Abstract: A vertical take-off and landing aircraft with a multi-element lifting system with integrated propulsion. The multi-element lifting system may have an upper wing element, a lower wing element, and a control wing element which is located below the upper wing element and above, and rearward of, the lower wing element. The system uses internal propulsion units, such as internal ducted fans, which flow air below the upper wing element and above the lower wing element such that the air flows through the multi-element lifting system. The control wing element may be articulated to route air vertically downward to allow for short or vertical take-off and landing. An aircraft with a multi-element wing assembly and a multi-element tail assembly raised above the wing assembly. An aircraft which resides on the ground with the wing assembly and the tail assembly pitched up.

Abstract: A compact harmonic drive system with a motor residing within the flexspline cup. The motor may reside further into the flexspline cup than the wave generator, and the air gap of the motor may be further out radially than the interior of the wave generator bearing. The motor may use an outrunner configuration with an outboard rotor made up of magnets, allowing for a large radial distance to the air gap and resulting in higher torque. The interior stator windings are thermally well coupled to the drive system structure. The harmonic drive may be coupled to a deployment system adapted to support moment loads perpendicular to the rotation axis such that those loads are not supported by the harmonic drive.

Abstract: A battery cell that includes a plurality of anodes and a plurality of cathodes is provided. The battery cell has a pouch laminate disposed over the plurality of anodes and the plurality of cathodes along with a temperature control mechanism centrally located within the pouch laminate. The temperature control mechanism is disposed between anodes of the plurality of anodes and cathodes of the plurality of cathodes such that the temperature control mechanism is centrally located within battery cell. The temperature control mechanism can regulate a temperature of the battery cell while also regulate an amount of pressure applied to the plurality of anodes and cathodes. The temperature control mechanism can include passageways through which heat transfer fluid can pass that be used to regulate the temperature and the pressure.

Abstract: An electrically powered aircraft powered by hydrogen fuel cells. The aircraft may have a split, or dual, fuselage with a multi-element wing joining the fuselages. The multi-element wing may have an upper wing element and a lower wing element with internal propulsion units, such as internal ducted fans. A control wing element may be located below the upper wing element and above, and rearward of, the lower wing element. The control wing element may be articulated to provide for aircraft attitude control. The hydrogen fuel and the fuel cell systems may reside in one of the fuselages of the dual fuselage aircraft, while the pilots and passengers may reside in the other of the fuselages.

Abstract: An aerial vehicle configured a main fuselage and an upper nacelle coupled to the top of the main fuselage. The aerial vehicle may have an air intake in an otherwise higher drag location. In some aspects, the aerial vehicle is a vertical take-off and landing aircraft. The aircraft may intake the air to provide air to a hydrogen fuel cell system or a turbogenerator within the aircraft, which may reside withing the upper nacelle. The aircraft may have electric motor driven rotor assemblies which provide thrust for both vertical take-off and landing and forward flight operations. The electric motor driven rotor assemblies may be powered by electric power from the fuel cell system. The aircraft may have pivoting wings with rotor assemblies which may provide thrust in both a forward flight configuration and a vertical take-off and landing (hover) configuration.

Abstract: A system and method for controlling a VTOL aircraft to minimize acoustic noise. In a hover mode, the aircraft may be controlled to utilize a blade pitch angle and corresponding angle of attack range which minimizes variations in the boundary layer separation location to a point or narrow region, which reduces noise generation. The propeller blades used in the system are configured to have a reduced or no shift of the point of flow separation on the airfoil as a function of angle of attack during the hover mode. The blade design may trade off overall blade efficiency in exchange for the reduced noise during hover.

Abstract: An aircraft including an airframe and a plurality of propulsion assemblies coupled to the airframe, wherein each propulsion assembly includes an electric motor, a propeller coupled to the electric motor, and a tilt mechanism that connects the propulsion assembly to the airframe and transforms the propulsion assembly between a forward configuration and a hover configuration; wherein the plurality of propulsion assemblies is transformable between a forward arrangement and a hover arrangement, wherein each of the plurality of propulsion assemblies is in the forward configuration in the forward arrangement, wherein each of the plurality of propulsion assemblies is in the hover configuration in the hover arrangement, wherein the spacing between at least two of the propellers of the plurality of propulsion assemblies changes between the forward arrangement and the hover arrangement.

Abstract: An aerial vehicle adapted for vertical takeoff and landing using a set of wing mounted thrust producing elements for takeoff and landing. An aerial vehicle which is adapted to vertical takeoff with the rotors in a rotated, take-off configuration and then transitions to a horizontal flight path, with some or all of the rotors rotated to a powered horizontal configuration. The aerial vehicle may have deployment mechanisms which deploy electric motor driven propellers from a forward facing to a vertical orientation. The aerial vehicle may be powered with electric motors.

Abstract: A hydrogen fuel cell powered electric vertical take-off and landing (eVTOL) aircraft with a high efficiency hydrogen fuel system. The eVTOL aircraft may utilized tilt-up rotors for hover flight, which then transition to a forward facing forward flight configuration. The fuel cell system may use one or more compressors to compress air to a sufficiently high pressure for the fuel cell. Liquid hydrogen may be compressed and then utilized in heat exchangers to cool the compressed air, maintaining the air at a temperature low enough for the fuel cell. The hydrogen may also be used to cool the fuel cell as it is also depressurized prior to its entry in the fuel cell cycle.

