Vertical take-off and landing aircraft and propulsion assembly

Abstract

A vertical take-off and landing aircraft is disclosed that includes a propulsion assembly adapted to lift a load. The propulsion assembly may include a primary lift surface for providing sufficient lift to lift the load when rotating about a central axis. The propulsion assembly may include a secondary lift surface for providing lift along a second axis to lift the propulsion assembly. The secondary lift surface may be configurable to induce rotation of the primary lift surface.

Description

[Technical Field]

[0001] The present invention relates to vertical take-off and landing (VTOL) aircraft and propulsion assemblies. [Background technology]

[0002] A problem in the design of various civil and military VTOL aircraft is that, while it is desirable to minimize the clearance area required for the aircraft to land, there is a trade-off between the size of the lifting system and the power required to generate thrust. Arbitrarily small thrusters require arbitrarily large power outputs. Power density and energy density limitations of the aircraft's power and power storage systems place practical limits on how compact the lifting system can be for a given payload.

[0003] Furthermore, even if surface level clearance is sufficient, there is the problem that obstacles such as trees and power lines may protrude into the vertical clearance required for takeoff.

[0004] Existing approaches to minimizing the size of lifting systems necessarily sacrifice efficiency by reducing the size of the system itself or by selecting a more efficient lifting system of comparable size, which may realistically only be realized in smaller form factors, such as ducted fans. Additionally, the clearance area required for landing a VTOL aircraft is determined not only by the size of the lifting system, but also by the downwash immediately below, which occurs even with a relatively efficient, small, and correspondingly high air velocity lifting system. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to at least substantially address one or more of the above-referenced problems, or at least to provide a useful alternative to the VTOL aircraft discussed above. [Means for solving the problem]

[0006] In a first aspect, the present invention provides a propulsion assembly for lifting a load, comprising: a primary lifting surface configured to provide sufficient lift to lift a load when rotating about the central axis; a secondary lift surface configured to provide lift along a second axis to lift the propulsion assembly, the second axis being configurable between a lift configuration in which the secondary lift surface lifts the propulsion assembly and a thrust configuration in which the secondary lift surface induces rotation of the primary lift surface; A propulsion assembly including:

[0007] Preferably, the primary lift surface is movable between a stowed configuration and a deployed configuration, the footprint of the primary lift surface being smaller in the stowed configuration than in the deployed configuration.

[0008] Preferably, the primary lifting surface is movable between a stowed configuration and a deployed configuration while being elevated by the secondary lifting surface.

[0009] Preferably, the second axis of the secondary lift surface is continuously movable between a lift position and a thrust position such that as the lift generated by the primary lift surface increases with increasing rotational speed of the primary lift surface about the central axis, the proportion of the secondary lift surface lift used to lift the propulsion assembly continuously decreases.

[0010] Preferably, the propulsion assembly further includes a lifting surface control system for providing cyclic and collective control of the primary lifting surfaces.

[0011] Preferably, the lifting surface control system includes a servo tab.

[0012] Preferably, the propulsion assembly further includes a tether for connecting the propulsion assembly to the load, the tether adapted to transfer power from the load to the propulsion assembly for powering the propulsion assembly.

[0013] Preferably, the tether is retractable.

[0014] Preferably, the propulsion assembly further includes a first docking hub located on the central axis, the first docking hub configured to engage the load when the tether is sufficiently retracted.

[0015] Preferably, the tether is connected to the propulsion assembly with a bearing to reduce the torque applied by the tether to the propulsion assembly when tension is applied to the tether.

[0016] Preferably, the primary lift surface includes a rotor, which preferably provides azimuth control for the propulsion assembly.

[0017] Preferably, the secondary lift surface includes a rotor rotating about a second axis, and preferably the rotor provides azimuth control for the propulsion assembly.

[0018] Preferably, the propulsion assembly further includes an emergency backup power supply for powering the propulsion assembly for powered descent.

[0019] Preferably, the secondary lift surface comprises a plurality of secondary lift surfaces.

[0020] Preferably, the tether includes an attachment interface for connecting the tether to a propulsion assembly.

[0021] Preferably, the attachment interface is a non-flexible, non-rotating end point of the tether.

[0022] Preferably, the propulsion assembly includes a system for determining spatial parameters of the propulsion assembly relative to the load.

[0023] Preferably, the spatial parameters include absolute and relative orientation parameters of the propulsion assembly with respect to the load.

[0024] Preferably, the system includes a magnetometer and / or a gyroscope for determining the spatial parameters.

[0025] Preferably, the system includes an encoder disposed between the propulsion assembly and the mounting interface for determining the spatial parameter.

[0026] Preferably, the attachment interface includes aerodynamic surfaces and / or thrusters for controlling the orientation of the tether.

[0027] Preferably, the tether includes a second attachment interface for connecting the tether to a load to allow the propulsion assembly to fly at a higher angle relative to the horizontal to enable faster flight speeds.

