Calculating CG
 

Hi all, i'm finishing up building an Ohio Ultimate Bipe (63"ws). The plans show the CG to be 4 in from the leading edge of the top wing. That looks really far forward (and I can't call them since they are no longer in business).

How do I calculate the CG for a bipe with positive stagger, swept wings, AND remember the center section of these wings has an un-swept portion?

thanks, David Soniat

CG
 

May i suggest you obtain the new April issue of Model Airplane News. There is a very good article there that cover all you wish to know.

Calculating CG
 

Posted this same question on another website and got this answer. Haven't tried it, but it sounds logical. "Find the MAC of the top wing and the bottom wing. Draw both MAC's in the side view. Draw a line from 25% of the top wing's MAC to 25% of the bottom wing's MAC. Divide the last line into two segments. The top segment length is proportional to the area of the bottom wing, and the bottom segment length is proportional to the area of the top wing. The point that is between the two segments is the aerodynamic center of the top and bottom wing together. Put your CG there to start with, and move it back in small increments between test flights until the desired reduction in stability is obtained." Good luck!