Asked by: Garry Hale, Swansea
Having fewer blades reduces drag. But two-bladed turbines will wobble when they turn to face the wind. This is because their angular momentum in the vertical axis changes depending on whether the blades are vertical or horizontal. With three blades, the angular momentum stays constant because when one blade is up, the other two are pointing at an angle. So the turbine can rotate into the wind smoothly.