Aircraft with pusher propellers

Abstract

Embodiments provide an electric aircraft with multiple lift fan assemblies configured to provide vertical lift and one or more pusher propellers configured to provide forward thrust. The lift fan assemblies may be coupled to wings of the aircraft via one or more support structures, and the wings may be coupled to an upper region of the fuselage. The pusher propellers may be coupled to the trailing end of the fuselage. The lift fan assemblies and the pusher propellers may provide thrust and movement in directions perpendicular to one another. A control system coupled to the aircraft may control the lift fan assemblies and the one or more pusher propellers to activate, increase power, and decrease power. The lift fan assemblies and the one or more pusher propellers may be operated independently and may be active at different times.

Description

[Technical field]

[0001] Related Applications This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 62 / 972,528, entitled "Aircraft with Pusher Propeller," filed February 10, 2020, the disclosure of which is incorporated herein by reference in its entirety for all purposes.

[0002] The described embodiments relate generally to aircraft having vertical takeoff and landing capabilities. In particular, the embodiments provide an aircraft with multiple lift fan assemblies that provide vertical thrust in a controlled manner for takeoff, hovering, and landing, and one or more pusher propellers for cruise flight. [Background technology]

[0003] Aircraft with vertical takeoff and landing capabilities utilize vertically oriented thrust for takeoff and landing activities. When airborne, horizontal thrust is also required to achieve movement to another location. This may be achieved through a thrust source that can tilt or otherwise change orientation. However, these types of moving parts can be complex to engineer and manufacture, and can introduce additional maintenance requirements. Summary of the Invention

[0004] Various embodiments provide an aircraft configured for vertical takeoff and landing (VTOL). The aircraft includes a fuselage, a pair of wings coupled to opposite sides of an upper portion of the fuselage in a high-wing configuration, a plurality of lift fan assemblies coupled to the pair of wings, and one or more pusher propellers coupled to the fuselage. The plurality of lift fan assemblies are configured to generate vertical lift. The one or more pusher propellers are configured to generate forward thrust.

[0005] The multiple lift fan assemblies and one or more pusher propellers may be configured to provide vertical lift directionally perpendicular to the forward thrust.

[0006] An embodiment provides a method implemented by a control system coupled to an aircraft configured for vertical takeoff and landing, the control system including receiving flight instructions, activating a plurality of lift fan assemblies coupled to the aircraft configured to generate vertical lift for vertical takeoff and landing, controlling the plurality of lift fan assemblies to generate vertical lift such that the aircraft launches vertically from a stationary position above the ground, activating one or more pusher propellers coupled to the aircraft configured to generate forward thrust, controlling the one or more pusher propellers to generate forward thrust such that the aircraft attains a forward speed after the aircraft launches vertically from a stationary position above the ground, and deactivating or reducing power provided to the plurality of lift fan assemblies after a predetermined amount of forward speed is attained.

[0007] These and other embodiments are described in further detail below. [Brief description of the drawings]

[0008] [Figure 1]1A-1D are top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL air vehicle with multiple lift fan assemblies and one pusher propeller provided at the tailing end of the aircraft, according to various embodiments. [Diagram 2] 1A-1C are top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL aircraft with a V-tail and a pusher propeller provided at the tailing end of the aircraft behind the V-tail, according to various embodiments. [Diagram 3] 1A-1C are top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL aircraft with multiple pusher propellers, according to various embodiments. [Figure 4] 1 is a flowchart illustrating an example process for controlling flight of a VTOL aircraft, in accordance with various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The techniques disclosed herein generally relate to an aircraft with multiple lift fan assemblies and one or more pusher propellers. More specifically, the techniques disclosed herein provide an electric VTOL aircraft with multiple lift fan assemblies for vertical movement and one or more pusher propellers provided at the trailing end of the aircraft for forward movement. Various invention embodiments are described herein.

[0010] FIG. 1 illustrates top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL air vehicle 100 with multiple lift fan assemblies 102A-L and one pusher propeller 104 provided at the trailing end of the air vehicle 100. In the example shown, the VTOL air vehicle 100 includes a fuselage (main body) 108 and a pair of wings 112 and 114. The pusher propeller 104 is provided at the trailing end of the fuselage 108. A set of three underwing support structures 106 (e.g., booms) are provided below each of the pair of wings. Each support structure 106 has two lift fan assemblies 102A-L mounted thereon, one forward of the wing and one aft of the wing. Each of the lift fan assemblies 102A-L and the pusher propeller 104 may be driven by an associated drive mechanism (e.g., a dedicated electric motor, etc.). One or more batteries 135 and / or an on-board generator may be used to power the lift fan assemblies 102A-L and the pusher propeller 104 and / or to charge / recharge the on-board batteries.

[0011] In some embodiments, VTOL aircraft 100 may be configured to carry one or more passengers and / or cargo. In the example shown in FIG. 1, VTOL aircraft 100 includes a fuselage 108 (e.g., a body portion), which may take on a variety of shapes or forms. In some embodiments, fuselage 108 includes a cabin section 110 for carrying passengers and / or cargo. For example, cabin section 110 may be provided toward the nose of VTOL aircraft 100.

[0012] VTOL air vehicle 100 may further include landing gear 130. Landing gear 130 may include any suitable combination of one or more skids, wheels, skis, pontoons, shock absorbers, struts, and / or any other suitable components for supporting VTOL air vehicle 100 when landing and / or being landed on the ground. In some embodiments, landing gear 130 may be retractable into a compartment within fuselage 108.

[0013] A pair of wings (e.g., first wing 112 and second wing 114) are coupled to opposite sides of the fuselage 108. According to an embodiment, the pair of wings may have any suitable shape and configuration.

[0014] In some embodiments, the first wing 112 and the second wing 114 may be coupled to the fuselage 108 in a high-wing configuration. That is, the first wing 112 and the second wing 114 may be mounted on an upper portion of the fuselage 108, as shown in FIG.

