Patent ID: 6343127
Filing Date: 2002-01-29
Classification: G10K

Abstract:
An active control system for a propeller driven aircraft having a fuselage with an interior surface and an exterior surface with trim attached to said interior surface and forming an aircraft cabin therein, said propeller causing propeller wash to impinge on said exterior surface of said fuselage along a plane of action so as to generate a sound pressure level within said aircraft cabin, said system comprising:(a) means for deriving a reference signal indicative of the propeller wash impinging on said fuselage, said means for deriving said reference signal located adjacent said interior surface of said fuselage and substantially in said plane of action of said propeller wash; (b) speaker means for generating a canceling wave form for reducing a sound pressure level within said aircraft cabin, said speaker means housed within said aircraft cabin in a box-like enclosure, said enclosure being attached to an interior surface of said trim within said aircraft cabin and inverted within said enclosure such that said canceling wave form is initially primarily directed toward a surface of said trim and then exits into said aircraft cabin in a direction substantially parallel to said surface; (c) error sensor means located within said aircraft cabin for deriving an error signal indicative of said sound pressure level within said aircraft cabin; and (d) electronic controller means for receiving said reference signal and said error signal, said electronic controller means producing a control signal for driving said speaker means, said control signal being responsive to said error signal so as to drive said speaker to produce a canceling wave form which endeavors to reduce said sound pressure level within said aircraft cabin to a minimum.