain obstacles. This default path results in an initial go-around (segment A-A*), cruise mode at optimal calm altitude (segment A*-B), a segment at higher altitude to avoid obstacles (B-B.1), a return to optimal cruise altitude when obstacle constraints are cleared (segment B.1-C), and cruise to the apex of the drop point (segment C-C.1), followed by a descent to landing (segment C.1-D). The path generation process uses the go-around and descent rate to determine the flight path midpoints (i.e., A.1, B.1, and C.1). Note that the optimal go-around and descent rate, cruise altitude and speed, and generator stop point (shown by a triangle between points C and C.1) are determined by the flight mode and range. For example, a "fast" mode over a moderate range would give the best rate of go-arounds for maximum altitude, which would allow peak power output using the range extension generators for all of the cruise, while an economical mode over the same distance might cruise at a slower speed, lower altitude, and with the range extension generators partially shut down throughout the cruise, completing the flight on stored energy alone. This route is provided to the energy optimization module, which in turn provides it to the route evaluation module of the FPOP. Returning to the exemplary optimization process illustrated in FIG. 13, in some embodiments (and as suggested by FIG. 14), in a typical optimization process, the environmental assessment module / function 1412 should check the weather indicators 1403 and attention factors 1405 for a potential cruise segment and determine whether further optimization should be performed based on wind speed, wind direction or speed changes, etc. (as indicated by the "yes" or "no" branch of the "Refine Route?" decision step 1415 in FIG. 14). The breakpoint creator 1414 first determines whether additional subdivision is needed for the existing cruise legs (i.e., A, B, and C) based on the wind gradient; in this case, the answer is "no" since the wind is constant for each leg (as suggested by the wind speeds W1 and W2 shown in FIG. 13). · Alternate flight path generation module 1413 changes the altitudes at A.1, B, and C, which modifies the locations of flight path points A.3, B.1, C, and C.1. Note that there are a limited number of possible modifications, since aircraft regulations require cruise to occur at incremental altitudes (e.g., every 2,000 feet in the United States). Cruise altitude downwards is set by minimum route altitudes (defined by MEA, terrain, and airspace), while upwards is set by aircraft performance capabilities. The result of this evolution process is a set of potential flight paths. Each potential flight path is analyzed by the flight path optimization module 1408 by performing a flight simulation process to find the lowest energy usage for that path. A path evaluation module 1402 is used to rank the paths, and both the default path(s) and the path(s) that minimize the objective function are returned.

[0104]

[0123] In this example (compared to the default flight path 1300 shown in FIG. 13), the route optimization module 1408 drops the initial altitude to a low limit to avoid the headwind and return at position A.3 to allow sufficient distance for a go-around to B to gain clearance from the terrain obstacle. The altitude at B remains unchanged, but after avoiding the obstacle, the lower cruise altitude at C can take advantage of the tailwind and the apex of the descent point (C.1) can be delayed to the extent that the tailwind can be utilized. The reduced energy usage in the initial segment allows the generators to be shut down earlier (as suggested by the triangle closer to point C in the diagram).

[0105]

[0124] The table below shows each waypoint in the optimized route, the source of the intermediate waypoints, the desired altitude and speed(s) for each leg, and how the optimization process modified the original default flight route. In the table, the speed and / or altitude of the A.2, B, B.1, and C waypoints have been optimized. The table also lists how the speed was determined for each leg. Note that the legs that have been optimized for altitude are also optimized for speed. [Table 6]

[0106]

[0125] As described, flight path planning for a regional hybrid electric aircraft with multiple power sources requires more complex tradeoffs than a conventional aircraft over long ranges. For example, the optimal flight altitude is determined by a combination of speed vs. efficiency goals, flight distance, airborne weather, aircraft aerodynamics, available energy, and the relative energy conservation vs. range-extending generator or alternative power source usage. The FPOP process enables this optimization both pre-flight and in-flight as conditions change to determine the optimal flight path(s).

[0107]

[0126] As described herein, in some embodiments, an FPOP platform or system for a hybrid electric airplane may have the following characteristics and / or perform the indicated functions: Generate one or more flight paths optimized for the flight mode and that meet the aircraft and environmental constraints (e.g., final energy state, and airspace restrictions). The determined or revised flight path may be uploaded to the FMS (shown in Figures 3 and 4) to be executed by the pilot or autopilot. Flight planning for regional hybrid electric aircraft with multiple energy sources requires more complex trade-offs than conventional aircraft, and flight safety is also more critical due to the complexity of using multiple source energy reserves. Aircraft performance over a mission is inherently nonlinear and is typically addressed using several levels of dynamic programming (e.g., simulation) coupled with optimization methods (e.g., energy methods to minimize total flight energy). Hybrid electric performance introduces an additional level of complexity in which energy contributions come from multiple sources, which are physically unique (either energy sources or power sources), and which may not be continuous with respect to time or cost over a flight. This results in a complex optimization process that cannot be addressed by conventional flight path planning. As described, a Flight Path Optimization Platform (FPOP) for a hybrid electric powertrain typically uses a two-step process: (1) flight path definition to set a comprehensive flight profile including cruise altitude, followed by (2) optimization within the current operating environment. Flight path definition may occur at one or two levels depending on environmental conditions. -Level 1: Initial definition of a 3D flight path using heuristics to provide optimal altitude, cruise speed, and energy planning for the desired range and flight mode. If the flight environment is relatively simple (low winds, no cautions or hazards), Level 1 is typically sufficient. -Level 2: Called to generate an alternate route when winds or cautions adversely affect the Level 1 route. Varies the altitude(s) of the Level 1 flight path cruise segment(s) to generate a set of corrective routes. · Optimization is performed for each flight path by adjusting the cruise speed and energy plan (power ratio) to minimize the objective function within the constraints, while taking into account the current operating environment (weather and aircraft conditions). The results are the atmospheric path, the energy plan, and the value of the objective function. In case of multiple flight paths, the path with the lowest objective function is returned as optimal.

