A rotor system including a hub; a rim configured to rotate about the hub, the rim including an interior surface and an engagement surface; a plurality of rotor blades extending from the hub and coupled to the interior surface of the rim; and one or more outer drive gears disposed adjacent to the engagement surface of the rim; each of the one or more outer drive gears including a plurality of teeth for engaging the engagement surface of the rim; wherein the one or more outer drive gears are configured to rotate the rim such that the plurality of rotor blades rotates about the hub. Other aspects provide an aircraft rotor system and methods of operating an aircraft rotor system.

There is disclosed in one example a flight control computer for a rotary aircraft, including: a first interface to communicatively couple to a flight control input; a second interface to communicatively couple to flight geometry actuators; a data source; a multi-dimensional lookup table including a data structure to correlate flight control inputs to flight geometry actuator outputs according to a third-factor; and circuitry and logic instructions to: receive an input via the first interface; query the data source for the third-factor; query the multi-dimensional lookup table for a control input modifier according to the flight control input and the third-factor; and compute and send via a third interface a flight geometry output according to the control input modifier.

The present invention includes an anti-torque assembly for a helicopter comprising a plurality of fixed blade pitch motors mounted on one or more pivots on the tail boom of the helicopter, wherein the plurality of fixed blade pitch motors on the one or more pivots are adapted to be oriented substantially in-plane with a tail boom of a helicopter during a first mode of operation that comprises a hover mode and wherein the fixed blade pitch motors are adapted to be oriented substantially off-plane from the tail boom of the helicopter during a second mode of helicopter operation that is different from the first mode.

An unmanned aircraft system has a vertical takeoff and landing flight mode and a forward flight mode. The unmanned aircraft system includes an airframe, a rotor assembly rotatably coupled to the airframe and a propeller rotatably coupled to the airframe. The rotor assembly including at least two rotor blades having tip jets that are operably associated with a compressed gas power system. The propeller is operably associated with an electric power system. In the vertical takeoff and landing flight mode, compressed gas from the compressed gas power system is discharged through the tip jets to rotate the rotor assembly and generate vertical lift. In the forward flight mode, the electric power system drives the propeller to generate forward thrust and autorotation of the rotor assembly generates vertical lift.

An electric propulsion system includes a static mast defining an axis of rotation and a stationary rotor hub assembly coupled to the static mast. A rotating system is rotatably mounted to the stationary rotor hub assembly. The electric propulsion system additionally includes an electric motor including a stator assembly associated with the rotor hub assembly and a rotor assembly associated with the rotating system.

An aircraft includes an airframe having an empennage, a counter rotating, coaxial main rotor assembly located at the airframe including an upper rotor assembly and a lower rotor assembly, and a translational thrust system positioned at the empennage and providing translational thrust to the airframe. At least two control surfaces located at the empennage are independently operable via commands from one or more flight control computers. A method of operating an aircraft includes transmitting a first signal from one or more flight control computers to a first control surface located at a first lateral side of a translational thrust system, and actuating the first control surface to a first position via the first signal. A second signal is transmitted to a second control surface located at a second lateral side opposite the first lateral side, and the second control surface is actuated to a second position via the second signal.

An aircraft includes an airframe having an extending tail, a counter rotating, coaxial main rotor assembly disposed at the airframe including an upper rotor assembly and a lower rotor assembly and a translational thrust system positioned at the extending tail and providing translational thrust to the airframe. A flight control computer is configured to control a main rotor rotational speed of the upper and the lower rotor assemblies of the main rotor assembly as a function of airspeed of the aircraft. A method of operating an aircraft includes retrieving a threshold main rotor rotational speed of the dual coaxial main rotor assembly and calculating an actual main rotor rotational speed according to an environment of the aircraft. The actual main rotor rotational speed is maintained to remain at or below the threshold main rotor speed according to an airspeed of the aircraft.

During a cruise mode, a cruise-only propeller provides thrust using power from a first power source. During a hovering mode and a transitional mode, the propeller provides no thrust. The first power source includes an internal combustion engine; a second power source includes a high discharge rate battery and a high energy battery. The propeller is electrically connected to the first power source and is electrically disconnected from the second power source. During the hovering mode and the transitional mode, a hover-and-transition-only tiltrotor provides thrust using power from the second power source. During a vertical landing, the tiltrotor switches power sources from the high energy battery to the high discharge rate battery, independent of current draw. The tiltrotor is electrically disconnected from the first power source and is electrically connected to the second power source. During the cruise mode, the tiltrotor provides no thrust.

The present invention includes a system and method for slowing the rotation of a rotor using, for example, rotor brake system for a rotorcraft comprising: one or more generators connected to a main rotor gearbox; an electric distributed anti-torque system mounted on a tail boom of the rotorcraft comprising two or more electric motors connected to the one or more generators, wherein the two or more electric motors are connected to one or more blades; and wherein a rotation of the rotor is slowed by placing a drive load on the main rotor gearbox with the one or more generators to bleed the mechanical power from rotor into electrical power via the two or more electric motors, wherein the electric distributed anti-torque system generates thrust in opposing directions.

An aircraft has a fuel cell, a battery configured to be charged by the fuel cell, a supercapacitor configured to be charged by the fuel cell, and a power management unit configured to receive electrical power from the fuel cell, the battery, and the supercapacitor.