Long-voyage electric transport aircraft system in air battery changing mode and use method

Abstract

The invention belongs to the technical field of new energy aircraft design and new energy electric energy power systems, and particularly relates to a long-voyage electric transport aircraft system in an air battery replacement mode and a using method. Two types of aircrafts are used for cruising in a multi-aircraft formation flight mode, the front aircraft is a traction aircraft and mainly serves as a cruising electric energy provider, and one or more aircrafts can be replaced midway; the rear aircraft is a transport aircraft, mainly undertakes a commercial loading task (manned or loaded), only stores part of backup electric energy for maintaining safety and completely has no cruise electric energy, the cruise electric energy completely comes from the front traction aircraft, and the two types of aircrafts are connected through a power line capable of being connected and disconnected. The energy cost of the aircraft is greatly reduced in the use stage, and the carbon emission and pollutant emission of the aircraft in the use stage are greatly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy aircraft design and new energy pure electric energy or hydrogen-electric hybrid power system, and specifically relates to a long-range electric transport aircraft system with an aerial battery exchange mode and a method of use. Background Art

[0002] Currently, electric aircraft powered by pure power batteries have attracted widespread attention due to their complete carbon emission-free operation and extremely low energy costs (according to the present invention, energy costs can be reduced by more than 80%). If used in civil aviation, they will have a cost advantage over existing high-speed rail and civil aviation. However, the mass and volume energy density of power batteries are extremely low compared to conventional aviation kerosene at present and for a long time to come, resulting in a range of about 300km for power battery electric aircraft. Limited by the progress of power battery energy density, the current mass energy density of power batteries is generally on the order of 300Wh / kg, less than 1 / 10 of aviation kerosene, which greatly affects the market application of such electric aircraft.

[0003] Hydrogen-powered electric aircraft also emit zero carbon emissions during their operation, but green hydrogen fuel is relatively expensive. Hydrogen-powered aircraft also suffer from the low volumetric energy density of hydrogen and the need for extremely low-temperature storage, which significantly consumes the aircraft's prime cargo space. Hydrogen fuel cells also have low power density, while hydrogen engines pose serious safety concerns. Major components like the aircraft's cabin and wings require significant modifications, and there are no effective safety measures or solutions to the physical and chemical explosions of hydrogen and its embrittlement of load-bearing metal components. Hydrogen-powered aircraft converted from existing aircraft will also have limited range due to the low volumetric energy density of hydrogen fuel.

[0004] The towing flight in the prior art, such as the glider towing process, is mainly used in the take-off phase. The towing rope provides the pulling force for the glider to take off. The existing aerial refueling aircraft and the receiving aircraft are only towed in formation for a short time during the refueling phase. The towing device only transmits liquid fuel at room temperature and cannot transmit electrical energy. The fleet will cruise in an aerial formation with a smaller spacing for a longer range, but they are not softly connected to each other. The aerial or take-off towing of the existing glider is towed by a load-bearing connection. The towing rope provides pulling force to pull the towed aircraft to take off and cruise. The towing rope does not transmit electrical energy. The aerial refueling aircraft only transmits liquid fuel at room temperature and cannot transmit electrical energy. The schematic diagram of the prior art is shown as follows. Figure 1 、 Figure 2 shown. Summary of the Invention

[0005] The purpose of this invention is to design a long-range electric transport aircraft system with an in-flight battery swapping mode and its use method. This is intended to significantly extend the range of existing pure electric and hydrogen-fueled aircraft, enabling them to match and replace conventional aviation fuel aircraft in practical application.

[0006] To solve this technical problem, the technical solution of the present invention is:

[0007] Provided is a long-range electric transport aircraft system with an in-flight battery swapping mode. The aircraft system is powered by pure battery energy or hydrogen energy and comprises two parts:

[0008] Transport aircraft are equipped with a pure electric propulsion system and power batteries for takeoff, landing and backup energy, but are not equipped with power batteries or hydrogen storage power generation devices to store cruise energy. The excess mass and space are left for commercial use; including the cabin, wings, takeoff and landing and backup power batteries, commercial cabin (cargo cabin and passenger cabin, cockpit), air formation towing and docking equipment, etc. The aircraft's outer wings are designed with a pair of split-type drag rudders to balance the yaw moment during lateral towing. The lateral force generated during lateral towing is offset by the lift deflection caused by weak roll. Weak here refers to roll deflection of no more than 3 degrees, 1 degree, 2 degrees, 3 degrees, etc. Generally, the lift is perpendicular to the horizontal plane and deflected at a small angle along the fuselage axis. The lift is also deflected, creating a small lateral force to offset the lateral force caused by towing.