[0108]

[0127] Compared to conventional aircraft operating on long-haul flights, the flight profile of a regional hybrid electric airplane is significantly more complex, with many more options for speed and altitude, and using multiple energy sources that respond differently to altitude and power demands, and have different costs. As part of this innovation, the inventors have recognized that conventional aircraft flight planning is inadequate to provide safe and efficient flight paths for hybrid electric airplanes, and that there is a need to provide this capability to ensure flight safety and reduced pilot workload. The implementation of the FPOP platform / system of the present invention is based on the inventors' recognition of the operational and optimization differences between hybrid electric powertrains and conventional aircraft powertrains. These differences or distinguishing characteristics include: · Traditional long-range aircraft use a limited set of prescribed go-around and descent profiles and cruise at altitudes between 31,000 and 40,000 ft. Cruise altitude is easily determined from airborne wind and air traffic requirements, and "optimization" is generally not much different than adjusting speed to adjust for fuel costs. Regional aircraft spend a much larger percentage of their flight path / time in go-arounds and descents, and cruise altitudes vary widely depending on range, weather, terrain, and air traffic control. Nevertheless, optimal cruise efficiency for traditional regional aircraft typically relies on go-arounds to the highest altitude practical given cruise range. Energy planning in a conventional aircraft is the process of ensuring that more fuel is available than is typically required for the flight. Fuel burn is calculated from the planned flight segments and the required reserves (expressed as time, or time + diversion to alternate). The calculation is done by the pilot or the FMS using a system of table lookups of aircraft weight, cruise altitude, and speed. Cruise speed is chosen between high speed cruise (maximum power) or long range cruise (best economical) depending on the time available and the cost of fuel. · Conventional aircraft engines lose power with altitude, and even "full power" (i.e. full throttle) flying does not deplete fuel reserves very quickly. Traditional flight path optimization is typically based on a simple ratio of fuel cost to operating cost. For example, some aircraft manufacturers call this the "cost factor", and a single number is set by the operator, which the aircraft FMS uses to set go-around speed, cruise speed, and apex of descent. In contrast, hybrid-electric regional aircraft are efficient over a wide range of altitudes, their cruise speed is determined by energy rather than available power, and their total cost vs. energy costs are more complex. Cruise altitude primarily affects speed and available power source / range extension generator power (this affects range for a given speed). Due to the much smaller change in efficiency, the optimizer will choose a higher altitude for speed (minimizing total cost) than for energy efficiency (opposite to conventional flight planning). Energy planning is significantly more complex with two / multiple energy sources having different operational characteristics. a. Stored energy provides a wide range of power output independent of altitude or speed, but has a relatively limited amount of energy. Stored energy can suffer from efficiency loss as a function of power output, effectively reducing the amount of stored energy when operating at high discharge rates. b. Range extension generators provide constant power output with total energy limited by available fuel. Range extension generator power and efficiency may vary with altitude. c. Sufficient reserve energy must be identified for each source to ensure that safe flight is maintained at all times. Cruise speed range resulting from maximum energy, as a function of range (total stored energy available for cruise + power generation * time), and minimum energy; cruise speed is set to match the target's future energy state. Electric propulsion does not lose power with altitude, so a pilot who continues to fly at full power at high altitude will experience a much more rapid depletion of stored energy than a conventional pilot would expect. Flight trajectory optimization trades the total cost of energy and power (cost of stored energy + cost of generated energy) against flight costs. The difference in cost of stored energy vs. generated energy extends basic optimization to include energy procurement optimization (e.g. POCS hybrid energy planner feature).

[0109]

[0128] As part of creating the inventive aircraft and regional transportation system, the inventors developed a process or set of processes for the design and optimization of a forward compatible hybrid electric airplane. The design process includes powertrain component sizing, propulsion integration, wing sizing, and noise reduction, which collectively resulted in an aircraft with 60-80% less direct operating costs, 20-30% shorter runway capacity, and 15-25 EPNdB less noise than conventional aircraft. Additionally, forward compatibility ensures that the aircraft can be adapted to future EV / hybrid technologies via relatively simple upgrades of specific powertrain modules. As a result, embodiments of the inventive aircraft are expected to remain competitive over the targeted lifespan of the aircraft, offering improved performance and lower costs with modular upgrades. Additionally, the same or similar processes can be used to develop variants of the aircraft with different performance capabilities tailored to specific markets (via selection of powertrain modules without any changes to the external airframe or propulsors). This allows for the development of aircraft optimized for specific markets with minimal engineering and recertification requirements. This set of design and optimization concepts and processes for aircraft that may be utilized as part of the regional air transportation system of the present invention will be described in further detail with reference to Figures 15 and 16. It should be noted that traditional aircraft design processes cannot size hybrid electric powertrain components, ensure that aircraft and powertrains can keep up with rapidly evolving EV / hybrid technology, or fully exploit the unique advantages of electric propulsion including breakthrough efficiency, short takeoff and landing capabilities, and quiet operation.

[0110]

[0129] 15 is a flow chart or diagram illustrating a hybrid electric airplane design process that may be used in implementing an embodiment of the air transportation system of the present invention. In some respects, the overall flow is similar to conventional aircraft design, but certain steps (shown in bold) are modified or entirely unique to the hybrid electric design process. The following table provides a description of each of these modified steps compared to the conventional process.

[0111]

[0130] The flow chart of Figure 15 illustrates the major components in the aircraft design cycle of the present invention. Aircraft design is a highly iterative process due to the interdependence of the primary design parameters of weight (payload, fuel, and aircraft), propulsion power, and primary structural sizing (wings, tail, landing gear, etc.). Note that the operations or processes shown in bold are those significantly influenced by the hybrid electric powertrain and its use as part of the regional air transportation system of the present invention. 1. The design process begins with top-level design requirements (step or stage 1502), including payload, cabin size, cruise speed and range, maximum altitude, takeoff and landing runway performance, and noise and cost requirements. 2. Weight is the single most important driving force in aircraft design. Maximum weight directly impacts required engine power, wing size, and structural weight, as well as required cruise power (energy). Each design cycle begins with an update to weight (step or stage 1504). 3. Based on maximum weight, the aircraft wing and tail sections are sized and a rough performance analysis is used to determine the required thrust power and energy capacity to meet range and speed requirements. The aircraft configuration also lays out the locations of the major components, wings, tail, landing gear, etc. (step or stage 1506). A unique aspect of hybrid vehicles is the powertrain component sizing that takes into account the amount of stored energy and power output capacity (step or stage 1507). The three-tier design process described herein uses scope and speed in combination with cost to provide the necessary requirements and constraints for this function. 4. From the dimensioning and configuration, weights can be accumulated from a series of models and component weights (step or stage 1508). For example, parametric weights for wings estimate a typical weight from the geometry taking into account thickness, span, area, sweep, and taper, while engines and landing gear are typically fixed and component weights are provided by a supplier. 5. The sum of all aircraft weights results in the empty weight, and if the empty weight + payload weight + fuel weight + stored energy weight exceeds the maximum weight, the relevant part of the design process is performed again using the updated weights. 6. Performance modeling (process or step 1510) is now used to estimate aircraft performance, which involves the application of representative aerodynamic and propulsion models using the weight, configuration, and powertrain information produced from the sizing process. 7. Note that hybrid electric propulsion requires two separate models, one for the propulsor and one for the powertrain (step or stage 1511). a. The propulsor model combines the motor sized in step (3) with the aerodynamic properties of the propulsor (e.g., propeller) to calculate the power required for a particular thrust level. b. The propulsor model determines the available thrust based on the powertrain model and includes the stored energy unit and generator. The powertrain model determines the maximum available power output, as well as the ratio of storage to generation for a given power requirement, the storage discharge rate, and the fuel burn for the range extension generator. 8. The lift and drag models are based on the configuration geometry (step 3) and allow performance calculations for various configurations including cruise, takeoff, landing, flaps up and down, gear up and down, speed brake configuration, etc. Note that electric propulsors may use regenerative braking in place of conventional spoilers. 9. Performance modeling employs physics-based models that may include numerical approximations and time-stepping methods to calculate time, fuel, energy, distance, and altitude changes for each step. The performance model may be modified from the previous version to control and track both the propulsor and powertrain models, including controlling the generator on / off, tracking fuel burn and run time, and use of stored energy. b. Costs may be calculated by applying the performance model to representative flight paths and applying cost values ​​to the aggregated totals of time, fuel burned, and stored energy used. 10. Here performance is checked against design requirements and deficiencies require design changes and another design cycle (step or stage 1512).

