Encyclopedia Astronautica
Delta 4 - 2


Lox/LH2 propellant rocket stage. Loaded/empty mass 24,170/2,850 kg. Thrust 110.05 kN. Vacuum specific impulse 462 seconds. Delta 3 second stage with hydrogen tank stretch.

Status: In production.
Gross mass: 24,170 kg (53,280 lb).
Unfuelled mass: 2,850 kg (6,280 lb).
Height: 12.00 m (39.00 ft).
Diameter: 2.44 m (8.00 ft).
Span: 4.00 m (13.10 ft).
Thrust: 110.05 kN (24,740 lbf).
Specific impulse: 462 s.
Burn time: 850 s.
Number: 6 .

More... - Chronology...


Associated Countries
Associated Engines
  • RL-10B-2 Pratt and Whitney lox/lh2 rocket engine. 110 kN. In production. Isp=462s. Used on Delta 3 , Delta IV launch vehicles. First flight 1998. Extendable exit cone for increased specific impulse; electromechanical actuators replace hydraulic systems. More...

Associated Launch Vehicles
  • Delta IV Medium+ (4.2) American orbital launch vehicle. As Delta 4 medium but with 2 x GEM-60 solid rocket boosters and a 4 m diameter payload fairing. More...
  • Delta IV Medium American orbital launch vehicle. Basic Delta-4 vehicle with no strap-ons, the core vehicle, and RL10B-1 upper stage with a 4 m diameter payload fairing. World's first all-cryogenic launch vehicle. More...
  • Delta IV Medium+ (5.2) American orbital launch vehicle. As Delta 4 medium but with 2 x GEM-60 solid rocket boosters and a 5 m diameter payload fairing. More...
  • Delta IV Medium+ (5.4) American orbital launch vehicle. As Delta 4 medium but with 4 x GEM-60 solid rocket boosters and a 5 m diameter payload fairing. 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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