You may have always thought that a propeller is just a propeller, that it exists only to move an aircraft forward. However, there is so much complexity in the world of aircraft propellers, including their design and the various types of propellers in use.
With that being said, let's take a look at some of the different types of propellers and why they exist.
Fixed Pitch Propellers
Fixed pitch propellers are made out of one single piece of material and the blade pitch cannot be changed. Fixed pitch blades are typically made from wood or metal.
- Wooden - Before WWII, wooden propellers were pretty much the only show in town. Wooden props are not carved from a single piece of wood but instead made of over five separate plies of wood that are laminated together to prevent warping.
- Metal - During their inception, metal propellers were made from steel and used for military applications. Now, propellers are constructed from a single piece of strong aluminum alloy. The majority of planes in service today have metal propellers due to their strength and longevity.
Ground Adjustable Pitch Propellers
As you may have guessed, with ground-adjustable pitch propellers, the pitch of the blades are able to be fine-tuned based on the aircraft they are to be used on. This allows for a single propeller to be applied to a variety of applications. Other benefits including the ability to compensate for different flying conditions, such as differing takeoff altitudes, and modifying the way an aircraft performs. This type of propeller works by employing a split hub that has clamps on the end of each blade, allowing the pitch adjustment to be made.
Other Types Of Aircraft Propellers
- Controllable Pitch - Using a hydraulic system, a pilot can adjust the pitch of the propeller while in flight giving more control to the flight characteristics of the aircraft.
- Constant Speed - The goal here is to maintain an engine speed that is constant. Using hydraulics or electrical means, the blade pitch is adjusted to compensate for increased or decreased engine power.
- Two Position - This type of propeller has two pitch positions the can be adjusted by the pilot in the cockpit.
- Reversing - Reversing propellers are constant speed propellers that are able to add negative pitch to the blades which produce negative thrust. This is often used to shorten the amount of runway need when landing larger aircraft.
- Full Feathering - Another constant speed propeller that has the ability to adjust its blades into the wind and eliminate drag in the event of an engine shutdown.