Encyclopedia Astronautica
Nitric acid/Amine


Drawing on the German World War II Wasserfall rocket, nitric acid (HNO3) became the early storable oxidiser of choice for missiles and upper stages of the 1950's. To overcome various problems with its use, it was necessary to combine the nitric acid with N2O4 and passivation compounds. These formulae were considered extremely secret at the time. By the late 1950's it was apparent that N2O4 by itself was a better oxidiser. Therefore nitric acid was almost entirely replaced by pure N2O4 in storable liquid fuel rocket engines developed after 1960. Early storable rocket systems sought to improve ignition characteristics and perforamance by eliminating the kerosene portion of the fuel. An amine is an organic compound produced when one or more hydrogen atoms of ammonia is replaced with organic groups. Mixed amine fuels were first developed by the Germans in World War II. TONKA-250, developed for the Wasserfall rocket, was used by the Russians after the war in various engines under the specification TG-02.

The propellant combinations WFNA/ JP-4 and later IRFNA/JP-4 were the first storable systems given serious consideration in the United States. Problems which caused the abandoning of these propellants were the absence of reliable hypergolic ignition and unstable combustion. IRFNA/UDMH and IRFNA/JP-X finally did prove satisfactory.

The composition of propellant-grade nitric acids is covered by Military Specification MIL-N-7254. The nitric acids are fuming liquids which vary from colorless to brown, depending on the amount of dissolved N2O4. The vapours from these acids have a characteristic pungent odour. They are highly corrosive, toxic, oxidising agents and attack most metals. They react with most organic materials violently enough to cause fire. The acids are soluble in water in all proportions, with an accompanying evolution of heat. They cannot be made to explode. Approximately 90 per cent of the nitric acid is made by the catalytic oxidation of ammonia with air or oxygen to yield nitric oxide (NO). The latter is oxidised to N2O4 which, when treated with water, yields nitric acid (HNO3) and may be concentrated by distillation with sulphuric acid. Red fuming nitric acids may be produced by passing gaseous N2O4 into nitric acid, a slight modification of the above process. Production of nitric acid was estimated at 3 million tonnes in 1959. The price of RFNA was $ 0.20 per kg in drum lots; IRFNA was slightly higher. The varieties of nitric acid propellants include:

  • WFNA - White fuming nitric acid is based on anhydrous nitric acid (HNO3), a colourless corrosive liquid which fumes in moist air. They contain a maximum of 2 per cent water and 0.5 per cent nitrogen dioxide, and decompose to yield amounts of water, nitrogen dioxide, and oxygen which are in chemical equilibrium.

  • IWFNA - Inhibited white fuming nitric acid. Since container materials are attacked by WFNA and equilibrium products, 0.6 per cent HF is added for passivation by deposition of a protective metallic fluoride coating.

  • RFNA - Red fuming nitric acid. Since WFNA or IWFNA exhibit excessive equilibrium decomposition pressures, reaching 75 bar at 700 deg C. To suppress the high pressure through a mass-action effect, some 13 per cent N2O4 and 3 per cent H20 are added, in order to reduce equilibrium pressures to 2 bar at 700 deg C. The colour of the resulting red fuming nitric acid is imparted by N204.

  • IRFNA - Inhibited red fuming nitric acid. Addition of 0.6 per cent HF to RFNA produces inhibited RFNA (IRFNA). The IRFNA specification was published in 1954 and thereafter Russian rocket engines using the same fuel appeared.

