I have a simple method of determining this. I raise the tail wheel until the top wing is level, then hang a string with end weights ( I tie nuts onto the string ends) over both wings. The distance between the strings is the whole chord, and you apply your percentage to that. The typical percentage on these older bipes is anywhere from 25 to 28% back from the front string, and I think I used the 25% on my Waco YMF, which flew beautifully.

I haven't set up my GP Super-Stearman yet, in fact I came in to see what the general consensus is, and there clearly isn't one here in this thread. On to the next thread!

Jim [8D]