This little guy is one of the only survivors from my childhood one-offs. I think I was maybe 10 or 11. I had just finished writing a book report on Robert Goddard (AKA the father of modern rocketry). The report was either for school or to earn a new BB gun. Anyway, for propellant I would unroll a handful of firecrackers, collect the gunpowder, dump it in an aluminum tube, feed the original fuse through a balsa wood disc and cap the end. I used piano wire, model airplane wheels from the local hobby shop and fishing line to bind it all together.
If you haven't figured it out yet, "R.C.E." is short for Rocket Car Engines! Pretty creative huh?