Annular convergent-divergent exhaust nozzle

Claim 1

AN ANNULAR CONVERGENT-DIVERGENT EXHAUST NOZZLE FOR AN AXIAL FLOW JET ENGINE INCLUDING: AN OUTER NACELLE; A GENERALY CYLINDRICAL SUPPORT STRUCTURE WITHIN SAID NACELLE; A GENERALLY CONICAL PLUG MEMBER MOUNTED CENTRALLY OF SAID SUPPORT STRUCTURE AND COOPERATING THEREWITH TO DEFINE THE NOZZLE THROAT AND FORM A CONVERGENT PORTION OF SAID NOZZLE; A CYLINDRICAL SHROUD MEMBER MOUNTED FOR RELATIVE AXIAL MOVEMENT ON SAID SUPPORT STRUCTURE AND DEFINING AN EXTERNAL BOUNDARY WALL FOR SAID NOZZLE IN COMBINATION WITH SAID NACELLE; A SINGLE SET OF FLAPS COMPRISING A PLURALITY OF AXIALLYEXTENDING MEMBERS PIVOTALLY MOUNTED INTERMEDIATE THE ENDS THEREOF ON THE DOWNSTREAM END OF SAID SHROUD MEMBER, EACH OF SAID FLAP MEMBERS HAVING FORWARDLY DIVERGENT EXTERIOR AND INTERIOR SURFACES, WHEREBY IN A FIRST POSITION SAID EXTERIOR SURFACES FORM A RELATIVELY LOW BOATTAIL ANGLE FOR SAID NOZZLE IN COMBINATION WITH A DOWNSTREAM POSITION OF SAID SUPPORT STRUCTURE AND IN A SECOND POSITION SAID EXTERIOR SURFACES FORM A GENERALLY CYLINDRICAL EXTENSION OF SAID SHROUD MEMBER AND SAID NACELLE FOR MINIMIZING AERODYNAMIC DRAG; AND MEANS TRANSLATING SAID SHROUD MEMBER AXIALLY TO LOCATE SAID SET OF FLAPS IN EITHER OF SAID FIRST AND SECOND POSITIONS.