A key requirement was that off-the-shelf technologies must be used, e.g. existing M-1, J-2 and RL-10 engines from the Saturn and Nova expendable launch vehicle programs.
Both stages were manned and employed lifting-body configurations. The (empty/gross) mass fraction was quite high (0.89 for the boooster,0.844 for the orbiter) and the designers attributed this to the thick-wing lifting body configuration which resulted in less weight due to lower stresses and thermal loads during reentry. After separating from the orbiter at an altitude of 82km, the booster would make an unpowered landing 830km from the launch site since it has no jet engines for atmospheric cruise. The flight rate assumptions were quite high: 240 flights per year for a fleet of 12 boosters & 24 orbiters with a turnaround time between missions of less than 18 days. A mobile launcher erector would eliminate the need for large gantries. The planned service life was 100 flights for the orbiter and 200 flights for the booster. The engines would have been capable of 50 firings between major overhaul (the airframes would last up to 300 flights). Development cost: $1.2 billion (1964 dollars -- $6.45B in FY 1999). Marginal cost per mission: $1.5M (=$41/lb at 1964 economic conditions; $485/kg in 1999).
Crew Size: 1.
Gross mass: 407,870 kg (899,190 lb).
Height: 49.00 m (160.00 ft).