VTOL AIRCRAFT PROPELLER PIVOT ARRANGEMENTS AND MECHANISMS

Abstract

An electric aircraft is described, comprising a fuselage and at least one wing attached to the fuselage. The electric aircraft includes a plurality of tilting propellers attached to the at least one wing, the tilting propellers being configured to move between a vertical lift position and a forward flight position. The electric aircraft includes a plurality of tilting mechanisms coupled to at least one tilting propeller. The electric aircraft includes a first actuator coupled to a first subset of the tilting mechanisms. The first subset of tilting mechanisms is identified among the tilting mechanisms according to a coupling scheme. The first actuator simultaneously tilts a first group of tilting propellers coupled to the first subset of the tilting mechanisms.

Description

VTOL AIRCRAFT PROPELLER PIVOT ARRANGEMENTS AND MECHANISMS Cross-References to Related Applications

[0001] This application claims the benefit pursuant to 35 USC§ 119(e) of United States of America Provisional Patent Application No. 63 / 106,197 filed on October 27, 2020, entitled Tilting Arrangements and Mechanisms of VTOL Aircraft Propellers, the disclosure of which is incorporated herein by reference in its entirety for all purposes. Background of the Invention

[0002] A vertical takeoff and landing (VTOL) aircraft can generally produce vertical thrust, enabling vertical, or primarily vertical, directions of movement. This vertical takeoff, landing, and hovering functionality can allow an aircraft to land and take off without the space limitations of a runway or other space required for traditional horizontal landing (such as an airplane). To provide this functionality, a VTOL aircraft may have vertical motion mechanisms, such as propellers, that provide vertical thrust.

[0003] However, it is generally desirable for the VTOL aircraft to also be capable of horizontal thrust and thus a transition to horizontal motion when the aircraft is not taking off, landing, or hovering, so that the VTOL aircraft can circulate at a constant speed in the air.As such, a VTOL aircraft may have separate propulsion mechanisms dedicated to providing vertical and horizontal thrust, respectively. A VTOL aircraft may have propulsion mechanisms that provide thrust in both directions.

[0004] In aircraft design in general, an important factor in the capabilities of the aircraft depends on limiting its weight. Limiting the number of components, and their associated weight, can allow for more energy-efficient flights, larger payloads, or a combination of both desired outcomes.

[0005] While limiting weight with fewer components is desirable, as discussed, this design configuration is tempered by the safety risks inherent in air travel. In particular, limiting the number of components in a power system can provide weight advantages to the design, but it can further limit the redundant features of the power system, creating a higher risk of failure due to individual component failure and resulting in an aircraft failure during flight.

[0006] In general, it would be advantageous to provide improved aircraft designs that allow for weight and cost savings, while providing beneficial safety and redundant design features to maintain a safe and reliable aircraft. Brief Description of the Invention

[0007] The described modalities generally refer to an aircraft with vertical takeoff and landing capability. In particular, the modalities provide an aircraft with one or more tilting propellers that provide vertical and horizontal thrust in a controlled manner for hovering, transition, and cruise (horizontal) flight. n / QQcn / cznz / a / vi

[0008] The modalities in general provide improved devices, systems, and methods for an aircraft with a plurality of tilting propellers. More specifically, the techniques disclosed herein provide a VTOL aircraft (e.g., an electric VTOL aircraft) with a plurality of tilting propellers that can be tilted between a horizontal position for vertical lift and a vertical position for forward flight. Various structures and configurations are provided that can enable the drive and control of the various tilting propellers, which can increase design efficiency, reduce cost and safety, and improve flight comfort and performance, by way of example.

[0009] In some configurations, the VTOL aircraft (hereafter referred to as the aircraft) may be powered by several power units. For example, in several configurations, the aircraft may have at least one power source that provides power to various aircraft components. For example, the aircraft may be electrically powered, such as with one or more batteries. An electrical power mechanism may provide electrical power to one or more motors, actuators, or other powered aspects of the aircraft.

[00010] According to various configurations, the aircraft may include a fuselage. The fuselage may constitute the central body of the aircraft. In various configurations, the fuselage may accommodate various layouts, such as a cockpit, a passenger compartment, and / or a storage area. As such, the fuselage may have one or more bulkheads that divide various sections of the fuselage. The fuselage may further comprise one or more doors to allow access to the interior. For example, the fuselage may have one or more overhead doors, side doors, front doors, or rear doors. Various door configurations are contemplated to allow convenient access to the aircraft fuselage.

[00011] In some embodiments, the aircraft may include at least one wing attached to the fuselage. For example, the aircraft may have a left wing and a right wing attached to each respective side of the fuselage. In several embodiments, the aircraft may have one or more wings spanning the entire width of the aircraft, such as those extending through the fuselage and attaching to the upper or lower portion of the fuselage. Various wing structures are contemplated that provide the desired aerodynamic advantages and / or a wing structure that allows for convenient entry and exit from the aircraft.

[00012] According to various embodiments, the aircraft may include one or more support elements (e.g., spars) that can be attached to the upper or lower portion of the wing. In several embodiments, the one or more support elements may have a generally tubular structure and may span transversely from at least one wing. For example, the support elements may span toward the front and rear of the aircraft to distribute or separate several propellers (or other thrust-providing mechanisms), such as for balance and thrust distribution of the aircraft. In several embodiments, the propellers may be attached to the support elements at opposite ends, such that a front propeller may be placed on the leading edge of the wing, and a rear propeller may be placed on the trailing edge of the wing.In several configurations, the support elements can be hollow and therefore can accommodate various aircraft components, and specifically can accommodate aircraft control system components. nv QQcn / cznz / a / vi

[00013] In some embodiments, the aircraft may include a plurality of propellers. The plurality of propellers may include stationary propellers, such that the stationary propellers provide thrust in a single direction. The plurality of propellers may include tilting propellers, where the tilting propellers can rotate or pivot to provide thrust in a variety of directions. For example, the tilting propellers may be moved between a vertical lift position and a forward flight position. In addition, the tilting propellers may be capable of providing thrust in various directions between the vertical lift position and the forward flight position, which may allow for partially vertical flight, partially horizontal flight, or may provide steering functionalities for the aircraft.Depending on the configuration, tilting and stationary propellers may include a variable-pitch mechanism to adjust the pitch of each propeller blade based on flight direction and speed. The variable-pitch mechanism may include an actuator that twists the blades around the blade axis.

[00014] In some embodiments, the aircraft may include a plurality of tilting mechanisms, which may be coupled with at least one tilting propeller. The plurality of tilting mechanisms may act to rotate or pivot the plurality of propellers between the vertical lift position and the horizontal flight position. The plurality of tilting mechanisms may include a variety of structures and components to provide this function, including, for example, motors, hydraulic pistons (having hydraulic lines), and / or coupling mechanisms (for example, coupling arms). The plurality of tilting mechanisms may be provided within a given support element.

[00015] According to various embodiments, the aircraft may include an actuator (or multiple actuators). The actuator may be coupled to one or more of the plurality of tilting mechanisms, for example, by means of control arms (and / or a drive shaft) or by means of hydraulic lines. For example, the actuator may operate one or more of the plurality of tilting mechanisms. According to various embodiments, the actuators described herein, which may drive the movement of the tilting mechanisms, may include, among other components, a rotary electric motor (with or without a gearbox), a linear direct-drive electric motor, a ball screw actuator (for example, a rotary electric motor with a ball screw drive to obtain linear motion), a compressor, a hydraulic piston, or a pneumatic piston.

[00016] In some embodiments, the aircraft control system can be designed according to a coupling scheme. The coupling scheme can provide the specific configuration of which of the plurality of tilt propellers are connected to each other, and by what means. Various examples of embodiments of control of the tilt aspect of tilt propellers are provided herein, such that various tilt propellers can be coupled, for example, by tilting mechanisms, so that a certain number of the plurality of tilt propellers are tilted operatively in coordination with each other. Brief Description of the Figures

[00017] Several modalities are disclosed in the following detailed description and attached figures. n / QQcn / cznz / a / vi

[00018] Figure 1A illustrates a simplified scheme of an example VTOL aircraft including tilting propellers in a forward flight position, according to various modes.

[00019] Figure 1B illustrates a simplified scheme of an example VTOL aircraft including tilting propellers in an example vertical lift position, according to various modalities.

