I think there was a russian engine that literally had 2x4's on fire stuck in the combustion chamber in place of torch ignitors or TEAB.<p>If anyone's interested the experimental high-power rocketry hobby is pretty fun, there's a lot to learn and hack on. A lot of people focus on propulsion and formulating, profiling, and flying various solid fuels they develop themselves. This guy is highly regarded <a href="https://www.nakka-rocketry.net/" rel="nofollow">https://www.nakka-rocketry.net/</a><p>Others focus on flight controllers, GPS trackers, and other electronics. <a href="https://altusmetrum.org/" rel="nofollow">https://altusmetrum.org/</a> (i think one of the two owners of altusmetrum is a pretty famous Debian Linux guy from back in the day)<p>There's also "hybrid" engines that use a solid fuel and a liquid oxidizer ( nitrous oxide ). Ex, this guy is probably the most well known in the hybrids side of the hobby <a href="https://contrailrockets.com/" rel="nofollow">https://contrailrockets.com/</a><p>Finally, there's the halfcat guys <a href="https://www.halfcatrocketry.com/" rel="nofollow">https://www.halfcatrocketry.com/</a> who do amateur liquid bi-prop engines in an approachable way. I've working on a design of my own based on their designs and plan to do a static fire in the Fall and hopefully a flight before end of year. The downside with liquid engines in the hobby is governing bodies Tripoli and NAR don't allow these engines at sanctioned launches. You either have to launch privately (including coordinating/paperwork with the FAA on your own ) or at FAR <a href="https://friendsofamateurrocketry.org/" rel="nofollow">https://friendsofamateurrocketry.org/</a>