I was reading over this post and it occured to me that I have never seen a general formula that relates this information. Is there one or is this just what you have had good results with?

I am looking for a formula that relates rear moment arm to horizontal stabilizer area and wing area.

While I am at it, is there a webstite or anything of the like that ever had formulas like this one? I have seen websites describe how to make a simple trainer and the like, they just used the chord of the wing times X to pick a tail moment. I am looking for something a little different.

Reason I ask is I want to design a plane with servo's in the tail, so this would add tail weight, so making a tail moment shorter would decrease this effect, at the same time it would change the effectiveness of the horizontal stabilizer.

Steve