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<DIV><FONT face=Arial size=2>John, we put 0.5 oz carbon mat between the foam and
sheeting, same amount of slow epoxy ( really thin rolled on to
the mat ), with a little brushed around the edges of the
foam, and bag them. Gives an incredibly strong wing,almost
monocaque, with little added weight. Also add a small piece at fuse end TE
to prevent the "pick up bends" .</FONT></DIV>
<DIV><FONT face=Arial size=2>Jerry</FONT></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=johnferrell@earthlink.net
href="mailto:johnferrell@earthlink.net">John Ferrell</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, December 21, 2004 11:28
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: fiberglass mesh in foam
wings</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>As I recall:</FONT></DIV>
<DIV><FONT face=Arial size=2>I believe Dave Guerin originated this process.
Examination of crash damaged and failed wings revealed that carbon fiber will
eventually peel a thin layer of foam loose since the foam flexes and the
carbon is rigid. In time, the carbon is just along for the ride. The fiber
glass window screening with its loose & wavy weave has a little give to
it. I have not observed any delamination of the screening in spite of noting
that different rolls of screening seem to be harder to wet with epoxy.
</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>If you are building a wing with a thin airfoil
some kind of spar-like structure is cheap insurance. I have had wing failures
with the screening in place that held together well. They were caused by off -
field landings.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Originally I think Dave carried the screening all
the way to the tip cap and lapped them over the edge. Experience indicated
this was not really necessary, the epoxy works well as an adhesive in this
application. I think the whole process originated with the very thin Desafio
wings but that is another story. It really is not necessary to carry the
screen to the tips but it is easier to do a neat job this way. If you put a
piece of sand paper a little wider than the screening on a piece of aluminum
angle it will only take a few swipes to recess the excess screen into the
foam. Don't mess with the sheeting, it is thin enough! In my shop I use the
same sanding bar that I use to true sheeting. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I doubt thicker wings benefit from this
treatment.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Someone (up Chicago way I think) puts glass
between the foam & sheeting. Sounds like a great idea but if I did it it
would be heavy.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>I have seen Prophecy wings that were glassed
after sheeting and painted. I expect they were a little heavy but they felt
like they were indestructible.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Remember, this is as I recall, and
YMMV!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV>John Ferrell <BR><A
href="http://DixieNC.US">http://DixieNC.US</A><BR></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=Ed_Alt@hotmail.com href="mailto:Ed_Alt@hotmail.com">Ed Alt</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=discussion@nsrca.org
href="mailto:discussion@nsrca.org">discussion@nsrca.org</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, December 21, 2004 7:39
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> fiberglass mesh in foam
wings</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>I'm getting ready to sheet a pair of Temptation
wings and have questions about using the fiberglass screen mesh
reinforcement strips they call for. First, how necessary is it to even
use any? I can see where it obviously adds strength and
stiffness in those sections directly under the mesh, but at the same
time, it will also create a raised-up section of sheeting directly adjacent
to the mesh strip. It seems possible that there would be no bonding of
sheeting to foam for about 1/4" to 1/2" wide all along those seems, at least
not if a thin layer of epoxy is used. It also seems that at the point
where the sheeting does begin to bond with the foam again, it would be
subject to shearing forces that might tend to pop the foam beads out over
time due to bending loads on the panel. Maybe not? I have no
experience with this method, so it's all speculation. It seems that a
fairly heavy application of epoxy would be needed to bond foam to mesh, mesh
to sheeting. Is it possible that the same or better strength result
could be accomplished with a slightly heavier wood selection and still be as
light or lighter than adding mesh and extra glue?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Asuming the mesh is really necessary: The
2nd question is about the adhesive to use if the mesh is used. I
normally use either Pro Bond or Elmers polyurethane glue, which does a
terrific job of bonding several bead layers deep into the core. I
think it probably stiffens the structure alot as a result. However,
it's not clear to me if this would be a good adhesive with the mesh
applied. In theory, it would do a good job of filling that gap I'm
worried about along the mesh edges. Has anyone tried this and are you
happy with the results?</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The last question is about how far to run the
aft reinforcement strip. Do you really need to run it all the way to
the tip? At some point, you really get diminishing returns as you get
further out in the panel. Sorry for so many questions!</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial
size=2>Ed</FONT></DIV></BLOCKQUOTE></BLOCKQUOTE></BODY></HTML>