ENGINE VIBRATION EFFECTS

Model internal combustion engines, usually one or two cylinders, tend to transmit their power to the propeller in a series of rapid jolts which cause great stresses in the propeller blade. There is also an aerodynamic effect of almost unknown importance. It may be that the boundary layer is repeatedly stripped off and left behind as the blade accelerates after

the power stroke of the motor, to re-form briefly before the next stroke. Just what effects this has on the efficiency of the propeller is hard to say. So far as known, no serious research has been done on the matter. This effect is not important with electric motors.