[fma]

I've watched people fly RC airplane and helicopters with gas engines. They still exist, and there are air fields for them. I've seen them since the 90s as a kid. They aren't expensive but, are bigger and require an actual landing and takeoff area.

https://www.hobbytown.com/gas-rc-airplanes/c7574

[TylerE]

Those aren’t usually gas, but rather a nitromethane mix, runs off glow plugs (saves all the issues of timing, spark plus, distributors...)