Last century I was gifted a gas powered model helicopter with one of these small gas engines. It had a propeller would fly up, run out of gas and fall back down (it had some larger blades to slow its decent).

You started by spinning the propeller and letting it spring back.

How I didn’t loose a finger…

They’re remarkable little devices.

Brings back memories from childhood. I used to build and fly model airplanes (by wire not rc). Starting those engines was also a challenge. I still have a scar on one finger from an engine kicking back when trying to flip the propeller.