[0009] A traction aircraft equipped with a pure electric propulsion system and power batteries for takeoff, landing, and backup energy, equipped with power batteries or hydrogen fuel cells for its own cruise energy and the cruise energy supplied to the transport aircraft, and retractable power lines and power supply devices, but does not carry any commercial loads. It includes the cabin, wings, takeoff and landing and backup power batteries, battery compartments (power batteries or hydrogen fuel cells and hydrogen storage devices are placed in the cargo hold, passenger cabin, and cockpit). Power batteries can also be placed inside components such as wings, long-distance power lines, power supply devices, and automatic retraction devices.

[0010] The transport aircraft are connected to each other via a connecting mechanism, which includes a power supply end and a power receiving end. The power supply end is a hose-type cable with a cone sleeve at the end, and the power receiving end is a pointed cone-shaped plug. The cone sleeve at the power supply end is convenient for inserting the power receiving end. The edge of the cone sleeve is an inflatable annular airbag. After inflation, the cone sleeve is kept open and kept horizontal by airflow, making it easy for the power receiving end to be inserted.

[0011] The power supply cable is in a "non-load-bearing" state, which means that the retractable power supply line does not play a role in pulling the transport aircraft. The transport aircraft relies on its own motor power for propulsion, and the power supply cable only provides electrical energy.

[0012] According to different connection forms in the towing mode, the power supply end is installed on the tail or wing tip of the towing aircraft, and the power receiving end is installed on the nose or wing tip.

[0013] The tractor aircraft and the transport aircraft both adopt a three-wing aerodynamic layout with a high aspect ratio and a supporting wing design, and the high lift-to-drag ratio design of the aerodynamic layout partially compensates for the insufficient mass energy density of the power battery and the volume energy density of hydrogen fuel; preferably, the aspect ratio is 13-25 and the lift-to-drag ratio is 16-25;

[0014] The tractor aircraft and transport aircraft are powered by propellers and use coaxial counter-rotating propellers, with a total of at least three pairs of propellers. All propellers are fully open during takeoff, while only one or two pairs of coaxial counter-rotating propellers are open during cruising (long-distance flight at a specified altitude and a specified Mach number). The power of the remaining coaxial counter-rotating propellers is turned off and the blades are folded under the resistance of the oncoming flow to reduce the aerodynamic resistance of the entire aircraft.

[0015] The nose of the tractor aircraft is in an openable form to facilitate the rapid replacement of the internal energy module. Specifically, the nose can be opened upward or sideways.

[0016] The tug plane can also adopt a hydrogen-electric hybrid mode, using hydrogen refueling instead of charging on the ground. Hydrogen refueling is faster than charging, but the current price of hydrogen fuel is too high. The tug plane can be regarded as a transport plane specifically for transporting charged power batteries.

[0017] The wingtips of the tractor aircraft and transport aircraft are designed with a pair of drag rudders to adapt to the yaw moment caused by the wingtips when they are not bearing load, and to roll and deflect lift to create side force to offset the side force. Figure 6 The drag rudder has an opening range of 0 to 30 degrees and is installed at the outermost side of the wing, preferably at 70% to 90% of the span, such as 10 degrees, 20 degrees, 30 degrees, etc. The specific location is, for example, at the outermost side of the wing, at 70% to 90% of the span.

[0018] The states of the towing aircraft and the transport aircraft include: ground charging state, aircraft take-off and landing state, climbing and descending state, air docking state, air separation state, and towing flight state (i.e., the aforementioned cruising state);

[0019] When in the air docking state, the distance between the towing aircraft and the transport aircraft ranges from 15 to 40 meters.

[0020] The towing aircraft can be manned or unmanned. When unmanned, the towing aircraft is controlled by the pilot of the transport aircraft.

[0021] The system further includes airport charging equipment: the airport charging equipment includes charging equipment or hydrogen refueling equipment at airports used by transport aircraft and airports used by towing aircraft.

[0022] The charging device is a replaceable whole power battery; the hydrogen refueling device is a hydrogen storage device.

[0023] The charging equipment or hydrogen refueling equipment is arranged underground to save ground space in the airport.

[0024] On the other hand, a method for using a long-range electric transport aircraft system in an air-battery swapping mode is provided. The method reserves multiple non-load-bearing towing aircraft in sections on the transport aircraft's route, supplies power to the transport aircraft in stages, and performs non-load-bearing towing flights in an air formation. Each towing operation involves one or more (for example, two) non-load-bearing towing aircraft. The transport aircraft takes off and lands only once during its entire voyage, but the towing aircraft takes off and lands multiple times. The relay-type non-load-bearing towing transport aircraft fly continuously over long distances far exceeding those of conventional electric aircraft, such as the 2,000km flight from Beijing to Guangzhou. On the return trip, the towing aircraft tows the transport aircraft even if the towing aircraft returns to the original towing airport.

