An autogyro includes a frame and a rotor hub coupled to the frame. The autogyro also includes a connector coupled to the rotor hub and configured to couple the rotor hub to a ground-based pre-rotator device to rotate the rotor hub during a vertical take-off operation. The autogyro further includes a plurality of rotor blades coupled to the rotor hub, each rotor blade configured such that rotation of the rotor hub, during the vertical take-off operation, results in twisting the rotor blade from a first blade pitch distribution to a second blade pitch distribution.

A method of modifying a rotor blade is provided for a rotor blade including a spar having an inboard portion with a substantially constant overall height, the inboard portion further including a top layer having a substantially constant first thickness and a bottom layer having a substantially constant second thickness. The method includes removing a root portion of the inboard portion to thereby modify the rotor blade and installing a cuff configured to couple to the rotor blade to an aircraft.

This invention is directed toward a propeller with one of more propeller blades. The propeller blades have some combination of a sharpened leading edge, one or more steps on the upper or lower surface of the propeller blade, and an S shape. The combination of these radical changes from traditional propeller design creates a quieter, more efficient propeller that has applications on any device that uses propellers: from quadcopters and airplanes to boats and fans. Propellers with one, two, three, four, five and more propeller blades are contemplated depending upon the substance the propeller is intended for use in.

An autogyro includes a frame and a rotor hub coupled to the frame. The autogyro also includes a connector coupled to the rotor hub and configured to couple the rotor hub to a ground-based pre-rotator device to rotate the rotor hub during a vertical take-off operation. The autogyro further includes a plurality of rotor blades coupled to the rotor hub, each rotor blade configured such that rotation of the rotor hub, during the vertical take-off operation, results in twisting the rotor blade from a first blade pitch distribution to a second blade pitch distribution.

A rotorcraft may include an airframe and a rotor connected to the airframe. The rotor may include a hub and a rotor blade connected to the hub to extend radially away therefrom. The rotor blade may include biasing fibers, oriented to increase the twist of the rotor blade in response to an increase in the speed of rotation of the rotor corresponding to a mission, task, or maneuver.

A rotor blade configured to be installed on a rotary wing aircraft includes a spar including an inboard portion extending from a root of the rotor blade to a first spanwise position of the rotor blade and an outboard portion meeting the inboard portion at the first spanwise position. The rotor blade further includes an upper skin and a lower skin coupled the outboard portion of the spar. The first spanwise position is defined by a most inboard point at which the upper and lower skins are coupled to the spar. The inboard portion includes a top layer, a bottom layer, and an inner cavity. The top layer has a substantially constant first thickness and the bottom layer has a substantially constant second thickness, and the distance between an outer surface of the top layer and an outer surface of the bottom layer is substantially constant.