[0015] The high-wing configuration can provide multiple advantages to the VTOL aircraft 100. For example, when the VTOL aircraft 100 is landed, the high-wing configuration can maintain the wings in an elevated position above passengers and personnel, allowing easier access to the fuselage 108 from various directions (e.g., for passenger boarding / unboarding and cargo loading / unloading). Additionally, the fuselage 108 can be the part of the VTOL aircraft 100 closest to the ground, allowing passengers and personnel to access the fuselage 108 without the aid of a portable boarding ramp or stairs. Furthermore, when the lift fan assemblies 102A-L are coupled to a pair of wings, the high-wing configuration can position the lift fan assemblies 102A-L above the cabin 110, such that the plane in which the lift fan assembly rotors rotate does not intersect with the fuselage and / or its human occupancy portions (e.g., for safety reasons). When the VTOL aircraft 100 lands, the high wing configuration can keep the lift fan assemblies 102A-L elevated above the ground and therefore unable to disturb dirt, sand, and other debris.

[0016] In other embodiments, first wing 112 and second wing 114 may be mounted to a lower portion of fuselage 108 in a low wing configuration or may be mounted to a mid-height portion of fuselage 108 in a mid wing configuration. Lower wing installations can provide easier access to the wings and lift fan assemblies 102A-L for maintenance, among other advantages.

[0017] The first wing 112 and the second wing 114 may take any suitable shape and form. For example, the pair of wings may be rectangular straight wings, tapered straight wings, rounded or elliptical straight wings, swept wings, delta wings, or any other suitable type of wing.

[0018] The first wing 112 and the second wing 114 may include any number of features or modifications to improve lift, reduce drag, improve aircraft controllability, improve stability, reduce turbulence, etc. For example, the first wing 112 and the second wing 114 may include a curved end (e.g., a winglet, etc.), which may be either a downturned winglet or an upturned winglet.

[0019] Multiple lift fan assemblies 102A-L (also known as "lift fans" and "vertical fans") may be coupled to a pair of wings. For example, VTOL aircraft 100 may include a total of twelve lift fan assemblies (e.g., fans, rotors, propellers) divided equally between the wings. In some embodiments, lift fan assemblies 102A-L may be coupled directly to the wings. In other embodiments, lift fan assemblies 102A-L may be mounted on a support structure 106 (e.g., a boom that may be coupled to the underside of wings 112, 114, etc.).

[0020] According to various embodiments, each lift fan assembly 102A-L may be in the form of an electric motor-driven rotor (e.g., a combined fan and motor) and may be configured to move the VTOL air vehicle 100 vertically, for example, during takeoff, hovering, and / or landing, and may be configured to stabilize and control the VTOL air vehicle 100.

[0021] The rotor may include any suitable number of blades (e.g., two blades, three blades, four blades, or five blades). The blades may have a predetermined angle of attack. The rotor may further include a hub. The blades may be attached to the hub. In some embodiments, the blades and integral hub may be manufactured as a single piece. The hub provides a central structure to which the blades connect, and in some embodiments is made in a shape that encases the motor. In some embodiments, the motor parts are low profile, allowing the entire motor to fit within the hub of the rotor and present less resistance to the airflow during forward flight. The rotor may be attached to the rotating parts of the motor. The stationary parts of the motor may be attached to the support structure 106. In some embodiments, the motor may be a permanent magnet motor and may be controlled by an electronic motor controller. The electronic motor controller may send current to the motor in a precise sequence to enable the rotor to spin at a desired speed or with a desired torque.

[0022] According to some embodiments, each wing 112, 114 may include three support structures 106 (e.g., booms). The support structures 106 are shown mounted substantially aligned with the horizontal plane of the VTOL aircraft 100 during horizontal flight. The support structures 106 may be coupled to the underside of a pair of wings. The support structures 106 may include a forward end that extends forward beyond the wings and an aft end that extends aft of the wings.

[0023] According to some embodiments, each support structure 106 can include a pair of lift fan assemblies 102A-L mounted thereon. For example, each lift fan assembly can be coupled to an end of support structure 106 such that a first lift fan assembly 102A is at the front of wing 112 and a second lift fan assembly 102L is at the rear of wing 112.

[0024] In some embodiments, each of the support structures 106 are identical, and thus the support structures 106 may be interchangeable between locations on the wing. For example, a first support structure 106 closer to the fuselage may be interchangeable with an adjacent second support structure 106 (e.g., a mid-boom above the wing) or with an additional third support structure 106 (e.g., a boom furthest from the fuselage).

[0025] In some embodiments (such as the example shown in FIG. 1 ), the orientation of lift fan assemblies 102A-L may be fixed. In other words, lift fan assemblies 102A-L may be mounted in a fixed position relative to wings 112, 114 and / or support structure 106.

[0026] While it may be possible to utilize lift fan assemblies 102A-L and / or support structure 106 that can vary in angle and thrust direction, it may be beneficial to utilize fixed lift fan assemblies 102A-L and support structure 106 to simplify the system, reduce potential points of failure, and reduce maintenance concerns.

[0027] According to some embodiments, lift fan assemblies 102A-L may be positioned and configured such that they provide thrust directly upward (e.g., in the z-direction) to VTOL air vehicle 100, thereby generating vertical lift for VTOL air vehicle 100. The vertical direction may be defined as the upward direction when VTOL air vehicle 100 is landed on the ground or in a stable hover. Lift fan assemblies 102A-L may provide sufficient thrust to lift VTOL air vehicle 100 off the ground and maintain control during, for example, takeoff, hovering, and / or landing.

[0028] Vertical thrust may be provided by lift fan assemblies 102A-L and / or support structure 106, which cause the rotor blades to rotate in a horizontal plane (e.g., a plane defined by the x-axis and y-axis) and about a vertical axis (e.g., the z-axis of the aircraft). In some embodiments, lift fan assemblies 102A-L may be configured so that all of the rotor blades rotate in the same plane. In other embodiments, lift fan assemblies 102A-L may be configured so that all of the rotor blades rotate in different parallel planes.

