Rocket nozzle protection system

Claim 1

IN A ROCKET HAVING A LONGITUDINALLY EXTENDING CASING FORMED WITH A GENERALLY ANNULAR TRANSVERSE REAR END PORTION WHICH BOUNDS A CENTRAL PASSAGE, A MAIN SOLID PROPELLANT BODY HOUSED IN SAID CASING UPSTREAM OF SAID REAR END PORTION AND ADAPTED, WHEN IGNITED TO PRODUCE HIGH TEMPERATRE MAIN COMBUSTION GASES TO ISSUE THROUGH SAID CENTRAL PASSAGE, A JET PROPULSION NOZZLE FITTED TO SAID REAR END PORTION AND HAVING A BARE AND SMOOTH CONVERGENTDIVERGENT INNER SURFACE OF NON-COMBUSTIBLE MATERIAL TO LEAD AND EXPAND THE GASES ISSUING THROUGH SAID CENTRAL PASSAGE, THE IMPROVEMENT COMPRISING A TROUGH-SHAPED RECESSED SEATING FORMED IN SAID TRANSVERSE REAR END PORTION AROUND SAID CENTRAL PASSAGE AND UPSTREAM OF SAID BARE CONVERGENT-DIVERGENT SURFACE, SAID TROUGH-SHAPED SEATING BEING WIDE OPEN FORWARDLY TOWARD THE INTERIOR OF SAID CASING AND HAVING REARWARDLY A SUNKEN BOTTOM, AND AN AUXILIARY SOLID PROPELLANT BODY FITTED IN SAID SEATING AND FREELY EXPOSED IN THE PATH OF SAID MAIN COMBUSTION GASES FOR PRODUCING, WHEN IGNITED, AUXILIARY COMBUSTION GASES AT A TEMPERATURE LOWER THAN SAID HIGH TEMPERATURE MAIN GASES THEREBY GENERATING A PERIPHERAL LAYER OF LOWER TEMPERATURE GASES AROUND THE HIGH TEMPERATURE GASES TO FORM A PROTECTIVE GASEOUS SHEATH FLOWING ALONG AND IN CONTACT WITH SAID BARE CONVERGENT-DIVERGENT SURFACE.