You might as well study the Nazi’s anti gravity flying saucers...or perhaps Charles Hapgood’s Hollow Earth Theory. All equally valid.
The NAZIs did have a flying saucer program, not based upon antigravity but straightforward boundary layer control as laid down by Prandtl in the 1920’s. The allies won the war & got all their secrets.
Why would $multibillion companies like Mitsubishi, STMicro, Toyota, and National Instruments stick their necks out for something like the hollow earth theory?
But...but the Kecksburg Incident!
The acorn shaped craft with nazi runes! God man! The Mothership!