[0029] In other embodiments, some or all of the lift fan assemblies 102A-L can be angled. The angled lift fan assemblies 102A-L can still combine to provide a net directly vertical thrust. For example, a partially non-vertical thrust provided by an angled lift fan assembly on the first wing 112 can be offset by an equal and opposite partially non-vertical thrust provided by an oppositely angled lift fan assembly on the second wing 114.

[0030] In some embodiments, two adjacent lift fan assemblies (e.g., 102A and 102L) can have their blades mounted at opposite angles of attack such that the two adjacent fan assemblies spin in opposite directions. The two adjacent lift fan assemblies can be coupled to opposite ends of the same support structure 104 (e.g., 102A and 102L). Alternatively, the two adjacent lift fan assemblies can be on the same wing but on different support structures (e.g., 102A and 102B) or on opposite wings (e.g., 102A and 102F). According to various embodiments, a first subset of lift fan assemblies 102A-L can spin in a first direction and a second subset (e.g., the remainder) of lift fan assemblies 102A-L can spin in a second direction opposite the first direction.

[0031] Configuring lift fan assemblies 102A-L so that some spin in a first direction and others spin in an opposite second direction can advantageously counter any angular momentum generated by the spinning blades, allowing VTOL air vehicle 100 to hover in a stable manner without rolling.

[0032] Additionally, rotational movement (e.g., yaw) about a vertical axis of VTOL air-vehicle 100 may be accomplished when desired by temporarily reducing the spin rotational speed of a first subset of some or all of lift fan assemblies 102A-L spinning in a first direction, and / or temporarily increasing the spin rotational speed of a second subset of lift fan assemblies 102A-L spinning in a second direction, such that the total angular momentum generated by the spinning blades is not cancelled. Thus, VTOL air-vehicle 100 can rotate through the use of lift fan assemblies 102A-L (which can all rotate in the same plane or parallel planes) without the need for another source of thrust directed in another direction.

[0033] The pusher propeller 104 may be configured to provide thrust to push the VTOL air vehicle 100 in a forward direction (e.g., along the x-axis) for forward flight, ascent, descent, and cruise. Forward thrust, or horizontal thrust (e.g., along the x-axis of the air vehicle), may be achieved by mounting the pusher propeller 104 on the VTOL air vehicle 100 such that the propeller blades rotate in a vertical plane (e.g., a plane defined by the z-axis and y-axis) and about a horizontal axis (e.g., the x-axis). The pusher propeller 104 is provided at the trailing end of the air vehicle 100, behind a pair of wings. According to various embodiments, the pusher propeller 104 remains in a stationary position relative to the VTOL air vehicle 100 (e.g., when activated, the blades of the pusher propeller 104 rotate, but the pusher propeller itself may be rotated relative to the VTOL air vehicle 100).

[0034] The pusher propeller 104 can be in the form of an electric motor driven rotor (e.g., a combined fan and motor). The rotor can include any suitable number of blades (e.g., two blades, three blades, four blades, or five blades). The blades can have a predetermined angle of attack. The rotor can further include a hub. The blades can be attached to the hub. In some embodiments, the blades and integral hub can be manufactured as a single piece. The hub provides a central structure to which the blades connect, and in some embodiments is made in a shape that encases the motor. In some embodiments, the motor parts are low profile, allowing the entire motor to fit within the hub of the rotor and present less resistance to airflow when flying forward. The rotor can be attached to the rotating parts of the motor. In some embodiments, the motor can be a permanent magnet motor and can be controlled by an electronic motor controller. The electronic motor controller can send current to the motor in a precise sequence to enable the rotor to spin at a desired speed or with a desired torque.

[0035] The combination of pusher propeller 104 and wings 112, 114 can provide both forward motion and lift. Thus, once VTOL air vehicle 100 reaches a sufficient speed (e.g., a predetermined amount of speed) such that the wings provide lift, lift fan assemblies 102A-L may no longer be required to provide lift. At this point, lift fan assemblies 102A-L may temporarily stop operating. For example, lift fan assemblies 102A-L may be initially active and provide thrust to lift VTOL air vehicle 100. Once VTOL air vehicle 100 leaves the ground and / or is at a predetermined height, pusher propeller 104 may activate and / or increase horizontal thrust such that VTOL air vehicle 100 gains horizontal speed. Lift fan assemblies 102A-L may continue to provide vertical lift while horizontal speed increases. The reason is that the wings may not provide sufficient vertical lift until a certain speed is achieved. The lift fan assemblies 102A-L may eventually (or gradually) reduce their vertical thrust contribution because the wings 112, 114 gradually provide more (e.g., an increasing amount) of vertical lift during the horizontal speed increase.

[0036] In some embodiments, when the VTOL aircraft 100 is at a given speed, it may be more efficient to utilize the pusher propeller 104 and wings 112, 114 to provide vertical lift instead of the lift fan assemblies 102A-L.

[0037] According to various embodiments, lift fan assemblies 102A-L may cease operating at any suitable time. For example, lift fan assemblies 102A-L may cease operating when pusher propeller 104 is active. According to various embodiments, pusher propeller 104 and at least a subset of lift fan assemblies 102A-L may be operable simultaneously or at least some of the time. For example, lift fan assemblies 102A-L may continue to operate during an initial period of forward thrust provided by pusher propeller 104, and then lift fan assemblies 102A-L may cease operating when VTOL air vehicle 100 achieves cruising speed and is in forward flight.

[0038] According to some embodiments, pusher propeller 104 may be oriented substantially orthogonal to lift fan assemblies 102A-L. As a result, pusher propeller 104 and lift fan assemblies 102A-L may be configured to provide thrust in orthogonal directions (e.g., vertical thrust from lift fan assemblies 102A-L and horizontal thrust from pusher propeller 104). Isolating directional thrust into two separate types of components can beneficially simplify the control and design of VTOL air vehicle 100 (e.g., as opposed to an air vehicle utilizing a tilting fan). In some embodiments, pusher propeller 104 and lift fan assemblies 102A-L may be operated, powered on, or otherwise controlled independently of one another, thereby allowing thrust to be applied independently in orthogonal directions (e.g., thrust may be applied in different directions at the same time and at different times).

