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:
“Friendship is never established as an understood relation.... It is a miracle which requires constant proofs. It is an exercise of the purest imagination and the rarest faith.”
—Henry David Thoreau (1817–1862)
“For myself and my loved ones, I want the heat, which comes at the speed of light. I don’t want to have to hang about for the blast, which idles along at the speed of sound.”
—Martin Amis (b. 1949)
“Even in harmonious families there is this double life: the group life, which is the one we can observe in our neighbour’s household, and, underneath, another—secret and passionate and intense—which is the real life that stamps the faces and gives character to the voices of our friends. Always in his mind each member of these social units is escaping, running away, trying to break the net which circumstances and his own affections have woven about him.”
—Willa Cather (1873–1947)