Encyclopedia Astronautica
N2O4/Aerozine-50


Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Aerozine was a 50-50 mixture of hydrazine and UDMH developed for use in the Titan 2 missile. Copied in one Russian missile but otherwise straight UDMH used more commonly. Higher boiling point than UDMH.

Nitrogen tetroxide consists principally of the tetroxide in equilibrium with a small amount of nitrogen dioxide (NO2). The purified grade contains less than 0.1 per cent water. Nitrogen tetroxide (N2O4) has a characteristic reddish-brown colour in both liquid and gaseous phases. The solid tetroxide is colorless. N2O4 has an irritating, unpleasant acid-like odour. N2O4 is a very reactive, toxic oxidiser. It is non-flammable with air; however, it will inflame combustible materials. It is not sensitive to mechanical shock, heat, or detonation. Nitrogen dioxide is made by the catalytic oxidation of ammonia; steam is used as a diluent to reduce the combustion temperature. Most of the water is condensed out, and the gases are further cooled; the nitric oxide is oxidised to nitrogen dioxide, and the remainder of the water is removed as nitric acid. The gas is essentially pure nitrogen tetroxide, which is condensed in a brine-cooled liquefier. 1959 production amounted to 60,000 tonnes per year. In carload lots of one-ton cylinders, the price was $ 0.15 per kg. By 1990 NASA was paying $ 6.00 per kg due to environmental regulations.

Oxidizer: N2O4. Fuel: Aerozine-50. Oxidizer Density: 1.450 g/cc. Oxidizer Freezing Point: -11 deg C. Oxidizer Boiling Point: 21 deg C. Fuel Density: 0.903 g/cc. Fuel Freezing Point: -7 deg C. Fuel Boiling Point: 70 deg C.

More... - Chronology...


Associated Spacecraft
  • Apollo LM American manned lunar lander. 10 launches, 1968.01.22 (Apollo 5) to 1972.12.07 (Apollo 17). More...
  • Apollo LM Taxi American manned lunar lander. Cancelled 1968. The LM Taxi was essentially the basic Apollo LM modified for extended lunar surface stays. More...
  • Apollo LM Shelter American manned lunar habitat. Cancelled 1968. The LM Shelter was essentially an Apollo LM lunar module with ascent stage engine and fuel tanks removed and replaced with consumables and scientific equipment for 14 days extended lunar exploration. More...
  • Apollo LM Truck American lunar logistics spacecraft. Cancelled 1968. The LM Truck was an LM Descent stage adapted for unmanned delivery of payloads of up to 5,000 kg to the lunar surface in support of a lunar base using Apollo technology. More...
  • Apollo LM AS American manned spacecraft module. 10 launches, 1968.01.22 (Apollo 5) to 1972.12.07 (Apollo 17). More...
  • Apollo LM DS American manned spacecraft module. 10 launches, 1968.01.22 (Apollo 5) to 1972.12.07 (Apollo 17). More...

