Karem Aircraft, Inc.

Dan Patt

Abe Karem

William Martin Waide

An electric linear actuator is disposed to pitch a blade of a hingeless, swashplateless rotor in rotary motion. This actuator can be equipped with an electric motor advantageously made fault tolerant by winding the motor for at least 4, 5, 6, 8, or even 12 phases. Rotational motion of the electric motor is preferably converted to a translatory linear actuator output motion using a planetary roller screw coupling the rotation of the motor with pitch of the blade. The output link of the actuator can be advantageously coupled to the planetary roller screw using an internal spherical joint providing an isolated load path through the actuator. It is contemplated that a preferred rotorcraft having an electric blade pitch actuator might also be equipped with a controller that could provide the vehicle with individual blade control, in which the pitch of any rotor blade can be controlled independently of the others.

Swashplateless rotorcraft with fault tolerant linear electric actuator

A tiltrotor aircraft having a fixed wing and tilting rotors has a rotor blade with a shaped tip portion that provides improved hover performance. The shaped tip portion preferably has a terminal anhedral of at least 20&#xb0; with respect to its stacking line, and the blade has an overall twist from root to tip of at least 20&#xb0;, and a thickness ratio between 19% and 30% at a radial station of 10%. These features advantageously conspire to provide a hover figure of merit of at least 0.84 and a cruise propulsive efficiency of at least 0.85. A controller preferably limits the rotor speed in sustained airplane-mode forward flight cruise of at most 40% of a hover maximum rotor speed, and alternatively or additionally limits a rotor edgewise advance ratio to at most 0.20.

Anhedral tip blades for tiltrotor aircraft

An aircraft is equipped with hingeless rotors on tilting nacelles, and the tilt angles of the nacelles are controlled using either or both of an actuator and a mast moment generated by a hingeless rotor. An aircraft with two or more rotors on tilting nacelles can achieve control of yaw orientation by differential tilt of its nacelles or masts. Hingeless rotors can be manipulated to control a tilt angle of a mast by changing the rotor blade pitch to produce a mast moment. The rotor and nacelle tilt of a tiltrotor rotorcraft can be controlled and effected in order to manipulate the yaw orientation and flight mode of a rotorcraft such as a tiltrotor. The use of mast moment to control nacelle tilt angle can reduce tilt actuator loads and allows for the control of nacelle tilt even in the event of an actuator failure.

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Lake Forest, CA, United States of America

Dan Patt