[0112]

[0131] The following table provides a description of certain modifications to the traditional aircraft design process that have been developed by the inventors for the hybrid-electric design process along with a comparison with the traditional process. [Table 7-1] [Table 7-2] [Table 7-3] [Table 7-4] [Table 7-5] [Table 7-6] [Table 7-7] [Table 7-8]

[0113]

[0132] Please note that at least the following are indicative of the modifications developed by the inventors for the hybrid-electric design process over the traditional aircraft design process. ·Design requirements are extended to allow sizing of major powertrain components in a manner that ensures compatibility with EV technology over the target life of the aircraft. This is accomplished using a set of three tiers of ranges and speeds for electric, hybrid, and extended cruise flight as described above that are specified across the range of future EV technologies. An example of this approach is shown in Figure 17, with regional operations representative of expected performance 15-20 years into the future and ranges and speeds for three levels of powertrain technology. In contrast, traditional design requirements are for a maximum speed and range target using a particular engine that typically remains fixed for the life of the aircraft. Wing design requirements and constraints are extended to match the three tier ranges and speeds. · The wing design is a weighted multi-point optimization to construct variants across a set of three tiers of range and speed that have maximum cruise efficiency at the optimum hybrid speed, and also very good efficiency for go-around, electric-only, and extended range cruise speeds. Conventional wing designs are typically focused on narrowly defined long range cruise conditions. Takeoff performance is typically a constraint on minimum wing size, and this is mitigated to some extent by the high peak power capacity from the electric propulsion motors. Peak power can be applied to balanced runway sizing requirements, and also regains much of the thrust lost after a propulsor failure, and dramatically reduces the "engine out" distance for a go-around. This results in a smaller wing for a given runway requirement, and more efficient at cruise. This is not available with conventional engines, and is limited to a maximum of 10% peak power increase for emergencies. Additional minimum wing size constraints unique to hybrid electric propulsion may be added to the design process to ensure flight operations can continue safely with reduced powertrain output capacity after the failure of any one energy source. · Propulsion system sizing includes both thrust production (thrust motors) and hybrid electric power generation (stored energy and power output), whereas traditional approaches only size thrust production. · Propulsion motors are typically sized by single-point performance criteria, the three most common being takeoff distance, peak go-around performance, and maximum cruise speed. Electric motors affect these sizing points. Takeoff power can be used for a limited period of time at peak power significantly higher than maximum continuous. This allows a smaller motor to meet the same takeoff requirements. The motors do not lose thrust with increasing altitude. As a result, electric aircraft are rarely power-limited at the apex of a go-around or during cruise. This combination of features allows for the selection of smaller motors, which may result in the aircraft being able to sustain the go-around ratio less than expected, leading to an additional sizing set point for the minimum sustained go-around ratio. · Hybrid powertrain output components are sized for stored energy and power output cannot be based on point performance conditions. Instead, they are sized using performance modeling over a set of mission profiles defined by three-tier range and speed requirements including future technology levels. Sizing is determined by minimizing an objective function for safety within the constraints of available system weight, volume, and minimum power from any source. The objective function may include one or several of the following terms with parameters defined by the operator: Exemplary objective function = Cost of fuel + Cost of stored energy + Cost of engine maintenance and reserves (amortized) + Cost of battery packs (amortized) + Cost of passenger and crew hours + Cost of aircraft + Cost of emissions. · Electric propulsion integration separates the available propulsive power (motor) from the thrust generating propulsor (blower, propeller). Designers size the motor power level with an assumed efficiency, and the propulsor is designed to the specification. This functional separation is made possible by electric motors that operate efficiently regardless of size, and are easily integrated with propellers, rotors, ducted fans, etc. In contrast, conventional propulsion engines are monolithic units that combine power and thrust generation, and once selected, route the aircraft design along only a few viable paths for integration (e.g., commercial jets always have the engines under the wing). By way of example, the embodiment shown in Figure 16 features three ducted fans for low noise and enhanced takeoff performance, with noise further reduced by shielding from the fuselage and tail. Enhanced drag reduction is achieved through clean, laminar airfoils, fuselage boundary layer intakes, and a shorter, lighter fuselage with fill from the ducted fans in the wake. · Propulsion models used in performance modeling are enhanced for the hybrid electric design process to represent the ability to store energy from thrust and thrust, power generation from multiple sources, system efficiency losses, non-propulsive power used, and regenerative braking. In contrast, traditional propulsion models are simpler and typically represent the engine by providing thrust and fuel burn for the current flight conditions. The motor model used in the system and method of the present invention provides power consumption as a function of torque, RPM, and controller losses. The model also indicates the motor's capability for time-limited peak power. The output generation model used in the system and method of the present invention represents the characteristics of each source and the losses due to transmission and conversion. For example: Stored energy is not altitude or speed dependent and can be drawn at a wide range of power levels. However, high discharge rates are inefficient and reduce the total energy available, and peak power decreases as the stored energy level decreases. · Generators consume fuel at a constant level to provide power. In contrast, in conventional models, power output and fuel efficiency are typically altitude dependent. Efficiency factors are specified for losses in power electronics and wiring. Propulsion models may include the availability of regenerative braking using propulsors to recharge stored energy during descent, including losses from motor and controller efficiency, power transmission and conversion, and stored energy charging efficiency. ·Performance modeling methods are enhanced to separately control and track power output (and output generation). Traditional performance methods control engine power output and also track fuel burn. In a hybrid-electric powertrain, the model controls motor power output, range extension generator state (on / off / output), stored energy output (charge or discharge), and also tracks stored energy used, fuel burn, and range extension generator operating time (which is different from flight time). These modifications to the methods are necessary to analyze hybrid electric airplane performance and also use performance modeling for sizing and optimization of powertrain components. · Performance modeling methods may be further enhanced to incorporate powertrain operation rules such as "stored energy first" and "power generation off during descent".