Associated Engines
  • AJ10-118K Aerojet N2O4/Aerozine-50 rocket engine. 43.4 kN. Isp=321s. Pressure-fed engine, optimized for altitude operation, used in Delta K stage from 1989. Not regeneratively cooled; used a rubber modified silica phenolic ablative at the combustion flame front. More...
  • AJ10-131 Aerojet N2O4/Aerozine-50 rocket engine. 9.8 kN. Subscale Apollo SPS. Subscale Apollo SPS More...
  • AJ10-137 Aerojet N2O4/Aerozine-50 rocket engine. 97.5 kN. Apollo SPS. Out of Production. Pressure-fed engine. Used as Apollo SM engine. Isp=312s. More...
  • AJ10-138 Aerojet N2O4/Aerozine-50 rocket engine. 35.6 kN. Out of production. Originally developed for Vanguard and Able. Two used, thrust uprated from 3540 kgf to 3628 kgf, with higher specific impulse, in Transtage. Isp=311s. Flown 1964-1980. More...
  • Ares Aerojet N2O4/Aerozine-50 rocket engine. 440 kN. SSTO ICBM. Development 1968. Isp=370s. Advanced Rocket Engine System - single shaft turbopump, integrated single pressure vessel in a staged combustion cycle configuration. More...
  • Astris German N2O4/Aerozine-50 rocket engine. 23.3 kN. Isp=310s. Used on Europa launch vehicle. First flight 1964. More...
  • Expansion-Deflection 50k Rocketdyne N2O4/Aerozine-50 rocket engine. Launch thrust 222.326 kN. Expansion-Deflection Booster (50,000 Ib thrust). Pressure-fed. Thrust and specific impulse values are at sea level. More...
  • Expansion-Deflection 10k Rocketdyne N2O4/Aerozine-50 rocket engine. Launch thrust 44.463 kN. Expansion-Deflection Booster (10,000 lb thrust). Pressure-fed. Thrust and specific impulse values are at sea level. More...
  • LE-3 Rocketdyne N2O4/Aerozine-50 rocket engine. 53.340 kN. MHI(Japan)/Rocketdyne Upper Stage. Pressure-fed. Isp=285s. More...
  • LR87-11 Aerojet N2O4/Aerozine-50 rocket engine. 1218.8 kN. Out of production. Isp=302s. Powered Titan 3 and 4 first stages. Replaced the -9 model, first flown 1968. First flight 1964. More...
  • LR87-11 AJ23-138 Aerojet N2O4/Aerozine-50 rocket engine. Launch thrust 1008.31 kN. Version of LR-87-11 tuned for launch pad ignition when used on Titan 3B. First flight 1966. More...
  • LR87-5 Aerojet N2O4/Aerozine-50 rocket engine. 1096.8 kN. Out of Production. Isp=297s. Used on Titan 2 launch vehicle. Engines refurbished for space launcher versions from decommissioned missiles between 1974-1982. More...
  • LR87-7 Aerojet N2O4/Aerozine-50 rocket engine. 1086.1 kN. Study 1961. Version of LR-87-5 used on Gemini Titan 2 launch vehicle. Isp=296s. Proposed for unflown Titan 3L2, Titan 3L4 boosters. First flight 1962. More...
  • LR87-9 Aerojet N2O4/Aerozine-50 rocket engine. Launch thrust 956.1 kN. Variant of LR-87 used on early versions of Titan III B,C First flight 1966. More...
  • LR87+ Aerojet N2O4/Aerozine-50 rocket engine. 1634.4 kN. Study 1965. Nominal improved LR87 in booster studies. Isp=293s. Used on Martin Astrorocket launch vehicle. More...
  • LR91-9 Aerojet N2O4/Aerozine-50 rocket engine. 448.605 kN. Titan III B, C, D. Out of Production. Version used in earlier versions of Titan 3 upper stages. Isp=316s. First flight 1965. More...
  • LR91-11 Aerojet N2O4/Aerozine-50 rocket engine. 467 kN. Out of production. Isp=316s. Second stage engine for Titan 3 and 4. First flight 1968. More...
  • LR91-5 Aerojet N2O4/Aerozine-50 rocket engine. 444.8 kN. Titan 2 ICBM Stage 2. Out of Production. Isp=315s. Scaled down version of stage 1 engine featuring fixed single chamber. Gas generator cycle. First flight 1962. More...
  • LR91-7 Aerojet N2O4/Aerozine-50 rocket engine. 444.8 kN. Study 1961. Version used on Stage 2 of Gemini Titan 2 Launch Vehicle. Isp=316s. Proposed for unflown Titan 3L2, Titan 3L4 boosters. First flight 1962. More...
  • P-7 Rocketdyne N2O4/Aerozine-50 rocket engine. Launch thrust 222.31 kN. Aspen Booster. Pressure-fed. Thrust from 12,000 lb to 50,000 lb at sea level. More...
  • RD-280 Glushko N2O4/Aerozine-50 rocket engine. 117.6 kN. Experimental engine. Study 1961. Experimental engine using Aerozine 50 (50% UDMH + 50% hydrazine) as fuel. Isp=350s. More...
  • RM-100T Rocketdyne N2O4/Aerozine-50 rocket engine. 0.441 kN. Lunar Flyer. Pressure-fed. Isp=296s. More...
  • RS-18 Rocketdyne N2O4/Aerozine-50 rocket engine. 15.563 kN. Apollo Lunar Ascent Module Engine. Pressure-fed. Isp=310s. More...
  • SE-10 Rocketdyne N2O4/Aerozine-50 rocket engine. 46.670 kN. Lunar Module Descent. Pressure-fed. Thrust throttleable 1050-10,500 lbs vac. Isp=305s. First flight 1968. More...
  • SE-9-3 Rocketdyne N2O4/Aerozine-50 rocket engine. 0.107 kN. Titan III Transtage. Pressure-fed. System included two modules of three engines plus two additional SE-9-5 separate engines, tanks, and a pressuirzation system. Isp=295s. First flight 1964. More...
  • SE-9-5 Rocketdyne N2O4/Aerozine-50 rocket engine. 0.196 kN. Titan III Transtage. Pressure-fed. System included two modules of three engines plus two additional SE-9-5 separate engines, tanks, and a pressuirzation system. Isp=300s. First flight 1964. More...
  • TR-201 TRW N2O4/Aerozine-50 rocket engine. 41.9 kN. Apollo lunar module ascent stage engines. Surplus engines used on Delta P stage. Isp=301s. First flight 1972. More...

