Keeping it grounded - Tether for flying machines

I have 3 different flying machines sitting on my desk now.

1. Dual-Contrarotor Chinook Style Helicopter
2. Single-Contrarotor non-swash plate Helicopter
3. The Quadcopter in build phase

I would like to make a flight controller flexible enough to fly all three from the same set of hardware, just different bits of software. The blades for the quadcopter arrived recently and with them health and safety concerns about unruly and out-of-control flying machines. To perform motion tests and calibration we had been contemplating a controlled flight platform I finally sketched one up and took it to the machine shop. Hopefully it will be fabricated in a month or so and ready for use with the helicopters and any other aerial platforms the department may have.