Different types of Propeller Blade
|Design||Fixed when installed||Only when stationary||Pitch can be adjusted while the propeller is rotating|
|Operation/Use||Best performance during takeoff and climb||Limited efficiency in different flight requirements||Can adjust during any flight condition|
|Pilot Control||N/A||N/A||Can be controlled by the pilot|
|Constant Speed||Reversible Pitch||Feathering|
|Design||Automatically changes the blade’s pitch||Blades can be rotated at a negative angle||Blades can be angled parallel to the flight direction|
|Operation/Use||While absorbing additional energy, the propeller can remain constant||Utilized for landing assist and maneuvering in the ground||Contributes to reducing drag during engine failure|
|Pilot Control||Can be controlled by the pilot||Can be controlled by the pilot||Can be controlled by the pilot|
How does a propeller produce thrust?
The propeller produces thrust the same as how the aircraft’s wing produces lift. But this time, instead of lift and drag, the main aerodynamic forces produced by a propeller are called thrust and torque.
The aircraft wing’s airfoil produces lift by the difference in pressure on the upper region (low pressure) and lower region (high pressure). Since the upper airfoil area has low pressure, the velocity of the air is higher on this part. Thus, producing lift.
The same concept applied to the propeller, the spinning propeller creates lower static pressure in front of it and a higher static pressure behind the propeller. Thus, creating thrust.
Methods used in checking tracking of propeller blades
- Turn the propeller in the beginning so that one of the blades is pointing straight down.
- Place a block of wood right beneath the blade, then mark the wood with the blade’s precise path.
- Keep the wood block in place while you turn the propeller to the subsequent blade.
- Rotate the propeller slowly to see if the following blade “tracks” or lines up with the mark left by the prior blade on the block. The difference in blade track should not be greater than what the propeller manufacturer specifies (usually plus or minus 1/16 inch).
- Propeller shops should fix bent or damaged blades as quickly as possible if a propeller blade is out of alignment.