Variable-area nozzle

Claim 1

A NOZZLE COMPRISING A HOLLOW FRUSTO-CONICAL MEMBER TERMINATING IN AN OPENING OF REDUCED CROSS-SECTION, THE INTERIOR SURFACE OF SAID FRUSTO-CONICAL MEMBER WHICH IS ADJACENT TO SAID OPENING BEING FORMED INTO A REGULAR PYRAMIDAL FRUSTUM OF N FLAT SURFACES WHERE N IS AN INTEGER GREATER THAN 2, A HOLLOW OPEN-ENDED REGULAR PYRAMIDAL FRUSTUM INSERT MEMBER OF N SIDES DEFINED BY RELATIVELY THIN FLAT LATERAL WALLS WHOSE LONGITUDINAL EDGES LIE IN ABUTTING CONTACT AND HAVING A TAPER ANGLE SUBSTANTIALLY EQUAL TO THAT OF SAID FIRST-MENTIONED FRUSTUM, THE OPEN MAJOR BASE OF SAID INSERT MEMBER HAVING A GREATER PERIMETER THAN SAID OPENING AND THE OPEN MINOR BASE OF SAID INSERT MEMBER HAVING A SMALLER PERIMETER THAN SAID OPENING AND AT LEAST TWO ADJACENT LONGITUDINAL EDGES OF SAID INSERT MEMBER BEING CONTINUOUSLY SLIT OVER AT LEAST A PORTION OF THEIR LENGTH INCLUDING THE MINOR BASE PORTION OF THE LATERAL WALL DEFINED BY SAID EDGES, SAID INSERT MEMBER BEING FITTED WITHIN SAID FRUST-CONICAL MEMBER AND PROTRUDING THROUGH THE OPENING THEREOF SO THAT THE MAJOR BASE PORTION OF EACH LATERAL WALL OF THE INSERT MEMBER IS IN UNIFORM AND CO-EXTENSIVE CONTACT WITH A CORRESPONDING FLAT SURFACE OF THE FRUSTO-CONICAL MEMBER, THE LATERAL WALL OF SAID INSERT MEMBER WHICH IS DEFINED BY SAID SLIT EDGES FORMING A RESILIENT CANTILIVER DEFLECTION MEMBER FREE TO DEFLECT OUTWARDLY FROM THE LONGITUDINAL AXIS OF SAID INSERT MEMBER AND INDEPENDENTLY OF THE OTHER LATERAL WALLS.