[0039] In the example shown in FIG. 1, the pusher propeller 104 is positioned and mounted at the aft end of the fuselage 108. The central location of the pusher propeller 104 can enable horizontal thrust to the VTOL aircraft 100 without applying undesirable rotational forces. Additionally, positioning the pusher propeller 104 at the rear of the fuselage 108 can maximize the distance from the cabin 110, which is positioned toward the front of the fuselage 108, thereby reducing propeller noise experienced by passengers in the cabin 110. Also, the rotation plane of the pusher propeller blades does not intersect with the fuselage 108 or the cabin 110, and therefore any reflected debris is unlikely to cause damage to the VTOL aircraft 100 or obstruction / damage to passengers / cargo.

[0040] According to some embodiments, pusher propeller 104 may be coupled to the trailing end of fuselage 108 in a fixed orientation. For example, pusher propeller 104 may remain in a stationary position relative to VTOL air vehicle 100 (e.g., while the blades of pusher propeller 104 rotate when activated, the pusher propeller itself cannot be rotated relative to VTOL air vehicle 100). Both pusher propeller 104 and lift fan assemblies 102A-L may have fixed orientations and may be configured to always provide thrust in orthogonal directions.

[0041] In some embodiments, the pusher propeller 104 may be located in other areas. For example, the pusher propeller 104 may be mounted on the nose of the fuselage 108 or may be mounted on the fuselage 108. Also, embodiments allow for additional pusher propellers to be included. For example, in addition to or instead of the pusher propeller 104, two pusher propellers may be coupled to the wings. A first pusher propeller may be mounted on the first wing 112 (e.g., on the top, bottom, or edge of the wing) and a second pusher propeller may be mounted on the second wing 114 (e.g., on the top, bottom, or edge of the wing). Also, such additional pusher propellers may have a fixed orientation.

[0042] In some embodiments, pusher propeller 104 may be configured with the ability to spin in either direction. As a result, pusher propeller 104 may be capable of spinning in the opposite direction, such that it provides reverse horizontal thrust. Reverse horizontal thrust may be useful for moving VTOL air vehicle 100 in a rearward direction (e.g., backing out of a hangar area from a hovering position). Additionally, reverse horizontal thrust may be used to reduce forward flight speed. For example, reverse horizontal thrust from pusher propeller 104 may be used instead of or in addition to flaps to slow VTOL air vehicle 100 and / or bring VTOL air vehicle 100 into a stationary hover. When VTOL air vehicle 100 slows down or returns to a hovering position, lift fan assemblies 102A-L may be reactivated and / or increase vertical thrust.

[0043] According to various embodiments, the VTOL aircraft 100 may include a drive shaft 122 that extends along the fuselage 108. The drive shaft 122 may couple the pusher propeller 104 to an engine 120 or a battery (e.g., provided closer to a leading edge of the aircraft 100).

[0044] VTOL aircraft 100 may include any other suitable control structures and control surfaces. For example, any suitable number of ailerons, rudders, elevators, slats, flaps, spoilers, and / or stabilizers may be included.

[0045] According to various embodiments, the VTOL air vehicle 100 may be an electric air vehicle. One or more battery units 135 may be coupled to the VTOL air vehicle 100 and may power the lift fan assemblies 102A-L and / or the pusher propeller 104. More specifically, the lift fan assemblies 102A-L and the pusher propeller 104 may be driven by electric motors, which are powered by a power system including one or more battery units 135. In some embodiments, each of the lift fan assemblies 102A-L and the pusher propeller 104 may have a dedicated battery unit 135. The battery units 135 may be provided on a support structure 106 carrying the lift fan assemblies 102A-L, provided within the fuselage, or a combination thereof. Each battery unit 135 may include a plurality of battery cells configured to power the lift fan assemblies 102A-L and the pusher propeller 104. Thus, VTOL aircraft 100 may be an electric aircraft. In an alternative embodiment, VTOL aircraft 100 may be a hybrid-electric aircraft.

[0046] According to various embodiments, the VTOL aircraft 100 may be automatically and / or remotely controlled (e.g., the aircraft may not require an onboard pilot to operate and may be controlled based on control signals or instructions received from a remote entity).

[0047] A control system 150 (e.g., a flight control system, etc.) coupled to aircraft 100 may be configured to control VTOL aircraft 100. Control system 150 may be configurable to control VTOL aircraft 100 automatically and / or remotely (e.g., via control signals received from a remote entity (e.g., a remote controller, a remote pilot, or a remote control tower, etc.)). In various embodiments, control system 150 includes one or more processors configured to perform the processing and control functions described herein.

[0048] Control system 150 may control when lift fan assemblies 102A-L and pusher propeller 104 should be operated and / or control the amount of power provided to lift fan assemblies 102A-L and pusher propeller 104. Control system 150 may be configurable to control multiple lift fan assemblies and one or more pusher propellers independently of one another. According to various embodiments, control system 150 may control pusher propeller 104 and lift fan assemblies 102A-L based on inputs received from a remote controller (e.g., a remote pilot), inputs received from an autopilot, 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.

[0049] Thus, control system 150 may be configured to convert pilot or other operator inputs and / or corrections computed by an on-board computer into forces and moments, and / or further convert such forces and moments into a set of actuators (e.g., lift rotors; propellers; control surfaces (e.g., ailerons, etc.) and / or related parameters (e.g., lift fan power, speed, or torque) to provide the required forces and moments. For example, pilot or other operator inputs may indicate a desired change in aircraft speed, direction, and / or orientation, and / or wind or other forces may act on the aircraft requiring that lift fans and / or other actuators be used to maintain a desired aircraft attitude (roll / pitch / yaw), speed, and / or altitude.

[0050] According to various embodiments, control system 150 may be configured to receive flight instructions (e.g., takeoff, hovering, cruise, or landing instructions, etc.). Control system 150 may then determine a current location and / or speed of VTOL air vehicle 100 and then control the operation of lift fan assemblies 102A-L and pusher propeller 104 based on the flight instructions. During operation of VTOL air vehicle 100, control system 150 may be configured to continuously monitor the operating conditions of lift fan assemblies 102A-L and pusher propeller 104 in view of the flight instructions.

