Model Forum / Radio Controlled / Air Models / April 2004

Hi;

I've tried to do a little research on blancing a biplane, but even so, it
seems two trains of thought emerge:

1)  Viewed from the top, consider the combined outline of both wings as a
single wing, and calculate the center of lift as you would for that single
wing.  It seems to me this method would disregard the leading edge of the
lower wing and the trailing edge of the upper wing, meaning you could move
either at will and not affect the center of lift.  That doesn't sound right
to me, unless the overlap renders that part of the wing less effective?
Maybe this is more of a rule-of-thumb method?

2)  Calculate the center of lift for each wing individually, then locate a
midpoint between the two, skewed toward the larger wing based on the areas
of the two.

Number two sounds like the preferred method to me.  Any thoughts on this, or
does anyone have a better idea?

The model, in case you're wondering, is something like a 14" Pitts S1-B.
I'm just setting it up for unpowered gliding at this point, so the main wing
incidence is 0-0, and I have a degree or two negative on the horizontal.

Thanks,
Dan.