designs were unusual for being not only forward swept but also tailless. Meanwhile in Germany, Hans Wocke was studying the problems of swept wings at the near-sonic speeds of which the new jet engines were capable. He recognised many of the advantages that forward sweep offered over the backwards-swept designs then being developed, and also understood the implications of aeroelastic bending and yaw instability. His first such design to fly was the Junkers Ju 287, on 16 August 1944. Flight tests on this and later variants confirmed the low-speed advantages but also soon revealed the expected problems, preventing high-speed trials. Wocke and the incomplete Ju 287 V3 prototype were captured and, in 1946, taken to Moscow where the aircraft was completed and flown the next year as the OKB-1 EF 131. The later OKB-1 EF 140 was essentially the same airframe re-engined with a pair of Mikulin-design Soviet jet engines of greater thrust. In 1948 the Soviet Union created the Tsybin LL-3. The prototype would subsequently have a great impact on the Sukhoi SYB-A, which was completed in 1982. When the German research reached the United States after the war, a number of proposals were put forward. These included the Convair XB-53 supersonic bomber and forward-swept variants of the North American P-51 Mustang, Bell X-1 rocket plane and Douglas D-558-I. The Bell proposal reached the wind tunnel testing stage, where the problems of aeroelasticity were confirmed. The structural problems confirmed by the Ju 287 series and the Bell X-1 studies proved so severe that the materials available at the time could not make a wing strong and stiff enough without also making it too heavy to be practical. As a result, forward sweep for high-speed designs was abandoned, until many years later when new structural materials would become available. Throughout World War II, numerous fighter, bomber, and other military aircraft can be described as having forward-swept wings, due to the average chord of their wings being forward-sweeping. However, these designs almost always utilized a rearward-swept leading edge, which would technically render them as high aspect ratio trapezoidal wings. The Nakajima Ki-43 is notable for being the only successful fighter aircraft with a truly forward-swept wing, although the forward sweep of its leading edge is nearly unnoticeable. Postwar general aviation Small amounts of sweep do not cause serious problems and even moderate forward sweep allows a significant aft movement of the