The aspect ratio of your h.tail will affect both the max coefficient of lift possible and the stall angle of attack of the h.tail.

You can hit the books and work out all those values exactly, or.............

Keep the AR around or above 4 and you'll be safe. I just measured my Tiger2/CalmatoSport and it's got a tail AR of 1:3.5 and that's a bit chunky I believe.

I have a very popular ARF that's just a model airplane, not a semi-scale or such. It has a very low aspect ratio tail. It's almost square. I've built a replacement h.tail for the sucker that has an AR of 1:4.5 and plan to replace the chunky one just to prove something. The airplane will very barely snap roll. I think that's because the chunky tail isn't effective at stalling the wing. While it's struggling to pitch fast enough to stall the wing, it's also BLOWING UP the drag back there like crazy. But I haven't taken the time to retrofit the new tail (been pumping out ARFs like they were going out of style). The airplane is very stable in pitch simply because it's got enough h.tail volume. But that shape isn't very efficient at producing pitch changes. The model is obviously designed to be very "safe" in pitch for the average flyer. And I'd like to loosen up the bird a bit. And I'm sure this will do it.

whatever.........