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From Wikipedia, the free encyclopedia
One of a
https://en.wikipedia.org/wiki/Lockheed_Martin_C-130J_Super_Hercules C-130J Super Hercules' 6 bladed
https://en.wikipedia.org/wiki/Dowty_Rotol Rotol R391 composite controllable- and reversible-pitch propellers.
Hamilton Standard variable-pitch propeller on a 1943 model
https://en.wikipedia.org/wiki/Stinson_Reliant Stinson V77 Reliant[dierzhang]
Propellers whose blade pitch could be adjusted while the aircraft was on the ground were used by a number of early aviation pioneers,
https://en.wikipedia.org/wiki/Alliott_Verdon_Roe A. V. Roe and
https://en.wikipedia.org/wiki/Louis_Charles_Breguet Breguet. In 1919
https://en.wikipedia.org/wiki/L._E._Baynes L. E.
https://en.wikipedia.org/wiki/L._E._Baynes Baynes AFRAeS patented the first automatic variable pitch airscrew.
The French aircraft firm Levasseur displayed a variable-pitch propeller at the 1921 Paris Airshow, which, it claimed, had been tested by the French government in a ten-hour run and could change pitch at any engine RPM.
https://en.wikipedia.org/wiki/Henry_Selby_Hele-Shaw Henry Selby Hele-Shaw and T. E. Beacham patented a hydraulically operated variable-pitch propeller (based on a variable stroke pump) in 1924 and presented a paper on the subject before the
https://en.wikipedia.org/wiki/Royal_Aeronautical_Society Royal Aeronautical Society in 1928, though it was received with scepticism as to its utility. The propeller had been developed with
https://en.wikipedia.org/wiki/Gloster_Aircraft_Company Aircraft Company — as the Gloster Hele-Shaw Beacham Variable Pitch Propellor — and was demonstrated on a
https://en.wikipedia.org/wiki/Gloster_Grebe Grebe, where it was used to maintain a near-constant RPM.
The first practical controllable-pitch propeller for aircraft was introduced in 1932.
Such propellers are used in
https://en.wikipedia.org/wiki/Propeller_(aeronautics) propeller-driven aircraft to adapt the propeller to different
https://en.wikipedia.org/wiki/Thrust thrust levels and air speeds so that the propeller blades don't stall, hence degrading the propulsion system's efficiency. Especially for cruising, the engine can operate in its most economical range of
https://en.wikipedia.org/wiki/Rotational_speed rotational speeds. With the exception of going into reverse for braking after touch-down, the pitch is usually controlled automatically without the pilot's intervention. A propeller with a controller that adjusts the blade pitch so that the rotational speed always stays the same is called a
https://en.wikipedia.org/wiki/Constant-speed_propeller constant-speed propeller. A propeller with controllable pitch can have a nearly constant efficiency over a range of airspeeds .
A common type of controllable-pitch propeller is hydraulically actuated; it was originally developed by Frank W. Caldwell of the
https://en.wikipedia.org/wiki/Hamilton_Standard Hamilton Standard Division of the
https://en.wikipedia.org/wiki/United_Technologies_Corporation United Aircraft Company. This design led to the award of the
https://en.wikipedia.org/wiki/Collier_Trophy Collier Trophy of 1933.
https://en.wikipedia.org/wiki/De_Havilland de Havilland subsequently bought up the rights to produce Hamilton propellers in the UK, while the British company
https://en.wikipedia.org/wiki/Dowty_Rotol Rotol was formed to produce its own designs. The French company of
https://en.wikipedia.org/wiki/Pierre_Levasseur_(aircraft_builder) Levasseur and Smith Engineering Co. in the United States also developed controllable-pitch propellers. Smith propellers were used by
https://en.wikipedia.org/wiki/Wiley_Post Wiley Post on some of his flights.
Another common type was originally developed by
https://en.wikipedia.org/wiki/Wallace_Rupert_Turnbull Wallace R. Turnbull and refined by the
https://en.wikipedia.org/wiki/Curtiss-Wright Curtiss-Wright Corporation.
https://en.wikipedia.org/wiki/Variable-pitch_propeller#cite_note-8  This electrically-operated mechanism was first tested in on June 6, 1927 at Camp Borden, Ontario, Canada and patented in 1929 (
https://www.google.com/patents/US1828348 U.S. Patent 1,828,348). It was favoured by some pilots in World War II, because even when the engine was no longer running the propeller could be feathered. On hydraulically-operated propellers the feathering had to happen before the loss of hydraulic pressure in the engine.
As experimental aircraft and microlights have become more sophisticated, it has become more common for such light aeroplanes to fit variable-pitch propellers, both
https://en.wikipedia.org/wiki/Ground-adjustable_propeller ground-adjustable propellers and in-flight-variable propellers. Hydraulic operation is too expensive and bulky, and instead light aircraft use propellers that are activated mechanically or electrically. The
https://en.wikipedia.org/wiki/Silence_Twister Silence Twister prototype kitplane was fitted with the
https://en.wikipedia.org/wiki/V-Prop V-Prop, an automatic self-energising and electronically self-adjusting VP propeller.
If you want to know more,
All the imformations are from Wikipedia
Thanks for your listening!propulsion system's efficiency. Especially for cruising, the engine can operate in its most economical range of
https://en.wikipedia.org/wiki/Pierre_Levasseur_(aircraft_builder) Levasseur and Smith Engineering Co. in the Un