Encyclopedia Astronautica
Thor DM-21


Lox/Kerosene propellant rocket stage. Loaded/empty mass 48,354/2,948 kg. Thrust 760.64 kN. Vacuum specific impulse 285 seconds.

Cost $ : 7.830 million.

Status: Retired 1969.
Gross mass: 48,354 kg (106,602 lb).
Unfuelled mass: 2,948 kg (6,499 lb).
Height: 18.41 m (60.40 ft).
Diameter: 2.44 m (8.00 ft).
Span: 2.44 m (8.00 ft).
Thrust: 760.64 kN (170,999 lbf).
Specific impulse: 285 s.
Specific impulse sea level: 250 s.
Burn time: 164 s.
Number: 106 .

More... - Chronology...


Associated Countries
Associated Engines
  • MB-3-1 Rocketdyne Lox/Kerosene rocket engine. 760.6 kN. Out of production. Designed for booster applications. Gas generator, pump-fed. Isp=285s. Boosted Delta A, B, C, Thor Able-Star. First flight 1960. More...

Associated Launch Vehicles
  • Thor Able-Star American orbital launch vehicle. As Thor Able but with enlarged Ablestar second stage with 2 1/2 x greater burn time. More...
  • Thor Agena B American orbital launch vehicle. Two stage vehicle consisting of 1 x Thor DM-21 + 1 x Agena B More...
  • Thor Ablestar 2 American orbital launch vehicle. Two stage vehicle consisting of 1 x Thor DSV-2A + 1 x Able-Star/AJ10-104D More...
  • Thor Agena D American orbital launch vehicle. Two stage vehicle consisting of 1 x Thor DM-21 + 1 x Agena D More...
  • Delta A American orbital launch vehicle. Three stage vehicle consisting of 1 x Thor DM-21 + 1 x AJ10-118 + 1 x Altair More...
  • Delta B American orbital launch vehicle. Three stage vehicle consisting of 1 x Thor DM-21 + 1 x AJ10-118A + 1 x Altair More...
  • Thor Delta C American orbital launch vehicle. Three stage vehicle consisting of 1 x Thor DSV-2A + 1 x Delta D + 1 x Altair 2 More...
  • Thor Delta C1 American orbital launch vehicle. Three stage vehicle consisting of 1 x Thor DSV-2A + 1 x Delta D + 1 x FW4D More...

Associated Propellants
  • Lox/Kerosene 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. In January 1953 Rocketdyne commenced the REAP program to develop a number of improvements to the engines being developed for the Navaho and Atlas missiles. Among these was development of a special grade of kerosene suitable for rocket engines. Prior to that any number of rocket propellants derived from petroleum had been used. Goddard had begun with gasoline, and there were experimental engines powered by kerosene, diesel oil, paint thinner, or jet fuel kerosene JP-4 or JP-5. The wide variance in physical properties among fuels of the same class led to the identification of narrow-range petroleum fractions, embodied in 1954 in the standard US kerosene rocket fuel RP-1, covered by Military Specification MIL-R-25576. In Russia, similar specifications were developed for kerosene under the specifications T-1 and RG-1. The Russians also developed a compound of unknown formulation in the 1980's known as 'Sintin', or synthetic kerosene. More...

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