[0028] Preferably, the second mounting interface comprises an articulating frame that allows the load to remain horizontal while the propulsion assembly is tilted and that can change its orientation in flight to allow the propulsion assembly to fly at high angles of attack relative to the horizontal and provide greater flight speeds.

[0029] Preferably, the load comprises an aerodynamic surface capable of providing lift during level flight.

[0030] In a second aspect, the present invention provides a method for producing a medicament for the treatment of a pulmonary arthritis, comprising: a fuselage having a load-bearing cavity or area for a load; a propulsion assembly in a first aspect for lifting the vehicle; a power generation assembly located within or on the vehicle configured to power the propulsion assembly; A vertical take-off and landing aircraft including:

[0031] Preferably, the aircraft further includes one or more directional control thrusters mounted on the airframe, the directional control thrusters acting in respective directions non-parallel to the central axis.

[0032] Preferably, the aircraft further includes one or more directional control thrusters mounted on the fuselage, the directional control thrusters acting in respective directions parallel to the central axis.

[0033] Preferably, the vector control thruster comprises a ducted fan, a rotor, a jet thruster and / or an impulse thruster.

[0034] Preferably, the vehicle has a center of gravity and includes a winch for retracting the tether, with the uppermost control point of the tether on the vehicle being above the center of gravity of the vehicle.

[0035] Preferably, the mounting interface has a center of gravity located above the center of gravity of the vehicle and spatially related to the center of gravity of the vehicle to facilitate stable flight and control.

[0036] Preferably, the vehicle further includes a second docking hub configured to engage with the first docking hub when the tether is sufficiently retracted.

[0037] Preferably, the airframe further includes one or more control surfaces for setting a preferred orientation relative to the direction of travel and / or for controlling the orientation of the aircraft relative to the direction of travel.

[0038] Preferably, the movable surface is usable to assist in changing the direction of movement.

[0039] Preferably, the aircraft includes wheels located on the fuselage and motors for driving the wheels to propel the aircraft on the ground.

[0040] Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0041] [Figure 1] 1 is a schematic front view of an aircraft equipped with a propulsion assembly in accordance with a preferred embodiment of the present invention; [Figure 2] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the propulsion assemblies in a stowed configuration. [Figure 3] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the propulsion assembly in a deployed configuration. [Figure 4] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the propulsion assembly initiating rotation of the primary lifting surfaces; [Figure 5] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the propulsion assembly lifting the aircraft. [Figure 6] FIG. 2 is a schematic front view of the aircraft of FIG. 1 demonstrating position control of the directional control thrusters. [Figure 7] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the fuselage retracting towards the propulsion assembly. [Figure 8] FIG. 2 is a schematic front view of the aircraft of FIG. 1 with the airframe docked to the propulsion assembly in flight. [Figure 9] 2 shows a perspective view of an aircraft according to a second embodiment of the present invention; [Figure 10] 10 shows the aircraft of FIG. 9 with the propulsion assembly docked. [Figure 11] 10 illustrates the aircraft of FIG. 9 with the propulsion assembly in an undocked and stowed configuration. [Figure 12] 10 illustrates the aircraft of FIG. 9 with the propulsion assembly moving toward the deployed configuration. [Figure 13] 10 illustrates the aircraft of FIG. 9 with the propulsion assembly in a deployed configuration. [Figure 14] 10 shows the aircraft of FIG. 9, with the propulsion assembly generating thrust through the primary lifting surfaces and thrust perpendicular to the primary lifting surfaces through the secondary lifting surfaces. DETAILED DESCRIPTION OF THE INVENTION

[0042] The preferred embodiment aircraft 200 shown in FIGS. 1-8 includes a propulsion assembly 100. The propulsion assembly 100 is adapted to lift a payload 10 and configured to be powered by the payload 10. As shown in FIG. 1, the propulsion assembly 100 includes a primary lift surface 110 that provides sufficient lift to lift the payload 10 when rotating about a central axis 102. In the preferred embodiment, the primary lift surface 110 includes large rotor blades 112 that are divided by joints 114 into a central portion 112a and a peripheral portion 112b that is hinged relative to the central portion 112a. In this manner, the primary lift surface 110 is movable between a stowed configuration having a smaller footprint, as shown in FIG. 1, and a deployed configuration having a larger footprint, as shown in FIG. 3. Preferably, movement of the primary lift surface 110 between the stowed and deployed configurations is effected by an actuator. As shown in these figures, the footprint of the primary lift surface 110, as defined by the swept area of ​​the primary lift surface 110 rotating about the central axis 102 in a plane perpendicular to the central axis 102, is smaller in the stowed configuration than in the deployed configuration. Other techniques are contemplated for moving the primary lift surface 110 between the stowed and deployed configurations. For example, the joints 114 may be arranged in a concertina shape or telescoping prismatic joints. The joints 114 may include vertical, horizontal, or diagonal pivots and may include bearings (not shown), hinges (not shown), locking mechanisms (not shown), and / or actuators (not shown). Multiple joints 114 may be present. In the deployed configuration, the radius of the primary lift surface 110 ranges from 5 m to 12 m, and more preferably is approximately 8.25 m. In the stowed configuration, the radius of the primary lift surface 110 is less than 3 m, and preferably is approximately 2.5 m. In another embodiment, primary lift surface 110 has a radius of greater than 12 meters in the deployed configuration to provide a sky crane. In yet another embodiment, primary lift surface 110 has a radius of less than 5 meters in the deployed configuration to provide a low-load version of aircraft 100.

