A Sailplane Split-Winglet Design Study

摘要

An optimization process was developed in order to design wingtip devices for the Standard Cirrus, a high-performance sailplane. The process is first used to design conventional winglets with the purpose of increasing the maximum cross-country speed of the sailplane. The process is then used to develop split-winglets for the same sailplane for the same objectives. The purpose of this study was to determine the suitability of split-winglets for this application and to understand further how they work. The split-winglet design presented in this study offered a maximum 1.2% increase in cross-country speed over the conventional winglets, with respect to the Standard Cirrus without winglets. This maximum increase was achieved when operating in the weakest thermals. As the thermals strengthened, the performance advantages of the split-winglets decreased to a minimum of 0.3% below that of the conventional winglets. This performance gain in weak weather appeared to be due to the way the split-winglets effected the stall characteristics of the wing.