reached wind-tunnel testing when the Allied forces reached the production facilities. No complete prototype was ever built. Source: http://en.wikipedia.org/wiki/Focke-W...iebfl%C3%BCgel Also, this: The Heinkel Lerche (English: Lark ) was the name of a set of project studies made by German aircraft designer Heinkel in 1944 and 1945 for a revolutionary VTOL fighter