The RL10 is a liquid hydrogen-fueled engine, which operates successfully in space. The engine has various models. The engine's thrust is 20,800-24-750 lbs., weight is 370-646 lbs., and it is fueled by liquid hydrogen and liquid oxygen. The mixture ratio is five-to-one to six-to-one. The engine's specific impulse is 444.4-465.5 s.
Pratt & Whitney, 400 Main St., East Hartford, CT 06108. Phone: 860-565-4321.