Can a rotating blade of a helicopter exceed the speed of sound?
The simple, and not so simple answer is yes. It can exceed the speed of sound if spun fast enough. However, there are several issues. Because the blade is rotating, and not flying straight into the air, then the outer tip will be moving through the air faster than the base. In fact, the airspeed of the blade will increase as you move out. So what will happen is that the tips of the blades will be the first to reach mach 1. A shock wave will form at the tip of the blade. As the blade increases rotational speed, the shockwave will move along the blade as more of the blade goes supersonic. The big problem with this is that the blades really aren’t designed to withstand the stresses of supersonic travel. They will end up disintegrating. It also means that a portion of the blade will be ‘transonic’ (at or near the speed of sound). In this region there are problems with airflow and controllability, which will severely hamper the performance of the blade. Loss of lift and poor control will be