  • AK20 - Russian formulation consisting of 80% nitric acid + 20% N2O4 (AK = Azotna Kislota = Nitric Acid)

  • AK20F - Russian formulation consisting of 80% nitric acid + 20% N2O4 + fluorine passivant

  • AK20I - Russian formulation consisting of 80% nitric acid + 20% N2O4 + iodine passivant

  • AK20K - Russian formulation consisting of 80% nitric acid + 20% N2O4 + unknown additive

  • AK27I - Russian formulation consisting of 73% nitric acid + 27% N2O4 + iodine passivant

  • AK-27P - Russian formulation consisting of 73% nitric acid + 27% N2O4 + unknown additive

TONKA-259 was 50% xylidine and 50% triethylamine by weight. In the United States the preferred amine was aniline, an organic base belonging to the phenylamines. In this case it was an ammonia in which one hydrogen atom was replaced by the radical phenyl. Other US fuels in the family included Hydyne.

Oxidizer: Nitric acid. Oxidizer: Nitric acid. Oxidizer: Nitric acid. Oxidizer: Nitric acid. Oxidizer: Nitric acid. Fuel: Amine. Fuel: Amine. Fuel: Amine. Fuel: Amine. Fuel: Amine. Propellant Formulation: AK27P/TG-02. Propellant Formulation: AK27I/TG-02. Propellant Formulation: AK271/TG-02. Propellant Formulation: AK20F/TG-02. Propellant Formulation: AK20K/TG-02. Optimum Oxidizer to Fuel Ratio: 3.2. Oxidizer Density: 1.510 g/cc. Oxidizer Density: 1.510 g/cc. Oxidizer Density: 1.510 g/cc. Oxidizer Density: 1.510 g/cc. Oxidizer Density: 1.510 g/cc. Oxidizer Freezing Point: -42 deg C. Oxidizer Freezing Point: -42 deg C. Oxidizer Freezing Point: -42 deg C. Oxidizer Freezing Point: -42 deg C. Oxidizer Freezing Point: -42 deg C. Oxidizer Boiling Point: 86 deg C. Oxidizer Boiling Point: 86 deg C. Oxidizer Boiling Point: 86 deg C. Oxidizer Boiling Point: 86 deg C. Oxidizer Boiling Point: 86 deg C. Fuel Density: 1.020 g/cc. Fuel Density: 1.020 g/cc. Fuel Density: 1.020 g/cc. Fuel Density: 1.020 g/cc. Fuel Density: 1.020 g/cc. Fuel Freezing Point: -6 deg C. Fuel Freezing Point: -6 deg C. Fuel Freezing Point: -6 deg C. Fuel Freezing Point: -6 deg C. Fuel Freezing Point: -6 deg C. Fuel Boiling Point: 184 deg C. Fuel Boiling Point: 184 deg C. Fuel Boiling Point: 184 deg C. Fuel Boiling Point: 184 deg C. Fuel Boiling Point: 184 deg C.

More... - Chronology...


Associated Spacecraft
  • XP-79 American manned rocketplane. Flown in 1945. The XP-79 was Jack Northrop's design for a rocket-propelled flying wing fighter. More...