[0025] Specifically, the traction modes in the usage method are divided into: single-machine non-load-bearing traction mode, double-machine non-load-bearing traction mode and triple-machine non-load-bearing traction mode;

[0026] The single-machine non-load-bearing traction mode has three connection forms:

[0027] I) The towing aircraft is connected to the nose of the transport aircraft at its tail, and the two aircraft are arranged to cruise at the same altitude;

[0028] II) The towing aircraft is connected to the nose of the transport aircraft at the left or right wingtip, and the aircraft is arranged to cruise at the same altitude;

[0029] III) Lateral cruise configuration at the same altitude, with the left wingtip of the tug connected to the right wingtip of the transport aircraft, or the right wingtip of the tug connected to the left wingtip of the transport aircraft. In this case, the tug must use the drag rudder of the corresponding outer wing to balance the yaw moment, and the roll and deflection lift to generate side force to offset the side force;

[0030] The dual-machine non-load-bearing traction mode has two connection forms:

[0031] I) Dual-aircraft towing includes connecting the tails of two tractors to the left and right wingtips of the transport aircraft respectively;

[0032] II) The right wingtip of the left tug is connected to the left wingtip of the transport aircraft, and the left wingtip of the right tug is connected to the right wingtip of the transport aircraft. In this mode, the tug must use the drag rudder of the corresponding outer wing to balance the yaw moment, and the roll and deflection lift to create side force to offset the side force.

[0033] The three-machine non-load-bearing traction mode has two connection forms:

[0034] 1) All three tractors are connected to the nose, left wingtip, and right wingtip of the transport aircraft by their tails;

[0035] II) The center tug connects its tail to the transport aircraft's nose, while the two tugs connect their wingtips to the transport aircraft's corresponding wingtips. The tugs must use the drag rudders of their respective outer wings to balance the yaw moment, using roll and yaw to generate lift and offset the side force. This is similar to the dual-tug mode II).

[0036] The technical indicators of the tractor and transporter are as follows:

[0037] The wing aspect ratio is 15-22, the cruising altitude is 10,000-16,000 meters, the flight Mach number is 0.55-0.65, the cruise lift coefficient is 0.8-1.2, and the maximum lift coefficient is 1.6 (used only during takeoff and landing, not during cruising). The cruise altitude density, cruise altitude sound speed, cruise altitude air pressure, and cruise altitude temperature are determined by standard atmospheric tables and altitude. The cruise altitude speed pressure, takeoff speed pressure, and other speed pressures are determined by atmospheric conditions and Mach number. The wing area is determined by the speed pressure, gross weight, and cruise lift coefficient.

[0038] The beneficial effects of the present invention are: the advantage and goal of the aerial battery swap mode flight is to be able to perform multiple automated aerial battery swaps for extended flight time, allowing electric transport aircraft to carry commercial loads and fly uninterrupted for a longer range. The specific technical effects are as follows:

[0039] 1) Using aerial formation and battery swapping modes to enable long-distance flights (2,000 km and above) for electric aircraft carrying a certain payload, this solves the primary issue of electric aircraft having significantly lower range than gasoline-powered aircraft. The flexible hose-type connection device used in the aerial battery swapping mode separates the aircraft's main energy supply components from its payload transport components, ensuring an adequate and efficient electrical energy supply for transport aircraft.

[0040] 2) The drag rudder of the tug aircraft and transport aircraft of the present invention is designed to open and close at an angle of 0 to 30 degrees and is installed at the outermost side of the wing to adapt to the yaw moment caused by non-load-bearing traction at the wing tip, and to generate side force by rolling and deflecting lift to offset the side force.

[0041] 3) The connection mechanism of the present invention includes a power supply terminal, a power receiving terminal, and the spacing between the front and rear aircraft, as well as the length of the power transmission cable and the aircraft spacing control device. The aerial power transmission connection can be various, namely, the connection between the power supply terminal and the power receiving terminal can be tail-to-nose, tail-to-wingtip, or wingtip-to-wingtip. The ratio of towing and transport aircraft can be one-to-one or two-to-one. Depending on the connection method, the power supply device and the power receiving terminal are installed at the tail or wingtip, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of an aerial refueling pipe in the prior art;

[0043] Figure 2 This is a schematic diagram of multi-aircraft formation aerial refueling in the prior art;

[0044] Figure 3 Schematic diagram of the foldable nose of a towing aircraft; (a) is a schematic diagram of the foldable nose that can be opened sideways, and (b) is a schematic diagram of the foldable nose that can be opened upwards;

[0045] Figure 4 It is a schematic diagram of the components of the towing aircraft;

[0046] Figure 5 This is a schematic diagram of the principle of a coaxial counter-rotating propeller;

[0047] Figure 6 Schematic diagram of the split-type drag rudder, where (b) is the A-direction sectional view in (a);

[0048] Figure 7 This is a schematic diagram of the connection mechanism of the present invention;