[0043] Returning to FIG. 1 , propulsion assembly 100 further includes a secondary lift surface 120 configured to provide sufficient lift to lift propulsion assembly 100 and / or provide a force moment to rotate propulsion assembly 100 when rotated about second axis 122. Preferably, secondary lift surface 120 is located a specific distance from center portion 112a of primary lift surface 110 so that a moment is generated by thrust generated by secondary lift surface 120. In another embodiment, secondary lift surface 120 is positioned at center portion 112a and configured to generate a moment about central axis 102. Most preferably, secondary lift surface 120 is located at the tip of primary lift surface 110 as a blade tip thruster. In one embodiment, secondary lift surface 120 is located at the tip of primary lift surface 110 when the primary lift surface is in a stowed configuration. In another embodiment, secondary lift surface 120 is located at the tip of primary lift surface 110 when the primary lift surface is in a deployed configuration. Preferably, the secondary lift surface 120 is driven by at least one motor (or motors) to generate sufficient lift to lift the load 10 off the ground. The motor may include a thruster. Preferably, the motor or motors combined have a total peak power of 50 kW to 150 kW, more preferably 80 kW to 85 kW, and a total continuous power of 50 kW to about 70 kW, preferably about 55 kW. In a preferred embodiment, the secondary lift surface 120 includes one or more small rotors 124 that rotate about respective second axes 122. The second axes 122 of the at least one small rotor 124 or of the plurality of small rotors 124 are adjustable, preferably continuously adjustable, to control the direction of the lift generated by the secondary lift surface 120. When the second axes 122 are adjusted non-parallel to the central axis 102, the lift force of the secondary lift surface 120 induces rotation of the primary lift surface 110 about the central axis 102. In other embodiments, the lift surfaces 110 , 120 may be arranged such that the second axis 122 need not be non-parallel to the first axis 102 .By adjusting, preferably continuously, the direction of second axis 122, the proportion of lift force of secondary lift surface 120 used to lift propulsion assembly 100 can be decreased or increased, and the proportion of lift force of secondary lift surface 120 used to induce rotation of primary lift surface 110 about central axis 102 can be correspondingly increased or decreased. Thus, thrust generated by secondary lift surface 120 in the direction of second axis 122 can be utilized to control the lift and orientation of propulsion assembly 100 by controlling momentum induction using the direction of second axis 202 and the amount of thrust generated by secondary lift surface 120. Preferably, secondary lift surface 120 is configured to operate at peak efficiency when inducing rotation of primary lift surface 110 to lift payload 20, as this is its most commonly used operating range. In other preferred embodiments, secondary lift surface 120 comprises a jet thruster, ramjet, or impulse device (such as a rocket). In some embodiments, the secondary lift surface 120 does not necessarily rotate about the second axis 122, but does provide thrust along the second axis 122. Preferably, the thrust of the secondary lift surface 120 may be increased above the design thrust to accommodate a performance margin, preferably for a finite period of time of about 300 seconds. Preferably, the performance margin is a maximum of 30%. As shown in FIG. 3, the primary lift surface 110 may be moved between a stowed configuration and a deployed configuration while being elevated by the secondary lift surface 120.

[0044] Propulsion assembly 100 may further include a lifting surface control system (not shown) including servo tabs (not shown), as embodied in, for example, the Kaman K-MAX helicopter, to provide cyclic and collective control of primary lifting surface 110. In other embodiments, the lifting surface control system may include a blade pitch pivot, which allows control of the position of primary lifting surface 110 in addition to control of the rotational speed of primary lifting surface 110.

[0045] As shown in FIG. 2 , propulsion assembly 100 may further include a tether 140 for connecting propulsion assembly 200 to load 10. Tether 140 is preferably connected to propulsion assembly 100 using a bearing (not shown), such as a gimbal, pivot bearing, or other device adapted to prevent tension on tether 140 from generating torque on propulsion assembly 100. Preferably, the bearing is located near or co-located with the center of gravity of propulsion assembly 100 when primary lifting surface 110 is in the deployed configuration and provides lift to lift propulsion assembly 100 from rotation induced by secondary lifting surface 120. Tether 140 is adapted to transfer power from load 10 to propulsion assembly 100 to power propulsion assembly 200, for example, by incorporating power lines carrying low-voltage, AC, and / or high-voltage DC power. Tether 140 is also adapted to transmit control signals from payload 10 to propulsion assembly 100, which may also include backup flight computers, flight sensors, and communication systems for independent control, if desired. For example, tether 140 may include a separate data cable for transmitting control signals. Preferably, tether 140 is retractable. Propulsion assembly 100 may further include a first docking hub 150, preferably located on central axis 102. First docking hub 150 is configured to engage payload 10 when tether 140 is sufficiently retracted, and preferably configured to secure the payload during cruise or ground operation of propulsion assembly 100.

