Aircraft’s propellers are thrust generating components. It has something common with the wing, they both are made up of airfoil sections. The airfoil shape is important in generating aerodynamic forces such as lift and thrust.
Types of propellers are classified on the basis of its pitch. If we consider a perpendicular axis from the center of the propeller the root of propeller line will be almost parallel to the axis at the root and it will be perpendicular at the tip of the propeller blade.
There are mainly two types of aircraft propeller on the basis of pitch one is fixed pitch propeller and another one is variable pitch propeller. Both of these two types of aircraft propellers are again subdivided. Propellers are mainly used in piston-engine aircraft and turboprop-powered aircraft.
Also Read: 4 Major Types of Aircraft Systems
#1 Fixed Pitch Propellers
Fixed pitch propellers are generally two blade propellers and it is the simplest type of propeller design. In this type, the blade angle cannot be changed.
The wooden propellers and the metal propellers are the two main type of aircraft propeller comes under the fixed pitch propeller.
The wooden propeller is the oldest propeller design, which is rarely used in recent days. In this type, the propeller is made up of layer by layer of wood. Usually, these propellers are made from woods like black walnut, sugar Mable, black cherry, yellow birch, etc.
Another type of fixed pitch propeller is propellers made of metals. At the beginning stage of metal propellers, it was used for military aircraft. Now metals propellers are the most common type of aircraft propellers.
These propellers are made of aluminum alloys.
The blades of the metal propellers are thinner than wooden propellers and it has high strength than its wooden counterparts. Metal type of aircraft propellers is less subject to heat Sand cold damages and warping.
#2 Variable Pitch Propellers
In this type of aircraft propellers, the pitch can be changed either from the ground before the flight or can be changed during flight.
#3 Ground Adjustable Pitch Propeller
In this type of propellers, the pitch can be changed by loosening the clamp mechanism that holds the propeller blade.
This can be done only at the ground. Pitch of the blade cannot be controlled during the flight.
#4 Controllable Pitch Propellers
Pitch or angle of the blade of this type of aircraft propellers can be changed during the flight.
This feature allows the pilot to set the appropriate performance for the particular flight conditions. This feature allows the pilot to achieve the desired engine RPM.
#5 Constant-Speed Propellers
A fixed pitch propeller may change its speed during the different condition in a flight, for example, the speed or the propeller slows down during the climb and speed increases during dives.
To keep the propeller speed constant a new feature will be added to the controllable pitch propeller called propeller governor. This device will sense the speed of the engine and adjust the propeller blade to maintain the desired speed.
The propeller governor system works in hydraulic pressure mostly used from the engine lubricating system. This pitch changing mechanism is connected to the engine crankshaft and it is sensitive to the change in engine rpm.
#6 Feathering Propellers
This type of aircraft propellers is used in multi-engine aircraft. During the engine failure conditions by using this method the propeller drag can be reduced to a minimum.
The pitch changing mechanism will change the propeller blade angle to 90 degrees.
In this condition, the propeller blade will be parallel to the air stream and propeller will stop rotating.
As same as constant speed propellers, the mechanism is controlled by hydraulic pressure. During the engine shutdown, the propeller blade will be feathered and locked using a latch.