[0049] Figure 8 This is a schematic diagram of the cone sleeve in the power supply end;

[0050] Figure 9 Schematic diagram of three connection forms for single-machine non-load-bearing traction mode;

[0051] Figure 10 Schematic diagram of two connection forms of dual-machine non-load-bearing traction mode;

[0052] Figure 11 Schematic diagram of two connection forms of three-machine non-load-bearing traction mode;

[0053] In the figure, 1 is the foldable nose, 2 is the replaceable energy module, 3 is the retractable power supply device, and 4 is the resistance rudder. DETAILED DESCRIPTION

[0054] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] The long-range electric transport aircraft system of the present invention, which is driven by pure power battery energy or hydrogen energy and uses an in-flight power exchange mode, includes two parts: (1) a transport aircraft, which is equipped with a pure electric propulsion system and power batteries for takeoff, landing, and backup energy, but is not equipped with power batteries or hydrogen storage power generation devices for storing cruise energy, and the excess mass and space are reserved for commercial use; (2) a towing aircraft, which is equipped with a pure electric propulsion system and power batteries for takeoff, landing, and backup energy, equipped with power batteries or hydrogen fuel cells for its own cruise energy and the cruise energy supplied to the transport aircraft, and a retractable power supply line and power supply device, but is not loaded with any commercial load. The power supply line here is in a "non-load-bearing" state, which means that the towing retractable power supply line does not play the role of pulling the transport aircraft. The transport aircraft relies on its own motor power for propulsion, and the power supply line only provides electrical energy.

[0056] Multiple non-load-bearing towing aircraft are reserved along the transport aircraft's route. Power is supplied to the transport aircraft in stages, allowing for formation non-load-bearing towing flights. Each towing operation involves one or more (e.g., two) non-load-bearing towing aircraft. The transport aircraft only takes off and lands once during its entire flight, but the towing aircraft performs multiple takeoffs and landings. This relay of non-load-bearing towing transport aircraft allows for uninterrupted flight, far exceeding the range of conventional electric aircraft, such as the 2,000km Beijing-Guangzhou flight. On the return trip, the towing aircraft tows the transport aircraft until it returns to its original towing airport.

[0057] Due to the large weight of power batteries and commercial payloads, the hydrogen storage and power generation systems are also heavy and extremely large in size, making it unsuitable to adopt the overall aerodynamic design of vertical take-off and landing, tilt-rotating, or tail-seat vertical take-off and landing aircraft. The take-off and landing thrust-to-weight ratio of such aircraft must be significantly greater than 1, so the load capacity is limited, and the economy of transport aircraft (including towing aircraft to transport batteries) is lost.

[0058] Since civil aviation airports are divided into different grades, such as Shijiazhuang Airport is a 4E-grade airport and Capital Airport is a 4F-grade airport, 4E-grade airports only allow aircraft with a wingspan of less than 65 meters to take off and land, and 4F-grade airports allow aircraft with a wingspan of 80 meters to take off and land, but some aircraft can take off and land at field airports, which only have dirt runways. In the present invention, the towing aircraft can take off and land and charge and change batteries (or refuel and change tanks) and stand by at low-grade airports (such as dirt runway airports or higher-grade airports) because it does not need to load any commercial loads; while transport aircraft take off and land and load cargo and passengers, as well as unload cargo or passengers at high-grade airports (4E-grade or other civil aviation airports) to reduce overall costs. The towing aircraft is similar to a movable "power bank" for transport aircraft, and the key component of the towing aircraft is a retractable long-distance power supply line, such as about 20 meters.

[0059] Transport aircraft: cabin, wings, take-off and landing and backup power batteries, commercial cabin (cargo cabin and passenger cabin, cockpit), air formation towing and docking equipment, etc. The aircraft's outer wings are designed with a pair of split-type drag rudders to balance the yaw moment during lateral traction. The lateral force generated during lateral traction is offset by the lift deflection caused by a slight roll.

[0060] Tow aircraft: Cabin, wings, takeoff and landing and backup power batteries, battery compartments (using the cargo hold, passenger compartment, and cockpit to house power batteries or hydrogen fuel cells and hydrogen storage devices), power batteries can also be placed inside wings and other components, long-distance power supply lines and automated retraction and deployment devices. Tow aircraft can also adopt a hydrogen-electric hybrid mode, using hydrogen refueling on the ground instead of charging. Hydrogen refueling is faster than charging, but the current price of hydrogen fuel is too high. Tow aircraft can be regarded as transport aircraft specifically for transporting charged power batteries.

[0061] Long-distance power lines refer to transmission cables and the cone sleeves at the ends, power plugs, and automated cable recovery devices.

