Patents Examined by Joesph W Sanderson
  • Patent number: 8066219
    Abstract: 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° with respect to its stacking line, and the blade has an overall twist from root to tip of at least 20°, 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.
    Type: Grant
    Filed: October 13, 2010
    Date of Patent: November 29, 2011
    Assignee: Karem Aircraft, Inc.
    Inventors: Dan Patt, Abe Karem