Claim: The first jet pack design (oxygen-and-methane-powered rocket with wings each roughly 1 m long) that was developed in 1919 by Alexander F. Andreev was issued a patent but apparently was not built or tested.
Evidence: The first pack design was developed in 1919 by the Russian inventor Alexander F. Andreev. It was oxygen-and-methane-powered (likeliest a rocket) with wings each roughly 1 m (3 feet) long. Later it was issued a patent but apparently was not built or tested.