Propeller-driven airplanes remain a staple of the aviation industry. While most airplanes used for long-haul flights are powered by turbofans, propeller-driven airplanes still account for about two-thirds of all flights globally.
Propeller-driven airplanes include those powered by piston and turboprop engines. Piston engines feature a combustion engine that burns fuel and air to turn a propeller. Turboprop engines, on the other hand, use a jet turbine engine to burn fuel and air to turn a propeller. Whether it’s a piston engine or turboprop engine, however, propellers are available in different materials.
Wood
You might be surprised to learn that some airplanes feature wooden propellers. During the early days of aviation, in fact, wood was the go-to material for propellers. Even today, vintage airplanes, ultralights and other specialized airplanes still feature wooden propellers.
Wooden propellers don’t consist of a single, solid block of wood. Instead, they are made of multiple layers via a laminating process. The layers of wood are pressed and bonded together, resulting in improved strength and protection from warping and splitting.
Aluminum
Some airplanes feature aluminum propellers. Aluminum propellers have been around for decades. They are strong, lightweight and offer excellent performance in both fixed-pitch and constant-speed propeller systems. Aluminum propellers can also be machined to very precise shapes and sizes.
It’s important to note that most aluminum propellers aren’t made of pure aluminum. Rather, they contain alloying elements. The presence of these alloying elements enhances the propeller’s physical properties, such as its strength, hardness and resistance to corrosion.
Composite
Finally, composite is commonly used in the construction of airplane propellers. It’s become an increasingly popular propeller material in recent years. Composite propellers offer a superior strength-to-weight ratio when compared to other materials. They also offer excellent corrosion and fatigue resistance.
What is composite exactly? The term “composite” refers to the use of multiple materials. For propellers, this may include carbon fiber, fiberglass, epoxy and various metals. These materials are layered or molded together to create a strong and durable propeller blade.
Combination
While some propellers are made entirely of wood, aluminum or composite, others are made of a combination of these or other materials. Wooden propellers, for instance, may feature a thin layer of aluminum on the leading edge. Aluminum propellers may feature a steel hub. Composite propellers may feature an aluminum or steel root fitting. The bottom line is that many propellers contain multiple materials.
