In any I beam, such as the KR-2 box spar, any G load tends to move the spar
caps closer together. The function of the webs is to resist that movement
to prevent the collapse of the spar. The strongest direction for lumber is
in the direction of the grain, either in compression or tension. In the
case of the web for the KR-2 spar, the web is always in compression, no
matter if positive or negative G, or any twisting load. The strongest
application would be orienting the primary (surface) grain of the plywood
web in the vertical direction. To get a single piece web to cover a spar
section 7 feet or so, you must scarf the plywood using 2 each 4-foot wide
pieces.
To salvage your original spar with the miss-oriented web, plane it off. One
or two passes with a bench power planer would do it in a couple minutes.
Sid Wood
Tri-gear KR-2 ex-N6242
California, MD, USA
smw...@md.metrocast.net
------------------------------------------------------------------------
Good Morning, So I think I messed up and have to redo the birch ply on the
spars, I scarfed the ply 12:1, but ran the grain horizontal instead of
vertical one side of the main and outer fwd spars before I closed them up.
acceptable? Plane it down? Box the other side of the spars in with vertical
grain? I've read all the post on here from years past and still confused,
horizontal grain..... vertical grain? Sent from my U.S.Cellular© Smartphone
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