Encyclopedia Astronautica
Interim HOTOL


Lox/LH2 propellant rocket stage. Loaded/empty mass 250,000/33,100 kg. Thrust 7,840.00 kN. Vacuum specific impulse 455 seconds.

Cost $ : 10.000 million. No Engines: 4.

Status: Study 1990.
Gross mass: 250,000 kg (550,000 lb).
Unfuelled mass: 33,100 kg (72,900 lb).
Height: 36.45 m (119.58 ft).
Diameter: 10.00 m (32.00 ft).
Span: 21.60 m (70.80 ft).
Thrust: 7,840.00 kN (1,762,500 lbf).
Specific impulse: 455 s.
Specific impulse sea level: 352 s.
Burn time: 122 s.
Number: 1 .

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Associated Countries
Associated Engines
  • RD-0120 Kosberg lox/lh2 rocket engine. 1961 kN. Energia core stage. Design 1987. Isp=455s. First operational Russian cryogenic engine system, built to the same overall performance specifications as America's SSME, but using superior Russian technology. More...

Associated Launch Vehicles
  • Interim HOTOL Initiated by a British Aerospace team led by Dr Bob Parkinson in 1991, this was a less ambitious, scaled-back version of the original HOTOL. The single-stage to orbit winged launch vehicle using four Russian rocket engines. It was to have been air-launched from a Ukrainian An-225 Mriya (Dream) aircraft. Interim HOTOL would separate from the carrier aircraft at subsonic speeds, and would then pull up for the ascent to orbit. It would return via a gliding re-entry and landing on gear on a conventional runway. Interim HOTOL suffered from the same aerodynamic design challenges as HOTOL and went through many, many design iterations in the quest for a practical design. More...

Associated Propellants
  • Lox/LH2 Liquid oxygen was the earliest, cheapest, safest, and eventually the preferred oxidiser for large space launchers. Its main drawback is that it is moderately cryogenic, and therefore not suitable for military uses where storage of the fuelled missile and quick launch are required. Liquid hydrogen was identified by all the leading rocket visionaries as the theoretically ideal rocket fuel. It had big drawbacks, however - it was highly cryogenic, and it had a very low density, making for large tanks. The United States mastered hydrogen technology for the highly classified Lockheed CL-400 Suntan reconnaissance aircraft in the mid-1950's. The technology was transferred to the Centaur rocket stage program, and by the mid-1960's the United States was flying the Centaur and Saturn upper stages using the fuel. It was adopted for the core of the space shuttle, and Centaur stages still fly today. More...

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