Encyclopedia Astronautica
Atlas MA-5A


Lox/Kerosene propellant rocket stage. Loaded/empty mass 4,187/4,187 kg. Thrust 2,093.70 kN. Vacuum specific impulse 299 seconds.

No Engines: 2.

Status: Out of production.
Gross mass: 4,187 kg (9,230 lb).
Unfuelled mass: 4,187 kg (9,230 lb).
Diameter: 4.90 m (16.00 ft).
Span: 4.90 m (16.00 ft).
Thrust: 2,093.70 kN (470,682 lbf).
Specific impulse: 299 s.
Specific impulse sea level: 263 s.
Burn time: 172 s.
Number: 49 .

More... - Chronology...


Associated Countries
Associated Engines
  • RS-56-OBA Rocketdyne Lox/Kerosene rocket engine. 1046.8 kN. Out of production. Designed for booster applications. Gas generator, pump-fed. Isp=299s. Booster engine for Atlas II, IIA, IIAS. First flight 1991. More...

Associated Launch Vehicles
  • Atlas II American orbital launch vehicle. The Atlas II booster was 2.7-meters longer than an Atlas I and included uprated Rocketdyne MA-5A engines. The Atlas I vernier engines were replaced with a hydrazine roll control system. The Centaur stage was stretched 0.9-meters compared to the Centaur I stage. Fixed foam insulation replaced Atlas I's jettisonable insulation panels. The original Atlas II model was developed to support the United States Air Force Medium Launch Vehicle II program. Its Centaur used RL10A-3-3A engines operating at an increased mixture ratio. The first Atlas II flew on 7 December 1991, successfully delivering AC-102/Eutelsat II F3 to orbit. More...
  • Atlas IIA American orbital launch vehicle. Atlas IIA was a commercial derivative of the Atlas II developed for the US Air Force. Higher performance RL10A-4 (or RL10A-4-1) engines replaced Atlas II's RL10A-3-3A engines. 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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