[00020] Figures 2A-2B illustrate the example VTOL aircraft including tilting propellers coupled in pairs to support elements, according to various modalities.

[00021] Figures 3A-3C illustrate an example control system of the VTOL aircraft, for providing pivoting or tilting of a plurality of tilting propellers, according to various modalities.

[00022] Figures 4A-4C illustrate an example control system of the VTOL aircraft, for providing pivoting or tilting of a plurality of tilting propellers, according to various modalities.

[00023] Figure 5A illustrates an illustrative modality where a front-tilting propeller and a rear-tilting propeller are coupled to a support element, according to various modalities.

[00024] Figure 5B illustrates the positions of the forward-tilt propeller and trailing-tilt propeller during the arrival (e.g., from flight to landing) and departure (e.g., from hover to flight) transitions of the VTOL aircraft, according to various modes.

[00025] Figures 6A-6C illustrate the trailing-tilt propeller tilting from a vertical flight position to a forward flight position, according to various modalities.

[00026] Figures 6D-6F illustrate the folding of trailing-angle propeller blades, according to various modalities.

[00027] Figures 7A-7C illustrate an example control system including an example tilting mechanism for the front-tilting propeller, according to various modalities.

[00028] Figures 8A-8C illustrate an example control system that includes example tilting mechanisms for the front tilt propeller and the rear tilt propeller, according to various modalities.

[00029] Figures 8-1A to 8-1C illustrate the control system of Figures 8A-8C which includes a drive shaft provided in the wing, according to various modalities.

[00030] Figure 9 illustrates a modality where a drive (e.g., compressor, valve, or primary piston) drives two tilting mechanisms coupled to respective tilting propellers that are matched based on the fault state, according to various modalities.

[00031] Figure 10 illustrates an individual actuator that drives a plurality of primary cylinders, according to various modalities.

[00032] Figure 11 illustrates an example control system that includes two actuators, each driving a plurality of primary cylinders, according to various modalities.

[00033] Figure 12A illustrates a cross-sectional view of an example primary cylinder system, pressurized by a single ball screw actuator, according to various embodiments. n / QQcn / cznz / a / vi

[00034] Figure 12B illustrates a cross-sectional view of an example primary cylinder system, for incorporating two redundant pistons in a single primary cylinder, according to various modalities. Detailed Description of the Invention

[00035] The techniques disclosed herein relate generally to an aircraft with a plurality of tilting propellers (e.g., propellers). More specifically, the techniques disclosed herein provide a VTOL aircraft with a plurality of tilting propellers that can be tilted between a horizontal position for vertical lift and a vertical position for forward flight. Various inventive embodiments, including methods, processes, systems, devices, and the like, are described herein.

[00036] To better appreciate the characteristics and aspects of the control systems and power configurations for aircraft in accordance with this disclosure, additional context is provided in the following section by analyzing particular modes of a VTOL aircraft in accordance with the modes of this disclosure. These modes are, for example, only examples, and other configurations may be used with respect to the VTOL aircraft described herein.

[00037] Figures 1A-1B show a simplified schematic of an example VTOL 100 aircraft. Figure 1A shows an example VTOL aircraft with 102 and 104 pitch propellers in a forward flight position. Figure 1B depicts an example VTOL 100 aircraft with 102 and 104 pitch propellers in a vertical flight position. According to various embodiments, the VTOL 100 aircraft may be an electrically powered aircraft (e.g., an electric aircraft). In some embodiments, the VTOL 100 aircraft may be configured to carry one or more passengers and / or cargo, and may be automatically and / or remotely controlled (e.g., it may not require a pilot on board to operate the aircraft). In the example shown, the VTOL 100 aircraft includes a 110 fuselage that may include a cabin section for carrying passengers and / or cargo.

[00038] The VTOL 100 aircraft may include at least one wing 108 that is attached to the fuselage 110. For example, the aircraft may have a left wing and a right wing attached to each respective side of the fuselage 110. In various embodiments, the VTOL 100 aircraft may have one or more wings that span the entire width of the VTOL 100 aircraft, such as spanning through the fuselage 110 and attaching to the top or bottom of the fuselage 110.

[00039] One or more 106 support elements (or spars) may be attached to the 108 wing of the 100 VTOL aircraft. For example, the 108 wing may include a left wing and a right wing. Each of the left and right wings may include three 106 support elements. For example, the 106 support elements may have an elongated shape spanning perpendicularly from the 108 wing, which has a front portion and a rear portion.

[00040] In various embodiments, the VTOL aircraft 100 may include a plurality of tiltrotors 102, 104. For example, the VTOL aircraft may have a forward tiltrotor 102 and a rear tiltrotor 104. In various embodiments, the plurality of tiltrotors 102, 104 may be coupled to one or more wings 108, and / or may be coupled to one or more support elements 106. For example, the support elements may each include a pair of tiltrotors 102, 104 mounted thereon, the tiltrotors n / QQcn / cznz / a / vi 102,104 of the VTOL100 aircraft may comprise a propulsion motor, which powers the tilt propellers 102,104. The tilting aspect of the tilt propellers may allow the tilt propellers to provide thrust from the propulsion motor in a variety of directions, allowing propulsion in both the vertical and horizontal directions, as well as variable pitching for steering and control of the VTOL100 aircraft.

[00041] The VTOL 100 aircraft may also include a combination of tilting propellers 102,104 and stationary propellers, such that the stationary propellers provide thrust in a single direction (such as either vertically or horizontally only). According to various embodiments, the tilting propellers and stationary propellers may include a variable pitch mechanism to adjust the pitch of the blades of each propeller depending on the flight direction and speed. The variable pitch mechanism may include an actuator that twists the blades around the blade axis. The tilt mechanisms may be coupled to the pitch of the tilting propeller blades.

[00042] Figures 2A-2B illustrate the example VTOL aircraft 100, which includes a right wing 206 and a left wing 208, each attached to the fuselage 110 of the VTOL aircraft 100. The at least one wing of the VTOL aircraft 100 includes a right wing portion 206 and a left wing portion 208. In the example configuration shown in Figures 2A-2B, the VTOL aircraft 100 further includes six support elements 106 and twelve tilt propellers, attached in pairs to six support elements 106. As shown in Figures 2A-2B, three support elements 106 are attached to each wing 206, 208 of the VTOL aircraft 100. For ease of reference, the tilt propellers may be numbered as shown. For ease of reference, the forward-tilting propellers 102 can be numbered from 1 to 6, and the rear-tilting propellers 104 can be numbered from 7 to 12.

[00043] The tilting propellers 1-12 can be switched (e.g., rotated or tilted) between a forward flight position (illustrated in Figure 2A) and a vertical flight position (illustrated in Figure 2B). That is, Figure 2A illustrates the tilting propellers 1-12 (e.g., the tilting propeller blades) in a vertical position for forward movement. Figure 2B illustrates the tilting propellers 1-12 (e.g., the tilting propeller blades) in the horizontal position for vertical flight (e.g., for moving the aircraft in the vertical direction during, for example, takeoff, hover, and / or landing). In the implementation shown in Figures 2A-2B, all the tilting propellers 1-12 are mounted on the respective support elements 106 in a fixed position relative to the wings 206, 208.The tilting propellers 1-12 can be coupled to the support elements 106 by means of one or more tilting mechanisms, including, for example, motors, hydraulic systems, and / or coupling mechanisms. According to various embodiments, each of the tilting propellers 1-12 may comprise a respective tilting mechanism.

[00044] A person skilled in the art will appreciate that the number and location of the tilt propellers are not limited to that illustrated in Figures 2A-2B and that the VTOL 100 aircraft may include fewer or more tilt propellers, provided in other positions on the wing or on individual support elements 106. n / QQcn / cznz / a / vi

[00045] According to various embodiments, the VTOL aircraft 100 may further include one or more stationary propellers, which provide thrust in only one direction (e.g., vertical lift or horizontal flight). For example, in various embodiments, one or more of the plurality of propellers on each support element 106 may be a stationary propeller that is stationary in a vertical lift position or in a forward flight position during operation.

