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US 7,677,492 B1Granted
Automatic mechanical control of rotor blade collective pitch
AssigneeCartercopters, L.L.C.
InventorsJay W. Carter, Jr., Jeffrey R. Lewis
Life of this patent
Estimating the term…
Abstract
A rotary aircraft has a fuselage with wings and a rotor. The blades of the rotor are twistable about a pitch axis to vary collective pitch. A collective pitch shaft moves in an advancing direction to increase the collective pitch. Weights are mounted to the blades for outward movement along the blades in response to an increase in rotational speed of the blades. A linkage between each of the weights and the collective pitch shaft moves the collective pitch shaft in the advancing direction in response to an increase in rotational speed. A spring acting through a cam mechanism exerts a non linear force in opposition to the outward movement of the blades.
Claims13
An autogyro rotor aircraft, comprising:
- a fuselage;
- a power source mounted to the fuselage;
- a thrust device coupled to the power source for providing forward thrust to the aircraft;
- a rotor mounted above the fuselage for providing lift during takeoff and landing, the rotor having blades extending outward from a hub, each of the blades being twistable about a pitch axis to vary a collective pitch from a minimum pitch to a maximum pitch, the rotor being operatively connected to the power source for rotation only prior to take-off and freewheeling after take-off;
- a collective pitch assembly mounted to the rotor that moves in an advancing direction to increase the collective pitch and in a decreasing direction to decrease the collective pitch;
- a mechanical pitch controller operatively coupled to the collective pitch assembly for automatically increasing and decreasing the collective pitch in a selected relationship to the rotational speed of the rotor while freewheeling;
- a lockout member cooperatively engaged with the pitch controller and having a locked position that prevents movement of the collective pitch assembly from the minimum pitch while the aircraft is on the ground and the rotor is being prerotated by the power source prior to its takeoff RPM, the lockout member being releasable to allow the collective pitch assembly to move in the advancing direction toward the maximum pitch in response to disengagement of the power source from the rotor;
- and
- wherein the pitch controller is free to increase and decrease the pitch between the minimum and the maximum pitches continuously while the rotor is autorotating after take-off for a duration of the flight.
6 more elements
An autogyro rotor aircraft, comprising:
- a fuselage;
- a thrust device mounted to the fuselage for providing forward thrust to the aircraft;
- a rotor mounted above the fuselage;
- a power source coupled to the thrust device for powering the thrust device, the power source being releasably coupled to the rotor for pre-rotating the rotor prior to liftoff and disengaging rotation of the rotor immediately before liftoff;
- the rotor having blades extending outward from a hub, each of the blades being twistable about a pitch axis to vary a collective pitch;
- a collective pitch shaft coaxial with the rotor that moves in an axial advancing direction to increase the collective pitch and in axial decreasing direction to decrease the collective pitch;
- a plurality of weights, each of the weights being mounted to one of the blades for outward movement along each blade in response to an increase in centrifugal force while the rotor is rotating after liftoff;
- a spring operatively engaged with the weights for causing the weights to move inward in response to a decrease in centrifugal force while the rotator is rotating after liftoff;
- a plurality of cables, each having one end connected to one of the weights and another end extending around a guide member and connected to the collective pitch shaft for moving the collective pitch shaft in the advancing direction in response to outward movement of the weights and the decreasing direction in response to inward movement of the weights;
- a piston and cylinder cooperatively engaged with the collective pitch shaft, defining first and second chambers on opposite sides of the piston for containing a fluid that resists relative movement between the piston and the cylinder while the chambers are closed, which prevents movement of the collective pitch shaft in the advancing and decreasing directions;
- a bypass passage extending between the first and second chambers to enable the fluid to flow between the chambers and allow relative movement between the piston and the cylinder, which allows movement of the collective pitch shaft in the advancing and decreasing directions;
- a valve that is in a closed position closing the bypass passage only during pre-rotation of the rotor to prevent movement of the collective pitch shaft from a minimum pitch position and is movable to an open position opening the bypass passage when the power source disengages from the rotor;
- and
- wherein the valve remains in an open position after takeoff for the duration of the flight and the weights are free to continuously move between fully inward and fully outward positions, which moves the collective pitch shaft between the minimum pitch and a maximum pitch during the flight in response to changes in the rotational speed of the rotor.
11 more elements
A method of controlling collective pitch of the blades of an auto gyro rotor aircraft having a power source and a thrust device for applying forward thrust to the aircraft, comprising:
- (a) operatively coupling a mechanical collective pitch controller to the rotor that has weights movable along the blades in response to centrifugal force to vary the collective pitch between a minimum level and a maximum level in a selected relationship to the rotational speed of the rotor;
- (b) operatively coupling a lockout member with the pitch controller that has a locked position and a released position;
- (c) placing the lockout member in the locked position, and with the power source, driving the thrust device and pre-rotating the rotor while with the lockout member, preventing the weights of the collective pitch controller from moving along the blades, so as to retain the collective pitch at the minimum level;
- then
- (d) disengaging the power source from the rotor and continuing to drive the thrust device, allowing the rotor to rotate due to inertial to cause lift off, then auto rotate due to air flow;
- and
- (e) moving the lockout member to the released position, thereby allowing the weights to move along the blades, causing the pitch controller, to automatically vary the collective pitch between the minimum level and the maximum level in selected relationship to an auto-rotational speed of the rotor after lift off and continuously during the flight.
4 more elements
Dependencies are inferred from the claim text.