I read only the posts through DBMathews first...

I didn't see a mention of the size of the plane. I think you're building way too big of a model for the engine you're using and that's before you add a glider to tow.

I think about 1600 inches of wing should be good and a final weight of no more than 15 lbs (and hopefully closer to 12).

The Eindecker I finished last fall as a G-26 and weighs a little over 18 pounds. It flies but it does not have an excess of power.

Your design sounds like too much for the available power, but then I've never been anywhere near a model tug so take it for what it's worth.

Now if you want to build a motor glider, your numbers are better, but taper the wings.

- Paul