Zippermayr's discovered Pfeil (Arrow) supersonic aircraft was under construction in Lofer, Austria at the end of the war. It was designed from Zippermayr's work on a high-speed glider torpedo and possessed a unique high-speed wing shape. Sub-scale models were tested as well as wind tunnel models, but the US Army seized the craft and did not allow the installation of Porsche jet units for it to fly. Rumor was that this was taken back to the US and completed, flown in secrecy. This would not be unusual as the US got the lion's share of German technology, especially radical jet and rocket aircraft, and sent them to Wright Field, then New Mexico, and on over to Area 51. There were two other German supersonic aircraft under construction as well in 1945- the DFS-346 captured by the Soviets and the Lp P.13B, which remains controversial... Read link below for the Pfeil.

http://discaircraft.greyfalcon.us/Zippermayr%20Pfeil.htm