Thanks for the education!  Despite heated exchanges I think some good information was posted . </p>

I don't have the experience to be able to add much here.  I will realate some limited experience.  My first try at a lage scale had an 8" box girder beam for the spar.  The chord of the wing was 18".  I made the spar out of spruce caps and luan for the webbing.  The middle 1/3 was has a solid piece of spruce inside the void in the box girder.  The airfoil was hot wired from blue foam.  The leading edge was pine half round moulding.  There was another piece of sprce, 1/4 x 2" on the trailing edge to hang the ailerons on and attach the barn door ailerons and trailing edge. The whole works got a coating of brown paper and  PVA.  </p>

Cave man tech to be sure.  Thing is the wing loading with a ready to fly weight of #22 and 2000sq inches was respectable.  It did fly well, until the elevator departed the structure.  The point is that about he only thing that survived the impact was the wing.  I bet I could have done chin ups on the main spar.  I am thinking there might be something to this construction strategy.  Perhaps a box girder made of lite ply or laminated balsa would have merit? Use the ply and put lightening holes of increasing size toward the wing tips.  I did knock out the wing is a fraction of the time it is taking to assemble my Bridi Big Bee.  The foam composite wing came out much straighter too.  If I had chosen ligher materials,monocote and balsa, I would bet the weight would be competititve with a built up structure.  </p>

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