Turboprops are one of the most popular types of aircraft engines. Unlike turbofans, they don’t rely on exhaust gases to produce thrust. Instead, turboprops burn a mixture of fuel and air to turn a propeller blade. Propeller blades, however, have different parts, including the blade root.
What Is the Blade Root?
The blade root is the part of the propeller blade that connects to the hub. It’s essentially the innermost end of the blade. When installed, the blade root sits close to the engine within the propeller hub.
Common features of blade roots include the following:
- Thick, heavy-duty construction
- Precision-machined surfaces
- Fittings or sleeves
- Pitch change linkages
The Different Parts of a Propeller Blade
Propeller blades used in turboprop airplanes typically have multiple parts. The tip, for example, is the outermost part. It’s located farthest away from the hub and features an aerodynamic shape to reduce drag.
The leading edge is the thick edge of a propeller’s main body. It’s designed to slice into the air as the propeller rotates. The trailing edge, on the other hand, is the thin edge of a propeller’s main body. It helps to smooth out the flow of air while also reducing drag and noise.
Opposite of the tip is the blade root. It typically consists of a thick, heavy-duty section that connects the propeller blade directly to the hub.
Why Turboprop Propellers Have a Blade Root
The blade root serves several purposes, one of which is to secure the propeller blade in the hub. Propeller blades are exposed to extreme forces during flight. As the blade spins, it will create centrifugal forces that attempt to “pull” it away from the hub. The blade root is designed to stabilize and secure the propeller blade in the hub so that it can withstand these forces.
For variable-pitch turboprops, the blade root also supports pitch changes. The blade on a variable-pitch turboprop can rotate along its axis. As a result, the blades can change their pitch, which represents the angle at which they bite into the air. The blade root allows for pitch changes with variable-pitch turboprops such as this.
The blade root also helps to transfer torque into the propeller blade. Turboprops work by burning air and fuel in a combustion chamber. This process creates hot combustion gases that turn the propeller blade. The blade root helps to efficiently transfer this torque into the propeller blade.
