Abstract: A primary load bearing structure particularly adapted for hypersonic aerospace vehicles utilizing a cryogenic liquid fuel, and comprised of a plurality of rigid load bearing, fluid passageways or tubes connected together in the form of a panel structure. Such panel structure and the passageways or the tubes thereof form the outside surface of the aerospace vehicle and are also positioned adjacent to or integral with a wall of the cryogenic liquid fuel tank. During flight, cryogenic liquid fuel is passed through the tubes to provide cooling for the external surface of the vehicle. When the aerospace vehicle is on the ground, the load bearing tubes can be evacuated to provide insulation for the cryogenic liquid fuel tank to thus prevent formation of frost and liquid air on the outside surface of the tank, as well as on the external surface of the aerospace vehicle and prevent heat transfer to the tank.