Patents by Inventor Lakshmi N. Sankar

Lakshmi N. Sankar has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Blade vortex interaction noise reduction techniques for a rotorcraft
    Patent number: 5711651
    Abstract: An active control device for reducing blade-vortex interactions (BVI) noise generated by a rotorcraft, such as a helicopter, comprises a trailing edge flap located near the tip of each of the rotorcraft's rotor blades. The flap may be actuated in any conventional way, and is scheduled to be actuated to a deflected position during rotation of the rotor blade through predetermined regions of the rotor azimuth, and is further scheduled to be actuated to a retracted position through the remaining regions of the rotor azimuth. Through the careful azimuth-dependent deployment and retraction of the flap over the rotor disk, blade tip vortices which are the primary source for BVI noise are (a) made weaker and (b) pushed farther away from the rotor disk (that is, larger blade-vortex separation distances are achieved).
    Type: Grant
    Filed: June 13, 1996
    Date of Patent: January 27, 1998
    Assignee: McDonnell Douglas Helicopter Company
    Inventors: Bruce D. Charles, Ahmed A. Hassan, Hormoz Tadghighi, Ram D. JanakiRam, Lakshmi N. Sankar
  • Blade vortex interaction noise reduction techniques for a rotorcraft
    Patent number: 5588800
    Abstract: An active control device for reducing blade-vortex interactions (BVI) noise generated by a rotorcraft, such as a helicopter, comprises a trailing edge flap located near the tip of each of the rotorcraft's rotor blades. The flap may be actuated in any conventional way, and is scheduled to be actuated to a deflected position during rotation of the rotor blade through predetermined regions of the rotor azimuth, and is further scheduled to be actuated to a retracted position through the remaining regions of the rotor azimuth. Through the careful azimuth-dependent deployment and retraction of the flap over the rotor disk, blade tip vortices which are the primary source for BVI noise are (a) made weaker and (b) pushed farther away from the rotor disk (that is, larger blade-vortex separation distances are achieved).
    Type: Grant
    Filed: May 31, 1994
    Date of Patent: December 31, 1996
    Assignee: McDonnell Douglas Helicopter Co.
    Inventors: Bruce D. Charles, Ahmed A. Hassan, Hormoz Tadghighi, Ram D. JanakiRam, Lakshmi N. Sankar