Associated Engines
  • 21AL-2600 Aerojet Nitric acid/Amine rocket engine. Nike Ajax. Launch thrust 11.7 kN. Development begun January 1946. Regeneratively cooled. Development and production First flight 1953. More...
  • 25AL-1000 Aerojet Nitric acid/Amine rocket engine. A-20 ATO. Launch thrust 4.41 kN. Development begun May 1942. Production version of GALCIT unit. First flight 1944. More...
  • 25XALD-1000 Aerojet Nitric acid/Amine rocket engine. JATO, Droppable for P-38, B-24, and B-25J. Thrust 4.41 kN. Development begun May 1942. Droppable version of XLR1, packaged compactly with parachute. First flight 1944. More...
  • 300LR-200 Aerojet Nitric acid/Amine rocket engine. XP-79 Launch thrust .882 kN. Development begun January 1943. Planned successor to XCALT-6000, developed under 'Project X' for the Northrop XP-79 Flying Wing rocket fighter. First flight 1945. More...
  • 30AL-1000 Aerojet Nitric acid/Amine rocket engine. GAPA. Launch thrust 4.41 kN. Development begun March 1947. Boeing surface-to-air missile, which would evolve into Bomarc and reach IOC in 1959. More...
  • 38ALDW-1500 Aerojet Nitric acid/Amine rocket engine. ATO Seaplanes. Launch thrust 6.66 kN. Development begun July 1943. Regeneratively cooled. Also a few 45ALDW-1500 were built. Droppable version. First flight 1945. More...
  • 40ALD-3000 Aerojet Nitric acid/Amine rocket engine. B-29 droppable ATO. Launch thrust 13.33 kN. Development begun October 1943. Droppable version, pressure fed, regeneratively cooled, supplied with 331 kg of propellant. First flight 1945. More...
  • 40XAL-4000 Aerojet Nitric acid/Amine rocket engine. PB2Y-3 ATO. Launch thrust 17.6 kN. Development begun July 1943. Gasoline engine driven pumps. Also 40ALD-6000 and 60ALD-8000 versions First flight 1945. More...
  • 45AL-2600 Aerojet Nitric acid/Amine rocket engine. Aerobee B. Launch thrust 11.7 kN. Development begun June 1948. Manufacture of complete Aerobee systems First flight 1955. More...
  • Aerobee Aerojet Nitric acid/Amine rocket engine. Aerobee. Development begun December 1947. Research with high altitude vehicle as carriers of scientific information. More...
  • AJ11-6 Aerojet Nitric acid/aniline rocket engine. 17.8 kN. Typical ideal dV=3839 m/s; gravity and drag losses = 1012 m/s. More...
  • Centrojet Aerojet Nitric acid/Amine rocket engine. R&D. Launch thrust 2.25 kN. Work begun June 1943. Torque to rotate the main shaft of the propellant pumps was developed by the canted engine nozzles themselves at the aft end of the shaft. Abandoned 1945. More...
  • Corporal Firestone Nitric acid/Aniline-Furfuyrl alcohol rocket engine. 89 kN. More...
  • Corporal E Douglas/JPL Nitric acid/Aniline-Furfuyrl alcohol rocket engine. 89 kN. More...
  • Isayev V-750V Isayev Nitric acid/Amine rocket engine. 30.4 kN. SAM-missile V-750V. Out of Production. Designation unknown. More...
  • Isayev 218 Isayev Nitric acid/Amine rocket engine. 218 (S-25 system). Out of Production. Launch thrust 166 kN. More...
  • Isayev P-15 Isayev Nitric acid/Amine rocket engine. 11.9 kN. P-15 Termit. Out of Production. Designation unknown. Thrust range 11.895-5.43 kN. More...
  • KTDU-5A Isayev Nitric acid/Amine rocket engine. 45.5 kN. Used on Luna E-6 probes. Out of Production. Isp=287s. First turbopump engine with surface tension propellant management devices in tanks, allowing re-ignition in zero-G. More...
  • R-101B.36000-0 Isayev Nitric acid/Amine rocket engine. R-101B/R-108 SAM. Developed 1950-51. Launch thrust 83.3 kN. Single chamber engine designed for use in the R-101B and R-108 (derivative of German Wasserfall). More...
  • RD-0200 Kosberg Nitric acid/Amine rocket engine. 58.8 kN. Lavochkin SAM, flew 1960. Out of Production. First liquid rocket engine by OKB-154, evolution of Isayev S2.1200 transferred to Kosberg. Thrust range 59 - 5.9 kN. Sea level specific impulse 230 - 166 sec More...
  • RD-0201 Kosberg Nitric acid/Amine rocket engine. 58.060 kN. SAM V1100 by Grushin stage 3. Out of Production. Thrust range 59 - 28 kN. Isp=260s. First flight 1960. More...
  • S09.29 Isayev Nitric acid/Amine rocket engine. 88 kN. V-300/V-303 (S-25 system). Out of Production. More...
