On Saturday, February 22, 2014 11:14:30 AM UTC-5, son_of_flubber wrote:
Let's say I'm on low tow and fly perpendicular to the "tube" of rotor (aka horizontal circular air flow/ vortex)... The tug goes abruptly up, the glider goes abruptly down. When the glider pulls down on the tug tail, can it increase the tug AOA and stall the tug wings?

No- Our experience is that you can't pull the tail down that much. We have towed at speeds so low in low tow when testing that the glider was adding to the stability of the pair by keeping the tug straight.
In any case it is so obvious that the glider pliot will take corrective action.
UH