Slide 6 of 100
The Douglas "Astro" was a VTHL TSTO system designed for launching space station crews and cargo by the 1968-70 period. 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 are manned and employ 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 results 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 gantrys. 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).
Liftoff Thrust: . Total Mass: 407,870kg. Total Length: 49m.
Payload capability: 16,851kg payload to 555km 28.5 degree orbit.
Stage Number 1: 1 x M-1 plus 2 x J-2. Gross Mass: 302,183kg. Empty Mass 32,558kg.
Thrust: . Isp: Length: 29m. Span: 18.6m. Propellants: LOX/LH2.
Stage Number 2: 2 x RL-10 plus 1 x J-2. Gross Mass: 89,290kg. Empty Mass 14,000kg.
Thrust: . Isp: Length: 20.7m. Span: 13.4m. Propellants: LOX/LH2.
”ASTRO Concept” -- Root & Fuller, Astronautics & Aeronautics 1964/January/p.42