<br><font size=2 face="sans-serif">People who have said that you cannot
build a pattern plane light enough with balsa are just wrong. The problem
lies with the fact that most in this hobby are fairly ignorant of the properties
of fiberglass, carbon fiber and kevlar. I have pasted a simple chart to
help with this, that references everything back to balsa as the standard,
that is make it "100" and everything else compares to this.</font>
<br>
<br><img src=cid:_1_0711161C071112100053068B86257140>
<br>
<br><font size=2 face="sans-serif">As you can see, fiberglass is not all
that light, but it is much stronger, but not all that stiff. Balsa
is really stiff but actually very weak. T-300 is cheap carbon fiber.</font>
<br><font size=2 face="sans-serif">Your plane, when stressed will ALWAYS
fail in some sort of compression mode, another fact that eludes most hobby
ist. Compression strength is also a property dominated by the matrix resin,
but fiber interaction has a serious impact. Compression failures rarely
break the fiber, instead they crush the resin holding the fiber.</font>
<br><font size=2 face="sans-serif">This is why, in short, kevlar blows.
Resin does not adhere well to kevlar and why it may not fail in tensile
(the numbers so high and why everyone thinks it is so strong) it will fail
in compression....just like balsa. Blasphemy right??? No Kevlar in Aeroslave
kits, only core structure fiberglass (for light weight and stiffness) and
two kinds of carbon fiber, T-300 and M-46J (has the modulus of steel or
3X that of T-300).</font>
<br>
<br><font size=2 face="sans-serif">In summary, composites are better to
fab a complexed curved fuselage with strength and weight advantages. If
you use balsa and keep the shape simple since basla is all flat, great
results can be achieved.</font>
<br>
<br><font size=2 face="sans-serif">I am also convinced that the Communist
Chinese and the French cannot pronounce "Kevlar". Buy American
(or Australian!).<br>
<br>
<br>
Gray Fowler<br>
Principal Chemical Engineer<br>
Composites Engineering</font>