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<p class=MsoNormal><font size=2 color=navy face=Arial id="role_document"><span
style='font-size:10.0pt;font-family:Arial;color:navy'>I want to hear about the
Hawaiian Locals!!!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 color=navy face=Arial><span style='font-size:
10.0pt;font-family:Arial;color:navy'><o:p> </o:p></span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=2 face=Tahoma><span
style='font-size:10.0pt;font-family:Tahoma'>-----Original Message-----<br>
<b><span style='font-weight:bold'>From:</span></b> discussion-request@nsrca.org
[mailto:discussion-request@nsrca.org] <b><span style='font-weight:bold'>On
Behalf Of </span></b>Rcmaster199@aol.com<br>
<b><span style='font-weight:bold'>Sent:</span></b> Monday, January 17, 2005
1:25 PM<br>
<b><span style='font-weight:bold'>To:</span></b> discussion@nsrca.org<br>
<b><span style='font-weight:bold'>Subject:</span></b> Re: epoxy joint</span></font></p>
<p class=MsoNormal style='margin-left:.5in'><font size=3 face="Times New Roman"><span
style='font-size:12.0pt'><o:p> </o:p></span></font></p>
<div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'>Interesting,
Gray. Would you also discuss some details about chopped filler (say 1/16"
to 1/2" chop length) and continuous strand filler? Also how material
stiffness and impact resistance are affected?<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'>MattK<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'>In a
message dated 1/17/2005 1:18:24 PM Eastern Standard Time,
amirneshati@earthlink.net writes:<o:p></o:p></span></font></p>
</div>
<blockquote style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt;
margin-left:3.75pt;margin-top:5.0pt;margin-bottom:5.0pt'>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'>-----
Original Message ----- <o:p></o:p></span></font></p>
</div>
<div style='font-color:black'>
<p class=MsoNormal style='margin-left:.5in;background:#E4E4E4'><b><font size=2
color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black;font-weight:bold'>From:</span></font></b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <a
href="mailto:gfowler@raytheon.com" title="mailto:gfowler@raytheon.com">Gray E
Fowler</a> <o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black;
font-weight:bold'>To:</span></font></b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'> <a
href="mailto:discussion@nsrca.org" title="mailto:discussion@nsrca.org">discussion@nsrca.org</a>
<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black;
font-weight:bold'>Sent:</span></font></b><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'> Monday, January 17,
2005 9:57 AM<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black;
font-weight:bold'>Subject:</span></font></b><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> Re:
epoxy joint<o:p></o:p></span></font></p>
</div>
<div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'><o:p> </o:p></span></font></p>
</div>
<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'><br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>John,</span></font><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> <br>
<br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>I do not
understand what you mean composite horns/balsa.....but I do know a thing about
joints ( I once lived in Hawaii hanging out with the locals).</span></font><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> <br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>Epoxy is
the "toughest" unfilled. By this I means in a seam joint the primary
stress will be flexing, and an unfilled epoxy can handle this the best.</span></font><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'> <br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>Milled
fibers are about 1/64" long. In a composite the fibers are far stronger
than the resin. The job of the resin is to flex a <b><span style='font-weight:
bold'>little</span></b> to enable stress to be transferred from one fiber to
another. The problem with milled fibers is that as the transfer stress it is
only for that 1/64 of a inch and then it terminates creating a stress riser.
The epoxy then fractures at the end of that fiber at a stress level much lower
than if the fiber was not there at all. These type of fibers work great on
thermoplastics which are much softer and flexable, but not so great on
thermosets. Milled fibers in an epoxy will<b><span style='font-weight:bold'>
reduce</span></b> elongation, <b><span style='font-weight:bold'>reduce</span></b>
tensile strength, <b><span style='font-weight:bold'>increase</span></b> the
heat distortion temperature, <b><span style='font-weight:bold'>increase</span></b>
hardness and <b><span style='font-weight:bold'>increase</span></b> compression
strength.</span></font><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'> <br>
<br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>Microballoons
are not structural, they are used to reduce density. The volume is huge and the
balloons are weak therefore the mixture is weaker in every aspect. The reality
is though that a microballoon epoxy is still usually strong enough for our
applications. Add this to the fact that we are always striving for weight
reduction and you can determine the proper application. </span></font><font
size=2 color=black face=Arial><span style='font-size:10.0pt;font-family:Arial;
color:black'><br>
<br>
</span></font><font size=2 color=black face=sans-serif><span style='font-size:
10.0pt;font-family:sans-serif;mso-bidi-font-family:Arial;color:black'>Filets in
general are useless other than for cosmetic reasons. On a properly assembled
bond joint the filet will never see stress until the load capacity of the joint
itself is exceed. At that point the joint breaks and considering that the joint
itself is orders of magnitude stronger than the filet, the filet breaks
instantly. Filets are dead weight, and usually more dead weight than you think
it is-but man they sure look GOOD when someone inspects the inside of your
plane-which in this hobby is second only to winning the NATs (sorry-cannot
always stop the sarcasm). <br>
<br>
<br>
<br>
Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</span></font><font size=2 color=black face=Arial><span
style='font-size:10.0pt;font-family:Arial;color:black'> <o:p></o:p></span></font></p>
</blockquote>
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<p class=MsoNormal style='margin-left:.5in'><font size=2 color=black
face=Arial><span style='font-size:10.0pt;font-family:Arial;color:black'> <o:p></o:p></span></font></p>
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