Physically? A lot harder than converting it to unleaded gasoline. For one, existing aircraft are designed around storing the heavy fuel near the center of lift/

Physically? A lot harder than converting it to unleaded gasoline. For one, existing aircraft are designed around storing the heavy fuel near the center of lift/mass. (One benefit, the aircraft keeps its trim as the fuel is burned.) This video by Real Engineering [0] is a great overview. You could fit a propane cylinder into the tail of a Cessna 172, but now there's a lot more weight aft, the aircraft might be difficult to trim and exhibit unsafe handling characteristics. This same packaging issue exists with hydrogen-powered aircraft. Retrofitting is infeasible, lifting body designs are one possible solution. Administratively, getting the FAA to certify it? Hahahahahaha. [0] https://www.youtube.com/watch?v=C_BK7PRugK4 https://www.youtube.com/watch?v=C_BK7PRugK4