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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 ...
Propulsive efficiency comparison for various gas turbine engine configurations. In the 1970s, Hamilton Standard described its propfan as "a small diameter, highly loaded multiple bladed variable pitch propulsor having swept blades with thin advanced airfoil sections, integrated with a nacelle contoured to retard the airflow through the blades thereby reducing compressibility losses and ...
A variable speed may or may not have a gearbox, depending on the manufacturer's desires. Wind turbines without gearboxes are called direct-drive wind turbines. An advantage of a gearbox is that generators are typically designed to have the rotor rotating at a high speed within the stator. Direct drive wind turbines do not exhibit this feature.
A variable pitch fan is similar in concept to that of a variable-pitch propeller and involves progressively reducing the pitch (or blade angle) of the fan on a turbofan as the engine is throttled. Although variable pitch fans are used in some industrial applications, the focus of this article is on their use in turbofan engines .
The area hosts a multitude of wind farms, comprising one of California's largest wind resource areas. The pass is undergoing much repowering activity. The area has multiple generations of wind turbine technology installed, including both single and double-blade turbines, as well as the more modern three-blade horizontal axis design.
Modern wind turbines and nuclear power plans kill about 0.3 to 0.4 birds per GWh generated, without climate change effects, in comparison with 5.18 birds per GWh with fossil fuels power plants. [4] However, the small turbines used at Altamont in 2007 were dangerous to various raptors that hunt California ground squirrels in the area.
The requirement for pitch variation is shown by the propeller performance during the Schneider Trophy competition in 1931. The Fairey Aviation Company fixed-pitch propeller used was partially stalled on take-off and up to 160 mph (260 km/h) on its way up to a top speed of 407.5 mph (655.8 km/h). [36]
The Turbomeca Astafan is a single-spool, variable-pitch turbofan engine developed from the Turbomeca Astazou. [1]: 553 [2]: 932 Despite successful flight-testing, an efficient, quiet and clean design (compared to turbojets and conventional turbofans) [1]: 554–555 [3]: 1648 [4]: 1872 and some commercial interest, [5]: 1683 the Astafan never entered series production.