To your reply #4...

That sounds more like what we'd call "whip control!" It can be done without elevator control, but an important point to flying ANY model tethered is a control to adjust its altitude in flight.

Whip control depends on YOU turning around fast enough that centrifugal force keeps the line taut. (If a control-line bellcrank is installed to operate the elevator you'll need two lines and a 'handle' to rotate it so it can move a pushrod to a 'horn' on the elevator.)

Whipping requires pretty fast stepping around. Without elevation control you can do very little more than just swinging it around like a rock on a string. You'll be too busy keeping up the needed speed, and trying not to get VERY dizzy, to enjoy it for very long.

An engine powered model like Tom N suggests allows you to fly a circle of more than 30' radius, and to turn around will take a more comfortable 3.5 seconds or longer. You can much more easily keep your feet from getting tangled up...

Tom's points about fuel proofing are very important. Fuel for the little Cox engines is mostly alcohol, which could be used as a lacquer thinner. It also has a percentage of nitro to help the engine operate. Both are good solvents. Oil is mixed with them in the fuel, and it can soak into the wood and paper as the exhaust blows by. ...Makes things heavier AND weaker, not to mention less pretty.

If there are any model clubs, or active flying fields near you, you might find some fliers there who HAVE flown control-line. They can help. Most will probably try to convince you to "go RC," because that's what they are enjoying now. In over 60 years of messing with model flight, I have tried almost everything (before the recent quads - they don't interest me.) Only control line flying is physical, you FEEL the model in flight, and as you control it. Joysticks on a transmitter don't do that. Pre-setting controls on a free flight model gives NO physical feedback once you turn it loose.

I like to fly what I'm flying. CL requires that, and I enjoy it..