"Some of the earliest stories about German flying saucers date back to an inventor named Victor Schauberger ... One of Schauberger's projects was to produce a flying machine, saucer shaped, that used a "liquid vortex propulsion" system. His theory was that "if water or air is rotated into a twisting form of oscillation, known as a 'colloidal,' a build-up of energy results, which, with immense power, can cause levitation." ... There are also reports that, according to a letter Victor Schauberger wrote to a friend, a full-sized prototype of one of his designs was constructed using prison labor at the Mauhausen concentration camp. This craft flew on February 19th of 1945 near Prague and obtained an altitude of 45,000 feet in only 3 minutes. The letter goes on to say the prototype was destroyed by the Nazis before it could be captured by the Allies."
"As Sir Roy Feddon, Chief of the Technical Mission to Germany for the Ministry of Aircraft Production stated in 1945...
"I have seen enough of their designs and production plans to realize that if they (the Germans) had managed to prolong the war some months longer, we would have been confronted with a set of entirely new and deadly developments in air warfare."
... That these events occurred is also supported by former CIA agent Virgil Armstrong who commented "We know that in the early parts of the war there were certain factions of the Allied forces that did not believe he (Hitler) had a secret weapon and it wasn’t until the Americans made much emphasis of this that they began to look at it seriously and indeed did discover that Hitler not only had a secret weapon, he had what we would call today a UFO or spacecraft.
So cutting to the chase, Operation Paperclip was a formerly classified (until 1973) Top Secret project in which the American government imported appx 126 German scientists after the war. The OSS (now the CIA) cleaned up their records because President Truman did not want to let "true" Nazis into the US, much less put them on the payroll. But they did, because they wanted this very technology - either they did it or the Russians would do it (and may have for that matter with other scientists). The "operation" is so old now, that at least some of it's secrets are no longer classified. It turns out however that the chief scientist on the NASA Apollo moon project - Dr. Wernher von Braun - was a former Nazi scientist. The "damage controllers" have always maintained that "they weren't really Nazis" but were simply men of science forced to work for the Nazis. Truth or Fiction? You decide.