Encyclopedia Astronautica
Centaur IIA


Lox/LH2 propellant rocket stage. Loaded/empty mass 19,073/2,293 kg. Thrust 185.01 kN. Vacuum specific impulse 449 seconds.

Cost $ : 30.000 million. No Engines: 2.

Status: Out of production.
Gross mass: 19,073 kg (42,048 lb).
Unfuelled mass: 2,293 kg (5,055 lb).
Height: 10.10 m (33.10 ft).
Diameter: 3.05 m (10.00 ft).
Span: 3.05 m (10.00 ft).
Thrust: 185.01 kN (41,592 lbf).
Specific impulse: 449 s.
Burn time: 392 s.
Number: 56 .

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Associated Countries
Associated Engines
  • RL-10A-4 Pratt and Whitney lox/lh2 rocket engine. 92.5 kN. Out of production. Isp=449s. Centaur stage for Atlas IIA, Atlas IIAS. First flight 1992. More...

Associated Launch Vehicles
  • 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...
  • Atlas IIAS American orbital launch vehicle. The Atlas II booster was 2.7-meters longer than the 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. Higher performance RL10A-4 or RL10A-4-1 engines replaced Atlas II's RL10A-3-3A. The Atlas IIAS model added four Thiokol Castor IVA solid rocket boosters (SRBs) to the core Atlas stage to augment thrust for the first two minutes of flight. 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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