No big deal, but a thought that may be maybe worth expressing. My concern with pre-fab wing skins (any wing skins) is the quality of bond with the spars.
We need to remember that the airplane is literally being picked up by the skin of its wings (well 2/3 of it is). That may not translate to a great force per sq. ft - a typical KR has a wing load of maybe 10 lbs /sq. ft. At say 4G that is 40 lbs /sg Ft - so maybe 27lbs of actual tug on each square foot of wing. We know that the load distribution is not even over the entire wing and the bit covered by the fuselage is counted, but carries zero aerodynamic load, so some areas must handle a bit more - say 38 lbs /sg ft for those parts in a heavy G turn /pull-up. On the face of it, no big deal - that is a mild 1.3G load for a piston twin. Consider the KR wing structure (below the skin) and imagine dividing the top surface of the wing into 1' x 1' squares and screwing a cup hook into each square. Turn it over and hang 38 lbs on each of the 80 or so cup hooks. How comfortable will we be with the bond between the skin and the spar(s)? How about coming back and hanging these weights on the wing after the bird gets to be 20 years old and sees many great gatherings sitting in the sun. The point is that the combined load is transferred to the wing structure via a much smaller area - for a KR this is essentially the spars. The COP moves around a lot, but typical numbers would suggest that the main spar carries the bulk of the load - particularly under high G loads when the COP tends to sneak fwd - maybe even ahead of the main spar. The typical, KR main spar (top surface area) amounts to maybe 2 sq ft. that could well be carrying up to 700 lbs or more. Still not a very big deal, that is only 700/288 = 2.4 lbs /sq ft, but we do need to keep this in mind when bonding the top skin. With his wing skins DD suggests that we taper the spar in section only and leave the plan view (width) constant for more glue area Have a great Sunday Steve J Mark J - Yeeee Haaa (hee haw) ?????
