I believe this was in the 90's. There was a very popular TV show about technology and DIY stuff. This guy was not the ordinary DIY-selfer. This was a retired aerospace engineer who actually worked designing jets for a living. Anyhow, after retirement, the guy was bored and he designed a very small jet engine, and some kind of micro-jet airplane to go with it. I think the whole "jet" was not any bigger than one of those ride-machine that kids play with at the mall. A pickup truck was all you needed to move the jet around.
The guy on the show wanted to break some kind of record. He flew the micro-jet through a hangar. That's all I remember and my google-fu has failed me tonight.