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<DIV><FONT size=2>My daughter, in a high school class, built a bridge using 1/4
sq balsa. She still holds the record at her school. The bridge was
12 inches long, 1 inch wide, weighed 14 grams and supported 70.5 lbs hung under
the bridge. Last year the max weight held was 42 lbs. She did
use good techniques in the construction but with a little more testing she could
have gone much higher.. I've seen balsa towers 12 inches tall weighing in
the 15 gram range hold over 300 lbs in compression.</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=wgalligan@goodsonacura.com
href="mailto:wgalligan@goodsonacura.com">Wayne Galligan</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">NSRCA Mailing List</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Wednesday, March 29, 2006 8:35
AM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] An
education in balsa usage for pattern</DIV>
<DIV><BR></DIV>
<DIV><FONT face=Arial size=2>Matt,</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>My son did his 5th grade science project using
balsa construction. His project was to determine what bridge truss
design held the most weight for a given span. It was truly amazing how
much weight the structure would hold. The spans he built
where 7"x7"x24" and weighted 1.5 oz, made of 1/4" square med grade
balsa glued together with thin c/a. The Warren truss held 42 lbs before
collapsing and the two other structures were close behind holding 32 to 38
lbs. It was a learning experience for both of us. It gave me a
better understanding of how certain truss structure builds stiffness, strength
and be light weight. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Wayne Galligan</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=rcmaster199@aol.com
href="mailto:rcmaster199@aol.com">rcmaster199@aol.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A
title=nsrca-discussion@lists.nsrca.org
href="mailto:nsrca-discussion@lists.nsrca.org">nsrca-discussion@lists.nsrca.org</A>
</DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, March 28, 2006 6:58
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [NSRCA-discussion] An
education in balsa usage for pattern</DIV>
<DIV><BR></DIV>
<DIV style="FONT-SIZE: 10pt; FONT-FAMILY: 'Verdana'">
<DIV>
<DIV>Balsa is pretty amazing stuff overall, particularly for a natural
material. The Xylem that makes up much of the superstructure of any wood
(that's what we commonly hear as grain), is essentially a huge number
of tubes arrayed side by side, but interconnected along the length. The
tubes serve a terrific function in the long direction and the interconnects
make the structure have reasonable transverse strength as well. </DIV>
<DIV> </DIV>
<DIV>The closest thing manmade that will surpass it in terms of mechanical
strength vs flex vs weight vs cost will likely be Buckytube if you
excluded the cost. That's just in laboratories now, being made in very small
quantities supporting very high end applications. This stuff is the
true unobtainium that some have complained about. But that's another
subject.</DIV>
<DIV> </DIV>
<DIV>There used to be an annual competition in colleges where a very small,
known quantity of balsa and glue were used creatively by students to build
some kind of support structure like a small bridge. These things would hold
unbelievable amounts of weight. </DIV>
<DIV> </DIV>
<DIV>Alas, the weakness is shock loading. </DIV>
<DIV> </DIV>
<DIV>Matt</DIV> <BR>-----Original Message-----<BR>From: Adam Glatt
<adam.g@sasktel.net><BR>To: NSRCA Mailing List
<nsrca-discussion@lists.nsrca.org><BR>Sent: Tue, 28 Mar 2006 16:44:02
-0600<BR>Subject: Re: [NSRCA-discussion] An education in balsa usage for
pattern<BR><BR>
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<DIV class=AOLPlainTextBody
id=AOLMsgPart_0_a3a3b4df-d994-412a-a29e-2c471d7b45f7><PRE><TT>Not directly applicable to pattern, but certainly a good start:
Buy and build a Stevens Aeromodel kit. The planes are small (35-50"
span, 1-2.5lbs) and electric powered. I'm about 1/2 done building the
Edge 540, and am actually enjoying the build because I am constantly in
awe of the genius wood design and its results (consider that this Edge
540 is 40-sized, but will weigh only 2lbs with more performance than all
but the most dedicated 40-sized 3D glow planes).
-Adam
White, Chris wrote:
>
> Can anyone tell me where a person can get a "Crash" course in learning
> about balsa weights and strength and its proper use in balsa pattern
> models.
>
> I notice a few years ago that in the 99 world champs most of the
> Japanese pilots models were balsa and light weight too. It seems that
> everything I read of late seems to indicate that light weight and
> strength only come with composite construction.
>
> Thanks..Chris
>
> ------------------------------------------------------------------------
>
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