On Friday, March 22, 2019 at 10:22:07 AM UTC-7, I wrote:

Taking the ASK21 maximum non-lifting mass of 410 kg as our metric, the ratio in question is 1000/410 = 2.43.

I think I miscalculated.

If we're considering the root bending moment caused by a launch that applies 1000 kg downward to an ASK21, we also have to consider the load applied by the non-lifting mass of the glider itself. The load being reacted by the wings is actually:

1000 kg delivered by winch cable
410 kg delivered by non-lifting mass of glider
------
1410 kg

The ratio 1410/410 = 3.44 is the equivalent g load of the bending moment reacted by the wings. Which puts us back in the neighborhood of the 3.5g I originally cited.

--Bob K.