Frank Stutzman wrote: > What are the interface difficulties you mentioned > in your note, Ron. Rigging aileron linkages are the only thing that I can > think of that would be that much of a headache. The main one I was thinking of was going from a box spar (wide) to a plank spar (narrow). Unless you come up with some massive kluge that joins the plank spar to BOTH the front and rear webs of the box spar, you'll have to just connect it to one web of the forward spar and one web of the aft spar. Access to the end of the spar pin is complicated by the box, unless you make a long enough spar pin to go through both both the webs in one spar. Matching the airfoil shape will take a bit of work, too. The front spar is a bit forward of the maximum thickness of the airfoil, which would make it a bit easier than if it was right at the thickest point. Finally, if you project the box spar all the way through the cabin, you'll see that it needs to occupy some of the space currently used by the control stick and linkage. None of these is unworkable (after all, there has been at least one such Fly Baby built) but could really, REALLY slow up your building process as you try to solve these problems. Ron Wanttaja