[0051] The number and location of the pusher propellers and lift fan assemblies are not limited to those illustrated in Figure 1. VTOL aircraft 100 may include a greater number of pusher propellers and may include a greater or lesser number of lift fan assemblies. For example, according to some embodiments and as described below in connection with Figure 3, the VTOL aircraft may include two pusher propellers.

[0052] The exemplary VTOL aircraft 100 illustrated in FIG. 1 does not include a tail. Control and stabilization provided by a tail may not be required because a lift fan assembly may provide control of the VTOL aircraft 100. However, embodiments are not so limited and similar propeller configurations may be used in connection with aircraft that include a tail. Such a tail may take a variety of shapes or forms. For example, according to some embodiments and as described below in connection with FIG. 2, the VTOL aircraft may include a tail (e.g., a V-tail, etc.).

[0053] FIG. 2 illustrates another exemplary VTOL aircraft with horizontal stabilizers. FIG. 2 illustrates top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL aircraft 200 with a horizontal stabilizer 206 provided on the tail 202 of the VTOL aircraft 200. The exemplary VTOL aircraft 200 illustrated in FIG. 2 includes multiple lift fan assemblies and a pusher propeller 204 provided at the tailing end of the aircraft 200 (on the tail 202 of the aircraft 200) behind the horizontal stabilizer 206. According to some embodiments, the VTOL aircraft 200 can be similar to the VTOL aircraft 100 described above in connection with FIG. 1, but with the addition of a tail 202, horizontal stabilizer 206, and the location of the pusher propeller 204 being behind the horizontal stabilizer 206 and mounted on the tail 202.

[0054] A horizontal stabilizer 206 (e.g., a tail) may be coupled to the aft end of the fuselage 102 (e.g., on the tail 202, etc.). The horizontal stabilizer 206 may be of any suitable shape or form. For example, as shown in FIG. 2, the horizontal stabilizer 206 may be V-shaped (taking the form of a V-tail). The V-tail may include two stabilizer surfaces that project at an angle from the tail. In some embodiments, each of the stabilizer surfaces may further include a hinged control surface on the aft edge. Additionally, as shown in FIG. 2, an additional (e.g., a third) vertical stabilizer surface may be mounted on the tail and extend vertically downward.

[0055] The introduction of horizontal stabilizer 206 can provide additional stability and control for VTOL aircraft 200. This can be particularly useful while the lift fan assemblies are disabled (e.g., during cruise flight) or are not otherwise utilized or relied upon for control and stability.

[0056] Pusher propeller 204 may be mounted aft of horizontal stabilizer 206 and may be positioned along the centerline of the fuselage. Mounting pusher propeller 204 behind horizontal stabilizer 206 may advantageously move pusher propeller 204 further away from the forward end of VTOL aircraft 200, which may further reduce propeller noise experienced by passengers in the cabin. Additionally, passenger safety may be improved by increasing the distance between passengers and pusher propeller 204 during boarding and deboarding activities.

[0057] According to some embodiments, pusher propeller 204 may be coupled to horizontal stabilizer 206 in a fixed orientation. For example, pusher propeller 204 may remain in a stationary position relative to horizontal stabilizer 206 and / or VTOL air vehicle 200 (e.g., when activated, while the blades of pusher propeller 204 rotate, the pusher propeller itself cannot be rotated relative to VTOL air vehicle 100). Both pusher propeller 204 and the lift fan assembly may have a fixed orientation and may be configured to always provide thrust in orthogonal directions.

[0058] Figure 3 illustrates another exemplary VTOL aircraft with multiple pusher propellers. According to some embodiments, VTOL aircraft 300 can be similar to VTOL aircraft 100 described above in connection with Figure 1, but with the addition of a horizontal stabilizer 306 (e.g., similar to horizontal stabilizer 206 described above in connection with Figure 2) and includes two pusher propellers 304A-B located above the edges of horizontal stabilizer 306.

[0059] FIG. 3 illustrates top, plan, side, and front views (starting clockwise from the upper left corner) of a VTOL aircraft 300 with two pusher propellers 304A-B, one on a first stabilizer surface 308 of horizontal stabilizer 306 and the other on a second stabilizer surface 310 of horizontal stabilizer 306.

[0060] According to various embodiments, pusher propellers 304A and 304B may be respectively coupled to respective edges of stabilizer surfaces 308 and 310. Stabilizer surfaces 308 and 310 and pusher propellers 304A and 304B may be positioned symmetrically relative to one another with respect to a vertical center plane of aircraft 300.

[0061] Pusher propellers 304A and 304B may be mounted such that the propeller blades are positioned forward of first stabilizer surface 308 and second stabilizer surface 310, as shown in Figure 3. This can advantageously improve safety for people (e.g., maintenance personnel or passengers) walking behind VTOL aircraft 300 when VTOL aircraft 300 is landed because the propeller blades do not have to be exposed at the aft end of VTOL aircraft 300.

[0062] Alternatively, in other embodiments, the propeller blades may be positioned behind the first stabilizer surface 308 and the second stabilizer surface 310. This positioning can increase the distance between the propeller blades and the front of the fuselage, reducing noise at the front of the fuselage and increasing the safety distance between on-board passengers and the propeller blades.

[0063] According to some embodiments, pusher propellers 304A and 304B may be coupled to horizontal stabilizer 306 in a fixed orientation. For example, pusher propellers 304A and 304B may remain in a stationary position relative to horizontal stabilizer 306 (e.g., when activated, while the blades of pusher propellers 304A and 304B rotate, the pusher propellers themselves cannot be rotated relative to horizontal stabilizer 306). Pusher propellers 304A and 304B and the lift fan assembly may all have fixed orientations and may be configured to always provide thrust in orthogonal directions.

