I have noticed that many of us here like model building and home made stuff. As a child in the 70's we used to fly control line planes. Your opponent & you would stand in the middle of a circle and fly your model around chasing each others tails. When you got behind him, the tail / ribbon would be ripped off with the prop. Now i for one are to old to spin in circles. Why not automate the middle part and control via linear actuators. Yes old school wires. A easy to build. B no interference. C you don't fall over when you get dizzy! The planes can be electric or glow plug and they can fly in either direction. Just an idea from my inner child.