[0114]

[0133] The range-optimized hybrid electric airplane of the present invention, designed for maximum efficiency in regional operations, may incorporate one or more of the following features, techniques, aspects, or elements, which collectively enable a 60-80% lower DOC than conventional aircraft. ·Energy storage unit capacity and range extension generator power output are optimized across the range for maximum efficiency. This results in a 60-80% lower DOC than conventional aircraft through the stored energy unit at 12-20% of the aircraft's maximum weight, and the range extension generator operating at less than 70% of the powertrain's maximum continuous power output. This contrasts with less efficient or pragmatic designs for hybrid aircraft that focus on longer range, and obtain less than a 30% reduction in DOC than conventional aircraft, based on lower stored energy capacity and higher generator power output. The aircraft is designed to minimize an objective function across the three-tier requirements, weighted primarily towards the hybrid cruise requirement (B). The objective function may include one or several of the following terms with parameters defined by the operator: Objective function = Cost of fuel + Cost of stored energy + Cost of engine maintenance and reserves (amortized) + Cost of battery packs (amortized) + Cost of passenger and crew hours + Cost of aircraft + Cost of emissions. The previously mentioned three tier set of speed and range design requirements are used for powertrain and aircraft design, an example of which is shown in Figure 17. In one embodiment, the tiers are defined by: Range A: Highest efficiency (80+% lower DOC than conventional aircraft) and optimum speed over the electric-only range. Range B: Medium efficiency (60-70% lower DOC than conventional aircraft) and optimal speed over a wider hybrid range Range C: Good efficiency (30-60% lower DOC than conventional aircraft) and lower speeds up to a maximum range beyond these determined by on-board stored energy and fuel minus safety reserves. As an example of the design process of the present invention, the table below compares fuel burn for each phase of a regional flight between a conventional turboprop and a range-optimized hybrid-electric. Note that for the entire flight, the hybrid fuel burn is 72% lower than the turboprop, due to a reduction of nearly 90% during takeoff and go-around, 67% during cruise, and 88% during descent and landing. [Table 8] · The aircraft of the present invention is designed for efficient operation at lower altitudes, targeting 50-90% lower fuel burn than conventional aircraft. As noted, regional operations typically involve a higher percentage of flight time in go-arounds or descents, and also cruise at lower altitudes compared to conventional long-range aircraft. This places a much greater focus on operational efficiency during these phases. Thus, the hybrid electric airplane of the present invention is designed for 70-90% lower fuel burn than conventional aircraft in go-arounds and descents, and 50-80% lower fuel burn at cruise altitudes between 4,000 and 30,000 feet, and speeds of 150-400 miles per hour. In some embodiments, this is achieved by one or more of the following: Propulsion by electric motors that provide high efficiency independent of altitude or speed, and consume no energy when unloaded. In contrast, aircraft gas turbines suffer from 30-50% lower efficiency at lower altitudes and speeds, and require minimal fuel burn even at flight idle. · The aircraft is designed to maximize flight possible with stored energy units, assuming a lower total cost for range-extending generators. This translates into exceptional low altitude, low speed performance, and assumes stored energy units, e.g., battery packs, offering very high conversion efficiency independent of altitude or speed. This is in contrast to aircraft engines, whose fuel efficiency is highly altitude and speed dependent. Pairing of propulsion motors with low pressure controllable pitch propellers or ducted fans designed for high efficiency over the low and medium speed ranges (e.g., 150-300 miles per hour) typical of regional operations. These offer much higher efficiency than conventional turboblowers, especially on go-arounds or in low altitude cruise. The aircraft will be designed for very high efficiency during operations near the airport (e.g., taxiing, takeoff, approach, landing), with a target of reducing fuel burn by more than 90% compared to conventional aircraft operation in these modes. Taxiing, approach and landing are designed to be electric only, utilizing highly efficient stored energy units. Unlike the minimum fuel burn required for aircraft gas turbines, a hybrid electric aircraft will not consume fuel during these phases, assuming the generators are switched off. The descent is designed to fly on zero energy with the generators switched off, unlike conventional aircraft engines which require sustained fuel burning during idle. The steeper descent is made possible by regenerative braking of electric propulsors, which allow for energy recovery, as opposed to the use of drag-generating devices such as spoilers on conventional aircraft. The takeoff uses a combination of stored energy units and generators, which translates into much lower fuel burn than conventional aircraft. The aircraft will be designed for quiet, short take-off and landing (STOL) operations, with operating noise levels 15-25 EPNdB lower than conventional aircraft, and will require runways 20-30% shorter, both with minimal impact to cruise efficiency. ·Aircraft will be designed for noise levels below 15-25 EPNdB as measured by standard 14 CFR Part 36 standards. This will be achieved by design to limit and control noise emissions across the three primary sources of aircraft noise (electrical power generation, thrust generation, and airframe). · Generator noise would be significantly reduced assuming the use of electric propulsion motors and energy storage units that do not generate significant noise, while the range extension generators would be scaled down to less than 70% of maximum continuous power and housed within a soundproof chamber within the aircraft (e.g., recessed within the aft fuselage). Thrust-generated noise is significantly reduced by the use of low-noise controllable-pitch propulsors (such as low-RPM, quiet propellers or controllable-pitch ducted fans). Additionally, the propulsors may be integrated into the aircraft in a manner that shields the noise from propagating to the ground, for example using flying surfaces on the aircraft wings, fuselage, or tail. Aircraft noise is significantly reduced through regenerative braking using low-noise propulsors instead of conventional spoilers. Aircraft operations may be optimized for further noise reduction by leveraging the unique capabilities of hybrid electric powertrains. - Silent taxiing, descent and landing with generator switched off and energy storage unit. Shorter ground runs and steeper go-around angles over noise sensitive areas reduce take-off noise. This is made possible by the high peak power capability of electric propulsion motors and the use of low noise ducted fans for high static thrust. Approach and landing noise is reduced by a rapid, controlled descent with regenerative braking using controllable-pitch electric propulsors. To achieve this without the typical performance losses, the aircraft and associated flight operations will be designed for the use of runways that are 20-30% shorter than conventional aircraft by leveraging the capabilities of the hybrid electric powertrain. Similar STOL performance would require larger wings and engines in conventional aircraft, resulting in reduced efficiency and payload. The design achieves thrust boost during takeoff by leveraging the peak power capability of the electric propulsion motors, thereby enabling STOL operation without the need to upsize the motors (e.g., 20% boost for 2-4 minutes above continuous power during takeoff and initial go-around). ·The design achieves a shorter balanced runway without larger wings or engines. The "balanced runway" calculates the maximum runway required after an engine failure during takeoff and balances the distance required by either stopping on the runway or continuing the takeoff on the remaining engines up to above the obstacle clearance height (FAA standard is 35 feet or 50 feet). The balanced runway (and therefore the required runway) is governed by the remaining engine(s)'s go-around rate (which is dramatically reduced after failure by boosting up to 200% of the non-failed propulsor upon partial or complete failure as part of the novel system) and the stopping distance (which is reduced by quickly reducing thrust to zero or negative (reverse thrust)). Fault detection and compensation thrust boost is automatically managed by the inventive Powertrain Optimization and Control System (POCS). In conventional aircraft, similar thrust overboost systems are limited to less than 10% boost, while stopping distances are hindered by spool down time and residual thrust from the surviving engine. In the event of partial or complete propulsor failure (e.g., due to a bird strike or the loss of one or more propulsor motors in flight), the POCS compensates by boosting the power of the non-failed propulsors for a limited period of time, thereby allowing the pilot an extended response window to take corrective action and provide a safe descent to the nearest airport or landing area. Unlike the limited boost capability of conventional aircraft engines, electric propulsion motors can be boosted up to 200% of their continuous power for a limited period of time, typically determined by the thermal limitations of the system. A controllable pitch propulsor coupled to an electric motor allows for very rapid reduction of thrust to zero, which means shorter stopping distances than aircraft gas turbines when spool down times and thrust residual effects are taken into account.

