The possibilities of sailplanes designed to use laminar flow control

Abstract

This paper is basically an aerodynamic study of the possible gains in performance that could be made by applying laminar flow control (LFC) to obtain more extensive laminar layers than those existing naturally. Several of the more practical problems such as diameter of a windmill to run the pump are also discussed. While the paper looks well ahead to assess the prospects, it means to be realistic and not to bypass many problems. As an example ol the realism no laminar flow control is applied to the tail surfaces. Yet if someday successful application is made to the wing, undoubtedly there would be serious thoughts about applying LFC to tail surfaces. It is found that for a sailplane of the general quality and characteristics of the Nimbus 3 or ASW 22 the L/D maximum could be increased to about 76. The Griffith airfoil was investigated as an alternate type to help solve the problems of fabrication. Although the Griffith looked very good when flow losses were not considered, when they were indeed considered it was definitely inferior to the conventional laminar flow control system. However the system is so little explored that considerable study is recommended to see if it cannot be substantially improved.