Encyclopedia Astronautica
Ares I-2


Lox/LH2 propellant rocket stage. Loaded/empty mass 158,500/20,500 kg. Thrust 1,304.00 kN. Vacuum specific impulse 448 seconds. Second stage figures as of summer 2008. Dry mass includes 2500 kg for avionics bay.

Status: In development.
Gross mass: 158,500 kg (349,400 lb).
Unfuelled mass: 20,500 kg (45,100 lb).
Height: 25.60 m (83.90 ft).
Diameter: 5.50 m (18.00 ft).
Span: 5.50 m (18.00 ft).
Thrust: 1,304.00 kN (293,150 lbf).
Specific impulse: 448 s.
Burn time: 450 s.

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Associated Countries
Associated Engines
  • J-2X Rocketdyne lox/lh2 rocket engine. 1310 kN. Ares I launch vehicle second stage. In development 2006-2016. Isp=448s. Began as an update to the J-2 engine of the 1960s, but final design was all-new, 20% more thrust, but double the weight. 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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