Josef Papp (1933? in Tatabánya, Hungary – April 1989 in Daytona Beach, Florida) was an engineer who was awarded U.S. patents related to the development of an engine, and also claimed to have invented a jet submarine.
Papp was issued several U.S. patents for these inventions, including his noble gas fuel mixture.
The engine continues to be considered by many scientists as a hoax. Papp's poor physics theoretic background is demonstrated in the abstracts of the patents, which had been criticized by Richard Feynman. Supposedly— no confirmation has been found in contemporary sources and — Papp presented to an audience, including Feynman, an ill-fated demonstration in 1966, in which his engine exploded, killing one man (never identified in later accounts) and seriously injuring two others  Feynman is said to have written an article for "LASER, Journal of the Southern Californian Skeptics" (reproduced in text form by the Museum of Hoaxes) asserting that Papp was a fraudster and the explosion an attempt by Papp to avoid discovery, although he notes that Caltech settled with Papp out of court.
- (U.S. Patent Nos. 3,680,431, U.S. Patent 4,428,193, and U.S. Patent 3,670,494)
- R. Feynman on Papp perpetual motion engine; said to have been "Originally published in LASER, Journal of the Southern Californian Skeptics", date not listed
- http://hoaxes.org/comments/papparticle.html which has a text that it identifies as being drawn from an article "The Dream Machine" By David Ansley, San Jose Mercury News (August 27, 1989), p. 8; "Papp became frantic; the engine was running without any controls, he said. Feynman relented and gave up the plug. Papp put it back in the socket right away and the engine blew apart ... A Mattel engineer died"; although Ansley was the Science & Medicine Editor for the San Jose Mercury News, a search of the archives of the Mercury News does not show an article written by him between August 9 and September 15 of 1989, nor an article in the Mercury News titled "The Dream Machine"
- Papp submarine page in the museum of hoaxes
- Sutton, H.I. (12 January 2015). "300mph home-build Supercavitating midget submarine". Covert Shores Blog.
- U.S. Patent 3,670,494
- U.S. Patent 3,680,431
- U.S. Patent 4,428,193