Balance on swept back wing

take the 'average' of the area of all wings, and project that as a single unswept wing, and use normal rules.

My tiger moth flies fine with the CG about 1/3rd of the way from the rear cabane strut to the forward one.

About 65% of top wing root chord.

On a constant chord wing, the balance point will be the same along the span. Treat it like a straight wing. However, on a biplane, the other wing must be considered also in finding the CG.

All planes need a CG (Carl Goldberg) to fly. This point is named for the famous R/C manufacturer and designer, Mr. Goldberg.

Most kits have a CG located somewhere on the plans. If yours is missing, I have several left over that I'll be happy to sell at a very reasonable price of $10, including shipping. :) Dr.1 Driver "There's a Hun in the sun!"

The CG point might be better calculated a bit forward of the span midpoint on a swept wing. The outer portion of the wing panel doesn't carry its share of the weight because of spillover (which causes tip vorices), so the centre of pressure of a panel will be inboard of the halfway point by a few percent. The aspect ratio of the wing will determine how much of the tip lift is lost. Probably better to make the airplane a bit noseheavy, then adjust for the desired flight behavior. The calculations to find CP on swept wings and biplanes can get complicated.

Dan