The RL60 (also called MB-60) is a rocket engine under development by Pratt and Whitney. The design is a high energy LH2/LOX expander cycle, capable of multiple restarts in space.
In 2003, Pratt & Whitney Rocketdyne had 90% of the work completed for the new RL-60 replacement of the RL-10. The RL60 cryogenic upper stage engine is designed to produce 60,000 pounds of thrust with a specific impulse of 465 seconds (4.56 km/s) to meet the evolving needs of expendable launch requirements or human-rated missions. The RL60 was to be built and tested domestically with key components to be provided by four international industry strategic suppliers; Volvo Aero of Sweden (Regen cooled nozzle), Ishikawajima-Harima Heavy Industries (IHI) of Japan (Fuel Turbopump), Techspace Aero of Belgium (Fuel Inlet and LOX control valve) and Chemical Automatics Design Bureau (CADB) of Russia (LOX Turbopump).