While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.

A rotor blade includes an actuator comprising an electric motor having a rotary drive shaft, a bearing for mounting the rotary drive shaft along an axis extending along the length of the rotor blade, and a lubrication system for lubricating the bearing. The lubrication system includes a sump closer to the tip of the blade than the bearing, and a pump for pumping lubricant from the sump to the bearing.

A rotor blade includes an actuator comprising an electric motor having a rotary drive shaft, a bearing for mounting the rotary drive shaft along an axis extending along the length of the rotor blade, and a lubrication system for lubricating the bearing. The lubrication system includes a sump closer to the tip of the blade than the bearing, and a pump for pumping lubricant from the sump to the bearing.

While an aircraft is mid-flight, a braking start point associated with a stoppable rotor is calculated where the stoppable rotor includes a first and second blade and the stoppable rotor is configured to rotate about a substantially vertical axis. A process to stop the stoppable rotor is started, while the aircraft is mid-flight, when the stoppable rotor reaches the braking start point, where the stoppable rotor is stopped with the first blade pointing forward and the second blade pointing backward.

A method for equalizing rolling moments at high advance ratios is disclosed including impelling an aircraft in a forward direction at an airspeed by means of a thrust source and rotating a rotor of the aircraft at an angular velocity with respect to the airspeed effective to cause a positive total lift on each blade due to air flow over the blades in the retreating direction when the blade is moving in the retreating direction. The rotor includes an even number of blades placed at equal angular intervals around the rotor hub. One or both of cyclic pitch and rotor angle of attack are adjusted such that a rolling moment of the retreating blade due to reverse air flow is between 0.3 and 0.7 times a rolling moment on the advancing blade due to lift.

A method for equalizing rolling moments at high advance ratios is disclosed including impelling an aircraft in a forward direction at an airspeed by means of a thrust source and rotating a rotor of the aircraft at an angular velocity with respect to the airspeed effective to cause a positive total lift on each blade due to air flow over the blades in the retreating direction when the blade is moving in the retreating direction. The rotor includes an even number of blades placed at equal angular intervals around the rotor hub. One or both of cyclic pitch and rotor angle of attack are adjusted such that a rolling moment of the retreating blade due to reverse air flow is between 0.3 and 0.7 times a rolling moment on the advancing blade due to lift.

A rotor blade assembly includes a rotor blade having inboard and outboard regions, a blade body, and an internal spar, the blade body defining leading and trailing edges. A trailing edge assembly extends from and is connected to the trailing edge, and has a trailing edge flap and an actuator configured to deploy the trailing edge flap between first and second positions. In one of the first and second positions, an upper surface of the trailing edge flap conforms in profile to an upper surface of the rotor blade, and in the other, the trailing edge flap is inclined relative to the blade. During hovering flight, at least one trailing edge flap segment is deflected to enhance hover performance. During forward flight, at least one trailing edge flap segment is either not deflected for reduced effect on forward flight or is deflected for additional thrust.

A rotor blade assembly includes a rotor blade having inboard and outboard regions, a blade body, and an internal spar, the blade body defining leading and trailing edges. A trailing edge assembly extends from and is connected to the trailing edge, and has a trailing edge flap and an actuator configured to deploy the trailing edge flap between first and second positions. In one of the first and second positions, an upper surface of the trailing edge flap conforms in profile to an upper surface of the rotor blade, and in the other, the trailing edge flap is inclined relative to the blade. During hovering flight, at least one trailing edge flap segment is deflected to enhance hover performance. During forward flight, at least one trailing edge flap segment is either not deflected for reduced effect on forward flight or is deflected for additional thrust.

A method of selectively preventing flapping of a rotor hub includes providing a flapping lock proximate to a rotor hub and shaft assembly and moving the flapping lock from an unlocked position to a locked position, the flapping lock operable in the locked position to prevent at least some flapping movement of the rotor hub relative to the shaft, the flapping lock operable in the unlocked position to allow the at least some flapping movement of the rotor hub relative to the shaft.

A method of selectively preventing flapping of a rotor hub includes providing a flapping lock proximate to a rotor hub and shaft assembly and moving the flapping lock from an unlocked position to a locked position, the flapping lock operable in the locked position to prevent at least some flapping movement of the rotor hub relative to the shaft, the flapping lock operable in the unlocked position to allow the at least some flapping movement of the rotor hub relative to the shaft.