First, a bit of background.
In the early 1900's, French aeronautical inventor Lucien Chauviere saw commercial success with his scimitar shaped 'Integrale' propeller design using laminated wood. 'Scimitar' comes from the shape of the blades, similar to a scimitar sword, which have an increasing sweep along the leading edge. Nowadays, scimitar propellers are constructed of lightweight or composite materials, which sees the combination of light weight and efficient aerodynamics producing more power and reduced noise.
So despite looking their sleek, stylish appeal, what makes the scimitar propellers better than their conventional straight blade counterparts?
Firstly, the shape of the blades aid in optimizing the performance of the propeller. As the blade tips on a propeller approach the speed of sound, they lose performance thanks to the formation of sonic shock waves. Increased drag on the aircraft is a result of the radiate energy from the shock waves. The curved shape of the propeller blades minimises the strength of the shock wave, much like swept wings. This provides optimal performance at higher power and RPM.
Not only does the reduction in the shock wave help optimise performance, it also reduces the noise signature of the blades. Most of the propeller noise comes from the blade tips operating near the speed of sound. The curved shape helps to reduce this noise without compromising performance.
And finally, with reduced drag and an enhanced aerodynamic design, scimitar blades may aid in improving fuel efficiency compared to conventional straight blades, reducing the operating costs.
At Bush Aero, we are proud to supply scimitar blade propellers for a variety of aircraft. In fact, we even run them on our own Savannah!
Check out bushaero.com.au/composite-propellers for more information.