  • S09.502 Isayev Nitric acid/Amine rocket engine. R-101 SAM. Developed 1949-50. Launch thrust 78.4 kN. Four chamber engine designed for use in the R-101 (derivative of German Wasserfall). Abandoned by 1950 in favour of single-chamber engine. More...
  • S2.1150 Isayev Nitric acid/Amine rocket engine. 671.2 kN. Burya booster. Out of production. Isp=250s. First flight 1957. Engines developed from R-11 S2.253 engine. More...
  • S2.721V Isayev Nitric acid/Amine rocket engine. 11.8 kN. KSR. Developed 1956-. More...
  • S2.720 Isayev Nitric acid/Amine rocket engine. 34.3 kN. Engine for SAM-missile V-755. Out of Production. Pump-fed engine. Used in engine unit of a special apparatus. Pump-fed engine. 20,4 kN sea level. More...
  • S2.713 Isayev Nitric acid/Amine rocket engine. 252.2 kN. R-13 (SS-N-4). Out of Production. First engine to employ gas generator on main propellants. One main and four vernier thrusters. (Mixture derived ratio from tank content.) More...
  • S5.1 Isayev Nitric acid/Amine rocket engine. 167 kN. SAM-missiles 217M and 218. Out of Production. Designation unknown. More...
  • S5.3 Isayev Nitric acid/Amine rocket engine. 392 kN. R-21 (SS-N-5). Out of Production. First engine to start underwater. 392 kN sea-level. More...
  • S5.3M Isayev Nitric acid/Amine rocket engine. 396.7 kN. R-9 (SS-8) missile stage 1. Out of Production. Proposed for R-9 missile stage 1. Four engines per stage. 396,7 kN sea-level. More...
  • S5.4 Isayev Nitric acid/Amine rocket engine. 15.830 kN. Vostok/Voskhod retorfire engine; spacecraft maneuvering engine. . Out of Production. Includes 4 small lateral steering nozzles. Isp=266s. More...
  • S5.44 Isayev Nitric acid/Amine rocket engine. 177 kN. SAM-missile 5Ya24. Out of Production. Could be throttled. 177-49 kN sea-level. Area ratio 118 - 44. More...
  • U-400-2 Isayev Nitric acid/Amine rocket engine. Shchuka. Out of Production. More...
  • WAC JPL/Douglas Nitric acid/aniline rocket engine. 6.7 kN. More...
  • X4-AL-1000 Aerojet Nitric acid/Amine rocket engine. Brake rocket for G-4A. Launch thrust 4.41 kN. Braking rocket for glider. Single uncooled chamber, pressure fed, 13 kg of propellant. More...
  • X45ALD-4000 Aerojet Nitric acid/Amine rocket engine. B-29 ATO. Launch thrust 17.6 kN. Development begun June 1948. Regenerative cooling, nitrogen pressure-fed, droppable but no recoverable. Early version using XLR-13-AJ-1 thrust chamber assembly. More...
  • X60ALD-4000 Aerojet Nitric acid/Amine rocket engine. ATO for XB-45, B-45A. Launch thrust 17.6 kN. Development begun May 1946. Pressurising tank surrounded propellant tanks. Regeneratively cooled. Parachute for dropping and recovery after takeoff. More...
  • X60AL-1300 Aerojet Nitric acid/Amine rocket engine. P-51 superperformance. Launch thrust 5.78 kN. Development begun January 1945. Superperformance More...
  • X90ALT-60000 Aerojet Nitric acid/Amine rocket engine. Launch thrust 264 kN. Development begun April 1947. Unspecified Application, 20,000 Ibf subscale tested, new vertical test facility More...
  • XASR-1 Aerojet Nitric acid/aniline rocket engine. 11.6 kN. More...
  • XCALR-2000A-1 Aerojet Nitric acid/Amine rocket engine for XP-79 Northrop Flying Wing. Thrust 9.12 kN. Aerotojet, a pair of canted 130 kgf thrust chambers mounted longitudinally on a drive shaft, which drove the turbopumps. Developed 1943-1945; blew up on first test. More...
  • XCALT-6000 Aerojet Nitric acid/Amine rocket engine. Thrust 26.67 kN. Conservative alternate to Aerotojet for XP-79 flying wing rocket fighter. Successfully tested in August 1945, but project cancelled. Regeneratively cooled, 4 thrust chambers, pump-fed. More...
  • XLR13-AJ-5 Aerojet Nitric acid/Amine rocket engine. B-29 ATO. Launch thrust 17.6 kN. Development begun June 1948. Ceramic chamber and nozzle, nitrogen pressure-fed, droppable but no recoverable. More...
  • XLR13-AJ-7 Aerojet Nitric acid/Amine rocket engine. Launch thrust 17.6 kN. Modification of -AJ-1. Regeneratively cooled by fuel, droppable. More...
  • XLR53AJ-1 Aerojet Nitric acid/Amine rocket engine. F-80. Out of Production. Launch thrust 4.41 kN. Development begun 1949. Superperformance, wing tip mounted, regenerative cooling, pressure fed, 240 sec duration, 1000 Ibf thrust each. More...