[0115]

[0134] As described herein, the aircraft and design process of the present invention are intended to provide forward compatibility across the airframe, powertrain and propulsion system(s). This is accomplished by incorporating several underlying principles or design guidelines. · The aircraft is designed to accommodate upgrades to future EV technologies over the life of the aircraft, including improved flight performance enabled by the upgrades. Given the rapid innovation in EV technology, this capability ensures that the aircraft remains competitive over time as technology (e.g., batteries, supercapacitors, electric motors, internal combustion engines, fuel cells, etc.) advances. Additionally, this capability allows for a smooth transition of the aircraft from hybrid-electric to all-electric as energy storage technology improves to the point that range-extending generators are no longer necessary. The ability to upgrade hybrid-electric powertrain components for rapid changes in performance improvements is unique to the hybrid electric airplane of the present invention and contrasts with conventional aircraft that have mostly monolithic engines. · To ensure forward compatibility, the hybrid electric airplane of the present invention is extensively designed with a powertrain sized for speed and the stated three-tier range requirements (A), (B), and (C), but based on the technology available at the time of launch of the aircraft and expectations of what will become available over its target life (including a potential transition from hybrid-electric to all-electric for some designs). This leads to expectations for the installed powertrain, which in turn determines performance characteristics over time (such as speed, electric and hybrid range, and operating costs) (including expectations of increased electric range and reduced operating costs as technology advances). · The aircraft is designed for multiple individual powertrains, reflecting the anticipation of upgrades to improved EV technology across the target design. For example, these may include changing the energy storage density from 300Wh / kg to 1,200Wh / kg, changing the motor power density from 4.5kW / kg to 10kW / kg, and changing the internal combustion engine power density from 1kW / kg to 5kW / kg. The aircraft design cycle is repeated for each of the individual powertrains by adjusting the three-tier range and speed requirements for the incrementally improving EV technology. In the example shown in the table below, each column represents an individual powertrain based on EV technology available at a future point in time. For each individual powertrain, speed and range design requirements (A), (B), and (C) may be determined by minimizing an objective function (e.g., DOC+I+COT). These individual requirements define an envelope over the service life of design points including speed, range, and altitude for which the aircraft must be designed over its target life. [Table 9] The airframe and propulsors are designed to operate efficiently over this lifespan flight envelope, and typically scale to fly faster and higher over time, as energy storage technology advances (as shown in Figure 17). One outcome of the design process described herein is the recognition that forward compatibility typically limits the weight of rechargeable energy storage units to 12-20% of aircraft weight, which keeps payload capacity roughly flat even as EV technology improves. A higher weight percentage will result in a larger and heavier aircraft than aircraft of similar payload in the initial years, but over time as payload increases the percentage will become lower, leading to suboptimal efficiency given the much greater use of range-extending generators.

[0116]

[0135] As described, in some embodiments, the hybrid electric airplane of the present invention is designed to incorporate a modular hybrid electric powertrain, including features to ensure that the powertrain can be adapted to various EV technologies by relatively simple swapping of compatible modules (such as rechargeable storage units, range extension generators, and electric motors). This may be accomplished by designing the airframe with bays to accommodate various current and anticipated modules, along with access for module swapping. The compatible modules are designed for operation with the powertrain platform, and are aided by the aircraft design. These may include standard and extended energy storage units, high and low power range extension generators, and alternative energy storage technologies. Such features may include the following: Multiple bays designed to house rechargeable energy storage units (standard or extended), all of which may not be utilized on any particular flight and some of which may be multi-use space (e.g., generators, storage units, fuel tanks, or cargo). Each bay provides structure, wiring, and access to allow for rapid installation or removal of storage units. These may include combinations of the following (some of which are shown in Figure 5): Wings inner, standard & extended. -In aerodynamic pods on the exterior of the wings. -In the center fuselage, located below the main cabin. In the aft fuselage, in addition to or instead of generators or cargo. Modular energy storage bays may be integrated directly into the primary aircraft structure (e.g., wing spar boxes), such that the modules serve the dual purpose of energy storage housing and primary load path. The presence of energy storage units in the modules may further strengthen the primary structure for increased structural efficiency and reduced weight. Energy storage units or other systems requiring cooling may utilize the skin of the aircraft to remove heat. This cooling may occur through passive contact or may be enhanced through the circulation of a refrigerant between the heat source and heat rejection coils in contact with the skin. Range extension generators may be incorporated into modular bays designed to accommodate generator replacements, generator upgrades and removals, and the bays may be used to accommodate energy storage units instead of or in addition to generators. This may be accomplished by sizing the bay and providing access, structural support, and supporting infrastructure (e.g., fuel lines, cooling, wiring, etc.). The generator bay may be located in one or more of several locations: -Fuselage bay aft of main cabin. -Wing mounted nacelles. -Non-structural fairing. · Propulsors are designed for upgrades to higher efficiency or higher power motors, which may include new blowers. Unlike conventional engines, this is accomplished with minimal (re)engineering.

