Between 1946 and 1976, 41 C-47 Skytrains were active within the Belgian Air Force. And recently I was lucky enough to get my hands a propeller blade of this iconic aircraft.

This type of propellor was made by Hamilton Standard and was used on a variety of aircraft. It's a variable pitch propellor. This means that the angle of attack of the blades can be ajusted to fit the varying flight conditions. This makes it more efficient than a Fixed-pitch propellor. It also has an impact on safety. When for example one of the engines stopped working, a fixed-pitch propellor would have caused a huge amount of drag. A variable pitch propellor can be fully feathered in a nutral position creating far less drag.

The Blades are put in between two clamps but can still be rotated around their axis. Due to the rings and the curved cuffs on the propellor blade’s end inside the clamps, the blade is blocked from getting loose. Inside the cupola, there is a cam and piston system which operates hydraulically. They drive the teeth at the bottom of the blade’s in order to rotate them at the same time into more or less pitch. In this case between 18-88 degrees. The pitch control is executed by the governor and is set related to the engine thrust of the aircraft.