[00046] Figures 3A-3C show example control systems 300 for providing pivoting or tilting of the tilt propellers 302, 304 of the VTOL aircraft 100. For example, the control system 300 may include a tilting mechanism 306. In various embodiments, the tilting mechanism 306 may be coupled or provided (for example, housed or embedded) within a support element 308. The forward-tilt propeller 302 and the trailing-tilt propeller 304 may be coupled to opposite ends of the support element 308. The support element 308 may be provided, for example, under the wing 310 and coupled to the wing 310 or to the fuselage of the VTOL aircraft 100.

[00047] The tilting mechanism 306 can be operationally coupled with a forward-tilting propeller 302 and a backward-tilting propeller 304. Therefore, the tilting mechanism 306 can control the forward-tilting propeller 302 and the backward-tilting propeller 304 simultaneously. As shown in Figures 3A-3C, the tilting mechanism 306 can be a mechanical mechanism that can be moved from a first position to a second position. For example, the tilting mechanism can include a drive shaft 314 that pushes one or more elongated elements (e.g., bars) 316 horizontally, or in a horizontal direction. The drive shaft 314 can be located within the support element 308.

[00048] In Figure 3A, the tilt mechanism 306 can be in the first position with the tilt propellers 302, 304 in a vertical lift position, providing thrust in a vertical direction. Specifically, the drive shaft 314 tilts toward the front of the VTOL 100 aircraft. As shown in Figure 3B, as the tilt mechanism 306 moves to the second position, the tilt propellers 302, 304 can transition to a forward flight position. Specifically, the drive shaft 314 tilts vertically such that the elongated element 316 is pushed rearward, forcing the tilt propellers 302, 304 into a horizontal position.

[00049] As shown in Figure 3C, the tilting mechanism 306 has reached the second position, such that the tilting propellers 302, 304 have fully transitioned to a forward flight position, where thrust can be applied in a horizontal direction. In the second position, the drive shaft 314 tilts rearward and forces the tilting propellers 302, 304 into a forward flight position.

[00050] In the vertical lift position, the forward-tilt propeller 302 can be positioned upward and above the support element 308. Conversely, the trailing-tilt propeller 304 can be oriented downward and below the support element 308 in the vertical lift position. With the tilt mechanism 306 in the second position, such that the tilt propellers are in a forward-flight position, the forward-tilt propeller 302 can be pointing forward, toward the front of the VTOL 100 aircraft, and the trailing-tilt propeller 304 can be pointing backward, toward the rear of the VTOL 100 aircraft. As such, with the tilt propellers 302 and 304 mirroring each other's orientation, a single movement actuating the tilt mechanism 306 can result in the simultaneous tilting of both tilt propellers 302 and 304.

[00051] According to some embodiments, both the forward-tilting propeller 302 and the trailing-tilting propeller 304 can be positioned on the same side (e.g., above or below) of the support element 308 in the vertical lift position. According to some embodiments, both the forward-tilting propeller 302 and the trailing-tilting propeller 304 can be facing the same side (e.g., forward or rear) of the support element 308 in the forward flight position.

[00052] In some embodiments, the VTOL 100 aircraft control system 300 may also include an actuator 312. The actuator 312 can be operationally coupled to the tilting propellers 302, 304 by means of the tilting mechanism 306. Specifically, as shown in the figures, the drive shaft 314 couples the actuator 312 to the rod 316. As such, the actuator 312 can act to change the angle of the drive shaft 314, thereby moving the rod 316. For example, the actuator 312 may be a motor or other powered system that moves the tilting mechanism 306 from the first position to the second position. As shown in Figure 3A, the actuator 312 is provided (e.g., housed or embedded) within the support element 308. This configuration may allow the actuator 312 to be close to the bar 316, such that the drive shaft 314 is shorter, such as to reduce weight.

[00053] According to various modalities, the actuators described herein, which can drive the movement of tilting mechanisms, may include, among other components, a rotary electric motor (with or without a gearbox), a linear direct drive electric motor, a ball screw actuator (e.g., a rotary electric motor with ball screw transmission to obtain linear motion), a hydraulic piston, or a pneumatic piston.

[00054] The example modality illustrated in Figures 3A-3C has the advantage of including half the number of actuators compared to having a first actuator for the trailing tilt propeller 304 and a second actuator for the forward tilt propeller 302. This configuration increases the reliability of the design by reducing the number of parts (e.g., actuators) that can potentially fail, as well as by reducing the weight and power loss of having two separate actuators (i.e., one for each tilt propeller 302, 304).

[00055] Figures 4A-4C show example control systems 400 for providing pivoting or tilting of the tilt propellers 402, 404 of the VTOL aircraft 100. For example, the control system 400 may include a tilting mechanism 406. In various embodiments, the tilting mechanism 406 may be coupled to, or provided (for example, housed or embedded) within (a support element 408). The forward-tilt propeller 402 and the trailing-tilt propeller 404 may be coupled to opposite ends of the support element 408. The support element 408 may be provided, for example, under the wing 410 and coupled to either the wing 410 or the fuselage of the VTOL aircraft 100.

[00056] The tilt mechanism 406 can be operationally coupled with a forward-tilt propeller 402 and a trailing-tilt propeller 404. As shown in Figures 4A-4C, the tilt mechanism 406 can include a mechanical system that can be moved from a first position to a second position. For example, the tilt mechanism 406 can include a drive shaft 414 that pushes one or more elongated elements (e.g., rods) 416 horizontally. The drive shaft 414 can be located at least partially within the wing 410.

[00057] In Figure 4A, the tilt mechanism 406 can be in the first position with the tilt propellers 402, 404 in a vertical lift position, providing thrust in a vertical direction. Specifically, the drive shaft 414 tilts toward the front of the VTOL 100 aircraft. As shown in Figure 4B, as the tilt mechanism 406 moves to the second position, the tilt propellers 402, 404 can transition to a forward flight position. Specifically, the drive shaft 414 tilts vertically such that the rod 416 is pushed rearward, forcing the tilt propellers 402, 404 into a forward flight position.

[00058] As shown in Figure 4C, the tilting mechanism 306 has reached the second position, such that the tilting propellers 402, 404 have fully transitioned to a forward flight position, where thrust can be applied in a horizontal direction. In the second position, the drive shaft 414 tilts rearward and has forced the tilting propellers 402, 404 into a horizontal direction.

[00059] In the vertical lift position, the forward-tilt propeller 402 can be positioned upward and above the support element 408. Conversely, the trailing-tilt propeller 404 can be oriented downward and below the support element 408 in the vertical lift position. With the tilt mechanism 406 in the second position, such that the tilt propellers are in a forward-flight position, the forward-tilt propeller 402 can be pointing forward, toward the front of the VTOL 100 aircraft, and the trailing-tilt propeller 404 can be pointing backward, toward the rear of the VTOL 100 aircraft. As such, with the tilt propellers 402 and 404 mirroring each other's orientation, a single movement actuating the tilt mechanism 406 can result in the simultaneous pivoting of both tilt propellers 402 and 404.

[00060] In several configurations, the VTOL 100 aircraft control system 400 may further include an actuator 412. The actuator 412 can be operationally coupled to the tilting propellers 402, 404 by means of the tilting mechanism 406. Specifically, as shown in the figures, the drive shaft 414 couples the actuator 412 to the elongated element (e.g., rod) 416 of the tilting mechanism 406. As such, the actuator 412 can act to change the angle of the drive shaft 414, thereby moving the rod 416. For example, the actuator 412 may be a motor or other powered system that moves the tilting mechanism 406 from the first position to the second position. As shown in Figure 4A, the actuator 412 is positioned inside the wing 410. This configuration allows the actuator 412 to be positioned away from the bar 416, so that an additional torsional force can be applied to the bar 416.Furthermore, the arrangement illustrated in Figures 4A-4C allows the rotation axis for the tilting propellers 402, 404 to be provided on the wing 410.

[00061] According to various embodiments, the drive shaft 414 connects a plurality of tilt propellers to one another such that a single actuator 412 drives the tilt of all the tilt propellers (individually, in subassemblies, or all together) of the VTOL aircraft 100. In the example embodiment illustrated in Figure 4A-4C, all the tilt propellers 402, 404 coupled to the same wing 410 can be controlled using a single drive shaft 414, such as one passing through the wing 410. For example, the drive shaft 414 may pass through the horizontal center of the wing 410. This example system may have improved reliability compared to having separate actuators (one actuator for each tilt propeller).

