In the past, aircraft used small diameter high-speed propellers for all modes of flight operations. This included take-off, climbing, landing maneuvers as well as loitering. The small diameter propeller spins at a high speed to provide sufficient propulsion. Spinning at a high speed is noisy. Therefore, in applications where it is desirable for quiet aircraft operations during loitering operations, a small diameter propeller is undesirable. Unfortunately, using a larger diameter slower-speed propeller to perform quieter during loitering operations will result in insufficient propulsion during take-off, climbing and landing, and in addition, the larger diameter propeller is likely to strike the ground during takeoff and landing.
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