Table of Contents
How does propeller feathering work?
On a variable pitch propeller, the drag can be minimized by rotating the blades until they are edgewise to the flight direction. This is called feathering the propeller. At this angle, the propeller does not rotate or rotates slowly; thus, its drag on the airplane is greatly reduced.
What is aircraft propeller feathering?
On many variable pitch propellers, the blade pitch can be increased to the point that the chord line of the blade is approximately parallel to the on-coming airflow. This process is referred to as feathering.
Why do we feather a propeller?
On a multi-engine aircraft, feathering the propeller on an inoperative engine reduces drag, and helps the aircraft maintain speed and altitude with the operative engines.
When would a pilot activate the propeller feathering system?
Therefore, if a propeller is to be feathered, it must be done before engine rpm decays below approximately 800. On one popular model of turboprop engine, the propeller blades do, in fact, feather with each shutdown.
How do small feathering propellers prevent feathering when the engine is shut down?
Featherable propellers have devices to prevent them from going into feather when the engine is shut down at the end of a normal flight and the engines oil pressure drops. These devices, called anti-feather lock pins, are connected to centrifugal flyweights in the spinning prop dome.
What forces are used to feather a propeller?
Almost all small feathering propellers use oil pressure to take the propeller to a low pitch, while counterweights, springs, and compressed air take the propellers to a high pitch.
What is blade feathering?
Feathering the blade means changing the pitch angle of the blade. By changing the pitch angle of the blades you can control the thrust and direction of the main rotor disc. Semi-rigid Rotor System. A semi-rigid rotor system is usually composed of two blades which are rigidly mounted to the main rotor hub.
What is flapping and feathering?
Flapping, the vertical up/down movement of the blades, is not directly controlled. What a pilot controls is the blade feathering or pitch angle. Increasing feathering / pitch generally increases the aerodynamic forces on the blades, which changes the flapping.
When a rotor blade is pitching or feathering it is?
Feathering the blade means changing the pitch angle of the blade. By changing the pitch angle of the blades you can control the thrust and direction of the main rotor disc. A semi-rigid rotor system is usually composed of two blades which are rigidly mounted to the main rotor hub.
What is cyclic feathering?
Cyclic feathering. The mechanical change of the angle of incidence, or pitch, of individual rotor blades, independent of other blades in the system. Cyclic pitch control.
What is feathering hinge?
A feathering hinge is used to change the pitch of each blade. A flapping hinge allows each blade to move up and down to compensate for dissymmetry of lift. Blades are able to move fore and aft or lead-lag, (called hunting) by use of a drag hinge.