De HAVILLAND HYDROMATIC AIRSCREW PROPELLER AIRCRAFT BRITISH EDUCATIONAL FILM 75764

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This British film describes the De Havilland Hydromatic Airscrew, produced under license from Hamilton Standard. The Hydromatic propeller represented a major advance in propeller design and laid the groundwork for further advancements in propulsion over the next 50 years. The Hydromatic was designed to accommodate larger blades for increased thrust, and provide a faster rate of pitch change and a wider range of pitch control. This propeller utilized high-pressure oil, applied to both sides of the actuating piston, for pitch control as well as feathering— the act of stopping propeller rotation on a non-functioningengine to reduce drag and vibration — allowing multienginedaircraft to safely continue flight on remaining engine(s).The Hydromatic entered production in the late 1930s, just in time to meet the requirements of the high-performance military and transport aircraft of World War II. The propeller’s performance, durability and reliability made amajor contribution to the successful efforts of the U.S. and Allied air forces.

The variable-pitch aircraft propeller allows the adjustment in flight of blade pitch, making optimal use of the engine’spower under varying flight conditions. On multi-engine daircraft it also permits feathering the propeller--stopping its rotation--of a nonfunctioning engine to reduce drag andvibration.The Hydromatic propeller was designed for larger blades,faster rate of pitch change, and wider range of pitch control than earlier types of controllable-pitch propellers. The Hydromatic played a distinguished role in allied combataircraft in World War II. Its continuing development hasincorporated many features used on later aircraft, including today’s turboprop planes.

By the end of the war in 1945, Hamilton Standard and its licensees had supplied more than 500,000 propellers, more than half of them Hydromatics, to U.S. and Allied military forces.The development of the feathering feature led tounexpected gains in another Hydromatic subsystem —deicing. Various methods of removing ice from propellersto reduce vibration and maintain blade efficiency were employed beginning in 1935. One early method commonly used among airlines involved spraying a combination ofalcohol and glycerine through nozzles to the propeller’sblades. Aided by centrifugal force, the loosened ice would then be ejected.

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This film is part of the Periscope Film LLC archive, one of the largest historic military, transportation, and aviation stock footage collections in the USA. Entirely film backed, this material is available for licensing in 24p HD and 2k. For more information visit http://www.PeriscopeFilm.com