[0046] Propulsion assembly 100 may further include an emergency backup power source (not shown) for powering propulsion assembly 100 for a powered descent. In one embodiment, the emergency backup power source is sized to have sufficient power available for the time required for propulsion assembly 100 to perform a powered descent from its maximum design cruise altitude while carrying payload 10. Note, however, that part of that descent may be unpowered due to automatic rotation of primary lifting surface 110. In another embodiment, the emergency backup power source is sized to have sufficient power available for the time required for propulsion assembly 100 alone (without payload 10) to perform a powered descent from an altitude corresponding to the length of tether 140. In one embodiment, power transmitted from tether 140 is supplied to the emergency backup power source, which in turn powers secondary lifting surface 120. Thus, propulsion assembly 100 may be indirectly powered by tether 140.

[0047] Returning to FIG. 1 , aircraft 200 is preferably a vertical take-off and landing (VTOL) aircraft and includes an airframe 210 having a load-bearing cavity or area 212. Airframe 210 may further include an access door (not shown), a cargo aperture (not shown), and / or a window (not shown). Airframe 210 may further include shock absorbers (not shown), vibration dampers (not shown), and / or suspensions (not shown) to reduce shock experienced by airframe 210 upon landing. In another embodiment, a cradle (not shown) may be provided to receive aircraft 200 upon landing. In one embodiment, the cradle may include a refueling or charging station to replenish the energy source of aircraft 200. Airframe 210 may include wheels 260 for moving aircraft 200 upon landing. In one embodiment, wheels 260 include motors (not shown), such as electric motors (e.g., hub motors), preferably for propelling aircraft 200 as a ground vehicle a limited distance, such as from target landing site 14 to a storage location (not shown) for aircraft 200. In one embodiment, wheels 260 may be retractable to improve the aerodynamic efficiency of aircraft 200 during cruise conditions. In another embodiment, wheels 260 may include fixed wheels to reduce weight and mechanical complexity. In one embodiment, wheels may include one or more of skids, skis, and pontoons. In one embodiment, a cradle may be provided with wheels 260 for propelling the aircraft as a ground vehicle. In one embodiment, movement of the cradle using wheels 260 may be remotely controlled. For purposes of the above discussion, airframe 210, including any contents or payload on board, may be considered load 10. Aircraft 200 includes propulsion assembly 100, as described above, and a power generation assembly (not shown) configured to power propulsion assembly 200. Upon landing, the aircraft 200 may connect to a ground power source or an external power generation assembly, which may include batteries, fuel cells, supercapacitors, and / or generator output. Preferably, the generator output is provided by an internal combustion engine, such as a Wankel rotary engine.Preferably, the aircraft includes supercapacitors to provide short periods of high current that would degrade lithium-ion batteries or require oversized generators. Aircraft 200 may also include one or more directional control thrusters 230 mounted to airframe 210. Each directional control thruster 230 preferably acts in a respective thruster direction 232 non-parallel to central axis 102. In one embodiment, thruster direction 232 is adjustable. In a preferred embodiment, directional control thrusters 230 include ducted fans. In other embodiments, directional control thrusters 230 include rotors, jet thrusters, and / or impulse thrusters (such as cold gas thrusters, hypergolic or other chemical impulse systems). Directional control thrusters 230 may be used to steer payload 10 in roll, pitch, yaw, and / or translation relative to propulsion assemblies 200 when the payload 10 is suspended from the propulsion assemblies. For example, directional control thrusters 230 can be mounted on the sides of the aircraft 200 to change the orientation of the payload 10, similar to a tail rotor on a helicopter. The directional control thrusters 230 can be aligned vertically, in a multicopter configuration, or non-parallel to gravity, or some combination thereof. The directional control thrusters 230 can be parallel to the central axis 112 or non-parallel to the central axis 112. In a preferred embodiment, the directional control thrusters 230 include three pairs of parallel opposed thrusters aligned orthogonally to one another, providing a combination of thrust and torque to enable full forward / backward, spanwise, roll, pitch, and yaw motion. In one embodiment, the directional control thrusters 230 can include a tail rotor (not shown) attached to the aircraft 200. In one embodiment, the payload 10 can include an aerodynamic surface capable of providing lift during horizontal flight, such as a wing, tail, canard, or the like.

