Walter HWK 109-509

The HWK 109-509 was a German liquid-fuel bipropellant rocket engine that powered the Messerschmitt Me 163 and Bachem Ba 349 aircraft. It was produced by Hellmuth Walter Kommanditgesellschaft (HWK) commencing in 1943.

Design and development

The HWK 109-509 used a two-component hypergolic fuel/oxidizer combination, controlled by a dual-flow turbopump, to regulate the rate of combustion and thereby the amount of thrust. The turbopump was driven by steam produced by a Walter steam generator which decomposed T-Stoff, which was a mixture of hydrogen peroxide (80% to 85% H₂O₂), remainder water, with traces (<0.1%) of stabilisers, in the presence of a solid catalyst. The engine worked on the principle of the "hot" Walter drive, which used C-Stoff in place of Z-Stoff, the latter tending to clog the jets in the combustion chamber, causing fluctuations in power and potentially explosions.

The fuel was known as C-Stoff, a mix of 30% hydrazine hydrate + 57% methanol + 13% water with a small amount of potassium-copper-cyanide. The oxidizer, known as T-Stoff, consisted of a hydrogen peroxide-based formulation, which reacted violently on contact with the C-Stoff fuel, as a hypergolic propellant combination. The violent combustion process resulted in the formation of water, carbon dioxide and nitrogen, and a huge amount of heat sending out a superheated stream of steam, nitrogen and air that was drawn in through the hole in the mantle of the engine, thus providing a forward thrust of approximately 17 kN (3,800 lbf).