- Townend ring
A Townend Ring is a narrow-chord cowling ring round the cylinders of a
radial engine to reduce drag and improve cooling. The Townend ring was the invention of Dr Hubert Townend of British-basedBoulton Paul Aircraft in 1929. [Original 1930 Canadian patent CA 304755 by Hubert Townend with drawings [http://patents.ic.gc.ca/cipo/cpd/en/patent/304755/summary.html#view_or_download_images] ] In the United States it was often called a "drag ring". It caused a reduction in the drag of radial engines and was widely used in high-speed designs of 1930-1935 before the long-chordNACA cowling came into general use. It was also said to generate forward thrust from the expansion of the air as it passed over the engine, adding 10 to 15 mph to the aircraft's top speed. ["A History of Aircraft Piston Engines" by Herschel Smith, (Sunflower University Press Manhattan, Kansas, 1981, ISBN 0-89745-079-5), 255pp.]Examples of aeroplanes with Townend rings were the
Douglas O-38 ,Vickers Wellesley , theWestland Wallace and theGloster Gauntlet . Early claims portrayed it as a superior design to the NACA cowling, but later comparisons proved aircraft performance worse when using a Townend ring. As airspeed increased above 250 mph, Townend ring lost competition to NACA design. [cite web|url=http://history.nasa.gov/SP-4219/Chapter1.html|title= Engineering Science and the Development of the NACA Low-Drag Engine Cowling|author=Hansen, James R|work= From Engineering Science to Big Science: The NACA and NASA Collier Trophy Research Project Winners|accessdate=2007-04-28]References
Links
* [http://www.aeroplanemonthly.com/glossary/T_news_70050.html The Spotters Glossary]
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