Encyclopedia Astronautica
Interim HOTOL



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Hotol 2
Hotol 2 is launched from the back of an Antonov 225
Credit: British Aerospace
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Buran Atop Mriya
Buran atop its An-225 Mriya carrier, as displayed at the Paris Air show shortly after its spaceflight.
Credit: © Mark Wade
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Interim HOTOL
68-H version of Interim HOTOL atop the An-225 launching aircraft. Diagram produced by Fastlight. Used with permission.
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Interim HOTOL Test S
Test empennage used to test effects of rocket exhaust from RD-0120 engine for Interim HOTOL, NIIKhimMash, March 1992.
Credit: © Dietrich Haeseler
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.

Launch Price $: 110.000 million in 1985 dollars.

Stage Data - Interim HOTOL

  • Stage 0. 1 x An-225. Gross Mass: 600,000 kg (1,320,000 lb). Empty Mass: 216,000 kg (476,000 lb). Thrust (vac): 1,387.072 kN (311,826 lbf). Isp: 9,000 sec. Burn time: 3,375 sec. Isp(sl): 8,000 sec. Diameter: 18.07 m (59.28 ft). Span: 88.40 m (290.00 ft). Length: 84.00 m (275.00 ft). Propellants: Air/Kerosene. No Engines: 6. Engine: D-18T. Status: Out of Production. Comments: Antonov cargo aircraft swept wing. Release conditions: Piggy-back, 275,000 kg, 38.0 m length x 24.0 m wingspan, 900 kph at 9,500 m altitude. Effective velocity gain compared to vertical launch 270 m/s.
  • Stage 1. 1 x Interim HOTOL. Gross Mass: 250,000 kg (550,000 lb). Empty Mass: 33,100 kg (72,900 lb). Thrust (vac): 7,840.000 kN (1,762,500 lbf). Isp: 455 sec. Burn time: 122 sec. Isp(sl): 352 sec. Diameter: 10.00 m (32.00 ft). Span: 21.60 m (70.80 ft). Length: 36.45 m (119.58 ft). Propellants: Lox/LH2. No Engines: 4. Engine: RD-0120. Other designations: Interim HOTOL. Status: Study 1990.

Status: Study 1990.
Gross mass: 250,000 kg (550,000 lb).
Height: 44.00 m (144.00 ft).
Diameter: 10.00 m (32.00 ft).
Thrust: 7,800.00 kN (1,753,500 lbf).

More... - Chronology...


Associated Countries
Associated Engines
  • D-18T Lotarev turbofan engine. 229.4 kN. Used on An-225 launch aircraft for Interim HOTOL, MAKS concepts. Development ended 1988. Isp=9000s. More...
  • 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...

See also
  • HOTOL This single-stage-to-orbit winged horizontal takeoff/horizontal landing launch vehicle concept was powered by the unique Rolls-Royce RB545 air / liquid hydrogen / liquid oxygen rocket engine. HOTOL development was conducted from 1982 to 1986 before the British government withdrew funding. It was superseded by the Interim HOTOL design which sought to reduce development cost through use of existing Lox/LH2 engines. More...
  • Winged In the beginning, nobody (except Jules Verne) thought anybody would be travelling to space and back in ballistic cannon balls. The only proper way for a space voyager to return to earth was at the controls of a real winged airplane. More...

Associated Manufacturers and Agencies
Associated Stages
  • An-225 Subsonic rocket carrier. Loaded/empty mass 600,000/216,000 kg. Thrust 1,387.07 kN. Specific impulse 9000 seconds. Antonov cargo aircraft swept wing. Release conditions: Piggy-back, 275,000 kg, 38.0 m length x 24.0 m wingspan, 900 kph at 9,500 m altitude. Effective velocity gain compared to vertical launch 270 m/s. More...
  • 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. More...

Interim HOTOL Chronology


1991 - . LV Family: HOTOL. Launch Vehicle: Interim HOTOL.
  • Interim HOTOL designed by British Aerospace - . Nation: UK. Summary: 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 aircraft..

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