Interesting thing about yaw effect with power on at low speed in fixed wing a/c is how extreme it is in high power aeroplanes. Remember reading (think it was in Feet Wet) about a low hour pilot on something hot like a Bearcat, who put on full power for a go around, failed to anticipate the yaw and as a consequence the a/c rolled inverted (fatally for the poor pilot).
Also, non aero pilots are sometimes surprised to hear that the most critical control surface (or perhaps just the one that takes the most thought) when flying a loop is the rudder.