Method and apparatus for suppressing the noise of jet-propelled aircraft

Claim 3

Apparatus as defined in claim 1 wherein said predetermined angle is between 3 to 6*.

Claim 4

In combination with an aircraft propelled by a jet engine, sound-suppressing apparatus comprising an elongate panel of hemicylindrical form mounted on said aircraft for movement between a first position wherein said panel is disposed in a stowed position relative to said aircraft and a second position wherein said panel is disposed in a deployed position relative to said aircraft and is situated at a predetermined angle which extends rearwardly and upwardly relative to the longitudinal axis of the thrust nozzle of said jet engine so as to intercept the expansion boundary of the jet stream issuing from said thrust nozzle from four to six nozzle diameters downstream of the aft end of the nozzle, and means on said aircraft for returning said panel to said first position after it has been moved to said second position thereof.

Claim 5

In combination with an aircraft propelled by a jet engine, sound-suppressing apparatus comprising an elongate panel of hemicylindrical form mounted on said aircraft for movement between a first position wherein said panel is disposed in a stowed position relative to said aircraft and a second position wherein said panel is disposed in a deployed position relative to said aircraft and is situated at a predetermined angle which extends rearwardly and upwardly relative to the longitudinal axis of the thrust nozzle of said jet engine so as to intercept the expansion boundary of the jet stream issuing from said thrust nozzle from four to six nozzle diameters downstream of the aft end of the nozzle, and means on said aircraft for returning said panel to said first position after it has been moved to said second position thereof.

Claim 6

Apparatus as defined in claim 3 including means on said aircraft for moving said panel from said first position to said second position thereof.

Claim 7

Apparatus as defined in claim 4 wherein said engine is enclosed in a nacelle and said panel conforms with the shape of the latter.

Claim 8

Apparatus as defined in claim 5 wherein said panel is slidably mounted on a pair of parallel rails which are attached to opposite sides of said nacelle and which extend longitudinally thereof.

Claim 9

In combination with an aircraft propelled by a jet engine, sound-suppressing apparatus comprising an elongate panel mounted on said aircraft for movement between a first position wherein said panel is disposed in a stowed position relative to said aircraft and a second position wherein said panel is disposed in a a deployed position relative to said aircraft and is situated at a predetermined angle relative to the longitudinal axis of the thrust nozzle of said jet engine so as to intercept the expansion boundary of the jet stream issuing from said thrust nozzle, means on said aircraft for returning said panel to said first position after it has been moved to said second position thereof, a nacelle enclosing said engine, said panel conforming to the shape of said nacelle, a plurality of vanes disposed in overlapped relation around the aft end of said nacelle and pivotally connected at their forward ends to the wall thereof, saiD vanes being rotatable between a first position wherein their forward and aft ends are substantially equidistant from the longitudinal axis of said nacelle and a second position wherein the aft ends thereof are swung outwardly relative to said nacelle to thereby control atmospheric air which flows through the gap between the nacelle and said panel when the latter is in said second position thereof.

Claim 10

In combination with an aircraft propelled by a jet engine, sound-suppressing apparatus comprising an elongate panel mounted on said aircraft for movement between a first position wherein said panel is disposed in a stowed position relative to said aircraft and a second position wherein said panel is disposed in a a deployed position relative to said aircraft and is situated at a predetermined angle relative to the longitudinal axis of the thrust nozzle of said jet engine so as to intercept the expansion boundary of the jet stream issuing from said thrust nozzle, means on said aircraft for returning said panel to said first position after it has been moved to said second position thereof, a nacelle enclosing said engine, said panel conforming to the shape of said nacelle, a plurality of vanes disposed in overlapped relation around the aft end of said nacelle and pivotally connected at their forward ends to the wall thereof, saiD vanes being rotatable between a first position wherein their forward and aft ends are substantially equidistant from the longitudinal axis of said nacelle and a second position wherein the aft ends thereof are swung outwardly relative to said nacelle to thereby control atmospheric air which flows through the gap between the nacelle and said panel when the latter is in said second position thereof.