[0062] like Figure 3 As shown, the nose of the tug aircraft is designed to open upward or sideways, facilitating quick replacement of the internal energy module and accelerating the replenishment of electricity or hydrogen fuel. A pair of split-type drag rudders are designed on the aircraft's outer wings to balance the yaw moment during lateral tugs. The side force generated during lateral tugs is offset by lift deflection caused by a slight roll.

[0063] In this invention, both the tractor and transport aircraft utilize a three-wing aerodynamic layout with a high aspect ratio and a strut wing design. This aerodynamic layout's high lift-to-drag ratio partially offsets the deficiencies in the mass energy density of the power battery and the volume energy density of hydrogen fuel. A three-wing layout refers to an aerodynamic layout in which the aircraft simultaneously possesses three lifting surfaces: a wing, a canard (located at the nose), and a horizontal tail (located at the tail). This layout offers relatively strong pitch control capabilities.

[0064] The aircraft adopts a three-wing layout design, including a barreled fuselage, wings, canards, horizontal tail and vertical tail, with at least 6 electric coaxial counter-rotating propeller propulsion devices. In addition to the conventional rudders on the outside of the wings, a pair of split-type drag rudders are also designed. Because the wing is a large-scale design (aspect ratio of 13 to 25), there is space in the span of the wing surface for the design of split-type main rudders. The canards and drag rudders are additional devices added to enhance the flight control ability of the aircraft in the connected state. Figure 5As shown, the coaxial counter-rotating propeller is a drive shaft that rotates in two directions, driving two propellers respectively. The counter-rotating effect eliminates the circumferential airflow of the propellers, thereby concentrating the propeller airflow energy on the axial flow, thereby improving propulsion efficiency. The main power is loaded on the inner or outer shaft, and the two shafts are connected through a planetary gear transmission to form a coaxial counter-rotating state. With coaxial counter-rotating propellers, each nacelle integrates two to three electric motors, which are used in parallel to increase the total power. During takeoff, all propellers are fully open, while during cruising (long-distance flight at a specified altitude and a specified Mach number is called cruising) only one or two pairs of coaxial counter-rotating propellers are open. The power of the remaining coaxial counter-rotating propellers is turned off, and the blades automatically fold under the resistance of the oncoming flow to reduce the aerodynamic drag of the entire aircraft.

[0065] Split drag rudder: Compared with the traditional rudder which is a whole, the split drag rudder has split surfaces. Figure 6 The rudders increase and decrease aerodynamic drag by opening and closing. At the same time, this type of rudder is generally designed on the outside of the wing, and its center has a large moment arm relative to the center of gravity of the fuselage, which makes it easy to form a yaw moment, which is the moment that controls the left and right deflection of the nose.

[0066] See Figure 7 、 Figure 8 The connection mechanism consists of a power supply end, which is a hose-like cable with a conical sleeve at the end, and a power receiving end, which is a pointed conical plug. The power supply end's conical sleeve is designed to facilitate the insertion of the power receiving end. The edge of the conical sleeve is an inflatable ring-shaped airbag. When inflated, it keeps the conical sleeve open and uses airflow to maintain a horizontal state, making it easier for the power receiving end to be inserted.

[0067] The power transmission adopts three-phase alternating current. The receiving end has a pointed cone, and the two conductors at the rear that can be radially inserted and ejected are three conductive devices to transmit three-phase electricity. The two elastic devices at the rear are designed to withstand a certain tensile force, and the aerodynamic resistance of the cone sleeve airbag at the power supply end must be greater than this tensile force threshold so that the receiving end can be inserted.

[0068] Since the connection between the power supply end and the power receiving end can only withstand a certain amount of pulling force, the distance between the front and rear aircraft and the length of the transmission cable must be strictly tested and designed. This is guaranteed by the aircraft spacing control device. Once the power transmission task is completed, the front and rear aircraft need to be separated in the air. It is only necessary to forcefully pull the power supply end and the power receiving end apart. This device can avoid excessive pulling force between the two aircraft once the distance is too large. After all, the transmission cable does not bear the task of dragging, and dragging each other will cause flight control problems.

[0069] The distance between the towing aircraft and the transport aircraft is controlled by an aircraft distance control mechanism. Because the power line and the transport aircraft are non-load-bearing, slight changes in the distance do not cause significant changes in the pulling force on the towing and transport aircraft. The aircraft distance control mechanism, at a set distance, reduces the speed of the leading aircraft or increases the speed of the trailing aircraft to reduce the distance if the distance measuring device detects that the distance is too large. If the distance measuring device detects that the distance is too small, it increases the speed of the leading aircraft or decreases the speed of the trailing aircraft to increase the distance. Both distance measurement and acceleration and deceleration are performed automatically under computer control.

[0070] Airport charging equipment: including charging or hydrogen refueling equipment for transport aircraft and towing aircraft, or replaceable power batteries, hydrogen storage devices, etc. Such equipment is arranged underground to save airport ground space.