[0117]

[0136] It should be noted that the modular nature of the hybrid electric powertrain allows for easy variants of the aircraft with performance tailored to different markets. The separation of thrust generation (by electric propulsors) and power generation (by hybrid electric powertrain) allows for the development of aircraft variants with widely varying performance through the adaptation of powertrain modules to the application, possibly coupled with propulsor modifications. This allows for the development of aircraft with widely varying performance, speed, range, and operating costs based on the choice of powertrain modules and propulsors. Given the limited impact on the handling and maximum weight of the resulting aircraft, the required (re)engineering and certification is modest. This is in contrast to conventional aircraft where variants require significant engineering and certification modifications. In some embodiments, the development of aircraft variants may be performed by the following process: Hybrid electric aircraft variants may be developed by modifying a baseline aircraft through a condensed aircraft design process that focuses on access, interior layout, pressurization, cockpit, and performance. In such cases, the following steps / phases may be used to design the variant: ·Define interior configuration and payload requirements. Define the cockpit configuration (e.g. manned systems with preparation for future unmanned operation). The following types of aircraft control may be supported: - Completely pilot limited. Pilot Control with Remote Backup - Primary control by one or more pilots on board the aircraft, with secondary control by a remote pilot. Remotely Piloted - Has primary control by a remote pilot, with or without a secondary pilot on board. Fully Autonomous - Has primary flight without human control and may have secondary control by a remote or on-board pilot. Identify performance requirements, including technology level differentials, for target market scope and operating conditions (such as the three tier (A), (B), and (C) scope / design requirements described herein) and optimize the powertrain to meet those requirements using mission analysis with baseline aircraft aerodynamics and propulsion.

[0118]

[0137] The following are examples of aircraft variations that may be designed and implemented using the methods described. Example 1: Commercial Variants · The cabin is configured for economy seating, allocation of passenger baggage in accordance with commercial airline standards. Baggage space within the cabin and baggage compartment interior. A control system, configured for at least one pilot, with a remote pilot as a backup, and optionally with a second pilot if needed or as a trainee. The upper range limit is the point at which passengers switch to commercial jet travel as it is more time and cost efficient. Extended range operations are rare. Market segment is highly sensitive to (DOC+I) and less sensitive to COT, hence those with range extension generators (e.g. TDI) which have lower cost along with lower design speeds will be matched. Pressurization to lower altitudes, except for variants used for very short legs (less than 200 miles). The sample speeds, ranges, and resulting powertrain configurations shown in Figure 17 are representative of this class of aircraft. Example 2: Business variants · The cabin is configured for business seating and baggage allocations higher than commercial airline standards. Baggage space within the cabin and baggage compartment interior. A control system, configured for at least one pilot, with a remote pilot as a backup, and optionally with a second pilot if needed or as a trainee. · Use less scheduled routes, extended ranges more frequently. · Extremely sensitive to COT, less sensitive to (DOC+I), variants may be adapted to higher power extended range generators (e.g. aircraft gas turbines) which coincide with higher design speeds and altitudes for extended range cruise, and pressurization for intermediate altitudes. Example 3: Cargo variant No pressurization or furnishing of cabins. The control system is configured for pilot-driven flight with remote pilot control for the unmanned legs. Speed ​​and range are specific to targets in the gap between ground transportation and commercial aviation, typically at intermediate speeds between 200-700 mph. · Market segments are highly sensitive to (DOC+I) and have little interest in COT, and therefore will accommodate lower cost range extension generators (e.g. TDI) matched to lower design speeds unless necessitated by longer range requirements.

[0119]

[0138] As described herein, the aircraft of the present invention is designed for safety and fault tolerance beyond aviation requirements (FAA and EASA) through a powertrain built for graceful degradation. This includes the ability to withstand failures in the power source (energy storage units, generators), motors (propulsion, generators), converters (inverters, rectifiers, DC-DC converters), distribution (bus, wiring), and controls (sensors, communications), as well as safety in the event of moderate or severe shocks to the systems.

[0120]

[0139] The aircraft and powertrain operation of the present invention are designed for optimal efficiency over a geographical area, which results in part from a flight path optimization process implemented by the FPOP and the operation of the powertrain for optimal efficiency, and may further include energy recovery through regenerative braking, and center of gravity adjustment for drag reduction through the positioning of stored energy. These aspects are described further below. Flight efficiency is improved through the hybrid electric aircraft's unique flight path optimization capabilities, which include flying efficiently at low altitudes and utilizing stored energy first. Optimization is achieved through the Flight Path Optimization Platform (FPOP) described herein. This contrasts with traditional flight path optimization, where efficiency is highly dependent on altitude and there is little opportunity to modify the flight path other than by flying as high as possible. During the optimized flight path as described herein, the powertrain is operated for optimum efficiency. As described herein, the powertrain is designed for energy recovery via regenerative braking of the propulsors. Conventional aircraft have no way to recover energy from drag producing devices such as spoilers. · Stored energy units within the fuselage may be used to adjust the aircraft center of gravity (CG) to simplify loading and reduce drag in cruise mode. Aircraft payload weight should be distributed so that the CG is within an established envelope close to the center of lift, and within the envelope, aircraft drag is reduced by moving the CG aft. The ability to adjust the CG location relatively quickly can increase operator efficiency by speeding up the loading process and also reduces drag. · CG movement using the stored energy unit may be accomplished by providing a series of bays along the fuselage and selectively utilizing only the forward or aft locations. Another implementation mounts the energy storage unit on tracks, allowing it to translate forward and aft when commanded by the pilot or flight control system. Conventional aircraft may have some ability to shift the CG by selective use of different tanks in the fuel system, but once fuel is burned in flight the advantage is reduced and typically lost.

