page_title: Walter HWK 109-507
section_title: Engine
hierarchical_section_title: Walter HWK 109-507 / Engine
caption_attribution_description: Deutsch: HWK 109-507, eigenes Bild,
context_page_description: The HWK 109-507 was a liquid-propellant rocket engine developed by Germany during World War II. It was used to propel the Hs 293 anti-ship guided missile.
  It was produced by Hellmuth Walter Kommanditgesellschaft. Like other Walter engines it used hydrogen peroxide as a propellant.
context_section_description: The engine's fuel chemistry used 80% high test hydrogen peroxide or 'T-Stoff'. This was a 'cold cycle' engine; the peroxide acted as a monopropellant and was decomposed by a catalyst into superheated steam and oxygen. The catalyst used was a consumable liquid solution of calcium permanganate or 'Z-Stoff'. As this catalyst is consumed, the engine is regarded as a bipropellant engine.
  Propellants are forced into the combustion chamber by compressed air, stored at 200 bar (2,900 psi) in two steel vessels. This pressure is released through an electrically-fired cartridge that opens a valve with a blow-out disc. This is the full extent of the electrical control system. Once fired, the valve does not close again. A pressure regulator delivers air at 33 bar (480 psi), through a shuttle valve that pressurised first the catalyst tanks and then the propellant tank. This delay ensures reliable ignition in the combustion chamber. A non-return valve ensures that no catalyst can flow backwards into the air or propellant plumbing, with an explosive result. A rubber diaphram, broken as propellant pressure builds, ensures that there is no backflow through the combustion chamber either. Z-stoff was known for problems of clogging injectors and so an inline filter was used.
  The propellant injector in the combustion chamber is a simple light alloy casting, cooled by the propellant flow. The combustion chamber is single-walled mild steel, with no provision for cooling. A steel mixing cup is downstream of the injector, with the radial Z-Stoff 6mm pipe leading into it. One 3 mm diameter injector nozzle points into the cup, thirty smaller radial 2 mm nozzles deliver most of the propellant along the walls of the chamber. Helical swirl baffles in the chamber promote good mixing and decomposition of the peroxide.
  Thrust varied through the boost phase, as air pressure and propellant flow fell, dropping from 600 kgf to 400 kgf.
  The engine pod had a dry weight of 517 kg, carrying 68 kg of propellants when full.
caption: Rocket motor, casing removed
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