Preliminary Test Results on a Compressed Multilayer Insulation System for a Liquid-Hydrogen-Fueled Rocket
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The development of economical travel to the moon in this decade and of interplanetary exploration in the next will depend in part on the successful storage of cryogens in space. In the vacuum of space, heat transfer to the cryogens from external heat sources is primarily by radiation; thus, radiation-type insulations are required. Presently available multilayer insulation materials are adequate for mo derate-duration space storage when used in a vacuum. The vacuum of space is ideal for multilayer insulation, but some means must be provided to maintain a vacuum in the insulation during ground-hold and boost through the atmosphere. Present multilayer insulation systems for ground storage use a heavy-walled vacuum jacket, which is impractical for flight use because of its large mass. Replacement of this outer wall with a lightweight and impermeable jacket lessens the weight penalty but introduces other problems. Evacuation of the flexible jacket with external pressure compresses the multilayer insulation, as shown in Fig. 1. This compression increases the apparent thermal conductivity. Small-scale tests have shown that the insulation nearly recovers its original thickness when the compressive load is removed. Protection of this flexible jacket against aerodynamic loads during boost through the atmosphere may require a shrouded tank structure.
KeywordsHeat Flux Compressive Load Test Tank Insulation System Heat Leak
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