Those engines were developed for model aircraft. Some people have put them on full size gliders. There’s a story that some bloke did that and discussed approval with the national approval agency, could’ve been CAA, or FAA. He wanted two, as a single one didn’t have the power. They then got into the certification rules for twin jets, which would have made the process prohibitively costly. He responded enthusiastically saying that now all hours on the plane would count towards multi jet engine pilot certification. They revised their view.
This racy-looking 12-rotor coaxial multicopter has been filmed in Croatia pulling extreme rolls and loops, and carrying a human on board. Not at the same time, mind you, but still, to see a drone of this size pulling stunts like this is astonishing.