Associated Stages
  • Astrorocket-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 151,927/23,500 kg. Thrust 2,150.00 kN. Vacuum specific impulse 345 seconds. X-20 Dynasoar configuration. LR87-derivative engines. More...
  • Astris N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 3,370/610 kg. Thrust 23.33 kN. Vacuum specific impulse 310 seconds. More...
  • Astrorocket-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 981,859/132,000 kg. Thrust 14,700.00 kN. Vacuum specific impulse 293 seconds. Delta wing configuration. LR87-derivative engines. More...
  • Barbarian MM-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 400,000/25,000 kg. Thrust 6,080.00 kN. Vacuum specific impulse 302 seconds. All values roughly estimated based on number of engines and diameter given. More...
  • Barbarian MM-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 80,000/6,000 kg. Thrust 1,214.00 kN. Vacuum specific impulse 302 seconds. All values roughly estimated based on number of engines and diameter given. More...
  • Delta K N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 6,954/950 kg. Thrust 43.63 kN. Vacuum specific impulse 319 seconds. More...
  • Delta P N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 5,434/820 kg. Thrust 41.92 kN. Vacuum specific impulse 301 seconds. More...
  • R-56 Block K N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 9,400/700 kg. Thrust 117.00 kN. Vacuum specific impulse 350 seconds. Empty mass estimated (rounded figures given in source material indicates impossible 9 tonnes gross with 8.7 tonnes propellant). More...
  • Titan 3B-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 37,560/2,900 kg. Thrust 460.31 kN. Vacuum specific impulse 316 seconds. More...
  • Titan Transtage Stretch N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 15,000/2,200 kg. Thrust 71.17 kN. Vacuum specific impulse 311 seconds. 20% stretch of Transtage to handle geosynch insertion of larger payloads launched by Titan 3C7. Masses estimated. More...
  • Titan Transtage N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 12,247/1,950 kg. Thrust 71.17 kN. Vacuum specific impulse 311 seconds. More...
  • Titan LDC-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 50,000/3,000 kg. Thrust 444.82 kN. Vacuum specific impulse 316 seconds. 15 foot diameter core Titan proposed in 1960's for space station logistics. Masses estimated. More...
  • Titan LDC-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 350,000/20,000 kg. Thrust 4,344.46 kN. Vacuum specific impulse 296 seconds. 15 foot diameter core Titan proposed in 1960's for space station logistics. Masses estimated. More...
  • Titan 4-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 163,000/8,000 kg. Thrust 2,428.31 kN. Vacuum specific impulse 302 seconds. More...
  • Titan 3B-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 139,935/7,000 kg. Thrust 2,413.19 kN. Vacuum specific impulse 302 seconds. More...
  • Titan 3A-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 29,188/2,653 kg. Thrust 453.71 kN. Vacuum specific impulse 316 seconds. More...
  • Titan 3A-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 116,573/5,443 kg. Thrust 2,339.76 kN. Vacuum specific impulse 302 seconds. More...
  • Titan 2-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 28,939/2,404 kg. Thrust 444.82 kN. Vacuum specific impulse 316 seconds. More...
  • Titan 2-1 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 117,866/6,736 kg. Thrust 2,172.23 kN. Vacuum specific impulse 296 seconds. More...
  • Titan 4-2 N2O4/Aerozine-50 propellant rocket stage. Loaded/empty mass 39,500/4,500 kg. Thrust 459.51 kN. Vacuum specific impulse 316 seconds. More...

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