Encyclopedia Astronautica
HOTOL



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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
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 It was superseded by the Interim HOTOL design which sought to reduce development cost through use of existing Lox/LH2 engines.

HOTOL development was begun in 1982 by a Rolls-Royce / British Aerospace team led by John Scott and Dr Bob Parkinson. The project was reasonably well advanced (engine detailed design and mockup) by the time the British government withdrew further funding in the mid-1980's. HOTOL would have taken off horizontally from a runway, from a purpose made, rocket propelled trolley. It would transition to pure rocket propulsion at Mach 5.0 - Mach 6.0 and ascend to orbit. A moderate re-entry profile would decrease the thermal loading constraints. HOTOL would return via a glide landing, to a landing on gear on a conventional runway.

The original HOTOL airframe design was derived from conventional vertical takeoff rockets with the engines mounted at the rear of a blunt based fuselage. Since such a vehicle's empty centre of gravity was dominated by the engine location, the wings and the tank for the dense liquid oxygen also had to be at the rear. The payload bay and hydrogen tankage were placed in a projecting forebody.

The resulting configuration suffered from a severe centre of pressure / centre of gravity mismatch during the air breathing ascent. The centre of pressure shifted 10 m forward, due to the wide Mach range, the large fuselage cross section to wing area ratio, and the long overhang of the forward fuselage. Various alterations were made to the design to handle these problems, all of which eroded the payload.

Conventional landing gear were replaced by a specially designed takeoff trolley in order to improve the marginal payload fraction. The final design had serious operational disadvantages and a small payload. The only way the designers could continue to claim to put a reasonable payload into orbit was by specifying untried and speculative structural materials.

in: 1985 dollars. Flyaway Unit Cost $: 10.000 million.

Stage Data - HOTOL

  • Stage 1. 1 x HOTOL. Gross Mass: 250,000 kg (550,000 lb). Empty Mass: 50,000 kg (110,000 lb). Thrust (vac): 1,103.200 kN (248,009 lbf). Isp: 700 sec. Burn time: 730 sec. Isp(sl): 2,000 sec. Diameter: 7.00 m (22.90 ft). Span: 28.30 m (92.80 ft). Length: 62.80 m (206.00 ft). Propellants: Liquid Air/Lox/LH2. No Engines: 3. Engine: RB545. Other designations: Horizontal Takeoff and Landing. Status: Study.

Status: Cancelled 1985.
Gross mass: 250,000 kg (550,000 lb).
Height: 75.00 m (246.00 ft).
Diameter: 7.00 m (22.90 ft).
Thrust: 3,152.20 kN (708,643 lbf).

More... - Chronology...


Associated Countries
Associated Engines
  • RB545 Rolls Royce air augmented rocket engine. 367.7 kN. Used Liquid Air/Lox/LH2. Development ended 1985. Isp=700s. Used on HOTOL launch vehicle. 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
Bibliography
  • "HOTOL-2", Aviation Week and Space Technology, 1991-09-09, page 68.
  • "Britain Urges ESA Members to Join HOTOL Development Project", Aviation Week and Space Technology, 1985-06-17, page 91.

Associated Stages
  • HOTOL Liquid Air/Lox/LH2 propellant rocket stage. Loaded/empty mass 250,000/50,000 kg. Thrust 1,103.20 kN. Vacuum specific impulse 700 seconds. More...

HOTOL Chronology


1982 - . LV Family: HOTOL. Launch Vehicle: HOTOL.
  • HOTOL development begun by a Rolls-Royce / British Aerospace team - . Nation: UK. The project was reasonably well advanced (engine detailed design and mockup) by the time the British government withdrew further funding in the mid-1980's. HOTOL would have taken off horizontally, transition to pure rocket propulsion at Mach 5.0 - Mach 6.0. and ascend to orbit. A moderate re-entry profile would decrease the thermal loading constraints. HOTOL would return via a glide landing, to a landing on gear on a conventional runway.

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