Back in the 1990's I was in regular email contact with a guy named Warren York. He claimed to be on a crew that recovered a crashed UFO. It wasn't Roswell; it wasn't Kecksburg. He said on the outside it was like 10 meters in diameter but because of space stretching tech, on the inside it was the size of a football field. He was very specific on the propulsion system: pulsed AC through plasma.