Over the years investigations have revealed that Nazi engineers were working on disc shaped craft, vertical take off and advanced propulsion systems. After World War 2, the U.S. military secretly took the designs back to the states along with thousands of German scientists and engineers. Two years later in 1947 the first wave of UFO sightings occurs across the United States and then around the world. Could UFO's be secret U.S. aircraft developed from captured German designs?