in 1918. The stall-related crash in August 1917 of a Rumpler C aeroplane prompted Lachmann to develop the idea, and a small wooden model was built in 1917 in Cologne, Germany. In Germany in 1918, Lachmann presented a patent for leading-edge slats. However, the German patent office at first rejected it, as the office did not believe the possibility of postponing the stall by dividing the wing.

Independently of Lachmann, Handley Page Ltd