[0064] Introducing two pusher propellers 304A and 304B can be advantageous for several reasons. For example, redundancy exists in case one of the two pusher propellers 304A and 304B is damaged or fails. Different amounts of power can be applied to each of the pusher propellers 304A and 304B to provide unequal thrust for maneuvering the VTOL aircraft 300. Also, because the thrust of the two pusher propellers 304A and 304B is combined, the same amount of horizontal thrust can be achieved with a lower rotational speed. This can reduce noise because two pusher propellers 304A and 304B rotating at a lower speed can produce less noise than a single pusher propeller rotating at a higher speed.

[0065] Additionally, locating pusher propellers 304A and 304B on the edge of the V-tail can elevate the location of pusher propellers 304A and 304B as compared to the pusher propellers shown in FIGS. 1-2. The higher location can increase safety by removing pusher propellers 304A and 304B from areas where people may walk when VTOL aircraft 300 is landed. Additionally, pusher propellers 304A and 304B can be above the plane in which the lift fan assembly rotors rotate. This can reduce the likelihood that pusher propellers 304A and 304B will be struck and / or damaged by debris ejected from the lift fan assembly.

[0066] The number and location of pusher propellers 304A and 304B on horizontal stabilizer 306 may be modified according to different embodiments. For example, in addition to or instead of the two pusher propellers 304A and 304B shown in Figure 3, a different pusher propeller may be coupled to the aft end of the tail (e.g., similar to pusher propeller 204 shown in Figure 2) and / or other pusher propellers may be included on the wings (e.g., above the wings, below the wings, or at the tips of the wings).

[0067] The embodiment advantageously isolates vertical lift components and functions from horizontal thrust components and functions. The lift fan assembly can provide vertical lift for takeoff, landing, and hovering functions. The pusher propeller can provide forward thrust and, in combination with the wing, can provide lift during flight when sufficient speed is achieved. This configuration provides a functional VTOL aircraft with simple fixed components. Both vertical takeoff and rapid horizontal movements can be accomplished without the need to tilt or adjust the fans / propellers. This can allow for simpler flight control, easier maintenance, and reduced moving parts that may be prone to failure.

[0068] Furthermore, embodiments provide redundancy. Vertical lift can be provided by the vertical lift fans as well as by the wings during forward movement. Additionally, overheating can be avoided since various components can be disabled at certain times. The vertical lift fan assembly can stop operating during forward flight and the pusher propellers can stop operating during hover, landing, and takeoff.

[0069] Embodiments also improve aircraft safety. With high wings, lift fan assemblies near or at the same level as the wings, and pusher propellers at the rear of the aircraft, the moving rotors are removed from areas where passengers may travel. Additionally, debris that may be deflected from the moving rotors is less likely to strike the fuselage. Also, coupling the lift fan assemblies to high wings can provide space between the lift fan assemblies and the ground, thereby reducing the possibility of introducing debris from the ground.

[0070] FIG. 4 is a flowchart illustrating an embodiment of a process for controlling flight of a VTOL aircraft configured for vertical takeoff and landing through the transition between vertical lift and forward flight.

[0071] In step S400, the aircraft may be in a stationary position above the ground. For example, the aircraft may be parked at a charging station to charge its batteries. Alternatively, the aircraft may be parked at a location waiting to receive cargo or passengers. The flight control system of the VTOL aircraft may receive a flight plan (e.g., from an autopilot, a pilot, or a remote controller pilot) for reaching a predetermined destination. The flight plan may include instructions for taking off from the ground.

[0072] In step S402, the flight control system can control one or more of the lift fan assemblies to be activated. For example, the thrust producing components of the aircraft can be inactive or in a standby mode. The flight control system can power up the lift fan assemblies from an inactive mode so that they are ready to provide vertical lift.

[0073] In step S404, the flight control system can initiate a takeoff sequence to lift the aircraft off the ground. For example, the flight control system can control a lift fan assembly to provide vertical thrust to lift the aircraft off the ground. The flight control system can continue to operate the lift fan assembly in this manner until a particular time has elapsed or until a particular height has been reached (e.g., a safe distance from the landing pad).

[0074] In step S406, after a predetermined amount of time has elapsed since performing step S404 and / or after altitude has been gained, the flight control system may receive instructions to transition to forward flight. Before switching to forward flight mode, the control system may check one or more of the aircraft's altitude, speed, and orientation to ensure that the parameters are within predetermined desired ranges. In some embodiments, the control system may communicate the parameters to a remote entity (e.g., a remote control tower or a remote pilot).

[0075] Upon receiving flight instructions to transition to forward flight, in step S408, the control system may control one or more of the pusher propellers to be activated. The pusher propellers may be powered on and begin to operate, and may then generate forward thrust for the aircraft. The flight control system may control the forward acceleration in any suitable manner. For example, the flight control system may gradually increase the power provided to the pusher propellers, such that the aircraft gradually gains forward speed.

[0076] In some embodiments, the pusher propeller can activate and begin to provide forward thrust while the aircraft is still in the process of gaining altitude from the vertical lift fan. As a result, the forward travel can overlap with the vertical lift. Additionally, the flight control system can modulate power to the lift fan assembly as needed to maintain stability and altitude while the pusher propeller causes the forward airspeed to increase.

[0077] In step S410, the flight control system may deactivate the lift fan assembly or otherwise reduce the power provided to the lift fan assembly. For example, once the propeller generates a predetermined speed such that the wings provide sufficient lift to maintain altitude, the lift fan assembly may no longer be needed for vertical lift. Thus, the lift fan assembly may be powered down, deactivated, placed in a standby mode, or operated at a reduced power level during forward flight of the aircraft.

[0078] In some embodiments, the power provided to the lift fan assemblies can be gradually decreased in coordination with gradually gaining forward speed. For example, as the propellers generate forward speed for the aircraft, the wing can gradually provide more vertical lift. As the lift provided by the wing increases, the lift fan assemblies can correspondingly decrease their vertical lift contribution. The lift fan assemblies can be gradually powered down until they are inactive. In some embodiments, the lift fan assemblies can maintain a low level of power and activity without shutting down completely. The aircraft can continue in this manner with the pusher propellers operating and the lift fan assemblies not operating (or operating at a reduced level) for the majority of the flight.

