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The Walter HWK 109-509 was a German liquid-fuel bipropellant
rocket engine A rocket engine is a reaction engine, producing thrust in accordance with Newton's third law by ejecting reaction mass rearward, usually a high-speed Jet (fluid), jet of high-temperature gas produced by the combustion of rocket propellants stor ...
that powered the
Messerschmitt Me 163 Komet The Messerschmitt Me 163 Komet is a rocket-powered interceptor aircraft primarily designed and produced by the German aircraft manufacturer Messerschmitt. It is the only operational rocket-powered fighter aircraft in history as well as ...
and
Bachem Ba 349 The Bachem Ba 349 Natter () is a World War II German point-defence rocket-powered interceptor aircraft, interceptor, which was to be used in a very similar way to a manned surface-to-air missile. After a vertical take-off, which eliminated the n ...
aircraft. It was produced by
Hellmuth Walter Kommanditgesellschaft Hellmuth Walter Kommanditgesellschaft (HWK), Helmuth Walter Werke (HWM), or commonly known as the Walter-Werke, was a German company founded by Professor Hellmuth Walter to pursue his interest in engines using hydrogen peroxide as a propellant. Ha ...
(HWK) commencing in 1943, with licensed production by the Heinkel firm's facilities in Jenbach, Austria.


Design and development

Early versions of the Me 163 had been powered by an earlier design running on a "cold engine" fueled with Z-Stoff. This fuel tended to clog the jets in the combustion chamber, causing fluctuations in power and potentially explosions. Worse, however, was the fact that the engine could not be throttled, and when the aircraft leveled off after its climb to altitude it quickly accelerated to speeds that caused serious compressibility issues. The RLM demanded that a version be developed with a throttle. During this period Walter had also been working with a new fuel known as
C-Stoff C-Stoff (; "substance C") was a Redox, reductant used in bipropellant rocket fuels (as a fuel itself) developed by Hellmuth Walter Kommanditgesellschaft in Germany during World War II. It was developed for use with T-Stoff (a high-test peroxide) ...
that gave off significant heat and was thus known as the "hot engine". C-Stoff was a mix of 30% hydrazine hydrate, 57%
methanol Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...
, and 13% water, with a small amount of potassium-copper-cyanide. The oxidizer, known as
T-Stoff T-Stoff (; 'substance T') was a stabilised high test peroxide used in Nazi Germany, Germany during World War II. T-Stoff was specified to contain 80% (occasionally 85%) hydrogen peroxide (H2O2), remainder water, with traces (<0.1%) of stabiliser ...
, consisted of an 80%-concentration
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscosity, viscous than Properties of water, water. It is used as an oxidizer, bleaching agent, and antiseptic, usua ...
-based formulation. The two reacted violently on contact. 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 (3,820 lbf). To address the throttling issue, the new engine included turbopumps with two settings. The pumps were driven by a single turbine, powered by steam created by decomposing the T-Stoff with a wire mesh
catalyst Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...
. Combined with a mechanical throttle, this provided four power settings from idle to full power for climbing. In practice it was found that throttling the engine dramatically decreased its fuel economy to the point that it did not extend the endurance of the aircraft as expected. This version was put into the Me 163B in spite of this problem. The ultimate solution to the throttling problem was the B and C series of the engine. These engines used two combustion chambers, the original one (retroactively given the name ''Hauptofen''), and a second, smaller ''Marschofen'' chamber directly beneath the main ''Hauptofen'' chamber, tuned to provide the cruise power needed for high-speed level flight, about . This chamber provided that power at peak efficiency, so it did not suffer from the problems found while throttling on the original models. The throttle on the original combustion chamber was removed, and throttling was instead provided by turning the main engine on and off. This new version dramatically improved cruise endurance, with overall flight times improving from eight to twelve minutes, a 50% improvement. It was also mechanically simpler as the turbopumps were no longer throttled. The engine was an integral design with all components of the drive, with the exception of fuel tanks, locked in a cubical frame — this frame was discarded for the 109-509C dual-chamber design.