[00062] As analyzed in Figures 4A-4C, a VTOL 100 aircraft having a forward-pitch propeller 402 and a trailing-pitch propeller 404 should be seen from a three-dimensional perspective, the VTOL 100 aircraft may have a number of support elements 408, each comprising a plurality of pitch propellers. As such, the forward-pitch propeller 402 and the trailing-pitch propeller 404 on one support element may be connected by a pitching mechanism 406 and positioned with an actuator 412. Furthermore, other pitch propellers mounted on other support elements 408, or other wings 410, may be connected to the same pitching mechanism 406 and / or positioned with the same actuator 412.For example, a right wing 206 may have three forward tilting propellers (4, 5, 6) and three aft tilting propellers (10, 11, 12), all of which are controlled by a control system 400, which includes an actuator 312. A similar structure may hold true for the plurality of propellers coupled to the left wing 208. In various embodiments, each of the plurality of tilting propellers on each of the wings, 206, 208, may be controlled by separate control systems 400, or may share several components, including the actuator 412. Alternatively, a predetermined number of tilting propellers (e.g., tilting propellers coupled to a particular wing, particular support elements, forward tilting propellers, or any other configuration) may be grouped and controlled using a single actuator.According to still other configurations, different drive shafts can be extended through the wing to drive different tilting propellers. According to still other configurations, the VTOL 100 aircraft can include stationary propellers in addition to 402 and 404 tilting propellers.

[00063] The actuator size required to tilt an individual propeller is at least partially related to the gyroscopic torque applied to the tilt mechanism due to the gyroscopic torque from aircraft attitude changes. The gyroscopic torque equation is: Gyrojorque = cross_product(omega_airplane, J*omega_fan) Where gyrojorque, omega_airplane, and omegajan are all vector quantities. Omega_airplane is the rate of change of aircraft attitude and omegajan is the speed at which the propeller rotates to provide thrust of n / QQcn / cznz / a / vi. The variable J is the polar moment of inertia of the propeller.

[00064] For aircraft with multiple propellers, omega_airplane is the same for all propellers because they are all attached to the same relatively rigid frame. In some configurations, all propellers may have the same polar moment of inertia. While some propellers may rotate clockwise, others may rotate counterclockwise. In some configurations, the number of clockwise-rotating propellers may be equal to the number of counterclockwise-rotating propellers. In some configurations, all propellers may rotate at the same rate (for example, the magnitude of omega_fan is the same for all propellers, but the sign may be positive or negative).

[00065] In some configurations where multiple propellers are tilted using a single actuator, the mechanism can be designed such that the return axis of all the propellers is approximately parallel. The configurations shown in Figures 3A-3C, 4A-4C, and 8A-8C are examples of this type of mechanism. In cases where two propellers are connected in this manner, it is possible to rotate one clockwise and the other counterclockwise. This configuration has the benefit that the gyroscopic torque of one propeller cancels the gyroscopic torque of the other (known as the cancellation effect), thereby reducing the size of the actuator required to provide the tilting motion. A smaller actuator will be lighter, which is a significant advantage in aircraft design.In additional modalities with multiple even numbers of propellers connected with a mechanism, the cancellation effect can be achieved if one half of the propellers rotate in one direction and the other half of the propellers rotate in the opposite direction.

[00066] In some configurations, the tilting propellers can be matched based on the failure status. According to various configurations, when one propeller fails, it is preferable to shut down a corresponding propeller to equalize (balance) the failure and maintain the aircraft in (or nearly in) equilibrium. The corresponding propeller can be diametrically symmetric to the failing propeller with respect to the aircraft's center of gravity. For example, with reference back to Figure 2A, propeller No. 8 can be matched with propeller No. 5. Propeller No. 8 is diametrically symmetric to propeller No. 5 with respect to the aircraft's center of gravity. If propellers No. 5 and 8 fail together, there is no impact on the VTOL 100 aircraft such that the remaining propellers maintain the aircraft in equilibrium. Therefore, tilting propellers that are matched based on the fault state can be connected to the same tilting mechanism.For example, pitch propellers can be connected to a drive shaft on the wing and coupled to the same actuator. Therefore, instead of having pitch propellers on the same support element coupled to the same actuator (as illustrated in Figures 3A-3C), pitch propellers that are paired based on the failure state can be coupled to the same actuator in Figures 4A-4C. The example configuration illustrated in Figures 4A-4C includes half the number of actuators as in a configuration where each pitch propeller has its own actuator, and yet provides the same level of safety as in the configuration where each pitch propeller has its own actuator.

[00067] Figure 5A illustrates an example embodiment of a VTOL 500 aircraft, where a forward-slant propeller 502 and a trailing-slant propeller 504 are attached to a support element 506. The support element 506 can be provided under the wing 510 and / or attached to the wing 510 or the fuselage of the VTOL aircraft. The trailing-slant propeller 504 is used during forward flight and has variable pitch. The forward-slant propeller 502 can include, for example, 2, 3, 4, or 5 blades. In the example embodiment, the trailing-slant propeller 504 can only provide thrust in vertical flight mode, has no variable pitch, and can be optimized for vertical flight. In forward flight, the trailing-slant propeller 504 cannot be used and, as such, will provide little or no thrust. The 504 trailing-angle propeller can include, for example, 2, 3, 4 or 5 blades.In forward flight, the trailing-piston propeller 504 can either advance without pedaling or fold down to reduce drag. The trailing-piston propeller 504 can be rotatably coupled to a rear end of the support element 506 by any suitable coupling means, such as an arm 508. One or more travel-limiting stops 516 can be coupled to the rear end of the support element 506, closer to the trailing-piston propeller 504. The travel-limiting stops 516 can act to limit the rotation angle of the arm 508, and therefore, the trailing-piston propeller 504.For example, arm 508 can only rotate between a vertical direction (such that trailing propeller 504 is positioned directly below the support element / wing / fuselage) and a horizontal direction (such that trailing propeller 504 is pointing directly behind the support element / wing / fuselage).

[00068] In some embodiments, a spring element 512 may retain the arm 508 against one of the travel-limiting stops 516. Similar to a spring-loaded hinge, the spring element 512 may act to provide a preload on the arm 508, such that the force required to tilt the trailing-piston propeller 504 from a vertical lift position to a forward-flight position may be reduced by the spring. The thrust 514 from the trailing-piston propeller 504 may exceed the preload of the spring element 512 at a predetermined rpm (a threshold thrust value) of the trailing-piston propeller 504, causing the arm 508 and trailing-piston propeller 504 to tilt.Therefore, the trailing-tilt propeller 504 can be moved passively, and it is passive in the sense that no actuator or powered mechanism is coupled to the trailing-tilt propeller 504 to tilt it from a vertical to a horizontal position, or vice versa. However, by using a passive tilting mechanism driven by the thrust of the trailing-tilt propeller 504, the trailing-tilt propeller 504 is configured to pivot or tilt from a vertical lift position (where the trailing-tilt propeller 504 can be used for thrust) to a forward flight position (where the trailing-tilt propeller 504 cannot be used for thrust).Furthermore, the passive movement capability of the 504 rear-tilt propeller allows it to be mechanically independent of other rear-tilt or forward-tilt propellers. As such, the ability of the 504 rear-tilt propeller to tilt from a vertical to a horizontal position (yn / QQcn / cznz / a / vi and vice versa), for example, as described, may not depend on the functionality of other tilt propellers. For instance, the failure of the tilt mechanisms or actuators of other tilt propellers (forward or rear) may not affect the continued operation of the 504 rear-tilt propeller.

[00069] For example, in the example VTOL 100 aircraft illustrated in Figure 2A, all the forward propellers (propellers Nos. 1-6) can be active tilt propellers, while all the rear propellers (propellers 7-12) can be passive tilt propellers. This configuration can result in reduced vibration in the VTOL aircraft as the rear propellers receive the highly turbulent wing wake, while the forward propellers ingest clean air, resulting in quiet flight and low vibration. The forward propellers can be coupled in various ways, such that any number of the forward propellers can be coupled to one drive (for example, each forward propeller can be coupled to its own individual drive, or any number of forward propellers can be grouped and coupled to one drive).

