I must have had at least 10 of the "50"-type. When they fuel was getting harder to find, we bought the kind of firework sticks
that you step on and they sizzle and crack. Crushed it carefully and filled the motor with it, it worked very well until I ran out
of fuse and tried to start it by holding a lighter under the nozzle. The whole thing overheated and exploded, luckily missing my
head, eyes etc!!!