U.S. Patent Specifications

An aeroplane wing having a laterally elongated opening leading from the lower to the upper surface thereof, a tube with its inner walls smooth and free from abrupt changes in direction, said tube being pivotally mounted about a laterally extending axis adjacent to one of said surfaces, disposed in said opening, and occupying substantially the full depth thereof, said opening having a lateral recess adapted to accommodate the end of said tube remote from said axis, and control means operable for rocking said tube so as to bring said last‐mentioned end alternatively into said recess and into register with the end of said opening in the adjacent wing surface.