[0121]

[0140] The following table contains certain parameters for an example hybrid electric airplane designed according to the principles and processes described herein. The four figures in FIG. 16 show a concept 40-passenger / seat regional hybrid electric airplane designed using the HEV aircraft design process of the present invention. The overall dimensions and weight are similar to a conventional ATR-42-500 (48 seats, twin engine turboprop). Given the energy requirements, the aircraft design is based on battery energy densities ranging from 600Wh / kg to 900Wh / kg. These allow for an electric range of 170-280nm, a hybrid of 425-500+nm, and a cruise altitude of 18,000-25,000 feet at a minimum cruise speed of 380KTAS.

[0122]

[0141] It should be noted that the aircraft illustrated in FIG. 16 depicts one possible configuration for an aircraft that meets the stated general requirements. In this embodiment, three integrated electric ducted blower propulsors are used to provide thrust, and the location on the aft fuselage reduces drag and wake momentum loss recovery through boundary layer intake. A pod at the base of the vertical stabilizer houses the gas turbine generators, and the intake and exhaust are faired over when the generators are not running to reduce drag. The subcritical cruise Mach allows the use of a lightweight straight wing, and the location of the propulsors on the tail allows for short, lightweight landing gear. Noise reduction may be achieved through a quiet ducted fan, with additional reduction by mounting it above the fuselage and between the tail to block most of the blower noise. The weight, dimensions, and performance of the designed aircraft are shown below, including improvements enabled by future higher energy density batteries. [Table 10] [Table 11] [Table 12] The table shows some of the unique aspects of the hybrid electric design. Fuel burn and fuel capacity are less than half of their conventional equivalents. Cruise performance is given at two levels of stored energy (600Wh / kg and 900Wh / kg) and improvements in this level are expected depending on advances in energy storage technology over the aircraft's operational life of 4 to 8 years. Finally, maximum cruise speed is much higher than could be expected with propulsion motors retaining full power at altitude.

[0123]

[0142] As mentioned, FIG. 17 is a diagram illustrating the efficiency of a given aircraft and propulsor configuration as a function of flight altitude and power required. The curve illustrates how an energy (not power) limited aircraft can cruise at successively higher speeds and altitudes with increasing energy limitations. The envelope stretches from an initial cruise speed of around 200 KTAS with an initial energy storage density of around 350 Wh / kg, increasing to over 260 KTAS as storage density improves to 900 Wh / kg, a projected change of 2.6 times over about a decade, assuming the current rate of improvement in energy storage technology. As part of this innovation, it is recognized that this performance improvement will only be available to operators if higher speeds and altitudes are included as design points from the beginning of the design process (as would be done with conventional propulsion, rather than limiting initial performance).

[0124]

[0143] FIG. 18 is a diagram illustrating several regional zones and associated airports or landing areas that may be used as part of implementing an embodiment of the regional air transportation system of the present invention. As shown in the figure, each regional zone (e.g., "Pacific Northwest", "Pacific Southwest", etc.) may include multiple landing fields and / or formal airports (represented by dots within the region). It should be noted that each regional zone may include dozens to hundreds of potential airports or takeoff / landing locations for aircraft of the present invention, and may also include locations that are regional hubs or other forms of central focus. The control aspects of the regional air transportation system may be located in one of several data centers or scheduling / flight monitoring facilities. Such facilities may operate individually and / or collectively to schedule flights at multiple airports, create flight plans / routes and corresponding instructions for one or more aircraft, communicate such instructions to one or more aircraft, and monitor flights and their flight data for one or more aircraft.

[0125]

[0144] The hybrid electric air transportation system of the present invention provides significantly shorter door-to-door travel times and lower total cost per mile than alternative local travel modes (such as highways, rail or high speed rail, or conventional air). This is accomplished through convenient, high frequency, "close by" flights to multiple regional airports near communities and settlements using quiet, range-optimized hybrid electric aircraft. Additional advantageous features of the system include: Availability of on-site electrical energy generation and storage at the airport. Many airports may be equipped with on-site generation and storage facilities to minimize electricity costs. On-site generation (e.g., solar, wind, etc.) may be used to recharge aircraft batteries and power the airport, with any surplus stored on-site or delivered to the grid. On-site electrical storage allows for optimal purchasing of electricity from the grid (e.g., at off-peak rates) and storing on-site generated electricity for later use. Retired aircraft batteries can be used for on-site storage throughout their later years before being decommissioned. · Airports have a variety of cost-effective last-mile ground transportation options from origin to destination. Regional airports may offer passengers a wider variety of ground transportation options than non-hub airports do today. Several powerful trends that have recently emerged are encouraging this: electric and autonomous vehicles (e.g., Tesla, Google, Uber, Apple), ride sharing (e.g., Lyft, Uber, Sidecar, RelayRides), partial car rental (ZipCar, Hertz on demand). Today, some regional airports are already connected to local mass transit, and over the next 5-10 years electric and autonomous shuttles will enable the majority of airports to provide inexpensive connections to mass transit. This will be complemented by multiple private car and taxi alternatives enabled by the trends above, such as pickups by autonomous cars, partial car rental, and various forms of ride sharing.

[0126]

[0145] According to an embodiment of the present invention, the systems, devices, methods, elements, processes, functions, and / or operations for enabling the aircraft, transportation systems, and aircraft or transportation system control systems of the present invention may be implemented, in whole or in part, in the form of a set of instructions executed by one or more programmed computer processors (such as a central processing unit (CPU) or microprocessor). Such processors may be incorporated in a device, server, client, or other computing or data processing device operated by or in communication with other components of the system. As an example, FIG. 19 is a schematic diagram illustrating elements or components that may be present in a computer device or system 1900 configured to implement methods, processes, functions, or operations according to embodiments of the present invention. The subsystems shown in FIG. 19 are integrated via a system bus 1902 (which may be one or more of the subsystems illustrated in FIGS. 4 and 5). Additional subsystems include a printer 1904, a keyboard 1906, a fixed disk 1908, and a monitor 1910, which is coupled to a display adapter 1912. Peripherals and input / output (I / O) devices coupled to I / O controller 1914 may be connected to the computer system by any number of means known in the art, such as serial port 1916. For example, serial port 1916 or external interface 1918 may be utilized to connect computer device 1900 to additional devices and / or systems including a wide area network such as the Internet, a mouse input device, and / or a scanner. The interconnection via system bus 1902 enables one or more processors 1920 to communicate with each subsystem and control the execution of instructions that may be stored in system memory 1922 and / or fixed disk 1908, as well as to exchange information between the subsystems. System memory 1922 and / or fixed disk 1908 may embody tangible computer readable media.

