I thought of CO2, but I couldn't figure out how to ignite it with a pinewood
derby start. I'm not sure if we can stand there and start it when the gate
drops or not. I think ignition would take some creativity. Maybe something
could be worked out to puncture the cartridge like a gun hammer does,
triggered by the initial motion of the car. It would roll for a second, the
hammer would drop, and vrrRRRROOOMMM!!!!
would probably blow right off the standard pinewood derby
track.
Hitting someone in the head would be just the thing Murphy would command.
This is also quite a problem, but I'm sure enough mass and downforce wings
could keep it down, but jumping the track is definitely a possibility, the
rails are very short for each lane. (I guess nobody ever figured a standard
pinewood derby car would jump a track and take out a spectator).
Another consideration: The track is 30ft long. How far do CO2 powered
cars go?