40% Stab size or 20%?

From: ykleetx <ykleetx_at_gmail.com>
Date: Sat, 23 Oct 2010 02:07:01 -0000

I notice that many F1D, EZB, and other models often have a stab size of about 40% of the main wing area. I am wondering why. I would reason that more than 40% increases the drag too much and having less than 40% significantly reduces the effective area of the lifting surfaces. The conventional wisdom is that the stab is not as efficient as the wing, but for maximum duration, indoor models need to use significant amounts of lift from the stab. 40% stab size seems to be a sweet spot for many models.

On the other hand, I see that indoor gliders have very small stabs. Something like 10% or less. Having a smaller stab allows gliders to be launched at extreme conditions required for high ceiling launches. A larger stab may not be strong enough to tolerate the high G's encountered at launch.

But how about a Cat I glider? I have never build a real indoor glider, so I am only guessing here. I imagine that a larger stab can withstand the decreased stress of low ceiling launches. So why not a 20% stab on an indoor glider, or 30%? Something more than 10%

With the Hunt design program, many have noticed that a stab less than 50% gives better results. I recently tried 40,30,20,and 10% stabs for my EZB using the Hunt program. I found that the 10% stab performs significantly better than 40%. Is this real? Or is it just an anomalous result from the program? I'm curious enough that I will do some experimentation in the future.

If you have some insights on this matter, please share them. I would love to hear what you think.

-Kang
Received on Fri Oct 22 2010 - 19:07:09 CEST