ORIGINAL: David Gladwin

Actually, Tom, the difference between upright and inverted spinning is not a function of wing planform it is wing SECTION AND INCIDENCE. The Bobcat wing and presumably the Kingcat since you align the two, has a thick symetrical root section tapering to a semi-symetrical tip which is washed out. At the stall the root stalls first, as it should, and makes the spin entry uncertain and the spin itself, oscillatory. Inverted, we now have a wing which has an adversely semi-symetrical section (flatter on top) and washed IN. Thus at the stall the tip stalls first, making the spin entry cleaner and the spin more stable.

That section change is what causes the wing rocking on the Bobcat as it gets near the stall, an excellent visual indication of the approach to the stall in a model as we have no tactile warnings of the stall or an ASI to refer to!

Thats exactly how my Bobcats behave and I have done great number of spins with them , both upright and inverted.

I suspect that if these models had symetrical section wings they would stall and spin in similar fashion uright and inverted but we would lose the benign handling at the approach to the upright stall.

Regards, David Gladwin.