Do you know the difference between a variable pitch and constant speed propeller? Most airplanes are powered by either a turbofan or a turboprop. Turbofans are airbreathing engines that burn fuel and air to generate propulsion, whereas turboprops generate propulsion by spinning a propeller blade. While some airplanes have a variable pitch propeller, however, others have a constant speed propeller.
What Is a Variable Pitch Propeller?
A variable pitch propeller is a type of propeller that supports angle or “pitch” adjustments when running. The pitch is the angle between a propeller’s chord line and its plane of rotation. Variable pitch propellers can change this angle when running. They can essentially be rotated along their axis.
What Is a Constant Speed Propeller?
A constant speed propeller, on the other hand, is a type of propeller that spins at the same speed all the time when running. In other words, the RPMs remain constant. Constant speed propellers reduce the need for manual adjustments, making them a popular choice for many small turboprop airplanes.
Differences Between Variable Pitch and Constant Speed Propellers
Variable pitch and constant speed are two of the most common types of aircraft propellers. One of the key differences between them is that the former supports manual pitch adjustments, whereas the latter does not.
With a variable pitch propeller, the pilot can adjust the pitch. With a constant speed propeller, on the other hand, the pitch is controlled automatically so that the RPMs remain constant.
Because they control the pitch automatically, constant speed propellers are more hands-off. Pilots don’t have to adjust the pitch of constant speed propellers. Instead, they can focus their attention elsewhere.
While they are easier to operate — and typically preferred by pilots — constant speed propellers have some drawbacks. They require more sophisticated components, including a governor and a hydraulic system. The end result is greater upfront costs as well as more frequent maintenance. Nonetheless, many pilots agree that constant speed propellers are worth the investment.
In Conclusion
Not all turboprop airplanes use the same type of propeller. Some of them use a variable pitch propeller, whereas others use a constant speed propeller. Variable pitch propellers allow pilots to change the pitch. Constant speed propellers, in comparison, make these pitch adjustments automatically. There are other nuances between them, but variable pitch and constant speed propellers are primarily distinguished by their pitch adjustments.
