Dave;. .. .When supporting the weight of the helicopter, the blades must have an upwards cone.. .. .The vertical component of the tension in the blade at the blade root holds the helicopter up against gravity (tension in the blade is therefore many times the weight of the helicopter).. .. .It's the same principle as suspending a weight from the middle of a piece of string and pulling the ends out sideways. No matter how hard you pull the two ends of the string apart, you'll never get the string to stretch out completely straight - it will always have a slight 'V' shape.. .. .If the blades stuck out exactly horizontally as you suggest there would be no vertical force component to lift the helicopter up.. . . . <small>[ 03 March 2002, 17:25: Message edited by: Grainger ]</small>