Slide 53 of 125
In 1979, Boeing and the US Air Force Rocket Propulsion Laboratory proposed a small unmanned
"Air-Launched Sortie Vehicle", ALSV consisting of a reusable spaceplane and a huge expendable
propellant tank. The vehicle could overfly any point on Earth within 90 minutes of the launch
order and also perform other military missions such as satellite inspection. It then returns to
a military airbase and lands horizontally like the Space Shuttle.
The ALSV stack would be carried piggy-back to an altitude of 11.3km by a modified Boeing 747
carrier aircraft, where it separates and fires its engines to head for Earth orbit. The tank
would be drained of fuel and jettisoned at 108.8km altitude. The concept would have required no
new technologies, although the Boeing 747 carrier aircraft would have required many
modifications including LOX,LH2 propellant tanks in the fuselage (the ALSV drop tank has little
insulation to save weight so the propellant must be transferred only shortly before launch) and
an SSME installed in the tail to allow a rapid 60 degree climb while carrying a fully fueled
ALSV. The vehicle would have been ready for a first launch in 1988, but USAF decided not to
pursue the project further due to its limited payload carrying capability.
Liftoff Thrust: 1381.725kN. Total Mass: 390,100kg. (Boeing 747+ALSV).
Payload capability: 1,590kg to 185km sunsynchronous orbit.
Payload bay size: 1.52 x 2.74m
Stage 1 : 9 x RL-10. Liftoff thrust: : 1381.725kN. Isp: Gross Mass: 124,738kg. Empty Mass: 9,070kg + 5,900kg drop tank. Length: 15.85m. Span: 9.14m. Drop tank length: 24.4m. Drop tank maximum diameter: 4.3m. Propellants: LOX/LH2.