[0079] In step S412, the control system may receive instructions (e.g., from an autopilot, a pilot, or a remote entity) to hover or land. For example, the aircraft may be approaching a destination landing area (e.g., within a predetermined distance).

[0080] Upon receiving instructions to transition to hover or landing, in step S414, the flight control system may control one or more of the lift fan assemblies to be re-energized. The lift fan assemblies may power on and begin operating, and may then generate vertical lift for the aircraft.

[0081] In step S416, the flight control system can initiate a hover or landing sequence to cause the aircraft to hover or land on the ground. For example, the flight control system can cause the forward speed of the aircraft to decrease while vertical lift is maintained. This can include a coordinated reduction in the power / thrust of the pusher propeller and an increase in the power / thrust of the lift fan assembly. For example, as the pusher propeller thrust is reduced, the aircraft speed will decrease due to drag, which in turn will reduce the lift provided by the wing. As the lift provided by the wing gradually decreases, the flight control system can gradually increase the power to the lift fan assembly to generate another source of lift. These contributing forces can be controlled so that the aircraft maintains the same altitude while the forward speed is reduced, or so that the aircraft begins a controlled vertical descent while the forward speed is reduced.

[0082] Embodiments allow the pusher propeller to be operated in various manners during the landing sequence. For example, the pusher propeller can be powered down gradually. Alternatively, the pusher propeller can be powered down abruptly, and the forward speed of the aircraft can naturally decrease due to drag. As another option, the pusher propeller can be transitioned to a reverse thrust mode, such that the forward speed of the aircraft is reduced more quickly.

[0083] In step S418, the flight control system may deactivate one or more propellers or otherwise reduce the power provided to the propellers. For example, when the aircraft arrives at a location where it is ready to hover or descend vertically (e.g., to a landing pad), the pusher propellers may be powered down, deactivated, placed in a standby mode, or operated at a reduced power level so that the lift fan assemblies may be used for a controlled descent. In some embodiments, the pusher propellers may maintain some amount of motion and / or thrust to control the position of the aircraft (e.g., in the event of wind turbulence, etc.).

[0084] In step S420, the flight control system may complete a landing sequence to land the aircraft on the ground. For example, the flight control system may control the lift fan assembly to provide vertical thrust so that the aircraft descends in a controlled manner. The aircraft may come to a stationary location above the ground (e.g., a landing pad and / or a charging station, etc.).

[0085] In step S422, the flight control system may deactivate the lift fan assembly or otherwise reduce the power provided to the lift fan assembly. In some embodiments, the lift fan assembly and / or pusher propeller may be powered down completely so that the rotor blades come to a stop. In other embodiments, the lift fan assembly and / or pusher propeller may remain at a low standby power level so that they are ready for subsequent flight.

[0086] For simplicity, various active and passive circuit components are not shown in the figures. In the foregoing specification, embodiments of the present disclosure have been described with reference to numerous specific details that may vary from implementation to implementation. Accordingly, the specification and drawings should be regarded in an illustrative and not a restrictive sense. The sole and exclusive indicator of the scope of the present disclosure, and what is intended by the applicant to be the scope of the present disclosure, is the literal and equivalent scope of the set of claims issuing from this application, including any subsequent modifications in the specific form in which such claims arise. The specific details of specific embodiments may be combined in any suitable manner without departing from the spirit and scope of the embodiments of the present disclosure.

[0087] The electronic components of the described embodiments may be specially constructed for the required purposes, or may include one or more general-purpose computers selectively activated or reconfigured by a computer program stored in the computer. Such computer programs may be stored in a computer-readable storage medium (such as, but not limited to, a floppy disk, an optical disk, a DVD, a CD-ROM, a magneto-optical disk, a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic or optical card, an application specific integrated circuit (ASIC), or any type of disk including any type of medium suitable for storing electronic instructions) and each coupled to a computer system bus.

[0088] Additionally, spatially relative terms (e.g., "front" or "back") may be used to describe the relationship of an element and / or feature to another element and / or feature, for example, as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and / or operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, an element described as being on a "front" surface may be oriented "back" from the other element or feature. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein will be interpreted accordingly.

Claims

1. The torso and; a pair of wings connected to opposite sides of the upper portion of the fuselage in a high wing configuration; a plurality of lift fan assemblies coupled to the pair of wings, the plurality of lift fan assemblies being mounted in fixed locations and having a fixed orientation configured to consistently generate vertical lift, the plurality of lift fan assemblies including a first subset of one or more lift fan assemblies having first rotor blades configured to rotate in a first plane and a second subset of one or more lift fan assemblies having second rotor blades configured to rotate in a second plane that is parallel to the first plane; one or more pusher propellers coupled to a tailing end of the fuselage, the one or more pusher propellers being mounted in a fixed position and having a fixed orientation configured to constantly generate horizontal thrust; Including, aircraft.

2. The aircraft described in claim 1, wherein the first plane and the second plane are each angled relative to the vertical, the multiple lift fan assemblies together produce a net vertical thrust that is directly vertical, and the multiple lift fan assemblies and the one or more pusher propellers are configured such that the net vertical thrust is directionally perpendicular to the horizontal thrust.

3. The aircraft of claim 1, wherein the plurality of lift fan assemblies further includes a third subset of one or more lift fan assemblies having a third rotor blade configured to rotate in a third plane that is angled in an opposite direction compared to the first plane.

4. 10. The aircraft of claim 1, further comprising a control system configurable to control the plurality of lift fan assemblies and the one or more pusher propellers independently of one another, the control system configurable to activate or deactivate the plurality of lift fan assemblies or the one or more pusher propellers based on one or more of flight instructions, flight data received from sensors coupled to the aircraft, or signals received from a remote entity.

5. The aircraft of claim 1, wherein the aircraft does not include a tilting fan, and the one or more pusher propellers are configured to generate both forward horizontal thrust and reverse horizontal thrust.

