Thrust spoiling apparatus and method

Abstract

A streamline shroud surrounding a jet aircraft engine terminates forwardly of the aft end of the engine tail pipe, which comprises a secondary nozzle. Two or more deflector doors in stowed position combine to form a sleeve surrounding the aft portion of the tail pipe, and the trailing edges of these doors extend downstream and converge beyond the tail pipe to form a primary nozzle, which has an exit flow area smaller than that of the secondary nozzle, and of proper size and configuration to provide required mass flow, velocity and pressure for normal flight operation. The doors swing outwardly and rearwardly on linkage carried by the sponsons to a deployed position spaced aft of the tail pipe and disposed transversely to the tail pipe axis to deflect flow laterally and nullify thrust. The blocking action of the deployed doors produces a back pressure effect which tends to reduce mass flow, but since the secondary nozzle exit area is greater than that of the primary nozzle, which is removed upon deployment of the doors, this compensates for the back pressure effect and maintains the mass flow substantially uniform.