Rotor collective pitch VS Mu to control flapping and mast/rotor tilt to control rotor RPM
AssigneeCartercopters, L.L.C.
InventorsJay W. Carter, Jr., Jeffrey R. Lewis
Life of this patent
Estimating the term…
Abstract
A method of operating a rotor aircraft involves measuring an airspeed of the aircraft and a rotational speed of the rotor. A controller determines a Mu of the rotor based on the airspeed of the aircraft and the rotational speed of the rotor. The controller varies the collective pitch of the rotor blades in relationship to the Mu, from an inertia powered jump takeoff, through high speed high advance ratio flight, through a low speed landing approach, to a zero or short roll flare landing. In addition as the rotor is unloaded and the rotor slows down, the controller maintains a minimum rotor RPM with the use of a tilting mast.
Claims17
A method of operating a rotor aircraft, comprising:
- (a) measuring the true airspeed of the aircraft;
- (b) measuring a rotational speed of the rotor;
- (c) determining a Mu of the rotor based on the true airspeed of the aircraft and the rotational speed of the rotor;
- (d) varying a collective pitch in relation to the Mu;
- and
- wherein step (d) comprises determining a Mu vs collective pitch curve, programming a controller with the curve, then with the controller, varying the collective pitch in accordance with at least a portion of the curve.
A method of operating a rotor aircraft, comprising:
- (a) measuring the true airspeed of the aircraft;
- (b) measuring a rotational speed of the rotor;
- (c) determining a Mu of the rotor based on the true airspeed of the aircraft and the rotational speed of the rotor;
- (d) varying a collective pitch in relation to the Mu;
- and wherein:
- step (d) comprises determining a Mu vs collective pitch curve that limits flapping to a selected range for each Mu, programming a controller with the curve, selecting a desired take-off level collective pitch, then with the controller:
- determining a higher Mu level on the curve that corresponds to the take-off collective pitch,
- at take-off of the aircraft, maintaining the collective pitch at a substantially constant take-off level collective pitch until reaching this higher Mu level, then
- decreasing the collective pitch in accordance with the curve as the Mu increases beyond this higher Mu level to a selected even higher Mu level;
- then
- maintaining the collective pitch substantially constant as Mu increases more than the even higher Mu level;
- and
- controlling the tilt of the rotor fore and aft to maintain a desired minimum rotational speed of the rotor.
A method of operating an aircraft having a rotor, a set of wings, and a propulsion source, comprising:
- (a) determining a Mu vs collective pitch curve for the aircraft and programming a controller with the curve;
- (b) pre-rotating the rotor, operating the propulsion source, and increasing a collective pitch of the rotor to cause the aircraft to lift off and commence forward flight;
- (c) during the forward flight, tilting the rotor aft to cause the rotor to auto-rotate;
- (d) measuring a true airspeed of the aircraft;
- (e) measuring a rotational speed of the rotor;
- (f) continuously calculating a Mu of the rotor based the airspeed of the aircraft and the rotational speed of the rotor;
- and
- (g) with the controller varying the collective pitch according to at least part of the Mu vs collective pitch curve.
Dependencies are inferred from the claim text.