Abstract: A thrust unit for an aircraft with a hydrogen fuel system. The aircraft may utilize compressors to compress air to a sufficiently high pressure for the fuel cell. Liquid hydrogen is compressed and then utilized in heat exchangers to cool the compressed air, maintaining the air at a temperature low enough for the fuel cell. The thrust unit may be an electrically powered fan unit with a fan within a fan tube. The fan tube may include air inlets for the fuel cell system, as well as outlets for exhaust from the fuel cell system. The fan tube may contain heat exchangers which are part of the fuel cell thermodynamic system.

Abstract: A vertical take-off and landing aircraft which uses fixed rotors for both VTOL and forward flight operations. Some of the rotors are forward canted, while some of the rotors are forward facing. The forward canted rotors are tilted forward slightly from vertical and provide some forward propulsion during horizontal flight. The forward facing rotors may be fixed in a forward facing configuration. Forward swept wings allow for rotor placement which brings efficiency during hover operations.

Abstract: The battery thermal management system includes a battery pack, a circulation subsystem, and a heat exchanger. The system can optionally include a cooling system, a reservoir, a de-ionization filter, a battery charger, and a controller.

Abstract: A vertical take-off and landing aircraft and method which uses fixed rotors for both VTOL and forward flight operations. The wing rotors are tilted forward and provide some forward propulsion during horizontal flight. The wing rotors are under power during forward flight and provide some lift during horizontal flight. The fraction of lift provided by the vertical thrusting rotors is greater than 0.2. The rotor assemblies may have rotating propellers with electric motors.

Abstract: The aircraft can include: an airframe, a tilt mechanism, a payload housing, and can optionally include an impact attenuator, a set of ground support members (e.g., struts), a set of power sources, and a set of control elements. The airframe can include: a set of rotors and a set of support members. By utilizing a larger rotor blade area (and/or larger rotor disc area) and adjusting the blade pitch and RPM, the rotors can augment the lift generated by the aerodynamic profile of the aircraft in the forward flight mode in addition to providing forward thrust. Variants generating lift with the rotors can reduce or eliminate additional control surfaces (e.g., wing flaps, ailerons, ruddervators, elevators, rudder, etc.) on the aircraft since the thrust and motor torque is controllable (thereby indirectly controlling lift) at each rotor, thereby enabling pitch, yaw, and/or roll control during forward flight.

Abstract: A method for determining airspeed of an aircraft that includes determining a rotor model relating a power coefficient of a propeller of the aircraft to an axial inflow velocity through the propeller as a function of a set of rotor operating parameters; determining the set of rotor operating parameters by sampling an electronic control signal associated with an electric motor actuating the propeller; computing the axial inflow velocity through the propeller based on the set of rotor operating parameters using the rotor model; and determining the airspeed based on the axial inflow velocity.

Abstract: An aerial vehicle adapted for vertical takeoff and landing using a set of wing mounted thrust producing elements for takeoff and landing. An aerial vehicle which is adapted to vertical takeoff with the rotors in a rotated, take-off attitude then transitions to a horizontal flight path, with the rotors rotated to a typical horizontal configuration. The aerial vehicle may have deployment mechanisms which deploy electric motor driven propellers from a forward facing to a vertical orientation. The aerial vehicle may have rear mounted rotors adapted to vertical takeoff with the rotors in a rotated, take-off attitude then transitions to a horizontal flight path, with the rotors rotated to a typical horizontal configuration. The aerial vehicle may be powered with electric motors.

Abstract: An aerial vehicle adapted for vertical takeoff and landing using a set of wing mounted thrust producing elements for takeoff and landing. An aerial vehicle which is adapted to vertical takeoff with the rotors in a rotated, take-off attitude then transitions to a horizontal flight path, with the rotors rotated to a typical horizontal configuration. The aerial vehicle may have deployment mechanisms which deploy electric motor driven propellers from a forward facing to a vertical orientation. The deployment mechanisms deploy the rotor forward and up as they deploy from a forward flight configuration to a vertical thrust configuration. A single motor may drive two co-axial propellers, with a first propeller driven when the motor spins in a first direction, and a second propeller driven when the motor spins in a second direction.

Abstract: An aerial vehicle adapted for vertical takeoff and landing using a set of wing mounted thrust producing elements for takeoff and landing. An aerial vehicle which is adapted to vertical takeoff with the rotors in a rotated, take-off attitude then transitions to a horizontal flight path, with the rotors rotated to a typical horizontal configuration. The aerial vehicle may have deployment mechanisms which deploy electric motor driven propellers from a forward facing to a vertical orientation. The aerial vehicle may be powered with electric motors.

Abstract: An extension linkage for a wing flap can include at least one arm that includes two elements connected by a joint. The linkage can include an actuation mechanism, additional arms and/or each arm can include more than two elements, tie rods and/or cross pieces connecting two or more arms, and any other suitable components. The linkage functions to translate and rotate a body attached to one end of the arm relative to a primary structure attached to a second end of the arm. The linkage resides entirely within a space defined by the upper skin and the lower skin of the wing rearward of the mounting when in a retracted configuration.

Abstract: An aerial vehicle configured with air intake in an otherwise higher drag location. In some aspects, the aerial vehicle is a vertical take-off and landing aircraft. The aircraft may intake the air to provide air to a hydrogen fuel cell system within the aircraft. The aircraft may have electric motor driven rotor assemblies which provide thrust for both vertical take-off and landing and forward flight operations. The electric motor driven rotor assemblies may be powered by electric power from the fuel cell system. The air intake may be on the forward portion of a nacelle placed in what would be a high drag location, such as at the junction of the wings and the fuselage, or the junction of the vertical stabilizers and the fuselage, for example.