Encyclopedia Astronautica
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.

After the spectacular explosion and cancellation of the government contract for the Aerotojet, Chandler Ross was assigned to nevertheless continue to perfect the design in a smaller-scale version called the Centrojet. Work had begun on this in June 1943. The engine operated on the same principle as the Aerotojet - the 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. The Centrojet shaft differed from the Aerotojet in that it terminated in a single thrust chamber with at first four, and finally two fixed nozzles projecting. This was expected to give the design dynamic balance, compared to the Aerotojet's swivelling separate combustion chambers.

The shaft drove a gear box which powered the propellant pumps at a more moderate speed than the Aerotojet. A high torque electric motor started the engine through the gear system. Unlike the Aerotojet, Centrojet development was successful and the resulting engine was a "delightful toy to work with". The engine was controlled simply by-passing fluid around the pumps to vary speed and torque. The principal problems remained an unexplainable and insoluble leakage of propellants at the pump and shaft transfer seals.

However tests showed that as the shaft speed increased, the overall specific impulse decreased faster than would be expected by losses due to the side components of thrust. The rotation was causing some kind of efficiency degradation in the combustion process, but this could never be understood. However the stable unit was run in a series of serious combustion studies. But tests showed that the rotating engine dynamic approach could not be scaled up to rocket engines of thousands of pounds of thrust. So the technology was abandoned in 1945.

Application: R&D.

Characteristics

Thrust (sl): 2.250 kN (506 lbf). Thrust (sl): 230 kgf. Propellant Formulation: RFNA/Aniline+Furfural Alcohol.

Thrust: 2.25 kN (506 lbf).
First Launch: June 1943.

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Associated Countries
See also
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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