6. The aircraft of claim 1, wherein each of the plurality of lift fan assemblies provides vertical thrust in the same direction, and wherein the first rotor blades of the first subset of one or more lift fan assemblies are configured to rotate in a first direction at a first angle of attack, and the second rotor blades of the second subset of one or more lift fan assemblies are configured to rotate in a second direction at a second angle of attack, the second direction being opposite to the first direction, and the second angle of attack being opposite to the first angle of attack.

7. 2. The aircraft of claim 1, wherein the fuselage includes a cabin configured for passengers or cargo, both the first plane and the second plane are positioned above the cabin without intersecting the cabin, a plane of rotation of the one or more pusher propellers is positioned behind the cabin without intersecting the cabin, and the cabin is positioned near a front of the fuselage at an opposite end of the fuselage relative to the one or more pusher propellers.

8. 10. The aircraft of claim 1, further comprising a horizontal stabilizer in the form of a V-tail coupled to an aft end of the fuselage, the one or more pusher propellers being coupled to the horizontal stabilizer.

9. The fuselage includes a cabin configured for passengers or cargo, the aircraft further includes a horizontal stabilizer in the form of a V-tail connected to an aft end of the fuselage, the V-tail including a first stabilizer surface protruding at a first angle and a second stabilizer surface protruding at a second angle opposite the first angle, the one or more pusher propellers including a first pusher propeller, a second pusher propeller, and a third pusher propeller, the first pusher propeller being connected to the first stabilizer surface with a first propeller blade positioned forward of the first stabilizer surface in a third plane of rotation behind the cabin and not intersecting the cabin, 2. The aircraft of claim 1, wherein the second pusher propeller is coupled to the second stabilizer surface with a second propeller blade positioned forward of the second stabilizer surface in a fourth plane of rotation aft of the cabin and not intersecting the cabin, and the third pusher propeller is coupled to an aft end of the trailing end of the fuselage with a third propeller blade positioned aft of the fuselage in a fifth plane of rotation aft of the cabin and not intersecting the cabin, and the first propeller blades and the second propeller blades are positioned above the first plane of the first subset of one or more lift fan assemblies.

10. 2. The aircraft of claim 1, further comprising a plurality of support structures coupled to the underside of the pair of wings, each support structure having a forward end extending forward of the pair of wings and an aft end extending aft of the pair of wings, each of the plurality of support structures being identical and interchangeable between locations on the pair of wings.

11. 11. The aircraft of claim 10, wherein a pair of lift fan assemblies of the plurality of lift fan assemblies are coupled to opposite ends of at least one of the plurality of support structures.

12. 12. The aircraft of claim 11, further comprising a plurality of battery units each including a plurality of battery cells configured to power the plurality of lift fan assemblies and the one or more pusher propellers, each of the plurality of lift fan assemblies coupled to a dedicated battery unit of a respective one of the plurality of battery units located on a corresponding one of the plurality of support structures, and each of the one or more pusher propellers coupled to a dedicated battery unit of a respective one of the plurality of battery units located within the fuselage.

13. 2. The aircraft of claim 1, wherein each of the plurality of lift fan assemblies includes an electric motor driven rotor, the fuselage includes a drive shaft extending from an engine near a leading edge of the fuselage to the one or more pusher propellers, and at least six lift fan assemblies are coupled to each of the pair of wings, the pair of wings including winglets.

14. receiving, by a control system coupled to the aircraft, flight instructions for takeoff; activating, with the control system, a plurality of lift fan assemblies coupled to the aircraft, the plurality of lift fan assemblies being mounted in fixed positions and having a fixed orientation configured to always generate vertical lift for vertical takeoff and landing, the plurality of lift fan assemblies including a first subset of one or more lift fan assemblies with first rotor blades configured to rotate in a first plane and a second subset of one or more lift fan assemblies with second rotor blades configured to rotate in a second plane that is parallel to the first plane; controlling, with the control system, the plurality of lift fan assemblies to generate vertical lift such that the aircraft launches vertically from a stationary position above the ground; activating, by the control system, one or more pusher propellers coupled to a trailing end of a fuselage of the aircraft, the one or more pusher propellers being mounted in a fixed position and having a fixed orientation configured to constantly generate horizontal thrust; controlling, with the control system, the one or more pusher propellers to generate horizontal thrust for the aircraft to achieve forward velocity; deactivating or reducing, by the control system, power provided to the plurality of lift fan assemblies after a predetermined amount of forward speed is achieved. A method comprising:

15. 15. The method of claim 14, further comprising controlling, by the control system, the plurality of lift fan assemblies to gradually produce decreasing amounts of vertical lift in coordination with gradually attaining forward speed.

16. The method comprises: receiving, by the control system, flight instructions for hovering or landing; reactivating, by the control system, the plurality of lift fan assemblies; controlling, with the control system, the one or more pusher propellers to produce a decreasing amount of horizontal thrust and reduce forward speed; controlling, with said control system, said plurality of lift fan assemblies to gradually produce decreasing amounts of vertical lift in coordination with a gradually decreasing forward speed; 15. The method of claim 14, comprising:

17. The method of claim 16, wherein the control system is configurable to activate or deactivate the multiple lift fan assemblies or the one or more pusher propellers based on one or more of flight instructions, flight data received from sensors coupled to the aircraft, or signals received from a remote entity, the method including deactivating the one or more pusher propellers by the control system in response to arriving at a location above a landing area.

18. 18. The method of claim 17, further comprising, after deactivating the one or more pusher propellers, controlling, by the control system, the plurality of lift fan assemblies to create vertical lift in a manner that causes the aircraft to descend vertically until it reaches a second stationary position above the ground.

19. 15. The method of claim 14, wherein the method includes controlling the plurality of lift fan assemblies and the one or more pusher propellers independently of one another with the control system.

20. The method according to claim 1, controlling the plurality of lift fan assemblies with the control system; by reducing a first spin rotational speed of a first subset of the plurality of lift fan assemblies; and increasing a second spin rotational speed of a second subset of the plurality of lift fan assemblies; generating a rotational movement of the aircraft about a vertical axis while maintaining vertical lift, comprising: the first subset spins in a first direction; the second subset spinning in a second direction. The method of claim 14 further comprising:

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