Robert Dingus does a lot of math.

The encouraging things you find on the internet. 

Robert Dingus on http://www.homebuiltairplanes.com came across a mostly built Affordaplane.  And he's doing the math to prove out the airframe.  I went far enough to determine "things were all messed up" and gave up.  He's carrying things right on to completion. 

His plane is disastrously over the Ultralight weight limit, but he's ok with that, and he knows it's not an ultralight.  All of the pictures i'm posting, are his.  And if you'd like to see the discussion of the airframe's engineering, it's available in the thread, here:

http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/20852-square-tubing-strength-specs-where-do-i-find-them.html

It's quite the read.  And I do like the choice of pilot seat.  It's what I think is an aluminum lawn chair.  They're very, very light, so it's a good choice in this case.