[0071] The states of the towing aircraft and the transport aircraft include: ground charging state, aircraft take-off and landing state, climbing and descending state, air docking state, air separation state, and towing flight state;

[0072] (1) Ground charging status

[0073] The ground charging or hydrogen refueling status of the traction aircraft, and the ground charging or hydrogen refueling status of the transport aircraft.

[0074] (2) Aircraft take-off and landing status

[0075] Includes takeoff and landing conditions of transport aircraft and towing aircraft, both of which take off and land independently.

[0076] The takeoff state consumes electrical energy, while the landing state recovers electrical energy.

[0077] (3) Climbing and descending state

[0078] Includes the climb and descent states of the transport aircraft and the towing aircraft, both of which climb and descend independently.

[0079] The climbing state consumes energy, while the descending state recovers electrical energy.

[0080] (4) Air docking status

[0081] During the aerial docking process of the transport aircraft's power receiving device and the towing aircraft's long-distance power supply line power supply device, the towing aircraft and the transport aircraft are spaced at a relatively large distance, for example, about 20 meters. The docking process must ensure that the end of the power line does not contact rotating parts such as the transport aircraft's propeller or fan.

[0082] (5) Air detachment

[0083] During the aerial separation process of the transport aircraft's power receiving device and the towing aircraft's long-distance power supply line power supply device, the towing aircraft is at a relatively large distance from the transport aircraft, for example, about 20 meters. The separation process must ensure that the end of the power line does not contact rotating parts such as the propeller or fan of the transport aircraft.

[0084] (6) Tow flight state

[0085] The transport aircraft is in a cruising flight state under the traction power supply of the towing aircraft. Since the transport aircraft does not carry any cruise power batteries, it must rely on the towing aircraft for power supply for cruising flight.

[0086] When in the air docking state, the distance between the towing aircraft and the transport aircraft is greater than or equal to 20 meters.

[0087] The traction modes of the transport aircraft and the traction aircraft in the present invention include: three single-aircraft non-load-bearing traction modes, two double-aircraft non-load-bearing traction modes and two triple-aircraft non-load-bearing traction modes, such as Figure 9 、 10 , as shown in 11.

[0088] The present invention includes a mode in which the aircraft is connected with the tail and the nose, and is arranged to cruise at the same altitude front and rear, or to cruise at the same altitude sideways, and the left wingtip of the tractor is connected to the right wingtip of the transport aircraft, or the right wingtip of the tractor is connected to the left wingtip of the transport aircraft. At this time, the tractor must use the resistance rudder of the corresponding outer wing to balance the yaw moment, and the roll deflection lift to generate side force to offset the side force.

[0089] Dual-aircraft towing includes the tails of the two tractors connected to the left and right wingtips of the transport aircraft, the right wingtip of the left tractor connected to the left wingtip of the transport aircraft, and the left wingtip of the right tractor connected to the right wingtip of the transport aircraft. The tractors must use the resistance rudder of the corresponding outer wing to balance the yaw moment, and the roll deflection lift to create side force to offset the side force.

[0090] The three-aircraft towing mode includes that all the tugs are connected to the nose of the transport aircraft with their tails, the middle tug is connected to the nose of the transport aircraft with its tail, and the tugs on both sides are connected to the corresponding wingtips of the transport aircraft with their corresponding wingtips. At this time, the tugs must use the resistance rudder of the corresponding outer wing to balance the yaw moment, and the roll deflection lift to create side force to offset the side force.

[0091] Conceptual design of traction aircraft and transport aircraft: The technical indicators are shown in Table 1 below.

[0092] Table 1

[0093]

[0094]

[0095] Example 1:

[0096] Taking the system design of the pure electric transport aircraft from Beijing Capital Airport to Guangzhou Baiyun Airport as an example, as shown in Table 2 below.

[0097] Table 2

[0098]

[0099]

[0100] Green electricity price: The green electricity price here is 0.3 yuan / kWh (deep valley electricity price). The actual green electricity market price may be much lower than this price. If the battery replacement mode is adopted and charging is carried out during the low electricity consumption period (the deep valley electricity price in many domestic areas is less than 0.2 yuan / kWh), and the recovery of abandoned electricity from wind, solar and hydropower generation is considered, the energy cost reduction will increase further; if a dedicated wind and photovoltaic power station is built near the airport for towing aircraft, the cost of purchasing electricity can be close to zero, and the energy price of pure electric air transportation is super low compared to that of aviation kerosene aircraft.

[0101] Assuming energy costs account for 30%, the cost of a single-person trip from Beijing to Guangzhou is 313 yuan (at a speed of 637 km / h). Based on a 10% profit margin (the global aviation industry's net profit is 3.1%), the ticket price can be set at 350 yuan. For comparison, high-speed rail tickets cost 1,000 yuan per person at a speed of 350 km / h, and passenger plane tickets cost 3,500 yuan (full fare) at a speed of 800 km / h. This shows that long-range electric aircraft have a significant market competitive advantage.