[00070] Figure 5B illustrates the positions of the forward-tilt propeller 502 and the trailing-tilt propeller 504 during the arrival (e.g., from flight to landing) and departure (e.g., from hover to flight) transitions of the VTOL aircraft. In stage 550, the VTOL aircraft 500 is in a hover (e.g., on the ground). The trailing-tilt propeller 504 is vertical with respect to the support element 506 (or the fuselage of the VTOL aircraft 500), and the forward-tilt propeller 502 is horizontal with respect to the support element 506 where the forward-tilt propeller 502 and trailing-tilt propeller 504 are coupled.

[00071] In stage 552, the VTOL 500 aircraft is in vertical flight mode (e.g., takeoff / landing mode). The trailing-tilt propeller 504 remains vertical with respect to the support element 506, and the forward-tilt propeller 502 is tilted at an angle toward the fuselage of the VTOL 500 aircraft. The total vertical thrust from the forward-tilt propeller 502 and trailing-tilt propeller 504 begins to lift the VTOL 500 aircraft if it is in the flow, or lowers it toward the ground if it is airborne. In stage 552, the thrust does not exceed the spring preload on the arm 508.

[00072] In stage 554, the VTOL 500 aircraft is airborne and in hover mode. Thrust exceeds the spring preload on arm 508, and trailing-tilt propeller 504 tilts to a horizontal position (e.g., parallel to support element 506 and / or the fuselage). Forward-tilt propeller 502 is also in a horizontal position relative to support element 506. In stage 554, both forward-tilt propeller 502 and trailing-tilt propeller 504 can provide thrust and allow the VTOL 500 aircraft to hover.

[00073] In stage 556, the VTOL aircraft 500 is in a transition mode. The trailing tilt propeller 504 remains in the horizontal position with respect to the support element 506, and the forward tilt propeller 502 is tilted at an angle away from the support element 506. The forward tilt propeller 502 is transitioning to forward flight mode where the forward tilt propeller 502 will be in a vertical position with respect to the support element 506. n / QQcn / cznz / a / vi

[00074] In stage 558, the VTOL 500 aircraft is fully downwind and in forward flight mode. The trailing-piston propeller 504 tilts to a vertical position relative to the support element 506 (e.g., perpendicular to the support element 506 and / or the fuselage). The forward-piston propeller 502 is also in a vertical position relative to the support element 506, providing thrust to move the VTOL 500 aircraft forward. In this example mode, during forward flight, the trailing-piston propeller 504 cannot be used and provides minimal or no thrust. According to various modes, the blades of the trailing-piston propeller 504 can be folded when the trailing-piston propeller 504 is not in use (e.g., in forward flight mode).

[00075] The sequential transition from stage 550 to stage 558 illustrates a takeoff transition where the VTOL 500 aircraft takes off from a stationary position on the ground to forward flight in the air. The sequential transition from stage 558 to stage 550 illustrates an arrival transition where the VTOL 500 aircraft lands on the ground from forward flight in the air.

[00076] Figures 6A-6C show a VTOL aircraft 600 where the trailing-piston propeller 604 tilts from a horizontal position with respect to a support element or the wing (e.g., vertical flight position) to a vertical position with respect to the support element or the wing (e.g., forward flight position). During forward flight, the trailing-piston propeller 604 may be passively moved and, for example, tilted due to the lack of centrifugal force on the blades 606 of the trailing-piston propeller 604. According to various embodiments, the tilting of the trailing-piston propeller 604 may be passive (e.g., achieved without the use of an actuator), such as by using a mechanism (e.g., a spring-driven mechanism) as discussed with respect to Figure 5A.The trailing-tilt propeller 604 can be used for vertical flight (e.g., takeoff, hover, and / or landing) and may not have variable pitch. The forward-tilt propeller 602 may include various aspects of a control system, such as those discussed with reference to Figures 3A-3C and / or 4A-4C. The forward-tilt propeller 602 may have variable pitch, as discussed above.

[00077] In addition to the tilting of the trailing-piston propeller 604, the blades 606 of the trailing-piston propeller 604 can be folded circumferentially toward one another due to the aerodynamic drag experienced during forward flight, as shown in Figures 6D-6F. Figures 6A-6F illustrate an individual blade 606 for ease of understanding; however, it is understood that the trailing-piston propeller 604 can include any number of blades. This folding of the trailing-piston propeller 604 can reduce aerodynamic drag on the VTOL 100 aircraft during forward flight. As the blades 606 are folded together, a first crank slider 608 coupled to a second crank slider 610 can tilt the trailing-piston propeller 604 to a low-drag configuration.The blades 606 fold back from being orthogonal to the rotation axis of the trailing-piston propeller 604 to being parallel to the rotation axis in the folded position. In various embodiments, the folding of the blades 606 can be coupled to the tilt of the trailing-piston propeller 604. For example, a spring element can hold the trailing-piston propeller 604 in a forward flight configuration where the rotation axis of the trailing-piston propeller 604 is parallel to the direction of travel of the VTOL aircraft. The spring element can tilt the trailing-piston propeller 604 substantially simultaneously with folding the blades 606 of the trailing-piston propeller 602.When the deployment of the blades 606 is coupled with the tilting of the trailing-pitch propeller 604, the rotation of the trailing-pitch propeller drive motor 602 tilts the trailing-pitch propeller 602 into the desired configuration to provide the desired thrust direction.

[00078] In various configurations, the forward-pitch propeller 602 may include a variable pitch mechanism, as discussed above. When the forward-pitch propeller 602 is tilted from the fly-over configuration to the forward-flight configuration, the pitch angle of the blades may change. The variable pitch mechanism includes an actuator that can twist the blades around the blade axis 612. The pitch of the forward-pitch propeller 602 may be coupled to the pitch of the blades of the forward-pitch propeller 602.

[00079] Figures 7A-7C show an example control system 700, which includes a tilt propeller 702, wherein the tilt mechanism 704 includes four rods 706. As described above, the tilt mechanism 704 can be provided entirely within the support element 708. For example, incorporating the tilt mechanism 704 within the support element 708 can provide a tight or flush connection between the tilt propeller 702 and the support element at the leading edge; such designs can provide reduced drag in the forward flight position.Figures 7A-7C illustrate a series of positions where the tilting mechanism 704 tilts the tilting propeller 702 from a horizontal position to provide thrust for forward flight (illustrated in Figure 7A), to a transition position (illustrated in Figure 7B), to a vertical position to provide thrust for vertical lift (illustrated in Figure 7C). The control system 700 may include one or more actuators (not shown) that are coupled to the tilting mechanism 704, such as with a drive shaft, as discussed above.

[00080] The tilting propeller 702 may be a forward-tilting propeller 702. The control systems 300 described above, with reference to Figures 3A-6F, show the forward-tilting propeller 302 connected to the actuator 312 by means of a single rod 316 that joins the forward-tilting propeller 302 and the drive shaft 314. In contrast, the tilting mechanism 704 may include four rods 706, which provide a multiple connection (e.g., a four-bar linkage) to the forward-tilting propeller 702. According to various embodiments, the four-bar tilting mechanism 704 may provide the advantage of faster and easier alignment of the forward-tilting propeller 702 with the support element 708 in the forward-flight position, such as to reduce drag without the need for multiple movable or hinged fairings.Furthermore, the four-bar linkage 706 of the control system 700 allows the load path between the forward-tilting propeller 702 and the support element 708 to extend through the wing 710. This load path experiences large vibratory loads that tend to break components and damage joints. The four-bar linkage 704 distributes the load among the four bars 706 instead of a single pivot point. Therefore, the four bars act as additional load paths.

[00081] Figures 8A-8C show an example control system 800, which includes a forward-tilting propeller 802 and a backward-tilting propeller 804. According to various embodiments, the control system 800 may include a tilting mechanism 806 that operatively connects the forward-tilting propeller 802 and the backward-tilting propeller 804 to an actuator, as described above.

[00082] In several embodiments, one or both of the forward-pitch propeller 802 and the rear-pitch propeller 804 may be coupled (linked) to the pitching mechanism 806 by means of a forward four-bar pitching mechanism 808 and a rear four-bar pitching mechanism 810, respectively, as illustrated in Figures 8A-8C. The forward four-bar pitching mechanism 808 and the rear four-bar pitching mechanism 810 may be provided within the support element 814 and may be connected to an actuator (not shown) by means of a single shaft 812, adapted to pitch both the forward-pitch propeller 802 and the rear-pitch propeller 804 simultaneously (e.g., substantially at the same time). The actuator may be provided in the middle of the support element 814 or within the wing 816, as discussed above.Figures 8A-8C illustrate a series of figures where the four-bar tilting mechanisms 808, 810 tilt the forward-tilting propeller 802 and the rear-tilting propeller 804 from a horizontal position to provide thrust for forward flight (illustrated in Figure 8A) to a transitional position (illustrated in Figure 8B) to a vertical position to provide thrust for vertical lift (illustrated in Figure 8C).

