Status: Design. Thrust: 289.10 kN (64,992 lbf). Unfuelled mass: 499 kg (1,100 lb). Specific impulse: 470 s.

The RL-60 was a new upper stage engine under development by Pratt and Whitney in collaboration with several international partners.. In 2001 it was reported that Pratt & Whitney had teamed with Volvo to develop the engine. With approximately the same dimensions as the RL-10, but over twice the thrust, the new engine could be used for many of the same applications. In 2003 it was reported that development reached a milestone with the arrival from Japan's Ishikawajima-Harima Heavy Industries of the first main liquid hydrogen turbopump. Sixty percent of the components of the 60,000lb thrust RL-60 were then said to be completed. The RL-60 development team is based in West Palm Beach, Florida

Engine: 499 kg (1,100 lb).