Yep. Now look here:
http://perrya.hubpages.com/hub/The-Flight-of-the-German-Flying-Saucer-Feb-1945
"Development on the saucer designs began in 1941-43 at the Prag, Czechslovakia, airbase under Ernst Udet and its main engineer was Georg Klein. In 1944, the SS took control of the secret project. . . . According to Klein, a saucer flew on February 14, 1945. According to one witness and test pilot, another saucer flight occurred as early as August or September,1943, at this facility. This saucer was about 15 to 18 feet in diameter and about as tall as a man. It was "aluminum" in color and sat on four thin, long legs. It flew to 900 ft. in one test flight."
That was in Germany, and was certainly one of the predecessors of the Avrocar. Do you really think the US just sat back and let the Germans develop such technology without starting a secret program of their own to counter the threat? And after the war, do you really think they just destroyed all the captured technology?