Flight, May 1932
Increasing the Speed Range
German Plane with Variable Wing Area and Profile
By EDWIN P. A. HEINZE
PROF. DR. SCHMEIDLER, of the College of Engineering at Breslau, in Germany, has developed a wing, the area and profile of which are
variable in flight to the extent of one-fifth of the full wing area. The manner in which the problem has been solved is very interesting. It is materially different to what has been done in this direction hitherto.
The invention was demonstrated on a monoplane, the wing of which contained a trailing edge portion having the shape roughly of a right-angled triangle, the acute angle of which is pivoted inside the wing at the tip end, while the side opposite is held in a guide on the cabin wall, or rather inside the central section of the wing, which covers the cabin. On its lower side this trailing edge of the wing is provided with a toothed rack, which engages with a pinion on a shaft passing through the central main-wing section to the other wing, where it likewise carries a pinion similarly engaging with a rack on the other wing section. The pinion shaft also carries a chain sprocket, and a chain transmission leads to a sprocket by the side of the pilot's seat, where a handle with a pawl arrangement is provided. The handle is worked in pump-handle fashion, and by its means the trailing edge portions are pushed out or pulled in. The retractable sections are so shaped as to form a continuation of the main wing profile so the latter assumes a different camber when the sections are pulled in.
The invention was demonstrated in flight, as also when starting and landing. With the wing sections drawn in, the starting distance was very materially increased (to the extent, it is asserted by the inventor, or 40 to 50 per cent.). In flight the drawing in of the wing sections effected a very pronounced increase of speed.