Wood grain orientation in a built-up spar

Seems like the grain in any wood structure should be the same direction it
was in the tree.
Why would the gods do it wrong?

In a wood bow, they use "quarter sawn" blanks. This ends up with the grain
oriented as above. along the length.





"cmyr" wrote in message
...
In my effort to learn/remember/practice correct building
procedures,I monitor several wood aircraft design sights. In the
emerauders group,much discussion about using a wingspar that was built
and purchased by another builder. The Emeraud spar consists of 2
laminated built ip beams,w ply intercoastals, and boxed front and rear
w/ply. The spar in question was made with vertical grain wood, and
laminated with the grain perpendicular relative to the wing chord, I
believe the spar caps and laminations should have grain approx.
parallel to the wing chord. If anyone has a definitive answer that may
even prevent an accident go yo yahoo groups,emerauders

On Jun 28, 2:18*pm, "Ron Webb" wrote:


OK, wood hasn't changed much, but what adhesive are they using? I didn't see
that mentioned.
I'm under the impression that modern epoxy (like West Systems) is stronger
than the parent wood .
That would make a laminated beam a much better idea than this study seems to
show..
-------------------------------------------------------------------------------------

Dear Ron,

It doesn't matter WHAT glue they used, it would still be stronger than
the softwoods we normally use.

This is kinda like the Horsepower Myth, where everyone goes around
citing HORSEPOWER when they should be thinking in terms of torque and
thrust.

So your epoxy is stronger than your wood. Big deal; so's casein, hide
glue, Plastic Resin and even Elmer's vinyl resin. The point here is
that we don't pick our adhesive for it's STRENGTH but for some other
characteristic.

-R.S.Hoover

Ron Webb wrote:
Seems like the grain in any wood structure should be the same direction it
was in the tree.
Why would the gods do it wrong?

In a wood bow, they use "quarter sawn" blanks. This ends up with the grain
oriented as above. along the length.





"cmyr" wrote in message
...
In my effort to learn/remember/practice correct building
procedures,I monitor several wood aircraft design sights. In the
emerauders group,much discussion about using a wingspar that was built
and purchased by another builder. The Emeraud spar consists of 2
laminated built ip beams,w ply intercoastals, and boxed front and rear
w/ply. The spar in question was made with vertical grain wood, and
laminated with the grain perpendicular relative to the wing chord, I
believe the spar caps and laminations should have grain approx.
parallel to the wing chord. If anyone has a definitive answer that may
even prevent an accident go yo yahoo groups,emerauders


Ron, read the next to last line--He believes, as do I, that the top &
bottom caps should have their grain parallel to the CHORD , with
the sides of the box extend the full ht of the spar, thus bonding to
every layer of the top & bottom caps--in this case the caps are not true
caps, but are the top & bottom members of the beam---of course the top &
bottom members have the grain running the LENGTH of the spar also..Jerry

This would be a FLAT sawn board rather than a qtr sawn-edge grain- board
which would probably have to be laminated itself to oppose warpage which
you cannot escape in flat sawn wood otherwise.

On Fri, 26 Jun 2009 00:08:28 GMT, Jerry Wass
wrote:

cmyr wrote:
In my effort to learn/remember/practice correct building
procedures,I monitor several wood aircraft design sights. In the
emerauders group,much discussion about using a wingspar that was built
and purchased by another builder. The Emeraud spar consists of 2
laminated built ip beams,w ply intercoastals, and boxed front and rear
w/ply. The spar in question was made with vertical grain wood, and
laminated with the grain perpendicular relative to the wing chord, I
believe the spar caps and laminations should have grain approx.
parallel to the wing chord. If anyone has a definitive answer that may
even prevent an accident go yo yahoo groups,emerauders


You might look at what some of the old timers did--NACA server
http://naca.larc.nasa.gov/search.jsp?No=10&Ne=26&N=17+45+269&Ns=HarvestDate| 1&as=false


strength of one-piece solid, build-up and laminated wood airplane wing beams

Author(s): Nelson, John H
Abstract: The purpose of this report is to summarize the results of all
wood airplane wing beams tested to date in the Bureau of Standards
Laboratory in order that the various kinds of wood and methods of
construction may be compared. ...
NASA Center: NASA (non Center Specific)
Publication Year: 1920=========================(=Lookie here ---1920!!!)
Added to NTRS: 2006-11-06
Accession Number: 93R20355; Document ID: 19930091065; Report Number:
NACA-TR-35



If you are interested--I can give you a blow by blow of how to get
there--or you can write the help desk--as I did.. Jerry

get the nasa web site up http://naca.larc.nasa.gov and search on the
document id number and you will go straight to it.
Stealth Pilot