Pratt and Whitney LOx/LH2 rocket engine. Study 1988. Part of launch vehicle proposed by Martin as alternative to NLS. All figures estimated based on 1,000,000 lb thrust single engine.
Status: Study 1988. Thrust: 4,457.00 kN (1,001,973 lbf). Specific impulse: 425 s. Specific impulse sea level: 354 s. Burn time: 420 s.