Vacuum insulated warhead
A vacuum insulation layer is wrapped around the length of a warhead to thermally insulate the warhead from fire or aerodynamic heating. The vacuum insulation layer may be integrally formed into the warhead casing or provided as a sleeve that may be permanently or removably positioned about the warhead casing. The vacuum insulation layer is held under vacuum with a pressure of less than 25 Torr and a thermal conductivity Tcond_vac of less than one-third of the thermal conductivity of air Tcond_air.
1. A warhead, comprising:
an explosive material positioned inside a warhead casing; and
a vacuum insulated casing including inner and outer walls defining an annular void space around a length of the warhead casing and explosive material, wherein the annular void space is held under vacuum with a pressure of less than 25 Torr and a thermal conductivity Tcond_vac of less than one-third of the thermal conductivity of air Tcond_air to form a vacuum insulation layer around the length of the warhead casing and explosive material.
2. The warhead of claim 1 , wherein the pressure in the void space is a medium vacuum between 25 Torr and 10 −3 Torr.
3. The warhead of claim 1 , wherein the pressure in the void space is a high vacuum between 10 −3 Torr and 10 −6 Torr.
4. The warhead of claim 1 , wherein Tcond_vac is less than one-fifth Tcond_air.
5. The warhead of claim 1 , wherein Tcond_vac is approximately 1/6.6 that of Tcond_air.
6. The warhead of claim 1 , wherein the warhead casing is formed of a metal material and the inner and outer walls are integrally formed with the warhead casing.
7. The warhead of claim 1 , wherein the inner and outer walls are formed as a sleeve that fits over the warhead casing.
8. The warhead of claim 7 , wherein the warhead casing wall is formed of a composite material.
9. The warhead of claim 7 , wherein the sleeve is permanently affixed to the warhead casing.
10. The warhead of claim 7 , wherein the sleeve is removable.
11. The warhead of claim 1 , wherein the warhead casing is formed of a metal material that forms a fragmentation layer, which upon detonation of the explosive material fragments with the outer wall to form a fragmentation pattern.
12. A warhead, comprising:
an explosive material; and
an integrally formed vacuum insulated metal warhead casing including an inner wall around a length of the explosive that forms a fragmentation layer and an outer wall that defines an annular void space, wherein the annular void space is held under vacuum with a pressure of less than 25 Torr and a thermal conductivity Tcond_vac of less than one-third of the thermal conductivity of air Tcond_air to form a vacuum insulation layer around the length of the warhead casing and explosive material.
13. The warhead of claim 12 , wherein the pressure in the void space is a medium vacuum between 25 Torr and 10 −3 Torr.
14. The warhead of claim 12 , wherein the pressure in the void space is a high vacuum between 10 −3 Torr and 10 −6 Torr.
15. The warhead of claim 12 , wherein Tcond_vac is less than one-fifth Tcond_air.
16. The warhead of claim 12 , wherein upon detonation of the explosive material the fragmentation layer and outer wall fragment to form a fragmentation pattern.
17. A warhead, comprising:
an explosive material positioned inside a warhead casing; and
a sleeve including inner and outer walls defining an annular void space that slides around the warhead casing and explosive material, wherein the annular void space is held under vacuum with a pressure of less than 25 Torr and a thermal conductivity Tcond_vac of less than one-third of the thermal conductivity of air Tcond_air to form a vacuum insulation layer around a length of the warhead casing and explosive material.
18. The warhead of claim 17 , wherein the warhead casing wall is formed of a composite material.
19. The warhead of claim 17 , wherein the sleeve is permanently affixed to the warhead casing.
20. The warhead of claim 17 , wherein the sleeve is removable.