[0048] Aircraft 200 may include a camera (not shown) for identifying the target landing site 14. Aircraft 200 may include a controller (not shown) operating a control system configured to detect the target landing site 14 using one or more of a designated marker, geometric shape, color, landing light, apron color, or letter "H." Aircraft 200 may further include one or more of a LIDAR sensor (not shown), an ultrasonic range finder, in addition to or instead of using a camera, for detecting obstacles around the target landing site 14. Aircraft 200 may activate an instrument landing system (ILS) to land aircraft 200. Aircraft 200 may include altitude and / or airspeed sensors (not shown) in propulsion assembly 100 and / or airframe 210 for use by the control system to adjust altitude and airspeed, in addition to or instead of one or more of a LIDAR sensor, an ultrasonic range finder, a camera, and radar (not shown).

[0049] As shown in FIG. 5 , airframe 210 has a center of gravity 214 and may further include a winch (not shown), preferably a motorized capstan. The winch preferably includes a locking mechanism (not shown) to prevent uncontrolled release of tether 140. The winch may also include an emergency mechanism (not shown) for cutting or releasing tether 140. Aircraft 200 may further include a safety mechanism (not shown) for load 20 when released by the emergency mechanism. Airframe 210, winch, and tether 140 are configured such that an uppermost control point 236 of tether 140 on airframe 210 is located above center of gravity 214, thereby suspending airframe 210 in a stable position below propulsion assembly 100. Airframe 210 may further include a second docking hub 240, preferably located on central axis 102. The second docking hub 240 is configured to engage with the first docking hub 150 when the tether 140 is sufficiently retracted. The engagement between the first docking hub 150 and the second docking hub 240 leaves some degrees of freedom between the first docking hub 150 and the second docking hub 240. For example, the first docking hub 150 may include a dome and the second docking hub 240 may have a matching dome-shaped recess.

[0050] Airframe 210 may further include one or more control surfaces (not shown), such as a rudder, tail, or teardrop, that may set a preferred orientation of airframe 210 during flight by generating corrective forces toward the preferred orientation when moving in direction of motion 12 shown in Figure 8. The one or more control surfaces may also be used to assist in changing and / or controlling direction of motion 12 by generating drag and / or lift forces non-parallel to direction of motion 12.

[0051] Vehicle 210 may further include a ballistic parachute (not shown) for use in an emergency. In an emergency, propulsion assembly 100 may be used to attempt an autoroll landing, or propulsion assembly 100 may be detached from vehicle 210 and the vehicle may land by ballistic parachute while propulsion assembly 100 optionally attempts a powered or unpowered landing, or deploys a separate ballistic parachute (not shown) or other impact mitigation mechanism (e.g., deployable gas bags or crumple zones). In the event of an emergency at higher altitudes, an autoroll descent may be performed first, followed by the above measures as the vehicle approaches the ground.

[0052] 9-14 show a second embodiment of an aircraft 200 and propulsion assembly 100, incorporating some of the previously discussed embodiments.

[0053] The use of various embodiments of VTOL aircraft 200 with propulsion assembly 100 will now be discussed.

[0054] FIG. 1 shows the VTOL aircraft 200 in a stationary state. To takeoff, if used and / or required, the docking hubs 150, 240 are disconnected, and the propulsion assembly 100 ascends due to lift generated by the secondary lift surfaces 120 rotating about the second axis 122, as shown in FIG. 2. If multiple secondary lift surfaces 120 are used, differential thrust between them can be used for pitch and / or attitude control. Upon reaching a height predetermined, indicated, or assessed as safe based on sensor inputs, the primary lift surface 110 moves from the stowed configuration to the deployed configuration by hinging the periphery 112b about the joint 114, as shown in FIG. 3. Once the primary lift surface 110 is in the deployed configuration, the second axis 122 rotates to create a moment arm about the central axis 102, such that the lift generated by the secondary lift surfaces 120 induces rotation of the primary lift surface 110. The rotation or movement of the second axis 122 may be implemented as a change in the lift contribution from the secondary lift surface 120 in different orientations such that the actual rotation of the secondary lift surface 120 or the resultant lift vector changes direction. As the rotational speed of the primary lift surface 110 increases, the lift generated by the primary lift surface 110 increases, causing the second axis 122 to rotate further, with a smaller proportion of the lift generated by the secondary lift surface 120 being used to lift the propulsion assembly 200 and a larger proportion being used to induce rotation of the primary lift surface 110. Once the lift generated by the primary lift surface 110 exceeds the weight of the aircraft 200, the airframe 210 lifts off, as shown in FIG. 5 . In another embodiment, the airframe 210 is lifted by operating a winch. While the vehicle 210 is suspended below the propulsion assembly 100 by the tether 140, the vehicle 210 may require position and / or orientation control, which is provided by a combination or selection of directional control thrusters 230 and the lifting surface control system 130 of the propulsion assembly 100, as shown in Figure 6. The tether 140 can be retracted using a winch, thereby shortening the distance between the vehicle 210 and the propulsion assembly 100 and reducing the range of motion of the vehicle 210, as shown in Figure 7.Preferably, tether 140 is retracted sufficiently so that docking hubs 240, 150 engage and connect airframe 210 to propulsion assembly 100, although in other embodiments, payload 10 or airframe 210 may remain suspended below propulsion assembly 100. At this point, airframe 200 is ready to fly as a helicopter, and in other embodiments, airframe 200 may travel at speeds of preferably 200 km / h with the load suspended. -1 More than 300km / h, preferably up to 300km / h -1 At a cruising speed of 1000mW and a cruising distance of 300km to 500km, the helicopter can carry a load of 200kg to 420kg for a flight time of approximately 2 hours, and operate at a noise level of 105dBA to 115dBA.