[00083] In several embodiments, the four-bar tilt mechanisms 808, 810 can be further coupled to a drive shaft 818 provided in the wing 816 by means of the single shaft 812, as illustrated in Figures 81A to 8-1C. Accordingly, the four-bar tilt mechanisms 808, 810 can be driven by the drive shaft 818 through the wing 816. Figures 8-1A to 8-1C illustrate a series of configurations where the four-bar tilt mechanisms 808, 810 tilt the forward-pitch propeller 802 and the trailing-pitch propeller 804 from a horizontal position to provide thrust for forward flight (illustrated in Figure 8-1A) to a transitional position, to a vertical position to provide thrust for vertical lift (illustrated in Figure 8-1C).

[00084] According to various embodiments, instead of the drive shaft 818 being a single linear structure (such as drive shaft 314), the drive shaft 818 may comprise a plurality of linear structures. For example, the drive shaft 818 may comprise multiple shafts 820, which can be connected by respective connecting joints 822. In operation, shaft 820A may be directly coupled to the actuator and may rotate similarly to drive shaft 314. Shaft 820A may be coupled to shaft 820B (at a joint 822), which is angularly adjusted after the movement of shaft 820A. Furthermore, shaft 820C may be coupled to shaft 820B (at a joint 824) and may be coupled at the opposite end to the single shaft 812 to provide movement to the tilting mechanism 806.The use of multiple 820 trees may allow a similar n / QQcn / cznz / a / vi movement as a single tree (such as the drive tree 314), but may be able to use less space, and better meet the space limitations of the wing 816 and / or support element 814.

[00085] For fault-tolerant aircraft design, it can be beneficial for the tilt mechanism to be fail-safe, meaning that after a tilt mechanism failure, it remains in or moves to a safe configuration, thus providing balance to the VTOL aircraft and preventing loss of control. Generally, for a VTOL aircraft, the thrust required by each propeller in hover is higher than the thrust required by each propeller in forward flight. Therefore, if a failure occurs, it would be fail-safe if the tilt mechanism could always move to the hover configuration, such that the tilt propellers are in the vertical lift position, even in the event of an actuator failure.As such, a fail-safe mechanism, such as a spring element or similar mechanism (e.g., a hydraulic piston), can be provided, for example, as part of the tilt mechanism, which can act to tilt or hold the tilt propeller in the flyby position. In order to tilt the propeller to the forward flight configuration, the actuator must overcome the force of the spring element. Specifically, in the event of an actuator failure, the spring element of the tilt mechanism can move the tilt mechanism so that the tilt propellers are in the vertical lift position to provide downward thrust.

[00086] Figure 9 shows an example schematic of a VTOL aircraft control system 900 having a drive 910 (e.g., actuator, compressor, valve, or primary piston) driving at least two tilt mechanisms 912, 914 coupled to respective tilt propellers 902, 904. The tilt propellers 902, 904 may be in various locations on the VTOL aircraft, and need not necessarily be tilt propellers placed on the same wing or on the same support element.

[00087] When designing the 900 control system, a coupling scheme can be determined in which the tilt helices are linked together by a particular tilting mechanism. As such, the coupling scheme can determine the functionality of which tilt helices are matched to each other. For example, a coupling scheme may include a first subset of tilting mechanisms, such as tilting mechanism 912 and tilting mechanism 914, which can be operatively coupled to drive 910 (e.g., an actuator). The 900 control system may further include a second subset of tilting mechanisms, a third subset of tilting mechanisms, and so on, each of which can be operatively coupled to one or more drives.

[00088] The plurality of tilting propellers can be divided into groups, such as a second group of tilting propellers, a third group of tilting propellers, and so on, each of which can have a separate subset of tilting mechanisms. Each of the groups, or a plurality of groups of tilting propellers (e.g., the first and second groups of tilting mechanisms), can be operatively coupled to the same actuator. For example, one actuator can tilt the first group of tilting propellers and the second group of tilting propellers. Conversely, groups of tilting propellers can be operatively coupled to separate actuators by means of subsets of tilting mechanisms.For example, a second actuator can be coupled to the second subset of the plurality of tilting mechanisms, such that the second actuator tilts the second group of tilting propellers coupled to the second subset of the plurality of tilting mechanisms simultaneously.

[00089] According to various docking schemes contemplated herein, the docking scheme may be diametrically symmetrical with respect to the center of gravity of the VTOL 100 aircraft. The docking scheme may further determine the number of tilt mechanisms and actuators required. In determining the docking schemes, a designer may take into account cost, weight, safety, and various other determinations pertinent to aircraft design.

[00090] For example, tilting propellers 902 and 904 can be selected for pairing based on the failure status. According to various modalities, when one of the twelve propellers fails, it is preferable to shut down a symmetrical tilting propeller to maintain the aircraft in equilibrium. The corresponding tilting propeller is diametrically symmetrical to the failing propeller with respect to the aircraft's center of gravity. For example, as illustrated in Figure 9, tilting propeller No. 8 (904) is diametrically symmetrical to, and therefore can be operatively coupled with, tilting propeller No. 5 (902). Therefore, tilting mechanism 914 is used to tilt propeller No. 8 (904), and tilting mechanism 912 is used to tilt propeller No. 5 (902). 5 (902) can be coupled to an individual drive 910. Therefore, in case either propeller 902 or 904 fails, the corresponding propeller 904 or 902 can be deactivated.In the embodiment illustrated in Figure 9, an individual drive (e.g., a ball screw actuator) 910 can be connected to the tilting propeller No. 8 (904) and the tilting propeller No. 5 (902) via hydraulic lines 920 and 922, respectively, which extend through the wing and fuselage. The two tilting mechanisms 912, 914 are coupled together and move (e.g., tilt) together. According to various embodiments, other mechanisms can be used to operationally couple the tilting propellers, as discussed in detail.

[00091] Similar to the linking of tilt propellers 902, 904 to a drive 910, several groups of tilt propellers can be paired or grouped together. For example, other sets of two tilt propellers can be selected based on diametral symmetry. In other embodiments, other groups of tilt propellers can be coupled to a drive according to other coupling schemes. Furthermore, while tilt propellers 902, 904 are paired based on diametral symmetry, other tilt propellers within the same VTOL 100 aircraft can be paired based on other criteria, and therefore may be on the same support element or wing. Other groups or pairs of tilt propellers may use the same drive 910 as tilt propellers 902, 904, or may otherwise share control system components.However, in several configurations, other groups or pairs of tilting propellers may comprise separate tilting mechanisms and actuators. n / QQcn / cznz / a / vi

[00092] According to various embodiments, the control system 900 may be a part of the flight control system of the VTOL aircraft 100. In some embodiments, the control system 900 may include a memory that stores executable instructions which, when executed by one or more processors of the control system, cause the one or more processors to tilt one or more of the tilt propellers 902, 904 using a tilt mechanism 912, 914 according to a coupling scheme.

[00093] As described above, any number of actuators can be used to drive the tilting mechanisms of the tilting propellers. Figures 10 and 11 show example configurations with different numbers of actuators. As shown in Figures 10 and 11, the coupling scheme for the control system includes all of the plurality of tilting mechanisms (e.g., primary cylinders and secondary cylinders), such that a shared actuator tilts all of the plurality of tilting propellers.