[0102] Example 2:

[0103] The system design of the pure electric transport aircraft from Capital Airport to Urumqi Diwopu Airport is shown in Table 3 below.

[0104] Table 3

[0105]

[0106]

[0107] Green electricity price: The green electricity price here is 0.3 yuan / kWh (deep valley electricity price). The actual green electricity market price may be much lower than this price. If the battery replacement mode is adopted and charging is carried out during the low electricity consumption period (the deep valley electricity price in many domestic areas is less than 0.2 yuan / kWh), and the recovery of abandoned electricity from wind, solar and hydropower generation is considered, the energy cost reduction will increase further; if dedicated wind and photovoltaic power stations are built near the airport towing the aircraft, the cost of purchasing electricity can be close to zero. The energy price of pure electric air transportation is super low compared to that of aviation kerosene aircraft. The energy recovery technology during the descent and landing phases has been considered here.

[0108] Here, the power system uses three pairs of coaxial counter-rotating propellers. Each power nacelle integrates two to three electric motors, which are used in parallel to increase the total power. For example, three electric motors are used in parallel and each motor has a rated power of 250kW. The power-to-weight ratio of automotive electric motors on the market has reached 4 to 6kW / kg, which is close to the power-to-weight ratio of general turboprop engines of 3 to 5kW / kg.

[0109] As the range increases, the energy cost of the electric shipping system increases, but the cost reduction compared to conventional aviation kerosene aircraft transportation is on a downward trend. If the further reduction of valley electricity prices and the comprehensive application of new energy power curtailment are taken into account, the energy use cost of the pure electric shipping system can be further reduced.

[0110] The primary obstacle to aircraft electrification lies in onboard energy storage, which must meet practical requirements in both volumetric and mass energy density while maintaining low energy prices. Directly storing electricity falls short of long-range design requirements in terms of mass and volumetric energy density, but offers excellent performance in terms of energy price and carbon emissions. Using an in-flight battery swap model avoids the first two issues while leveraging its advantages of low cost and cleanliness. The current energy market price for hydrogen-electric hybrids is relatively high, and the volumetric energy density of energy storage is a significant issue, requiring significant aircraft modifications. Hydrogen embrittlement and safety issues are also prominent. Sustainable aviation fuel (SAF) faces challenges primarily due to insufficient production and excessively high market prices.

Claims

1. Long-range electric transport aircraft system with air-to-air battery exchange mode, characterized by: The aircraft system is driven by pure battery energy or hydrogen energy, and the system includes two parts: Transport aircraft, equipped with a pure electric propulsion system and power batteries for takeoff, landing and backup energy, but not equipped with power batteries for storing cruising energy or hydrogen storage power generation devices, with excess mass and space reserved for commercial use; including cabin, wings, takeoff and landing and backup power batteries, commercial cabin, air formation towing and docking equipment, etc. A pair of split-type drag rudders are designed on the outer wings of the aircraft to balance the yaw moment during lateral towing, and the lateral force generated during lateral towing is offset by the lift deflection caused by weak rolling; Towing aircraft, equipped with a pure electric propulsion system and power batteries for takeoff, landing and backup energy, equipped with power batteries or hydrogen fuel cells for its own cruising energy and the cruising energy for the transport aircraft, and retractable power lines and power supply devices, but without any commercial load. Including the cabin, wings, takeoff and landing and backup power batteries, battery compartments, and power batteries are also arranged inside the wings; The traction aircraft is connected to the transport aircraft through a connection mechanism, which includes a power supply end and a power receiving end. The power supply end is a hose-type cable with a cone sleeve at the end, and the power receiving end is a pointed cone-shaped plug. The cone sleeve of the power supply end is convenient for the power receiving end to be inserted. The edge of the cone sleeve is an inflatable annular airbag. After inflation, the cone sleeve is kept open and kept in a horizontal state by airflow, which is convenient for the power receiving end to be inserted. The power supply cable is in a "non-load-bearing" state, which means that the retractable power line does not play a role in pulling the transport aircraft. The transport aircraft relies on its own motor power for propulsion, and the power supply cable only provides electrical energy. According to different connection forms in the traction mode, the power supply end is installed on the tail or wing tip of the traction aircraft, and the power receiving end is installed on the nose or wing tip.

