[F4U-1_Corsair]

well, I doubt that a UFO aircraft (a literal one this time) would be handled correctly by the game engine, and plus, Isn't there some doubt it was even intended to be a levitating craft?

Also, like several other ideas, Its likely the idea, while sound, would require materials or other beyond what the germans had, not unlike their ideas for an "electric gun", which we would now call a rail-gun, which they lacked the materials to make even as effective as a typical gunpowder weapon.