Constant Speed Units
A constant speed unit (CSU) or propeller governor is the device fitted to one of these propellers to automatically change its pitch so as to attempt to keep engine speed constant. Most engines produce their maximum power in a narrow speed band. The CSU can be said to be to an aircraft what the CVT is to the motor car: the engine can be kept running at its optimum speed no matter what speed the aircraft is flying through the air. The advent of the CSU had another benefit: it allowed the designers of aircraft engines to keep ignition systems simple - the automatic spark advance seen in motor vehicle engines is simplified in aircraft engines.
Three methods are used to vary the pitch. Engine oil pressure is the usual mechanism used in commercial aircraft and the Continental and Lycoming engines fitted to light aircraft. Alternatively or additionally centrifugal weights may be attached directly to the propeller as in the Yak-52. Small modern engines such as the Rotax 912 which have a CSU may use either the traditional hydraulic method or an electrical pitch control mechanism. A pilot requires some additional training and, in most jurisdictions, a formal signoff before being allowed to fly aircraft fitted with a CSU. CSUs are not allowed to be fitted to aircraft certified under the USA Light-sport Aircraft regulations.
Read more about this topic: Constant Speed Propeller
Famous quotes containing the words constant, speed and/or units:
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