SELF-EVACUATED MULTILAYER INSULATION OF LIGHTWEIGHT PREFABRICATED PANELS FOR CRYOGENIC SPACE PROPULSION VEHICLES

or by sealing the insulation with an air-tight barrier.• "A new concept for simplifying the application of radiation shield insulation to propellant tanks A number of multilayer insulation systems have has been developed and tested for both ground and been and are being investigated for hydrogen fueled space performance.Vacuum-tight flexible casing space propulsion vehicles(_ to 4).The primary material of laminated aluminized Mylar encloses the differences between the various investigations are multilayers forming panels that are bonded to tank the methods used to exclude air from the insulation walls in an overlapping shingle arrangement.The during ground-hold and methods used to attach the panels, weighing only 0.34 lb/sq ft, are filled multilayers to the propellant tank walls.Basic with CO2 gas which cryopumps to provide required characteristics of multilayer insulation have also vacuum when the tank is filled with a cryogen, been investigated(5) * to determine the fuudamental Thermal performance of insulation was determined in properties of these insulations and to improve flat plate and cylindrical calorimeters.Of the their thermal performance.Purging the _ultilayers many materials tested in flat plate calorimeter, with a noncondensible gas such as helium(1,2)to expolyurethane foam was chosen for separators between clude air results in high heat transfer through the radiation shields because of their small increase insulation during ground-hold because of the high in heat flux when compressed to 14.7 psi in panels thermal conductivity of the gas.The purged sysevacuated in the atmosphere.During ground-hold tem also poses a venting problem during the extertests, insulation panels as large as 3-by 6-ft nal pressure decay from ground to space during mounted on a cylindrical calorimeter of liquid hy-launch and prolongs the achievement of the required drogen, cryopumped down to at least 5×10-3 torr and vacutunfor long term storage in space because of resulted in a heat flux of 23 Btu/(hr)(sq ft) for the slow escape of helium from within the insulaan external temperature of 70° F. In simulated tion.By sealing the multilayers with an air-tight space tests, panels evacuated by outside vacuum re-barrier, a vacuum can be established within the insulted in a heat flux of 0.86 Btu/(hr)(sq ft) with sulation which lowers the heat transfer by gaseous outsldesurfaces at 70° F.conduction.Mechanically pumped static-type vacuum systems require impermeable vacuum casing materials