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In 1919 L. E. Baynes patented the first automatic variable-pitch airscrew. Wallace Rupert Turnbull of Saint John, New Brunswick, Canada is credited in Canada for creating the first variable pitch propeller in 1918. [5] The French aircraft firm Levasseur displayed a variable-pitch propeller at the 1921 Paris Air Show. The firm claimed that the ...
In marine propulsion, a variable-pitch propeller is a type of propeller with blades that can be rotated around their long axis to change the blade pitch. Reversible propellers—those where the pitch can be set to negative values—can also create reverse thrust for braking or going backwards without the need to change the direction of shaft revolution.
Blade pitch acts much like the gearing of the final drive of a car. Low pitch yields good low speed acceleration (and climb rate in an aircraft) while high pitch optimizes high speed performance and fuel economy. It is quite common for an aircraft to be designed with a variable-pitch propeller, to give maximum thrust over a larger speed range ...
Therefore, most propellers use a variable pitch mechanism to alter the blades' pitch angle as engine speed and aircraft velocity are changed. A sailor checks the propeller of a Landing Craft Air Cushion hovercraft. A further consideration is the number and the shape of the blades used.
A ground-adjustable propeller is a simple type of aircraft variable-pitch propeller where the blade angle can be adjusted between pre-set limits of fine and coarse pitch. [1] As its name implies, a ground-adjustable propeller may be adjusted only when the aircraft is on the ground and when the engine is not running.
The propeller characteristics are commonly expressed as dimensionless ratios: [31] Pitch ratio PR = propeller pitch/propeller diameter, or P/D; Disk area A 0 = πD 2 /4; Expanded area ratio = A E /A 0, where expanded area A E = Expanded area of all blades outside of the hub.
Variable-pitch propellers of an E-2C Hawkeye. Propeller-driven aircraft generate reverse thrust by changing the angle of their controllable-pitch propellers so that the propellers direct their thrust forward. This reverse thrust feature became available with the development of controllable-pitch propellers, which change the angle of the ...
Variable-pitch propeller (aeronautics) Variable-pitch propeller (marine) Voith Schneider Propeller This page was last edited on 27 March 2024, at 21:42 (UTC). Text is ...