Abstract: A compound rotorcraft comprises a fuselage, a rotor coupled to the fuselage and a wing mounted to the fuselage. The rotorcraft further comprising a first outboard propeller, a first inboard propeller, a second outboard propeller, and a second inboard propeller. The first outboard propeller having a propeller body and propeller blades, the body mounted to a first wing-half at a first incidence angle. The first inboard propeller having a propeller body and propeller blades, the body mounted to the first wing-half between the first outboard propeller and the fuselage at a second incidence angle. The second outboard propeller having a propeller body and propeller blades, the body mounted to a second wing-half at a third incidence angle. The second inboard propeller comprising a propeller body and propeller blades, the body mounted to a second wing-half between the second outboard propeller in the fuselage at a fourth incidence angle.

Abstract: A system to prevent or limit resonance in a rotocraft. The system comprises an airframe, a rotor system having a natural frequency and including a rotor and a mast attached to the airframe, and a non-linear spring positioned between the rotor system and the airframe. The rotor system and the airframe are operable to move relative to each other as the rotor system begins to oscillate. The non-linear spring is configured to be deformed when the rotor system and the airframe move relative to each other such that the deformation of the non-linear spring causes the natural frequency of the rotor system to change. Also disclosed is a related method for preventing or limiting resonance in a rotorcraft.

Abstract: A compound rotorcraft comprises a fuselage, a rotor coupled to the fuselage and a wing mounted to the fuselage. The rotorcraft further comprising a first outboard propeller, a first inboard propeller, a second outboard propeller, and a second inboard propeller. The first outboard propeller having a propeller body and propeller blades, the body mounted to a first wing-half at a first incidence angle. The first inboard propeller having a propeller body and propeller blades, the body mounted to the first wing-half between the first outboard propeller and the fuselage at a second incidence angle. The second outboard propeller having a propeller body and propeller blades, the body mounted to a second wing-half at a third incidence angle. The second inboard propeller comprising a propeller body and propeller blades, the body mounted to a second wing-half between the second outboard propeller in the fuselage at a fourth incidence angle.

Abstract: A compound rotorcraft comprises a fuselage, a rotor coupled to the fuselage and a wing mounted to the fuselage. The rotorcraft further comprising a first outboard propeller, a first inboard propeller, a second outboard propeller, and a second inboard propeller. The first outboard propeller having a propeller body and propeller blades, the body mounted to a first wing-half at a first incidence angle. The first inboard propeller having a propeller body and propeller blades, the body mounted to the first wing-half between the first outboard propeller and the fuselage at a second incidence angle. The second outboard propeller having a propeller body and propeller blades, the body mounted to a second wing-half at a third incidence angle. The second inboard propeller comprising a propeller body and propeller blades, the body mounted to a second wing-half between the second outboard propeller in the fuselage at a fourth incidence angle.

Abstract: An embodiment includes a system for controlling blade pitch in a rotorcraft having an engine; a drive shaft with a first end and a second end and connected at the first end to the engine; a rotor with two or more blades connected to the second end of the drive shaft; and one or more actuators positioned adjacent to the rotor blades operable to change a blade pitch of the rotor blades.

Abstract: A compound rotorcraft comprises a fuselage, a rotor coupled to the fuselage and a wing mounted to the fuselage. The rotorcraft further comprising a first outboard propeller, a first inboard propeller, a second outboard propeller, and a second inboard propeller. The first outboard propeller having a propeller body and propeller blades, the body mounted to a first wing-half at a first incidence angle. The first inboard propeller having a propeller body and propeller blades, the body mounted to the first wing-half between the first outboard propeller and the fuselage at a second incidence angle. The second outboard propeller having a propeller body and propeller blades, the body mounted to a second wing-half at a third incidence angle. The second inboard propeller comprising a propeller body and propeller blades, the body mounted to a second wing-half between the second outboard propeller in the fuselage at a fourth incidence angle.

Abstract: An embodiment includes a system for controlling blade pitch in a rotorcraft having an engine; a drive shaft with a first end and a second end and connected at the first end to the engine; a rotor with two or more blades connected to the second end of the drive shaft; and one or more actuators positioned adjacent to the rotor blades operable to change a blade pitch of the rotor blades.

Abstract: Animal feeders useful in feeding particular groups of animals are disclosed. Animal feeders described herein may, for example, include an electrically conductive exterior structure; a door; a door lock; a species recognition device; and an electric shock deterrent. Methods of feeding animals utilizing an electric shock deterrent are also disclosed.

Abstract: Apparatus and methods for eliminating back drive in a push pull type control system, are provided. An exemplary apparatus includes a control rod including a pair of spaced apart piston displacement members each configured to carry a check valve. The apparatus also includes a pair of opposite-face check valves each configured to seal against respective opposing face of a piston head to form a hydraulic lock, preventing back drive in the control system.

Abstract: Animal feeders useful in feeding particular groups of animals are disclosed. Animal feeders described herein may, for example, include an electrically conductive exterior structure; a door; a door lock; a species recognition device; and an electric shock deterrent. Methods of feeding animals utilizing an electric shock deterrent are also disclosed.

Abstract: Apparatus and methods for eliminating back drive in a push pull type control system, are provided. An exemplary apparatus includes a control rod including a pair of spaced apart piston displacement members each configured to carry a check valve. The apparatus also includes a pair of opposite-face check valves each configured to seal against respective opposing face of a piston head to form a hydraulic lock, preventing back drive in the control system.

Abstract: A rotor aircraft has an engine, a propeller, wings, and a rotor. An electric motor is coupled to the rotor drive shaft for applying torque to the rotor drive shaft. The electric motor is sized to supply all of the torque to pre-rotate the rotor to a selected speed prior to liftoff of the aircraft. The wings are capable of providing substantially all of the lift required during forward flight at a cruise speed. The rotor being is capable of being trimmed to provide substantially zero lift and auto-rotate at cruise speed. Sensors sense flight conditions of the aircraft and provide signals to a controller that selectively causes the electric motor to cease applying torque to the rotor drive shaft during autorotation at cruise speed. The controller also causes the electric motor to apply torque to the rotor drive shaft if the sensors indicate additional rotor speed is needed.

Abstract: Apparatus and methods for eliminating back drive in a push pull type control system, are provided. An exemplary apparatus includes a control rod including a pair of spaced apart piston displacement members each configured to carry a check valve. The apparatus also includes a pair of opposite-face check valves each configured to seal against respective opposing face of a piston head to form a hydraulic lock, preventing back drive in the control system.

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.

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.