[0055] The above steps may be performed in reverse order to land the vehicle 200. If the target landing site 14 is not sufficiently constrained, the vehicle 200 may land without extending the tether 140 and / or detaching from the propulsion assembly 100.

[0056] Advantages of various embodiments of aircraft 200 will now be discussed.

[0057] The small footprint of the main lift surfaces 110 in the stowed configuration allows the propulsion assembly 100 to take off from the ground with relatively little clearance and deploy the main lift surfaces 110 necessary to lift the aircraft 200 at an altitude safe from obstacles, thereby reducing downwash and noise on the ground. The main lift surfaces 110 can be substantially larger in the deployed configuration than a helicopter, since the only limiting factor is the stowed footprint of the main lift surfaces. Additionally, the smaller footprint significantly reduces rotor droop, improving ground clearance requirements and reducing the probability of the rotor striking the ground.

[0058] The use of secondary lift surfaces 120 to both lift the propulsion assembly 100 and induce rotation of the primary lift surfaces 110 can optionally reduce the number of components and systems required for the propulsion assembly 100, thereby reducing weight and complexity. Gradual control of the direction of the second axis 122 allows the secondary lift surfaces 120 to smoothly transition between lifting the propulsion assembly 100 and powering the primary lift surfaces 110. The use of lift surface control system 130 allows the orientation and position of the propulsion assembly 100 to be controlled without multiple primary lift surfaces 110 providing differential thrust, such as in a quadcopter layout. The use of rotors for the primary lift surfaces 110 and secondary lift surfaces 120 is desirable for the length of the aircraft 200's planned flight path. Because the primary lifting surfaces 110 are driven by secondary lifting surfaces 120, which are effectively air impulse transfer devices from the ambient air to the primary lifting surfaces 110, the reaction force for driving the primary lifting surfaces 110 is not transferred to the hub 150 but acts on the ambient air. This effectively eliminates the need for a tail rotor, which is required for a direct-drive primary rotor. By using multiple secondary lifting surfaces 120, their air impulses can be counteracted by driving them in opposite directions, and any remaining torque caused by imperfect balance or friction in the various bearings can be countered using directional control thrusters 230.

[0059] The use of tether 140 to transfer power from airframe 210 to propulsion system 100 reduces power system redundancy and allows propulsion system 100 to be very light in weight so that it can be lifted by secondary lifting surfaces 120, preferably carrying only emergency backup power source 160 in case the connection between airframe 210 and propulsion system 100 is compromised. The retractability of tether 140 allows reconnection between airframe 210 and propulsion system 100, improving the stability of aircraft 200. The use of docking hubs 240, 150 facilitates disconnection and reconnection between airframe 210 and propulsion system 100.

[0060] The directional control thrusters 230 can be used to control the position of the vehicle 210 while suspended by the tether 140. The directional control thrusters 230 can also be used to steer the vehicle 200 during flight. The use of ducted fans for the directional control thrusters 230 improves the safety of the directional control thrusters 230 and improves the aerodynamic efficiency of the directional control thrusters 230 over their designed performance range. The directional control thrusters 230 can be used in place of a tail rotor to counteract unwanted torque acting on the vehicle 200.

[0061] A primary limitation of helicopters is that their design limits their maximum speed during horizontal flight due to the reverse airflow passing over the retreating blades. Tiltrotor rotorcraft circumvent this limitation by tilting their rotors horizontally forward so that the oncoming airflow approaches parallel to the rotor axis. This technique has now been adapted and extended to tethered propulsion assemblies by adding the ability for the tethered propulsion assembly to tilt and point downward until the tethered assembly pulls on the load, much like a towplane. Thus, the direction of movement of the propulsion assembly, and therefore the direction air enters the propulsion assembly, is generally aligned with the propulsion assembly's axis of rotation.