Variants

*: Pre-production model, manufactured from May 1943. The thrust of this engine was regulated between 300 kp (2.9 kN) and 1500 kp (). *: The first series production engine was used in the Messerschmitt Me 163 B from August 1944. The thrust here was adjustable between 100 kp (1 kN) and 1600 kp (). *: Version for the Messerschmitt Me 163B-1a. Weighing only complete, this engine consisted of two main assemblies, the roughly-cubical shape framed forward assembly comprising the turbine housing, the fuel pumps geared to the turbine shaft, the control box, a pressure-reducing valve and the electric starter motor, with the aft assembly made up of the combustion chamber, connected to the fore unit by a cylindrical "thrust-tube" containing pipes which carried fuel to the combustion chamber's individual injector jets. The thrust was adjustable between 200 kp () and a maximum of 1700 kp (). *: Increased performance version of the 509 A-1. This engine was the initial version to feature the twin ''Hauptofen'' main chamber above, and lower thrust ''Marschofen'' cruise chamber design directly below the main chamber, with an additional thrust of 300 kp (). This auxiliary chamber proved necessary due to the actual T-Stoff oxidizer consumption of the main unit, at nearly 5 kg/s, exceeding estimates by 100%. Thrust from main chamber adjustable between 100 kp () and 2000 kp (). Fully restored examples of both the Me 163B's single-chamber rocket motor, as well as the only known example — stated as the third prototype example — in the United States of the experimental twin-chamber Walter "509B" rocket motor, are each on display in front, one each to either side of the NMUSAF's restored Me 163B, bearing ''Werknummer'' (serial number) 191 095 on its vertical fin. *: Dual-chamber motor like the B-series, based on the uprated version of the 509 A-2, but having a main ''Hauptofen'' chamber with a differing forward shape from that on the 509B, while also discarding the open-structure cubical frame for lighter weight. The main combustion chamber gave between 400 kp () and 2000 kp (), the ''Marschofen'' auxiliary chamber 400 kp (). To be used in the Me 263 (Ju 248). One surviving example on museum display at the Royal Air Force Museum Cosford. *: Variant of the 509 C-1 for use in the improved B-series airframes of the
Bachem Ba 349 The Bachem Ba 349 Natter () is a World War II German point-defence rocket-powered interceptor aircraft, interceptor, which was to be used in a very similar way to a manned surface-to-air missile. After a vertical take-off, which eliminated the n ...
''Natter''. Engine designed to be recovered by parachute, along with the entire rear section with empennage. * A completely revised lightened version for use as a permanently installed booster rocket on the Messerschmitt Me 262 ''Heimatschützer IV'' home defence interceptor. *HWK RII-211 - Company designation for prototype engines of the 509A-2 series


Applications

* Arado Ar E.381 *
Bachem Ba 349 The Bachem Ba 349 Natter () is a World War II German point-defence rocket-powered interceptor aircraft, interceptor, which was to be used in a very similar way to a manned surface-to-air missile. After a vertical take-off, which eliminated the n ...
* DFS 228 * Focke-Wulf ''Volksjäger'' 2 * Messerschmitt Me 163 * Messerschmitt Me 262C, in ''Heimatschützer'' prototype evaluation designs.


Engines on display

*
National Museum of the United States Air Force The National Museum of the United States Air Force (formerly the United States Air Force Museum) is the official museum of the United States Air Force located at Wright-Patterson Air Force Base, northeast of Dayton, Ohio. The NMUSAF is ...
(bot
single-chamber 509 A
an
twin-chamber 509 B
versions) * National Museum of Flight * CosmosphereKomet engine at the Cosmosphere
/ref> * Luftwaffenmuseum der Bundeswehr * Shuttleworth Collection * Ballarat Aviation Museum


Specifications (509A)


See also


References


Notes


Bibliography

*Gooden, Brett. ''Natter: Manned Missile of the Third Reich: Historic Step to Human Spaceflight''. Rundle Mall, Australia: Brett Gooden, 2019. *''Jane's Fighting Aircraft of World War II''. London. Studio Editions Ltd, 1989.


External links


The Hellmuth Walter Rocket Engine


* ttp://www.walterwerke.co.uk/museum/usafmb1.htm#third Walter 109-509B rocket motor photo-page
The NMUSAF page on the 509B


and ttp://www.walterwerke.co.uk/museum/cosford.htm photos of the preserved UK-housed 509C rocket motor {{Aeroengine-specs Aircraft rocket engines Rocket engines using hypergolic propellant 109-509 Rocket engines using the gas-generator cycle Rocket engines using hot cycle hydrogen peroxide propellant