Thanks, I mentioned it especially to show that we DID some reserch and analyses after first flight of Nobler :-))
And yet, I will mention another great analyze in SN article - about tails by David F. - there he wrote he had good results with thin tail. So that is why.
I would note (since I was very close to that investigation) that there were two real kickers on that on - he was comparing a 1/2" or so flat plate and turbulators wires all over it with a airfoiled stab of similar thickness. We both thought that the consequential issue there was the flat plate and the rather wild pressure gradient's around the LE (and no normal pressure at all on the flat part), and that the airfoil maintained a positive normal pressure over a much larger space. The other key takeaway was that the alignment - which is the best reason to use a flat stab, since it's very easy - generally has a preferred rigging bias (1/4 degree on the Infinity and up to 0.6 on the Trivial Pursuit/Star Gazer and now, apparently, the Thundergazer) which obviates the need to get it exactly 0-0 as previously suggested. BTW, the flat stab and the rigging seems to be FAR, vastly, more critical than the airfoiled stab, probably because of separation on the "bottom" right where the nose radius ends (which is why the turbulators help - it bends the air around that corner).
Also note the variant he *didn't* try - a really thick airfoiled stab like on the Imitation. I think if you want it to be thick (and I don't know) you probably do want it to be a stabilator vice conventional, just because the "top" ends up with a MASSIVE gap in the surface when it is deflected since the hinge line is so thick. Even rounding off the corners on the 1/2 thick stab (flat or airfoiled) seems to make a big difference, but when you have a 1" wide gap in the surface, that has to do something, probably bad. It had absolutely catastrophic effects on the wing when I build several airplanes with "integral flaps". So I am not sure you are comparing apples to oranges when it comes to thick tails.
On the other hand, I agree completely with the observation about the thicker stab Cl - yes, it's *some* better but not tremendously so, and you still have the same separation issue, even if it's slightly reduced. Again, the same thing has been found on wings, with very thin airfoils (like Howard's Jive Combat teammate Phil Granderson) performing better, or much better, than extremely thick airfoils with faulty LE shapes, like the Strega ARF and the Patternmaster.
I had at one point convinced myself that it didn't matter at all, now it is clear that at least the proper LE shape and fairing in the rest of it smoothly makes a huge difference, so again, I agree with you, making it much thicker doesn't necessarily help from an aerodynamic standpoint. I think the 3/4" I suggested above is a good compromise between the aerodynamics and the axle size, but I am still not compelled to make a really thick stabililator system.
Brett