The hobby store used to sell a "jet engine"...wonder if anyone remembers. All it was was a metal container about 2", maybe 2.5" long about 3/4" diameter the tapered top unscrewed. It had a small hole in it. It came with pellets, you'd put one in, screw top on & put a fuse through the hole. It had a metal bracket. You'd light fuse & snap it on bracket.
I mounted one to a plastic model car. A friend & I were at either end of the concrete porch so he could flip it around to me. It worked great until it melted through the car's roof!