Associated Stages
  • Aerobee 100-2 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 500/119 kg. Thrust 11.50 kN. More...
  • Aerobee 75-1 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 500/142 kg. Thrust 13.00 kN. More...
  • Aerobee 350-2 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 3,000/1,050 kg. Thrust 72.00 kN. More...
  • Aerobee 150-2 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 700/133 kg. Thrust 17.80 kN. More...
  • Aerobee 150A-2 Nitric acid/Amine propellant rocket stage. Loaded/empty mass 611/133 kg. Thrust 17.80 kN. Vacuum specific impulse 209 seconds. Nitric acid/Aniline propellants. Typical ideal dV=3839 m/s; gravity and drag losses = 1012 m/s. More...
  • AJ60-92 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 700/131 kg. Thrust 22.60 kN. More...
  • Burya booster Nitric acid/Amine propellant rocket stage. Loaded/empty mass 27,000/4,000 kg. Thrust 771.70 kN. Vacuum specific impulse 250 seconds. Booster for Burya missile. Two used to boost ramjet second stage to ignition conditions. Engines developed by Isayev from R-11 S2.253 engine. Early Buryas had S2.1100 engine. Masses estimated based on known total vehicle mass. More...
  • Corporal-1 Nitric acid/Amine propellant rocket stage. Loaded mass 5,200 kg. Thrust 89.00 kN. Nitric acid/Aniline-Furfuyrl alcohol propellants. More...
  • Corporal E-1 Nitric acid/Amine propellant rocket stage. Loaded mass 4,500 kg. Thrust 89.00 kN. Nitric acid/Aniline-Furfuyrl alcohol propellants. More...
  • Hermes A-1-1 Nitric acid/Amine propellant rocket stage. Loaded mass 5,000 kg. Thrust 71.00 kN. Nitric acid/Tonka propellants. More...
  • Hermes A-3A-1 Nitric acid/Amine propellant rocket stage. Loaded mass 3,800 kg. Thrust 80.00 kN. Nitric acid/Tonka propellants. More...
  • Hermes A-3B-1 Nitric acid/Tonka propellant rocket stage. Loaded/empty mass 5,300/2,000 kg. Thrust 100.00 kN. More...
  • R-13 Nitric acid/Amine propellant rocket stage. Loaded mass 13,700 kg. More...
  • V-1000-1 Nitric acid/Amine propellant rocket stage. Thrust 103.00 kN. More...
  • WAC-1 Nitric acid/Aniline propellant rocket stage. Loaded/empty mass 300/125 kg. Thrust 6.70 kN. More...
  • Wasserfall-1 Nitric acid/Tonka propellant rocket stage. Loaded/empty mass 3,500/1,700 kg. Thrust 80.00 kN. More...

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