Convex thermal shield for rocket engine with extendable divergent nozzle
A rocket engine with an extendible exit cone including an exhaust nozzle for gas from a combustion chamber, the nozzle presenting a longitudinal axis having a first portion defining a nozzle throat and a stationary first exit cone segment, at least one extendible second exit cone segment of section greater than the section of the stationary first exit cone segment, and an extension mechanism for extending the extendible second exit cone segment, the mechanism being located outside the first and second exit cone segments. A rigid thermal protection shield is interposed between the extension mechanism and the stationary first exit cone segment. The thermal protection shield presents a convex wall on its face facing towards the stationary first exit cone segment.
1. A rocket engine with an extendible exit cone, comprising:
an exhaust nozzle for gas from a combustion chamber, the nozzle presenting a longitudinal axis and including a first portion defining a nozzle throat and a stationary first exit cone segment, at least one extendible second exit cone segment of section greater than the section of the stationary first exit cone segment, and an extension mechanism for extending the extendible second exit cone segment, the mechanism being located outside the first and second exit cone segments; and
a rigid thermal protection shield interposed between the extension mechanism and the stationary first exit cone segment,
wherein the thermal protection shield presents a convex wall on its face facing towards the stationary first exit cone segment,
wherein the thermal protection shield further comprises side fins on either side of the convex wall, and
wherein said rocket engine further comprises a flexible thermal protection strip arranged between the rigid thermal protection shield and the extension mechanism.
2. A rocket engine according to claim 1 , wherein the flexible thermal protection strip extends over a full height of the stationary first exit cone segment while the rigid thermal protection shield extends over only a lower portion of the stationary first exit cone segment.
3. A rocket engine according to claim 1 , wherein the rigid thermal protection shield is made of a refractory metal material.
4. A rocket engine according to claim 3 , wherein the rigid thermal protection shield is made of a tungsten alloy, of a molybdenum alloy, or of a tungsten and molybdenum alloy.
5. A rocket engine according to claim 1 , wherein the flexible thermal protection strip is made of an alumina fiber and borosilicate fabric.
6. A rocket engine according to claim 2 , wherein the flexible thermal protection strip is made of an alumina fiber and borosilicate fabric.
7. A rocket engine according to claim 1 , wherein the extension mechanism comprises a wormscrew secured to the stationary first exit cone segment and a ball nut engaged on the wormscrew and secured to the upper portion of the movable second exit cone segment.
8. A rocket engine according to claim 7 , wherein the ball nut is connected to the upper portion of the movable second exit cone segment by a fin-shaped part.
9. A rocket engine according to claim 1 , wherein the side fins of the thermal protection shield are connected to tabs that are secured to a fastener strip on the downstream portion of the stationary first exit cone segment.