Author Topic: Spar ply type and grain direction?  (Read 244 times)

Offline vands

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Spar ply type and grain direction?
« on: July 29, 2022, 11:35:16 AM »
On my Taylor Monoplane the plans called for the spar face grain to be vertical for max bending strength.  Has there been any reference to grain direction on the Eagle?  Has Gaboon (Okoume) been used for spar webs?  I have all the spruce cut and ribs made and am ready to order the ply for the spars and leading edge.  A good article on butt joints versus scarf joints is in Sport Aviation December 1995 page 77 which require 20 T. for butt joint backing to transfer stresses.

Offline Kamcoman77

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Re: Spar ply type and grain direction?
« Reply #1 on: July 29, 2022, 03:04:24 PM »
On my XL plans the wing spar drawings show hand-drawn grain lines running roughly horizontal. I used 3mm aircraft birch ply with scarfed joints and ran the outside grain horizontally. I think most builders are using butt joints like the plans show and running their outside grain horizontally. Perhaps someone will answer your Okoume question.

 

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