Brodhead Pietenpol Association

Original Posted By: Doug413(at)aol.com
I have some flat grain hemlock that would make great spars, however, they are flatgrain (not vertical grain). Is this a strength issue, or something else? anyinput? ________________________________________________________________________________

Original Posted By: JamesJboyer(at)aol.com
Subject: Re: Pietenpol-List: vertical grain?In a message dated 4/22/01 11:35:58 AM Pacific Daylight Time, nhh76(at)hotmail.com writes:> I have some flat grain hemlock that would make great spars, however, they > are flat grain (not vertical grain). Is this a strength issue, or > something else? any input?> > Neal,It is not a strength issue. It is that wood expands the least in the direction across the grain. That is why vertical grain (quarter sawn) wood is used for spars. If flat grain were used, it could expand and break the cap strips off the ribs. The hemlock could be ripped, stacked (laminated) and then planed, but that would be a lot of work, or used for some other part of the airplane. Doug Bryant Wichita Ks ________________________________________________________________________________

Original Posted By: kgardner(at)odu.edu
Flat grain wood, also called plain sawn, has a tendency to warp in a cup shape from it's edges.Quarter sawn wood has a tendency to just expand and contract in a vertical direction.The point is, with quarter sawn wood, there is much less a tendency for a spar to warp away from the origonal shape.Bob>From: "Neal Hinson" >Reply-To: pietenpol-list(at)matronics.com>To: pietenpol-list(at)matronics.com>Subject: Pietenpol-List: vertical grain?>Date: Sun, 22 Apr 2001 12:34:10 -0600>>>>>>I have some flat grain hemlock that would make great spars, however, >they are flat grain (not vertical grain). Is this a strength issue, >or something else? any input?>>>>>>>>>>>________________________________________________________________________________