One of the biggest challenges that stymied researchers and aerodynamicists in the 1940s through the 1950s was the so-called “sound barrier:” Nearing the speed of sound, aircraft of that era encountered heavy stick forces and airflow separation from the wing, and pilots sometimes lost control, usually with fatal results. Toward the end of World War II, German researchers and engineers were very close to a solution to this problem with modestly swept-wing aircraft, but their designs never left the drawing board. After the war, the Allies recovered the science and furthered their own research into swept-wing aircraft to easily (and controllably) exceed Mach 1.
World War II German engineers also explored the flight characteristics of a movable single wing. One of their designs, the oblique-wing Messerschmitt P-1109, was first drafted in 1944. A high-mounted wing would swivel on its vertical axis, sweeping one wing forward and one wing back to enable the aircraft to achieve high-speed flight without changing the center of lift, and with less thrust. For takeoff and landing, the wing would be positioned to a symmetrical straight-wing configuration, thereby optimizing performance for those phases of flight over swept wing aircraft. The P-1109 was never built, and it isn’t known if a wind-tunnel model of the aircraft was ever constructed or tested.