NASA's Dual-Fuel Airbreathing Hypersonic Vehicle Study

A Mach 10 cruise vehicle provides a quick response, global reach capability with high survivability. For operations from CONUS, mission radii on the order of 8,000 nmi are sufficient. For missions which return to CONUS, a dual-fueled vehicle is superior, due to its capability to in-flight refuel. However, for one-way mission, an all-hydrogen vehicle is preferable because of its higher specific impulse.