FS 32: A NEW GLIDER PROJECT WITH RETRACTABLE EXTERNAL AIRFOIL FLAP

Abstract

The FS 32 of the Akaflieg Stuttgart is a glider project to test a new wing section which can be used in two configurations: A) Hinged flap: The performance is equal to that of the flap wing sections of modern 15-meter class ships, B) External airfoil flap: The flap is lowered below the main wing which closes the trailing edge from 50 percent of the chord. An elastic membrane gives a smooth rounding. The maximum lift coefficient is about 2.3 at a profile drag coefficient of about 0.02. The extended flap configuration is made for thermaling only. For wide thermals and high speed flight, the flap will be retracted. The name of the wing section is FX 81 k 144; it was designed in the laminar wind tunnel of the University of Stuttgart by Mr. Althaus assisted by a member of the Akaflieg. The FS 32 will be a glider of the 15-meter class. The flaps, which extend over the whole wing span, will serve as aileron, hinged flap or external airfoil, depending on the configuration. The T-tail gets also a new wing section of 12 percent thickness. The vertical tail uses glass fiber prepregs. The fuselage will be made in the molds of Schempp-Hirth's Ventus B. Carbon and aramid-fibres will reduce the weight.