Encyclopedia Astronautica

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.

In 1942 Jack Northrop proposed to the Army Air Force a super high-performance, flying wing, rocket-powered manned interceptor. Development was authorised in January 1943 under extreme secrecy, the official XP-79 designation being assigned but the work being simply known as 'Project X'. GALCIT at the California Institute of Technology, the only organization in the United States capable of such work, began parallel design of two liquid propellant rocket engine variants for the XP-79 in November 1942. One, the XLR-7, used what would become the later standard gas turbine pump feeding four combustion chambers. The other, using an ancient Greek concept, was dubbed the Aerotojet. The Aerojet company was formed to handle the Project X and JATO government contracts coming GALCIT's way.

The XLR-7 was regeneratively cooled and used 4 x 680 kgf thrust chambers of the type developed by Aerojet for JATO units. The engines had variable thrust, using a gas generator to drive the pumps and a turborocket for main aircraft propulsion. Protracted technical problems and wartime shortages of skilled engineering staff and materials stretched the development schedule. The Aerotojet was abandoned after insoluble propellant leakage problems and the explosion of the first flight version on the test stand in 1944. The XLR-7, on the other hand, was successfully tested in August 1945. But then the P-79 aircraft itself was then cancelled at the end of 1945 when the prototype crashed on its first flight, killing the pilot.

Application: XP-79 Northrop Flying Wing.


Throttled thrust(vac): 1,360.000 kN (305,740 lbf). Thrust (sl): 26.670 kN (5,996 lbf). Thrust (sl): 2,720 kgf. Engine: 193 kg (425 lb). Chamber Pressure: 17.00 bar. Propellant Formulation: RFNA/80% Aniline+20% Furfural Alcohol.

Unfuelled mass: 193 kg (425 lb).
Height: 2.13 m (6.98 ft).
Diameter: 0.91 m (2.98 ft).
Thrust: 26.67 kN (5,996 lbf).
Burn time: 300 s.
First Launch: November 1942.

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Associated Manufacturers and Agencies
  • Aerojet American manufacturer of rockets, spacecraft, and rocket engines. Aerojet, Sacramento, CA, USA. More...

Associated Propellants
  • 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. More...

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