Sealing the gap in front of the control surface leads to less resistance and better controllability of the glider. This essentially prevents the flow of air from one side to another and protects control surfaces from dirt (dust) and water.
There are several methods for sealing control surfaces. In newer sailplanes, the sealing is already prescribed by the manufacturer. In older sailplanes that have been constructed without Mylar / Teflon sealing, may be have the sealing retrofit.
Basic sealing with textile tape was used with older gliders, and offers basic protection of bearings and control surfaces and thus prevents air transference from the lower to the upper side of the wings. The condition being that the bearings of the control surface are not in the middle of the control surface seam.
Mylar and teflon seal is used for complete sealing of the gaps in front of the control surface. Teflon tape serves as a stop for air transference from the bottom to the top of the wing. Mylar tape can be attached to the upper as well as the lower surface of the wing and thus slide on the control surface. They enable reduction in resistance, since they close the gap between the wing and the control surface.
For sealing, we use the best materials and approved procedures, so as to provide maximal efficiency and sustainability of the seal.
