Sounded like the old Glow Plug engines but could be electric I suppose. You had to be quick pulling your finger out of the way of the prop when starting one.
Yeah just cuz it is old school and planes on a string, don't mean it will be a walk in the park.
you can do it with cars too, and also a class example of the doppler effect.
Or a boat.
Off course with tethered cars and boats, the challenge are in the speed and getting the most of it, there are no controls on these apart for when they run out of fuel.