[0062] To enable this, the load is preferentially equipped with a pivoting tether mount so that the propulsion assembly can change its angle under tether tension while the load remains horizontal. The pivoting mount preferably requires the tether attachment and linkage points to be axially aligned with the center of gravity and may include a tether force sensor, locking mechanism, or actuator. The propulsion assembly is preferentially equipped with a feathering mechanism for the propulsion assembly's primary lifting surfaces to obtain the appropriate angle of attack relative to the headwind.

[0063] During rotational flight, the propulsion assembly does not have a fixed orientation relative to the load. The aerodynamic surfaces of the propulsion assembly apply control inputs in a continuously rotating frame of reference, but maintaining effective control requires adjustments to the desired absolute orientation. Helicopters solve this problem by using cyclic control, which indexes rotor pitch inputs to a reference angle applied to the swashplate. Because the tether cannot apply torque along the axis of rotation, a different approach must be used.

[0064] In a preferred embodiment, tether 140 may include an attachment interface for connecting the tether to propulsion assembly 100. The attachment interface may be a non-flexible and non-rotating end point of tether 140. The attachment interface may be co-located within docking hub 150. Alternatively, the attachment interface may be located on the propulsion assembly 100, external to docking hub 150. Those skilled in the art will appreciate that tether 140 must rotate at the attachment interface (i.e., its connection to propulsion assembly 100) to prevent tether 140 from wrapping. Furthermore, the attachment interface has a center of gravity that is located above the center of gravity of airframe 210 and is spatially related to the center of gravity of airframe 210 to facilitate stable flight and control.

[0065] A system for determining spatial parameters of the propulsion assembly 100 relative to the load 10 is also provided. The spatial parameters include absolute and relative orientation parameters of the propulsion assembly 100 relative to the load 10. To determine the spatial parameters, the system may include a magnetometer and / or a gyroscope. Additionally, the system may include an encoder (e.g., a Hall Effect sensor or similar absolute orientation sensor) disposed between the propulsion assembly 100 and the mounting interface to determine the spatial parameters.

[0066] A combination of inertial or magnetic reference systems can be used to determine the orientation of the payload 10 and the orientation of the propulsion assembly 100, thus calculating the relative orientation and computing the correct control inputs to provide the desired trajectory during flight. Because constant high speed rotation can make the measurements of the inertial and magnetic systems unreliable, an orientation reference system can be provided at the attachment interface connected to the tether 140. Encoders can determine the orientation of the propulsion assembly relative to the attachment interface and are provided between the attachment interface and the propulsion assembly as described above. The attachment interface can optionally be stabilized by aerodynamic surfaces such as tails, control surfaces, or thrusters to maintain the desired orientation for the payload.

[0067] Tether 140 may include a second attachment interface at the opposite end of tether 140 for connecting tether 140 to payload 10. The second attachment interface may be co-located within hub 240 or located external to hub 240 on payload 10. The second attachment interface may include an articulating frame that can change its orientation in flight to allow payload 10 to remain horizontal while propulsion assembly 100 is tilted. The articulating frame also allows the propulsion assembly to fly at a high angle of attack relative to horizontal and provide higher flight speeds.

[0068] Using a computer or similar system, the relative rotation between the propulsion assembly and the mounting interface can be calculated, and then based on this, an orientation relative to the load 10 and the surrounding environment can be calculated. Thus, appropriate control signals can be calculated to steer the propulsion assembly 100 in a desired direction for any given orientation of the propulsion assembly 100, the mounting interface, and the load 10. [Explanation of symbols]

[0069] 10 Load 12 Direction of movement 14 Target Landing Site 100 Propulsion Assembly 102 Center axis 110 Main lifting surface 112 Large rotor 112a central part 112b Periphery 114 Joint 120 Secondary Lifting Surface 122 Second Axis 124 Small Rotor 130 Lifting Surface Control System 132 Servo Tab 140 Tether 150 First Docking Hub 160 Emergency backup power supply 200 aircraft 210 aircraft 212 Cavity or area 214 Center of gravity 220 Power Generation Assembly 230 Directional Control Thruster 232 Thruster Direction 234 Winch 236 Top Control Point 240 Second Docking Hub 260 wheels

Claims

1. 1. A propulsion assembly for lifting a load, comprising: a primary lift surface configured to provide sufficient lift to lift said load when rotated about a central axis; a secondary lift surface configured to provide lift along a second axis to lift the propulsion assembly, the second axis being configurable between a lift configuration in which the secondary lift surface lifts the propulsion assembly and a thrust configuration in which the secondary lift surface induces rotation of the primary lift surface; a propulsion assembly including:

2. the primary lift surface is movable between a stowed configuration and a deployed configuration, the footprint of the primary lift surface being smaller in the stowed configuration than in the deployed configuration; The propulsion assembly of claim 1 .

3. the primary lift surface is movable between a stowed configuration and a deployed configuration while being elevated by the secondary lift surface; The propulsion assembly of claim 1 .

