A Russian by the name of A. Andreev, filed a patent back in the 1920's for a back pack flying device that used Methane and LOX. Most people have never seen this before. The Patent and a description can be found in a book called "Journal of Interplanetary Communications" by N. Rynin. This book was interpreted into English back in the 70's. The most unique thing about this device is that the pump was powered by a wind up spring motor.