Encyclopedia Astronautica

ROOST - Reusable One-stage Orbital Space Truck
Credit: © Mark Wade
American SSTO VTOVL orbital launch vehicle. Bono's earliest design for an expendable single-stage-to-orbit LH2/Lox booster. The baseline version used conventional engines.

Douglas Aircraft Co. engineer Phil Bono did much to promote the concept of reusable ballistic space vehicles during the 1960s. Bono and his team at Douglas Aircraft examined fifteen different Nova concepts during 1962-64, including two nuclear powered vehicles. Safety considerations would however rule out the possibility of using nuclear power on vertical takeoff-&-landing SSTOs such as the RITA concept. HTHL SSTOs were also rejected as impractically large since they require a very large wing area to keep wing loading within acceptable limits; the total area will be bigger than is needed to store the liquid hydrogen fuel. Smaller wings, on the other hand, would produce prohibitive landing velocities. Consequently, the only realistic SSTO launch and landing configuration appeared to be VTVL.

Among the reusable chemical rocket concepts, winged two-stage vehicles such as ASTRO would have to be impractically large for heavy-lift missions. The preferred reusable concept was ROOST (Recoverable One Stage Orbital Space Truck, left), which would have used an inflatable blunt-body drag cone for recovery at sea. ROOST would have impacted the water at 33.5 meters per second so the refurbishment cost would have been high. An alternative "buoyant" ROOST would have incorporated a buoyancy torus and ballute/balloon inflated by warm residual hydrogen to reduce the landing speed, but the additional mass of the recovery system naturally increased the gross liftoff weight too. Another possibility was that the vehicle could be recovered in air by a helicopter and towed, under aerostatic lift, to a refurbishment site. ROOST would have cost $16/lb (7-8 reuses) vs. $250/lb for the Saturn V at 1962 rates. The equivalent costs in 1999 dollars would be $195/kg for ROOST and $3,040/kg for the Saturn V.

Bono concluded that high pressure LOX/LH2 engines and a 7-1 oxygen/hydrogen mixture ratio would reduce the size & weight of the vehicles. Disposable tanks & parallel staging were initially rejected since complex cross-plumbing would be required, but Douglas would rather return to the drop tank concept in order to achieve greater weight margins for its future SSTO designs.

LEO Payload: 454,500 kg (1,002,000 lb) to a 325 km orbit.

Stage Data - OOST

  • Stage 1. 1 x OOST. Gross Mass: 7,982,000 kg (17,597,000 lb). Empty Mass: 431,000 kg (950,000 lb). Thrust (vac): 123,191.000 kN (27,694,438 lbf). Isp: 410 sec. Burn time: 242 sec. Isp(sl): 345 sec. Diameter: 21.30 m (69.80 ft). Span: 21.30 m (69.80 ft). Length: 85.40 m (280.10 ft). Propellants: Lox/LH2. No Engines: 4. Engine: 5 mlbf. Status: Study 1963.

AKA: One stage Orbital Space Truck.
Status: Study 1963.
Gross mass: 8,527,400 kg (18,799,600 lb).
Payload: 454,500 kg (1,002,000 lb).
Height: 102.00 m (334.00 ft).
Diameter: 21.30 m (69.80 ft).
Thrust: 103,660.80 kN (23,303,875 lbf).
Apogee: 325 km (201 mi).

More... - Chronology...

Associated Countries
Associated Engines
  • 5 mlbf Notional lox/lh2 rocket engine. 41,361 kN. OOST, ROOST studies 1963. Isp=410s. First flight 1977. More...

See also
  • OOST Bono's earliest design for an expendable single-stage-to-orbit LH2/Lox booster. The baseline version used conventional engines. More...
  • SSTO Category of launch vehicles. Single Stage To Orbit. More...
  • VTOVL The concept of a reusable single-stage-to-orbit Vertical Take-Off Vertical Landing (VTOVL) launch vehicle that would reenter and return to its launch site for turnaround and relaunch was first proposed by Philip Bono in the 1960's. The appealing simplicity of the concept has been offset by the technological risk in developing it. The problem with any single-stage-to-orbit concept is that if the empty weight of the final vehicle has been underestimated it will not be able to deliver any payload to orbit, or even reach orbit. Since weight growth of up to 20% is not unknown in aerospace projects, this is a very real threat which has made both NASA and private investors reluctant to invest the billions of dollars it would take to develop a full-scale flight vehicle. More...

Associated Manufacturers and Agencies
  • Douglas American manufacturer of rockets, spacecraft, and rocket engines. Boeing Huntington Beach, Huntington Beach, CA, USA. More...

  • Bono, Philip, "Design Objectives for Tomorow's Big Boosters", Advanced in the Astronautical Sciences, 1963.

Associated Stages
  • OOST Lox/LH2 propellant rocket stage. Loaded/empty mass 7,982,000/431,000 kg. Thrust 123,191.00 kN. Vacuum specific impulse 410 seconds. More...

Home - Browse - Contact
© / Conditions for Use