Rotorcraft autorotation control through electrical braking
AssigneeSiFly Aviation, Inc.
InventorsBrian L. Hinman, Jeffrey G. Bernstein, Muhammad Mubeen Javaid
Life of this patent
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Abstract
A method of operating an electrically powered rotorcraft of the type having a fuselage and a set of N rotors driven by a set of electric motors and coupled to the fuselage, N≥4, under a failure condition preventing ordinary operation of the rotorcraft. The method includes entering a failsafe mode of operation wherein autorotation of at least four of the rotors is enabled. The method also includes using electrical braking associated with a selected group of the rotors to control pitch, roll and yaw of the rotorcraft.
Claims27
A method of operating an electrically powered rotorcraft having a fuselage and a set of N rotors, N≥4, wherein each rotor has a rotor hub and a set of blades, each blade having an angle of incidence, the set of rotors driven by a set of electric motors and coupled to the fuselage, the rotorcraft having a system controller configured to control operation of the set of N rotors, the method comprising:
- biasing each blade with a spring force to cause such blade to have an angle of incidence of approximately zero degrees when rotor torque on the rotor hub of such blade is absent, wherein the spring force is overcome when rotor torque on such rotor hub exceeds a threshold;
- under a condition wherein a failure prevents supplying, to each rotor hub, rotor torque exceeding the threshold, operating the rotorcraft in a failsafe mode wherein (i) the spring force associated with each rotor hub such shall have caused blades thereof to have an angle of incidence of approximately zero degrees and (ii) autorotation is enabled in at least four of the rotors;
- and (iii) differential control of electrical braking of the set of rotors is enabled by the system controller to affect attitude of the rotorcraft.
An electrically powered rotorcraft comprising:
- four rotors driven by a set of electric motors, each rotor comprising a rotor hub and a set of blades;
- a system controller configured to control operation of the four rotors and the set electric motors;
- each rotor comprising a spring, the spring providing a spring force and being coupled to the rotor hub and the set of blades;
- wherein the spring force biases each set of blades to have an angle of incidence of approximately zero degrees when rotor torque is absent, wherein the spring force is overcome when the rotor torque exceeds a threshold;
- wherein, in the presence of rotor torque below the threshold, autorotation of the four rotors is enabled and the system controller is configured to cause differential electrical braking of the four rotors to adjust an orientation of the rotorcraft.
A method of operating an electrically powered rotorcraft having a fuselage and a set of N rotors driven by a set of electric motors and coupled to the fuselage, N≥4, as well as a system controller configured to control operation of the set of N rotors, the method operating under a failure condition preventing ordinary operation of the rotorcraft and comprising, under the failure condition:
- entering, by the system controller, into a failsafe mode of operation wherein autorotation of at least four of the rotors is enabled;
- and
- causing, by the system controller, control of electrical braking of each rotor in the set relative to electrical braking of each other rotor in the set, to affect pitch, roll and yaw of the aircraft
- wherein each rotor has a rotor hub and a set of blades, wherein each rotor hub is configured to provide a spring force to bias the angle of incidence of each corresponding blade toward approximately zero degrees in the absence of rotor torque.
Dependencies are inferred from the claim text.