A method of automating entry of an aircraft into autorotation includes detecting a loss of engine power, analyzing a sensed height and sensed airspeed of the aircraft, determining an adjusted position of one or more control surfaces of the aircraft in response to the sensed height and sensed airspeed, and automatically moving the one or more control surfaces to the adjusted position.

A system to prevent or limit resonance in a rotocraft. The system comprises an airframe, a rotor system having a natural frequency and including a rotor and a mast attached to the airframe, and a non-linear spring positioned between the rotor system and the airframe. The rotor system and the airframe are operable to move relative to each other as the rotor system begins to oscillate. The non-linear spring is configured to be deformed when the rotor system and the airframe move relative to each other such that the deformation of the non-linear spring causes the natural frequency of the rotor system to change. Also disclosed is a related method for preventing or limiting resonance in a rotorcraft.

Off-board gyrocopter take-off systems and associated methods are disclosed. A representative method includes restraining a gyrocopter from vertical and lateral movement, pre-rotating a fixed-pitch lift rotor of the gyrocopter via a power source located off the gyrocopter, and releasing the gyrocopter for vertical movement to allow the gyrocopter to lift under a force provided by the lift rotor. Optionally, the method can further include interrupting or reducing power from the power source to the gyrocopter as a way to release the gyrocopter for vertical movement.

A method of automating entry of an aircraft into autorotation includes detecting a loss of engine power, analyzing a sensed height and sensed airspeed of the aircraft, determining an adjusted position of one or more control surfaces of the aircraft in response to the sensed height and sensed airspeed, and automatically moving the one or more control surfaces to the adjusted position.

A multi-rotor aircraft includes a fuselage, a propulsion engine coupled to the fuselage that generates thrust to propel the aircraft along a first vector during forward flight, and rotors coupled to the fuselage, each rotor comprising blades, each rotor coupled to a motor, and each motor configured to supply power to and draw power from the coupled rotor. The aircraft includes a flight control system configured to control the motors coupled to the rotors in a power managed regime in which a net electrical power, consisting of a sum of the power being supplied to or drawn from each rotor by its motor, is maintained within a range determined by a feedback control system of the flight control system. The flight control system can also be leveraged to adjust rotor control inputs to modify at least one of thrust, roll, pitch, or yaw of the multi-rotor aircraft.

A system for altitude control of an autogyro includes an unpowered rotor for generating lift and a forward propulsion system for generating a horizontal thrust component of a thrust vector for propelling the autogyro forward during flight. The system for altitude control also includes at least one thrust steering control devices configured to steer thrust generated by the forward propulsion system such that the forward propulsion system generates a vertical thrust component of the thrust vector.

A multi-rotor aircraft includes a fuselage, a propulsion engine coupled to the fuselage that generates thrust to propel the aircraft along a first vector during forward flight, and rotors coupled to the fuselage, each rotor comprising blades, each rotor coupled to a motor, and each motor configured to supply power to and draw power from the coupled rotor. The aircraft includes a flight control system configured to control the motors coupled to the rotors in a power managed regime in which a net electrical power, consisting of a sum of the power being supplied to or drawn from each rotor by its motor, is maintained within a range determined by a feedback control system of the flight control system. The flight control system can also be leveraged to adjust rotor control inputs to modify at least one of thrust, roll, pitch, or yaw of the multi-rotor aircraft.

A gyroplane employing torque compensated main rotor and hybrid power train is disclosed. The invention incorporates a torque-compensated main rotor system with a common Collective pitch control, which can be driven transiently during flight to allow Vertical Take-Off, Landing and Hovering (VTOLH) flight operations. Torque compensation is via a coaxial counter-rotating (CACR) rotor system, or alternatively using a single rotor in conjunction with one or more electronically-controlled, fixed-pitch, thruster motors. The use of electric motors for lift and torque compensation facilitates electronic and potentially autonomous control of all phases of vertical flight.

Aircraft capable of vertical takeoff and landing, hovering, and efficient forward flight are described. An aircraft includes two side mounted tiltable proprotors and a central rotor disposed above the proprotors. The proprotors are tiltable between at least a horizontal position for forward flight and a vertical position for vertical or hovering flight. The central rotor may be powered for vertical and transitional flight modes and may turn by free autorotation during forward flight. The proprotors may be differentially tilted during vertical or hovering flight to counter torque effects of the central rotor. The central rotor may be foldable and/or easily detachable from the aircraft to facilitate storage and transportation. Left and right proprotors may provide both forward thrust and attitude control. Control inputs to left and right proprotors may be connected directly to an autopilot creating closed loop actuation using motor RPM feedback.

A multi-rotor aircraft includes a fuselage, a propulsion engine coupled to the fuselage that generates thrust to propel the aircraft along a first vector during forward flight, and rotors coupled to the fuselage, each rotor comprising blades, each rotor coupled to a motor, and each motor configured to supply power to and draw power from the coupled rotor. The aircraft includes a flight control system configured to control the motors coupled to the rotors in a power managed regime in which a net electrical power, consisting of a sum of the power being supplied to or drawn from each rotor by its motor, is maintained within a range determined by a feedback control system of the flight control system. The flight control system can also be leveraged to adjust rotor control inputs to modify at least one of thrust, roll, pitch, or yaw of the multi-rotor aircraft.