There is a circulation, or vortex which exists along a wing producing lift. At the wing tips, the axis of this vortex gradually turns 90 degrees and forms the tip vortices which trail behind the wing tips. Along the span of the wing, the vortex produces an up-wash ahead of the wing and a down-wash behind the wing. The acceleration of the down-wash times the mass of the down wash is equal to the lift force. For a given amount of lift the down-wash is short and intense for low aspect ratio wings but longer and less intense for high aspect ratio wings. It is the lower intensity of the vortex at the tips that produces lower induced drag. If the wing tips are are equipped with infinite tip plates, the vortex is cut at the tips and there is no vortex flow beyond the tips. The two dimensional flow at such tips is more efficient. For finite tip plates the vortex is reduced but not eliminated. Various practical tip shapes can affect the flow around the tip by moving the tip vortex in or out a small fraction of the wing chord at the tip. This small change in effective aspect ratio has only a small affect on the induced drag. Unless the mission of the aircraft involves fuel economy, range or glide ratio the small differences in drag are quite inconsequential. In the case of aerobatic aircraft, drag which limits acceleration can even give a competitive edge.