Patent ID: 9701394
Date: 2017-07-11
CPC Classifications: B64C,Y02T

Claim:
1. An apparatus for minimizing noise generated by blades of an aircraft propeller where the noise has a target origin and an associated frequency with a corresponding wavelength, the apparatus comprising: a mechanism disposed on the blade that produces a sound having a first frequency that is substantially the same frequency as the associated frequency of the noise; an aperture defining an opening that is part of the mechanism; a hollow vessel that is part of the mechanism, the aperture connected to the hollow vessel having a first volume, the aperture disposed so that air flows over it and into the hollow vessel during the rotation of the blade; the area of the opening of the aperture and the first volume of the hollow vessel each contributing to controlling the first frequency of the sound; the aperture located a distance from the target origin of the noise that is substantially one half of the wavelength of the noise so that the sound arrives at the target origin of the noise substantially 180 degrees out of phase with the noise.