The Opel-Sander RAK.1 (1929) above is described as the first purpose-built rocket-powered airplane. I have looked through the Part 103 documentation and I haven't found anything that says a powered Part 103 ultralight aircraft must use an internal combustion engine or a propeller. So here's an idea...what about building a rocket-powered self-launching glider under Part 103? There are lots of practical questions to answer, to be sure, and it would probably be totally impractical but would it be legal in the USA as long as it met the weight and speed (and fuel, if liquid) requirements?
