Encyclopedia Astronautica
Nerva NTR

DoE nuclear/lh2 rocket engine. 333.4 kN. Study 1991. Late 1980's update of 1960's Nerva design. Isp=925s.

Engine: 8,500 kg (18,700 lb). Area Ratio: 500. Thrust to Weight Ratio: 4. Coefficient of Thrust sea level: 0.

Status: Study 1991.
Unfuelled mass: 8,500 kg (18,700 lb).
Diameter: 5.00 m (16.40 ft).
Thrust: 333.40 kN (74,951 lbf).
Specific impulse: 925 s.

More... - Chronology...

Associated Countries
See also
Associated Launch Vehicles
  • Nerva 2 American nuclear-powered orbital launch vehicle. Version of 1960's nuclear fission engine proposed in 1990's. More...

Associated Manufacturers and Agencies
  • AEC American agency overseeing development of rocket engines and rockets. Atomic Energy Commission, USA. Responsible for development of nuclear weapons and nuclear power applications. Became part of the newly-created Department of Energy in 1971. More...

Associated Propellants
  • Nuclear/LH2 Nuclear thermal engines use the heat of a nuclear reactor to heat a propellant. Although early Russian designs used ammonia or alcohol as propellant, the ideal working fluid for space applications is the liquid form of the lightest element, hydrogen. Nuclear engines would have twice the performance of conventional chemical rocket engines. Although successfully ground-tested in both Russia and America, they have never been flown due primarily to environmental and safety concerns. 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...

Associated Stages
  • Nerva 2/NTR Nuclear/LH2 propellant rocket stage. Loaded/empty mass 158,400/27,000 kg. Thrust 333.00 kN. Vacuum specific impulse 925 seconds. Design as revised in detail in 2005. More...

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