2. The system according to claim 1, characterized in that: The traction aircraft and the transport aircraft both adopt a three-wing aerodynamic layout, a large aspect ratio and a support wing design, and the high lift-to-drag ratio design of the aerodynamic layout partially compensates for the deficiencies in the mass energy density of the power battery and the volume energy density of the hydrogen fuel; the aspect ratio is 13 to 25, and the lift-to-drag ratio is 16 to 25; The traction aircraft and transport aircraft are powered by propellers and use coaxial counter-rotating propellers, with a total of at least three pairs of propellers. All propellers are fully open during takeoff, while only one or two pairs of coaxial counter-rotating propellers are open during cruising. The power of the remaining coaxial counter-rotating propellers is turned off and the blades are in a folded state under the resistance of the oncoming flow to reduce the aerodynamic resistance of the entire aircraft.

3. The system according to claim 1, characterized in that: The nose of the tractor aircraft is openable to facilitate rapid replacement of the internal energy module.

4. The system according to claim 1, characterized in that: The traction aircraft adopts a hydrogen-electric hybrid mode, and hydrogen is added on the ground instead of charging.

5. The system according to claim 1, characterized in that: A pair of drag rudders are designed at the wingtips of the tug aircraft and the transport aircraft to adapt to the yaw moment caused by non-load-bearing traction of the wingtips, and the roll deflection lift creates a lateral force to offset the lateral force; the opening and closing degree range of the drag rudder is 0 to 30 degrees; the installation position is located on the outer side of the wing, at 70% to 90% of the span.

6. The system according to claim 1, characterized in that: The states of the towing aircraft and the transport aircraft include: ground charging state, aircraft take-off and landing state, climbing and descending state, air docking state, air separation state, and towing flight state; When in the air docking state, the distance between the towing aircraft and the transport aircraft ranges from 15 to 40 meters.

7. The system according to claim 1, characterized in that: The system further comprises airport charging equipment: the airport charging equipment comprises charging equipment or hydrogen refueling equipment at airports used by transport aircraft and airports used by towing aircraft; The charging device is a replaceable whole power battery; the hydrogenation device is a hydrogen storage device. The charging equipment or hydrogen refueling equipment is arranged underground to save ground space in the airport.

8. A method for using the long-range electric transport aircraft system in an air-power-swap mode as claimed in claim 1, characterized in that: The method reserves multiple non-load-bearing traction aircraft in sections on the route of the transport aircraft, supplies power to the transport aircraft in stages, and performs non-load-bearing traction flight in air formation. Each traction operation involves one or more non-load-bearing traction aircraft. The transport aircraft takes off and lands only once during the entire voyage, but the traction aircraft takes off and lands multiple times. The relay non-load-bearing traction transport aircraft flies uninterruptedly over a long distance that far exceeds that of conventional electric aircraft. During the return trip, the traction aircraft tows the transport aircraft even if the traction aircraft returns to the original traction airport.

9. The method according to claim 8, characterized in that: The traction modes in the method of use are divided into: single-machine non-load-bearing traction mode, double-machine non-load-bearing traction mode and triple-machine non-load-bearing traction mode; The single-machine non-load-bearing traction mode has three connection forms: I) The towing aircraft is connected to the nose of the transport aircraft with its tail, and the front and rear are arranged to cruise at the same altitude; II) The towing aircraft is connected to the nose of the transport aircraft at the left or right wing tip, and the front and rear are arranged to cruise at the same altitude; III) Lateral same-altitude cruising arrangement, with the left wing tip of the tractor connected to the right wing tip of the transport aircraft, or the right wing tip of the tractor connected to the left wing tip of the transport aircraft. In this case, the tractor must use the drag rudder of the corresponding outer wing to balance the yaw moment, and the roll deflection lift to create side force to offset the side force; The dual-machine non-load-bearing traction mode has two connection forms: I) Dual-machine traction includes connecting the tails of two tractors to the left and right wing tips of the transport aircraft respectively; II) The right wing tip of the left tractor is connected to the left wing tip of the transport aircraft, and the left wing tip of the right tractor is connected to the right wing tip of the transport aircraft. In this mode, the tractor must use the resistance rudder of the corresponding outer wing to balance the yaw moment, and the roll deflection lift to create side force to offset the side force. The three-machine non-load-bearing traction mode has two connection forms: I) All three tractors are connected to the nose, left wing tip and right wing tip of the transport aircraft by their tails; II) The tail of the middle tractor is connected to the nose of the transport aircraft, and the tractors on both sides are connected to the corresponding wingtips of the transport aircraft. At this time, the tractor must use the resistance rudder of the corresponding outer wing to balance the yaw moment, roll and deflect lift to create side force to offset the side force. Same as the form II of the dual-aircraft traction mode.

10. The system according to any one of claims 1 to 7, characterized in that: The technical indicators of the tractor and conveyor are as follows: The wing aspect ratio is 15-22, the cruising altitude is 10,000-16,000 meters, the flight Mach number is 0.55-0.65, the cruising lift coefficient is 0.8-1.2, and the maximum lift coefficient is 1.6.

Images