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BMW 109-718

From PlaneSpottingWorld, for aviation fans everywhere

The BMW 109-718 is a liquid fuelled rocket motor developed by Germany during the Second World War.

The 109-718 (109 for the Reichsluftfahrtministerium, or RLM, designation for rocket and jet projects)[1] was designed as an assist rocket for aircraft, for rapid takeoffs or to enable them to achieve high-speed sprints,[2] akin to what Americans called "mixed power" postwar. It was fitted with a variant of the BMW 003 jet engine, the 003R, providing 1250 kg thrust each;[3] it was expected the units would be fitted in pairs. Unlike JATO, the 781 was not intended to be expendable.[4]

The rocket motor had internal and external main chambers which were cooled by the nitric acid fuel, fed through a coiled spiral tube.[5] The cenfrifugal fuel pumps[6] (operating at 17,000rpm)[7] delivered a mix of nitric acid and hydrocarbon[8] at 735 psi,[9] a rate of 5.5kg per 1000 kg thrust per second.[10] The 718s fuel pumps were driven by a power take-off from the jet engine which ran at 3,000 rpm.[11]

Before war's end, a Messerschmitt Me 262C-2b Heimatschützer (Home Defender II) was tested with a pair of 718, climbing to 9150 m (30,000 ft) in just three minutes.[12] The 109-718 was also tested aboard an He 162E,[13] though records do not indicate the results of this test.

Only twenty 109-718 engines were completed by war's end, each taking some 100 hours to complete.[14]


  1. Christopher, John. The Race for Hitler's X-Planes (The Mill, Gloucestershire: History Press, 2013), p.124.
  2. Christopher, p.124.
  3. Christopher, p.124.
  4. Christopher, p.124.
  5. Christopher, p.124.
  6. Christopher, p.124.
  7. Christopher, p.125.
  8. Christopher, p.124.
  9. Christopher, p.125, calls it 50 atmospheres.
  10. Christopher, p.124.
  11. Christopher, p.125.
  12. Christopher, p.124.
  13. Christopher, p.125.
  14. Christopher, p.125.


  • Christopher, John. The Race for Hitler's X-Planes. The Mill, Gloucestershire: History Press, 2013.