When teenagers for winter activity my brother and I made a couple of wire frame three wheelers with Cox engines. We ran them in the attic of the house we were in on a 2 x 6 board floor. And since it was an attic storage space it had gaps between the boards. We used about a 5-6' line anchored by a nail. We would have run them in the basement but couldn't figger out how to get a nail to hold in concrete!
Made a heck of a racket. And we just got to listen, we were too chicken to stick our heads out of the stairwell to watch. Mom, of course, wanted to know what the heck we were up to THIS TIME! The exhaust and tire wear left a circle on the floor of the attic. I always wondered if the next house occupant wondered what caused the circle. And we didn't think about taking pictures!