 These balance weights are tear drop shaped (to reduce drag), which make them appear quite different from spades, although both project forward and below the aileron.In addition to reducing flutter, mass balances also reduce the stick forces required to move the control surface in flight.Some aileron designs, particularly when fitted on swept wings, include fences like wing fences flush with their inboard plane, in order to suppress some of the spanwise component of the airflow running on the top of the wing, which tends to disrupt the laminarity of the flow above the aileron, when deflected downwards.