bcol-wax makes a surprisingly good solid fuel, steady and complete burn. Nice job.
Someone tagged gerbil, space, and program. Please modders if you're listening make this a thing.
Staggeringly ineffiecent...but fun. +1
Those are QUITE inefficent.
Firework rocket = useful on July 4, but wait 'til next year.
In the spirit of making rocket engines, I created a pretty good one with Hydrogen, Oxygen and Wax. It does not have the same lighting mechaism but it works good. I stuck 4 together, added fins for decoration, and put a nuke on top triggered by the pressure of the burning, all together making a cool ICBM, check it out! https://powdertoy.co.uk/Browse/View.html?ID=1897043
The National Wolf Space Program NWSP would like you to join them in their engineering program. Please consider.