I'm building the tail-plane of my wooden aircraft and the plans have
specific measurements of the ribs every couple of inches to get the
shape from leading edge back. Unfortunately when I built the ribs it
came out looking as if it would create a whole lot of drag. In fact
when I follow the measurements, the first 3 inches go from 1/2" to 3"
in thickness immediately, and then smooth out. Not only does this just
look wrong, but not even close to the drawing supplied. I've checked
my numbers 3 times now, and keep getting the same results. Can anyone
tell me where to find information on the design and construction of
tail-planes? I may have to redesign this part.

Tailplane drag is not likely to be all that significant in the grander
scheme of things. A thicker tailplane can give you more authority. The
TurbineLegend and its descendants had tailplane thickness of either 13
or 16% (forget which), and I believe the RV series is at 9%. This isn't
an engineering answer, of course, but it doesn't sound to me like you've
necessarily got a problem.

What kind of plane is it, and what speed range? What are the chord,
thickness, and span of the tailplane?

Ed Wischmeyer