Multiple-propellant air vehicle and propulsion system

Abstract

An aircraft having a propulsion system which utilizes a dual fuel system having an inner tank for containing a cryogenic fuel and an outer tank surrounding the inner tank for containing a second fuel wherein the second fuel is a fuel having a low freezing point and a high boiling point which acts as an insulator for the cryogenic fuel in the inner tank. Both the inner tank and the outer tank are non-vacuum type tanks, and by surrounding the inner tank containing for example, liquid hydrogen, with pre-cooled liquid and/or gaseous hydrocarbon in the outer tank, excessive boil-off of the liquid hydrogen is prevented at high altitudes. By using this propulsion system and method, the outer wall of the outer tank is the skin of the aircraft, and the shape of the outer wall of the outer tank conforms to the aerodynamic shape of the aircraft.

Dependencies are inferred from the claim text.