[00094] Figure 10 illustrates an example control system 1000 that includes an actuator 1002 operatively connected to a plurality (for example, 12) of primary cylinders 1004. For example, the plurality of primary cylinders 1004 may function to distribute power from the actuator 1002 to a respective secondary cylinder 1006 coupled to a tilting propeller. As such, a tilting mechanism may include a first primary cylinder 1004 operatively coupled to a first secondary cylinder 1006, which may be operatively coupled to a first tilting fan. As discussed below, with reference to Figures 12A-12B, the actuator 1002 may include a shaft (such as a ball screw shaft). As the shaft rotates, the actuator 1002 can apply a force to a plurality of pistons, each one enclosed respectively within each of the plurality of primary cylinders 1004.As such, the rotation of the actuator shaft 1002 can create hydraulic pressure within the primary cylinders 1004. The hydraulic pressure within the primary cylinders 1004 can be applied through a respective hydraulic line or lines to the respective secondary cylinder 1006. The secondary cylinders 1006 can act to convert the hydraulic force in the hydraulic lines into mechanical force, such as with a piston. Each of the secondary cylinders 1006 can then be linked to a tilt propeller of the VTOL aircraft, and the piston of a secondary cylinder 1006 can cause the respective tilt fan to tilt. As such, an individual actuator 1002 can operatively tilt each of the tilt propellers simultaneously by creating hydraulic pressure that is applied by a respective secondary cylinder 1006 to the tilt propeller.According to various methods, a similar functional effect can be achieved using non-hydraulic systems, such as a mechanical system that links the actuator 1002 to the respective tilting propellers (such as with gears and mechanical tilting mechanisms).

[00095] The example 1000 control system in Figure 10 can therefore provide a reduction in the number of components required to tilt a plurality of tilt propellers, by having multiple tilt propellers driven by a single actuator. Furthermore, programming to control the plurality of tilt propellers can be simplified, requiring only the control of a single actuator. However, the shared components can increase the potential for a single failure (e.g., actuator failure) to result in an immobile aircraft. As such, additional control system components, as discussed below, can be further included in the VTOL 100 aircraft to provide redundant power and tilt control of the tilt propellers.

[00096] Figure 11 illustrates an example control system 1100 that includes two actuators 1102 and 1104, which operate in parallel with each respective primary power cylinder 1106, 1108. For example, in a VTOL aircraft 100 that has 12 tilt propellers, each of the actuators 1102, 1104 can have 12 corresponding primary cylinders 1106, 1108. A pair of primary cylinders 1106, 1108 can be coupled to a specific secondary cylinder 1110 that corresponds to a tilt propeller through hydraulic lines 1112, 1114. For example, actuator 1102 can be coupled to and power primary cylinder 1106, and actuator 1104 can be coupled to and power primary cylinder 1108. The cylinders Both primary cylinders 1106 and 1108 can be linked to secondary cylinder 1110 to control a tilting propeller (e.g., tilting propeller no. 6).Similarly, the pairs of both a primary cylinder coupled to actuator 1102 and another primary cylinder coupled to actuator 1104 can be connected to another individual secondary cylinder. Whereas Figure 11 illustrates hydraulic lines 1120, 1122 for only one individual secondary cylinder 1110, the secondary cylinders of all tilt propellers can have hydraulic line connections similar to their respective pair of primary cylinders.

[00097] As such, this configuration of the 1100 control system adds redundancy to increase the fault tolerance of the overall system. A failure (e.g., a leak) anywhere within the 1100 control system could result in the failure of one propeller. However, because each actuator 1102, 1104 (and their respective primary cylinders 1106, 1108) is independent of each other, in the event of a failure, only an individual tilting propeller would fail. Each actuator 1102, 1104 may include a ball screw actuator. The redundant ball screws eliminate them as individual points of failure (e.g., the ball screws cannot be driven backward).

[00098] According to various embodiments, the system may include additional actuators (for example, a third actuator that also drives 12 primary cylinders in addition to the first two actuators). According to some embodiments, the system may include a plurality of actuators, each actuator driving any number (for example, 1 to 12) of primary cylinders. As such, a control system 1100 could have multiple sets of respective actuators and primary cylinders in parallel with the actuators 1102, 1104 and the primary cylinders 1106, 1108 shown, providing additional layers of fail-safe protection, by way of example.

[00099] According to various embodiments, the example control system 1100 of Figure 11 may further include a pitching mechanism in addition to the tilting mechanism coupled to each of the tilting propellers. The pitching mechanism and the tilting mechanism may each correspond to one of the secondary cylinders 1110. The primary cylinders 1106, 1108 (and, therefore, the actuators 1102, 1104) may drive both the tilting mechanism and the pitching mechanism together. [000100] Figure 12A illustrates a cross-sectional view of an example 1200 primary cylinder system, according to various embodiments. In general, primary cylinders can be powered by one or more actuators, such as a ball drive actuator. It should be noted that various other mechanisms that perform the same function can also be used or are used in addition to it. [000101] In Figure 12A, the primary cylinder system 1200 may include a ball screw shaft 1202, which may be centrally located in a circular structure, for example. The ball screw shaft 1202 may be configured to provide push and pull forces to the pistons in the primary cylinders 1204 positioned circumferentially around the ball screw shaft 1202. The primary cylinder system 1200 may further include a plurality of bores 1206, where at least one bore 1206 corresponds to each primary cylinder 1204. The bores 1206 may be positioned proximal to the outer edge of the circular structure, such as pointing radially away from the ball screw shaft 1202. Functionally, the bores 1206 may act as a hydraulic connection for the force applied to the primary cylinders 1204 by the ball screw shaft 1202.For example, when a pushing force is applied by the ball screw shaft, the pistons of the primary cylinders 1204 can force the hydraulic fluid out of the primary cylinder 1204. Conversely, when a pulling force is applied to the primary cylinders 1204 by the ball screw shaft 1202, a suction force can draw the hydraulic fluid back through the ports 1206 into the respective primary cylinder 1204. As such, the ports 1206 can each be coupled with a hydraulic line, as discussed above, which carries the hydraulic fluid to various tilting mechanisms, resulting in the tilting of a tilting propeller. For example, each of the primary cylinders 1204 can be connected to the hydraulic line via port 1206. This hydraulic line can then, for example, be connected to a secondary cylinder for a particular tilting propeller. [000102] Figure 12B shows a cross-sectional view of a primary cylinder system 1201, incorporating two redundant pistons in a single primary cylinder 1204, according to various embodiments of this disclosure. The primary cylinder system 1201 may include a first ball screw actuator 1210 and a second ball screw actuator 1220. The first and second ball screw actuators 1210 and 1220 may, for example, be arranged facing each other and be concentric with the circular structure housing the primary cylinders 1204. The first ball screw actuator 1210 may be coupled to the primary cylinder system 1201 by means of mechanisms 1212 on the left side, and the second ball screw actuator 1220 may be coupled to the primary cylinder system 1201 by means of mechanisms 1222 on the right side. [000103] Both ball screw actuators 1210 and 1220 can be connected to the same hydraulic circuit and, therefore, both can act to move the same piston in a primary cylinder 1204. According to various configurations, each of the ball screw actuators 1210 and 1220 can provide an opposing force. For example, the first ball screw actuator 1210 can push a piston from the left side into the centrally located bore 1206 in the primary cylinder 1204. The second ball screw actuator 1220 can push a piston from the right side into the bore 1206. As such, each can provide an equal amount of hydraulic force through the bore 1206.However, to provide a fail-safe configuration, each of the ball screw actuators 1210, 1220 can be configured to move beyond the center nvQQcn / cznz / a / vi of the primary cylinder 1204 such that if one of the ball screw actuators 1210, 1220 fails to perform the full range of motion required to generate the desired hydraulic pressure (such as in the case of failure), the other ball screw actuator 1210, 1220 can be configured to move beyond the center of the primary cylinder 1204 to provide the desired hydraulic force. Specifically, in the event that one of the ball screw actuators 1210,1220 fails, the remaining ball screw actuator 1210,1220 can move all the way to where the failing ball screw actuator 1210, 1220 stopped, thereby generating the same maximum travel as both ball screw actuators 1210, 1220 operating in tandem. [000104] The primary cylinder system 1201 illustrated in Figure 12B is an example implementation of the primary cylinder system 1200 illustrated in Figure 12A. In the primary cylinder system 1201 of Figure 12B, the primary cylinders 1204 can be much smaller (i.e., approximately half the size) compared to other systems where additional, completely separate primary cylinders 1204 are provided. Furthermore, the embodiment illustrated in Figure 12B can reduce the number of seals used in the primary cylinder system 1201, and as such, can provide fewer components that may leak or otherwise fail. [000105] In various configurations, the flight control system (or other control system coupled to the VTOL 100 aircraft) can control the tilt mechanisms to switch the tilt propellers from the forward flight position to the vertical position, and vice versa. In various configurations, the control system (e.g., flight control system) can control the tilt propellers between these two positions based on sensor data and / or flight data received from sensors (e.g., sensors measuring air temperature, electric motor temperature, aircraft airspeed, etc.), computers, and other input / output devices coupled to the aircraft. [000106] For simplicity, several active and passive circuitry components are not shown in the figures. In the foregoing specification, the disclosure modalities have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense. The sole and exclusive indicator of the scope of the description, and what the applicants propose to be the scope of the description, is the literal and equivalent scope of the set of claims issued from this application, in the specific form in which these claims are issued, including any subsequent amendments. The specific details of the particular modalities may be combined in any suitable manner without departing from the spirit and scope of the disclosure modalities.[000107] The electronic components of the described modalities may be specially constructed for the required purposes, or may comprise one or more general-purpose computers selectively activated or reconfigured by a computer program stored on the computer. This computer program may be stored on a computer-readable storage medium, such as, but not limited to, any type of disk including floppy disks, optical disks, DVDs, CD-ROMs, magnetic-optical disks, read-only memories (ROM), random-access memories (RAM), EPROMs, EEPROMs, magnetic or optical cards, application-specific integrated circuits (ASIO), or any other type of medium suitable for storing electronic instructions, each coupled to a computer system bus. [000108] Furthermore, spatially relative terms, such as front or back and the like, may be used to describe a relationship of one element and / or feature to another element and / or feature, as illustrated, for example, in the figures. It is understood that spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, the elements described as a “front” surface may then be oriented “backward” from other elements or features. The device may be oriented in other ways (for example, it may be rotated 90 degrees or in other orientations), and the spatially relative descriptive elements used herein may be interpreted accordingly. [000109] Since the invention has been described with reference to specific embodiments, those skilled in the art with access to this disclosure will appreciate that variations and modifications are possible. [000110] It should be understood that all numerical values ​​used herein are for illustrative purposes and may vary. In some cases, intervals are specified to provide a sense of scale, but numerical values ​​outside of a disclosed interval are not excluded. [000111] It should also be understood that all diagrams herein are proposed as schematic. Unless specifically stated otherwise, it is not proposed that the figures imply any particular physical arrangement of the elements shown therein, or that all the elements shown are necessary. Those skilled in the art with access to this disclosure will understand that elements shown in the figures or otherwise described in this disclosure may be altered or omitted and that other elements not shown or described may be added. [000112] The foregoing description is illustrative and not restrictive. Many variations of the embodiments will become apparent to those skilled in the art after review of the disclosure. The scope of patent protection, therefore, shall not be determined by reference to the foregoing description, but shall be determined by reference to the following claims together with their full or equivalent scope.

