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 rotorcraft includes a fuselage, a rotor assembly, a tail section connected to the fuselage, a propulsion system including an engine mounted to the fuselage, and a wing mounted to the fuselage. The rotor assembly includes a rotor having either a single or a plurality of rotor blades which can produce a resultant force vector which can pass through or near the center of gravity of the rotorcraft, and a spindle to connect the rotor with a flight control assembly. The rotor assembly also includes a tilting mast assembly having a tilting mast frame also connected to the spindle to support the rotor. The tilting mast tilts the rotor and provides cyclic control through a cyclic control linkage connected to the tilting mast frame. A mast control cylinder is provided to tilt the tilting mast assembly.

Abstract: A rotor for a rotary wing aircraft includes a blade having a leading edge, and a trailing edge. The rotor has a leading edge tip extension at a tip of the blade and a weight within the leading edge tip extension. The rotor also includes a trailing edge tip extension extending from a selected point at an outboard portion of the blade to the tip of the blade, a leading edge of the extension extending rearward from the trailing edge of the blade.

Abstract: A rotorcraft includes a fuselage, a rotor assembly, a tail section connected to the fuselage, a propulsion system including an engine mounted to the fuselage, and a wing mounted to the fuselage. The rotor assembly includes a rotor having either a single or a plurality of rotor blades which can produce a resultant force vector which can pass through or near the center of gravity of the rotorcraft, and a spindle to connect the rotor with a flight control assembly. The rotor assembly also includes a tilting mast assembly having a tilting mast frame also connected to the spindle to support the rotor. The tilting mast tilts the rotor and provides cyclic control through a cyclic control linkage connected to the tilting mast frame. A mast control cylinder is provided to tilt the tilting mast assembly.

Abstract: A rotor for a rotary wing aircraft includes a blade having a leading edge, and a trailing edge. The rotor has a leading edge tip extension at a tip of the blade and a weight within the leading edge tip extension. The rotor also includes a trailing edge tip extension extending from a selected point at an outboard portion of the blade to the tip of the blade, a leading edge of the extension extending rearward from the trailing edge of the blade.

Abstract: A variable pitch aircraft propeller control uses a two-speed planetary gearbox between a turbine engine and an adjustable pitch propeller. For maximum efficiency, the rotation rate of the propeller is high at aircraft take-off to generate maximum static thrust. However, when at high altitude and at high speed, the propeller rotation rate is reduced to hold the vector sum of the aircraft forward speed and the propeller rotational tip speed at the speed that results in the highest efficiency for the propeller. The two-speed transmission supplies these two gear ratios. At takeoff and low altitude flight, a low gear ratio is used. At high altitude, a high gear ratio is used. The gear ratio may be manually selected by the pilot, or automatically changed by the propeller controller to obtain the best combined efficiency for the engine and the propeller.

Abstract: A fixed wing rotorcraft uses differential thrust between wing mounted propellers to provide counter torque when the rotor is being powered by a power source. The rotorcraft is comprised of a fuselage to which fixed wings are attached. A rotor is attached on an upper side of the fuselage and provides lift at low speeds while the wings provide a majority of the lift at high speeds. When at high speeds the rotor may be slowed to reduce advancing tip speed and retreating blade stall. Forward thrust and counter torque is provided by propellers mounted on either side of the fuselage or even on the wings.

Abstract: An airfoil has a concave rear top surface, a concave rear bottom surface, and a rounded trailing edge to increase the lift-to-drag ratio of the airfoil at small angles of attack when air is flowing from the trailing edge to the leading edge (reverse flow), while maintaining a high lift-to-drag ratio when air is flowing from the leading edge to the trailing edge (forward flow). The airfoil design results from a performance compromise between forward and reverse airflow. For structural reasons, the thickness of the airfoil in proportion to its chord length may change along the blade radius. Thus, a family of airfoils has been designed that promote low-drag laminar flow with both forward and reverse flow, permit operation of the airfoil with reverse flow over a reasonable range of angles of attack, and achieve high lift with forward flow.

Abstract: A method of operating a rotor aircraft at high speeds applies negative collective pitch to the rotor. The rotor aircraft has a wing, a thrust source and a rotor. During horizontal flight, the pilot operates the thrust source to move the aircraft forward. This supplies lift due to air flowing over the wing. By controlling tilt of the rotor, and without supplying power to the rotor, the pilot causes the rotor to auto-rotate due to the forward movement of the aircraft. The speed of rotation of the rotor is controlled by the degree of tilt of the rotor relative to the direction of flight. Once the aircraft speed is sufficiently high to cause reverse flow of air over the entire retreating blade of the rotor, the pilot reduces the collective pitch of the rotor to less than zero to reduce the flapping as desired.

Abstract: A rotor for rotary wing aircraft includes a number of features that reduce the collective forces required to control the pitch of the rotor. The spar caps of the spar become joined to one another at the same point where bonding begins between the blade and the spar. The tendency of blade to want to flatten out is minimized since the centrifugal force acting on the spar is located at or near the pitch change axis. Tip weights are located at or near the pitch change axis as well. In a preferred embodiment, the tip weights are located evenly in front of and behind the structural center of the inboard section of the spar. The blade of the rotor and the tip are not swept back.

Abstract: An aircraft landing gear includes a sealed cylinder divided by a cylinder head to define an upper chamber and a lower chamber. The lower chamber is further divided by a piston having a piston rod passing in a sealed manner through the lower cylinder end. The cylinder head includes one or more orifices, the opening of each containing an electromagnetic coil configured to control the viscosity of the magneto-rheological oil passing therethrough. The electrical current through the electromagnetic coil is continually controlled by a microcomputer with attached sensors for piston position and pressure between the desired piston and the cylinder head, such that the pressure between the piston and the cylinder head decelerates the aircraft evenly throughout the desired piston stroke. The pressure also is limited to a desired maximum level so that, in a severe crash, the shock absorber will absorb significant energy before it fails structurally.