<br><font size=2 face="sans-serif">I will answer the "local" question first, since it is more fun. 1978, Kailua Hawaii. Lived with my parents during first summer off from college.</font>
<br><font size=2 face="sans-serif">Got a job a aTexaco station, where as I was the only Haole other than the owner. My co workers were a Japanese, a Chinese a Potugese, a Hawaian and a Samoan. Worked nights alone with the Chinese dude. Every night we ordered Chinese food, and then he would say......smoke a joint? in twisted Hawaian-Chineses English. He then proceeded to whip out a half smoked joint of approximately 0.125" in diameter, counter to the "american fatty". Two tokes (thats all it took) and back to work. I always declined of course. Never could figure out when he had smoked the first half.</font>
<br><font size=2 face="sans-serif">Surfed the North Shore all day, pumped gas at night.</font>
<br><font size=2 face="sans-serif">My favorite pastime was giving directions to the tourists...like I knew where these places were.....but they got directions anyway.<br>
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Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>
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<td><font size=1 face="sans-serif"><b>"Cameron Smith" <dentdoc007@bellsouth.net></b></font>
<br><font size=1 face="sans-serif">Sent by: discussion-request@nsrca.org</font>
<p><font size=1 face="sans-serif">01/17/2005 12:42 PM</font>
<br><font size=1 face="sans-serif">Please respond to discussion</font>
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<br><font size=1 face="sans-serif"> To: <discussion@nsrca.org></font>
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<br><font size=1 face="sans-serif"> Subject: RE: epoxy joint</font></table>
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<br><font size=2 color=#000080 face="Arial">I want to hear about the Hawaiian Locals!!!</font>
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<p><font size=2 face="Tahoma">-----Original Message-----<b><br>
From:</b> discussion-request@nsrca.org [mailto:discussion-request@nsrca.org] <b>On Behalf Of </b>Rcmaster199@aol.com<b><br>
Sent:</b> Monday, January 17, 2005 1:25 PM<b><br>
To:</b> discussion@nsrca.org<b><br>
Subject:</b> Re: epoxy joint</font>
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<p><font size=2 face="Arial">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?</font>
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<p><font size=2 face="Arial">MattK</font>
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<p><font size=2 face="Arial">In a message dated 1/17/2005 1:18:24 PM Eastern Standard Time, amirneshati@earthlink.net writes:</font>
<br><font size=2 face="Arial">----- Original Message ----- </font>
<p><font size=2 face="Arial"><b>From:</b> </font><a href=mailto:gfowler@raytheon.com><font size=2 color=blue face="Arial"><u>Gray E Fowler</u></font></a><font size=2 face="Arial"> </font>
<p><font size=2 face="Arial"><b>To:</b> </font><a href=mailto:discussion@nsrca.org><font size=2 color=blue face="Arial"><u>discussion@nsrca.org</u></font></a><font size=2 face="Arial"> </font>
<p><font size=2 face="Arial"><b>Sent:</b> Monday, January 17, 2005 9:57 AM</font>
<p><font size=2 face="Arial"><b>Subject:</b> Re: epoxy joint</font>
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John,</font><font size=2 face="Arial"> <br>
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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).</font><font size=2 face="Arial"> </font><font size=2 face="sans-serif"><br>
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.</font><font size=2 face="Arial"> </font><font size=2 face="sans-serif"><br>
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>little</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> reduce</b> elongation, <b>reduce</b> tensile strength, <b>increase</b> the heat distortion temperature, <b>increase</b> hardness and <b>increase</b> compression strength.</font><font size=2 face="Arial"> <br>
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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. </font><font size=2 face="Arial"><br>
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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>
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Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font><font size=2 face="Arial"> </font>
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