The Devil's Hoverbike
Inventors of the 50s really didn't care about how ridiculous their inventions looked. If it worked, it was a success! This aircraft (if you could even call it that) is an early hovercraft. Luckily, nothing bad happened with this invention, but if the pilot would have one misstep, he'd easily get chopped up by the blades!
The Christmas Bullet
Dr. William Whitney Christmas designed this aircraft with the intention of killing the pilot. It was well-known that if this plane got up into the atmosphere, it would become lethal. Test flight pilot Cuthbert Mills perished as the wings of the aircraft caved in on itself. Super weird all around.