Fundaments Operations of Aircraft Propellers

Contents Abstract Introduction Pitch Blades Forced Acting on a Propeller Propellers Types Fixed-Pitch Propeller Ground-Adjustable Variable-Pitch Propeller Constant-Speed Propeller Appendix 1 References Abstract: _This text outlines the fundaments operations and aspects of aircraft propellers. It details the components, forces and workings of a propeller as well as discussing the difference between the different propeller types._ Introduction: Propeller types are defined by blade pitch as being fixed or variable which will be further detailed later in the text. To fully appreciate the differences and understand the advantages of different pitched propellers we must first consider the fundamental characteristics of propellers. Usually propellers have two, three, or four blades; for high-speed or high-powered airplanes, six or more blades are used. In some cases these propellers have an equal number of opposite rotating blades on the same shaft, and are known as dual-rotation propellers. Small single engine aircraft have the propeller mounted on the front as multi-engine aircraft have them set on the wings. Pitch: What is pitch? Pitch is important as it is the main differential from propeller type to propeller type. Essentially pitch relates to the angle of the blade in respects to a flat plane. It is the helical blade path or simpler the distance the propeller blade covers during a full rotation and the cut it has on the air. Pitch is referred to in two ways, fine and coarse. A fine pitch propeller has a low blade angle, will try to move forward a small distance through the air with each rotation, and will take a 'small ' bite of the air. It requires relatively low power to rotate, allowing high propeller speed to be developed, but achieving only limited airspeed. This is like having a low gear in your automobile. (Brandon 2008) A coarse pitch propeller has a high blade angle, will try to

References: Climb and high speed cruise. A medium speed setting is used when high power is needed on a continuous basis, such as during an extended climb, or high speed cruise. (Brandon, 2008) Economic cruise. A low speed setting is used for a comfortable cruise with a low engine speed. This operation produces low fuel consumption and longer range, while the advantages of low noise and low engine wear are also enjoyed. (Brandon, 2008)