4. the second axis of the secondary lift surface is continuously movable between the lift position and the thrust position such that as the lift generated by the primary lift surface increases with increasing rotational speed of the primary lift surface about the central axis, the proportion of the secondary lift surface lift used to lift the propulsion assembly continuously decreases. The propulsion assembly of claim 1 .

5. a lifting surface control system for providing cyclic and collective control of said primary lifting surfaces. The propulsion assembly of claim 1 .

6. the lift surface control system includes a servo tab; 6. The propulsion assembly of claim 5.

7. and a tether for connecting the propulsion assembly to the load, the tether adapted to transfer power from the load to the propulsion assembly for powering the propulsion assembly. The propulsion assembly of claim 1 .

8. the tether is retractable; 8. The propulsion assembly of claim 7.

9. and a first docking hub located on the central axis, the first docking hub configured to engage the load when the tether is sufficiently retracted.

8. The propulsion assembly of claim 7.

10. the tether is connected to the propulsion assembly using a bearing to reduce torque applied to the propulsion assembly by the tether when tension is applied to the tether; 8. The propulsion assembly of claim 7.

11. the primary lift surface includes a rotor, preferably the rotor providing azimuth control for the propulsion assembly; The propulsion assembly of claim 1 .

12. the secondary lift surface includes a rotor rotating about the second axis, preferably the rotor providing azimuth control for the propulsion assembly. The propulsion assembly of claim 1 .

13. an emergency backup power source for powering the propulsion assembly for powered descent; The propulsion assembly of claim 1 .

14. the secondary lift surface includes a plurality of secondary lift surfaces; The propulsion assembly of claim 1 .

15. the tether including an attachment interface for connecting the tether to the propulsion assembly.

8. The propulsion assembly of claim 7.

16. the attachment interface being a non-flexible and non-rotating end point of the tether; 16. The propulsion assembly of claim 15.

17. a system for determining spatial parameters of the propulsion assembly relative to the load; 17. The propulsion assembly of claim 16.

18. the spatial parameters include absolute and relative orientation parameters of the propulsion assembly with respect to the load; 18. The propulsion assembly of claim 17.

19. The system includes a magnetometer and / or a gyroscope for determining the spatial parameter.

17. The propulsion assembly of claim 16.

20. the system includes an encoder disposed between the propulsion assembly and the mounting interface to determine the spatial parameter.

20. The propulsion assembly of claim 18.

21. the attachment interface includes an aerodynamic surface and / or a thruster for controlling the orientation of the tether; 16. The propulsion assembly of claim 15.

22. the tether includes a second attachment interface for connecting the tether to the load to allow the propulsion assembly to fly at a higher angle relative to the horizontal to enable faster flight speeds.

16. The propulsion assembly of claim 15.

23. the second mounting interface includes an articulating frame that allows the load to remain horizontal while the propulsion assembly is tilted and that can change its orientation in flight to allow the propulsion assembly to fly at a high angle of attack relative to the horizontal and provide a higher flight speed; 23. The propulsion assembly of claim 22.

24. the load comprises an aerodynamic surface capable of providing lift during horizontal flight; The propulsion assembly of claim 1 .

25. Control surfaces can be effectively feathered for faster axial flight; 6. The propulsion assembly of claim 5.

26. a fuselage having a load-bearing cavity or area for a load; A propulsion assembly according to any one of claims 1 to 25 for lifting the vehicle; a power generation assembly located within or on the vehicle configured to power the propulsion assembly; Vertical take-off and landing aircraft, including

27. and one or more directional control thrusters mounted on the vehicle, the directional control thrusters acting in respective directions non-parallel to the central axis.

27. The aircraft of claim 26.

28. and one or more directional control thrusters mounted on the vehicle, the directional control thrusters acting in respective directions parallel to the central axis.

27. The aircraft of claim 26.

29. the directional control thruster includes a ducted fan, a rotor, a jet thruster, and / or an impulse thruster; 28. The aircraft of claim 27.

30. the vehicle has a center of gravity and includes a winch for retracting the tether, and an uppermost control point of the tether on the vehicle is above the center of gravity of the vehicle.

27. An aircraft according to claim 26 when dependent on claim 7.

31. the mounting interface has a center of gravity located above the center of gravity of the vehicle and spatially related to the center of gravity of the vehicle to facilitate stable flight and control; An aircraft according to claim 30 when dependent on claim 15.

32. the airframe further includes a second docking hub configured to engage with the first docking hub when the tether is sufficiently retracted.

27. An aircraft according to claim 26 when dependent on claim 8.

33. the airframe further includes one or more control surfaces for establishing a preferred orientation relative to a direction of travel and / or for controlling the orientation of the aircraft relative to a direction of travel; 27. The aircraft of claim 26.

34. The movable surface can be used to assist in changing the direction of movement.

33. The aircraft of claim 32.

35. wheels located on the fuselage; and a motor for driving the wheels to propel the aircraft on the ground.

27. The aircraft of claim 26.

Images