Claims

1. An electric aircraft comprising: a fuselage; at least one wing coupled to the fuselage; a plurality of tilt propellers coupled to the at least one wing, wherein the plurality of tilt propellers is configured to move between a vertical lift position and a forward flight position; a plurality of tilt mechanisms, each of the plurality of tilt mechanisms coupled with at least one tilt propeller among the plurality of tilt propellers; and a first actuator coupled to a first subset of the plurality of tilt mechanisms, wherein the first actuator tilts a first group of tilt propellers coupled to the first subset of the plurality of tilt mechanisms simultaneously, wherein the first subset of the plurality of tilt mechanisms is identified among the plurality of tilt mechanisms according to a coupling scheme.

2. The electric aircraft of claim 1, further comprising one or more support elements coupled below the at least one wing and spanning transversely from the at least one wing, wherein a forward-tilting propeller of the plurality of tilting propellers and a rear-tilting propeller of the plurality of tilting propellers are coupled to opposite ends of a first support element of the one or more support elements, wherein the forward-tilting propeller is provided on a leading edge of the at least one wing, and the rear-tilting propeller is provided on a trailing edge of the at least one wing.

3. The electric aircraft of claim 2, wherein a first tilting mechanism among the plurality of tilting mechanisms is coupled to the front tilting propeller and the rear tilting propeller, wherein the first tilting mechanism is provided within the first support element.

4. The electric aircraft of claim 2, further comprising: at least a second actuator coupled to a second subassembly of the plurality of tilting mechanisms, wherein the first subassembly of the plurality of tilting mechanisms consists of a first tilting mechanism such that the first actuator is coupled to the first tilting mechanism and is provided within the first support element.

5. The electric aircraft of claim 2, wherein a first tilting mechanism among the plurality of tilting mechanisms is coupled to at least one of the front tilt propeller or rear tilt propeller, wherein the first tilting mechanism includes a four-bar linkage and is provided within the first support element.

6. The electric aircraft of claim 1, wherein each of the first subassembly of the plurality of tilting mechanisms comprises a fail-safe mechanism, wherein after a first failure of the actuator or a tilting mechanism, the first group of tilting propellers moves to the vertical lift position.

7. The electric aircraft of claim 1, wherein the first subassembly of the plurality of tilting mechanisms further comprises a drive shaft located within at least one wing, the drive shaft operatively coupling the first actuator to the first group of tilting propellers.

8. The electric aircraft of claim 1, wherein the first actuator comprises a compressor and wherein the first subassembly of the plurality of tilting mechanisms further comprises hydraulic lines connecting the first subassembly of the plurality of tilting mechanisms to the first actuator.

9. The electric aircraft of claim 8, wherein each of the first group of tilting propellers comprises a respective tilting mechanism of the first subset of the plurality of tilting mechanisms.

10. The electric aircraft of claim 1, wherein the first group of tilting propellers consists of a plurality of front tilting propellers provided on a leading edge of at least one wing.

11. The electric aircraft of claim 10, wherein the plurality of tilting propellers further comprises a plurality of trailing tilting propellers provided on a trailing edge of at least one wing, wherein the plurality of trailing tilting propellers is configured to move passively from the vertical lift position to the forward flight position, wherein the plurality of trailing tilting propellers are mechanically independent of each other.

12. The electric aircraft of claim 11, further comprising: a support element coupled to at least one wing; a passive tilting mechanism coupled to a rear portion of the support element, the passive tilting mechanism further comprising: an arm rotatably coupling a determined trailing-tilt propeller from the plurality of trailing-tilt propellers to the support element; a spring element encompassing the determined trailing-tilt propeller and the support element, wherein the spring element is configured to cause the arm to rotate when the horizontal thrust exceeds a threshold thrust value; and at least one travel-limiting stop configured to limit a rotation angle of the arm.

13. The electric aircraft of claim 12, wherein the passive tilting mechanism is configured to reduce aerodynamic drag in the forward flight position by causing a plurality of blades of the determined trailing-tilt propeller to fold together while in the forward flight position.

14. The electric aircraft of claim 1, wherein the coupling scheme is diametrically symmetrical with respect to a center of gravity of the electric aircraft. n / QQcn / cznz / a / vi 15. The electric aircraft of claim 14, wherein the coupling scheme includes the entire plurality of tilting mechanisms, the first group of tilting propellers comprises the entire plurality of tilting propellers, and such that the first actuator tilts the entire plurality of tilting propellers.

16. The electric aircraft of claim 1, wherein the first subassembly of the plurality of tilting mechanisms comprises a plurality of primary cylinders operatively coupled with the first actuator, wherein each of the plurality of primary cylinders is operatively coupled to a secondary cylinder of a plurality of secondary cylinders that is operatively coupled to a predetermined tilting propeller of the first group of tilting propellers, wherein the plurality of secondary cylinders is configured to receive hydraulic pressure from the plurality of primary cylinders.

17. The electric aircraft of claim 16, further comprising a second actuator operatively coupled with the plurality of secondary cylinders in parallel with the first actuator, such that a determined actuator of the first and second actuators each tilts the determined tilt propeller of the first group of tilt propellers.

18. The electric aircraft of claim 1, further comprising: a second group of tilting propellers among the plurality of tilting propellers; and a second subset of the plurality of tilting mechanisms, each of the second subset of the plurality of tilting mechanisms coupled with at least one tilting propeller of the second group of tilting propellers.

19. The electric aircraft of claim 18, wherein the first actuator tilts the first group of tilting propellers and the second group of tilting propellers.

20. The electric aircraft of claim 18, further comprising: a second actuator coupled to the second subassembly of the plurality of tilting mechanisms, wherein the second actuator tilts the second group of tilting propellers coupled to the second subassembly of the plurality of tilting mechanisms simultaneously.

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