Encyclopedia Astronautica
SLS Stage A


Lox/LH2 propellant rocket stage. Loaded/empty mass 59,000/6,000 kg. Thrust 889.33 kN. Vacuum specific impulse 424 seconds. Smallest Lox/LH2 stage planned for SLS series. Empty mass estimated. Sized for rail transport within USA.

Status: Study 1961.
Gross mass: 59,000 kg (130,000 lb).
Unfuelled mass: 6,000 kg (13,200 lb).
Height: 15.00 m (49.00 ft).
Diameter: 4.28 m (14.04 ft).
Span: 4.28 m (14.04 ft).
Thrust: 889.33 kN (199,928 lbf).
Specific impulse: 424 s.
Burn time: 250 s.

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Associated Countries
Associated Engines
  • J-2 Rocketdyne lox/lh2 rocket engine. 1033.1 kN. Study 1961. Isp=421s. Used in Saturn IVB stage in Saturn IB and Saturn V, and Saturn II stage in Saturn V. Gas generator, pump-fed. First flight 1966. More...

Associated Launch Vehicles
  • SLS A-410 American orbital launch vehicle. The smallest identified member of the SLS family, selected to place the Air Force Lunex lunar lander re-entry vehicle in a low earth orbit for initial tests, was the A-410. This consisted of the 'A' Lox/LH2 stage supplemented by 100-inch diameter solid fuel booster rockets. More...
  • SLS AB-825 American orbital launch vehicle. The AB-825 represented a medium launch vehicle of the USAF 1961 Space Launching System family. The AB-825 would have conducted earth orbit tests of partially-fuelled Lunex lunar lander stages, and also have boosted the Lunex manned glider on circumlunar test flights. It consisted of the 'A' stage and 'B' stages with 180 inch diameter short-length solid fuel booster motors. More...
  • SLS A-388 American orbital launch vehicle. The A-388 was the version of the Space Launching System family proposed to fill the SLV-4 requirement - boost to orbit of the Dynasoar manned spaceplane. The booster was dubbed 'Phoenix' - perhaps a hope it could be rescued from the ashes of the manned space program having been turned over to NASA.... 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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