[0127]

[0146] In describing the embodiments of the regional air transportation system of the present invention, it should be noted that the following variables, parameters, and units are understood to be used: [Table 13-1] [Table 13-2] [Table 14]

[0128]

[0147] As discussed above, it should be understood that the present invention can be implemented in the form of control logic in a modular or embedded manner using computer software. Based on the disclosure and teachings provided herein, one of ordinary skill in the art will know and understand other ways and / or methods to implement the present invention using hardware and combinations of hardware and software.

[0129]

[0148] Any of the software components, processes, or functions described in this application may be implemented as software code executed by a processor using any suitable computer language (such as, for example, Java, JavaScript, C++, or Perl), for example using conventional or object-oriented techniques. The software code may be stored as a series of instructions or commands on a computer-readable medium, such as a random access memory (RAM), a read-only memory (ROM), a magnetic medium (such as a hard drive or floppy disk), or an optical medium (such as a CD-ROM). Any such computer-readable medium may reside on or within a single computing device, or may be present on or within different computing devices within a system or network.

[0130]

[0149] All references, including publications, patent applications, and patents, cited in this specification are incorporated by reference herein to the same extent as if each reference was individually and specifically indicated to be incorporated by reference and / or set forth in its entirety.

[0131]

[0150] The use of terms such as "a" and "an" and "the" and similar directives in the specification and the following claims should be construed to include the singular and the plural, unless otherwise indicated herein or clearly overruled by context. The use of terms such as "having," "including," "containing," and similar directives in the specification and the following claims should be construed as open-ended terms (e.g., meaning "including, but not limited to"), unless otherwise noted. The recitation of ranges of values ​​herein is merely intended to serve as a shorthand method of individually referring to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated herein as if it were individually set forth herein. All methods described herein can be performed in any suitable order, unless otherwise indicated herein or clearly overruled by context. The use of any and all examples or exemplary language (e.g., "such as") provided herein is intended merely to better illuminate embodiments of the invention, and does not pose a limitation on the scope of the invention, unless otherwise asserted. No language in the specification should be construed as indicating any non-claimed element as essential to each embodiment of the invention.

[0132]

[0151] Different arrangements of the components shown in the drawings or described above, as well as components and steps not shown or described, are possible. Similarly, some features and subcombinations are useful and may be employed without reference to other features and subcombinations. Embodiments of the invention have been described for illustrative and non-limiting purposes, and alternative embodiments will be apparent to the reader of this patent. Thus, the invention is not limited to the embodiments described above or illustrated in the drawings, and various embodiments and modifications can be made without departing from the scope of the following claims.

Claims

1. at least one energy storage unit having an electrical connector configured to be recharged via a ground-based charging station; at least one range extension generator; at least one electric propulsor configured to provide thrust to the aircraft; a distribution bus coupling the energy storage unit and the range extension generator such that the electric propulsor can selectively draw power from the energy storage unit and the range extension generator; a Powertrain Optimization and Control System (POCS) communicatively coupled to the at least one range extension generator and the at least one energy storage unit; The POCS is configured to control a mixing ratio of electrical power supplied from the at least one range extension generator to the at least one electric propulsor and electrical power supplied from the at least one energy storage unit to the at least one electric propulsor. Powertrain for aircraft.

2. at least one of the range extension generators is electrically coupled to the energy storage unit and configured to selectively recharge at least one of the energy storage units. The powertrain of claim 1 .

3. and a hybrid energy planner communicatively coupled to the range extension generator and the energy storage unit, the hybrid energy planner configured to determine an energy plan for the flight path describing an amount of energy to be drawn from each of the energy storage unit and the range extension generator for each of a plurality of segments of the flight path, the energy plan being determined in part based on an amount of energy stored in the energy storage unit, and configured to preferentially deplete energy stored in the energy storage unit over fuel over the course of the flight path. The powertrain of claim 2.

4. a hybrid power manager configured to determine a control strategy in real time to optimize energy distribution between the range extension generator and the energy storage unit. The powertrain of claim 2.

5. the distribution bus is a first distribution bus; the POCS is configured to reroute power through a second distribution bus if a failure occurs on the first distribution bus; The powertrain of claim 1 .

6. the electric propulsor includes an electric motor; the range extension generator includes at least one of an internal combustion engine or a fuel cell; the motor power density of the electric motor is in a first range of 4.5 kW / Kg to 10 kW / kg; the energy storage density of the energy storage unit is in a second range of 300 Wh / kg to 1200 Wh / kg; The motor power density of at least one of the internal combustion engine or the fuel cell is in a third range of 1 kW / kg to 5 kW / kg; The powertrain of claim 2.

7. The powertrain has a maximum continuous power output of the range extension generator providing a power level of energy to the aircraft; the power output level being less than 70% of the maximum continuous power output of the powertrain; The powertrain of claim 2.

8. a module interface including electrical wiring, a plurality of electrical interfaces, an electric motor, and a converter; the module interface includes a plurality of mechanical interfaces that enable mechanical connection and disconnection to and from the aircraft for at least one of: (i) the energy storage unit, (ii) the range extension generator, (iii) the electric motor, or (iv) the converter; the plurality of electrical interfaces permitting electrical connection and disconnection to and from a distribution bus for at least one of: (i) the energy storage unit, (ii) the range extension generator, (iii) the electric motor, or (iv) the converter; The powertrain of claim 2.

9. In addition to the powertrain of claim 2, the powertrain further comprises an airframe, the airframe includes a plurality of accessible bays for facilitating installation, storage, and removal of the energy storage unit, each bay from the plurality of accessible bays including electrical and mechanical interfaces for facilitating electrical and mechanical connection and disconnection of the energy storage unit from an electric propulsor and an aircraft; aircraft.

10. the energy storage unit includes a first energy storage unit; the range extension generator comprises a first range extension generator; the electric propulsor includes a first electric propulsor; a second energy storage unit; a second range extension generator electrically coupled to the second energy storage unit and configured to recharge the second energy storage unit; a second electric propulsor configured to provide thrust to the aircraft and electrically coupled to the second energy storage unit and the second range extension generator to selectively derive electrical power from the second electric propulsor; a switch configured to selectively electrically couple the first electric propulsor to at least one of the second energy storage unit or the second range extension generator. The powertrain of claim 1 .

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