|All Curved tip hang gliders are not the same -- Experience does make a difference.|
The purpose of the curved fiberglass wing tip design in hang gliders is numerous and is implemented in the simplest possible way. The considerations are a shorter break down package, a more flexible tapering of the tip leading edge tube structure improving the roll rate to attain higher performance, maintaining good trailing edge sail tension and to take advantage of the benefits of a raked or swept aft tip shape. Model builders call it a Sweepette tip design. A modern HLG design today is the Apogee. The Sunseed had raked wing tips in 1974 and the latest research on tip design proves earlier findings from Schuemann, Hoerner, van Dam and others.
Well designed raked tips reduce induced drag as much as 5.5% compared to 3 or 4% reduction for winglets. The good model builder’s rule of thumb has been that the maximum span should be at; near or aft of the trailing edge line. So, in a curved tip hang glider design, the tip grommet and the end of the fiberglass curved tip should be as far aft as possible with the sail or planform closing to a near point at the trailing edge. The point is to get the tip vortex as it sheds off the wing as far aft and away from the low pressure lift producing part of the rest of the wing.
The last and one of the most important aspects of a good curved tip hang glider design is the trailing edge flatness and sail tension in the last tip panel which is usually Mylar for the life of the glider without becoming wavy and loose and flipping up.