Model Forum / Radio Controlled / Air Models / September 2010

After watching the video, all I can think is that when you do it to an
airplane, your fuselage won't be sitting there thinking "I'm getting
paid for this, I'm getting paid for this".  Or perhaps "I have to get a
new boyfriend, I have to get a new boyfriend".

This is done with fiberglass -- it's called "chopper gun layup".  It's
how you make shower stalls and cheap boats and other items where
strength to weight isn't important.  It takes a skilled operator to get
an even layup, and it is exceedingly difficult to get sufficient
material into inside corners without excessive build-up in the
surrounding areas.

Fiberglass mat* is made with chopper-gun layup, too, with a low-strength
binder instead of resin.  But it's made on a flat platen or web, with a
machine doing the spraying.  So it comes out (hopefully) in a nice,
even, controlled thickness, which higher-quality manufacturers then lay
into molds by hand for much better quality control.

For comparison, Corvette bodies are made** in matched metal molds.  A
measured blob of goo that consists of chopped fibers mixed with a
heat-sensitive polyester resin is deposited in some strategic spot
(perhaps several) on the mold, then the matching piece is put in place,
squishing the goo across the whole mold.  Then steam is injected into
the molds which activates the resin.  The resin starts curing; when it's
partially cured the part is taken from the mold and put onto a buck to
finish curing, hopefully without warpage.  As a way of making fiberglass
parts it results in something that's even more overloaded with resin
than chopper gun layup, but it is quick.

* Not veiling mat -- that has longer fibers.  Veiling mat is available
in both fiberglass and carbon fiber.  I don't know if there's an
equivalent to fiberglass mat in carbon fiber, but if there is it's
probably made the same way, backed up by some very frustrated mechanical
engineers trying to keep the chopper blades sharp.

** Well, possibly _were_ made -- my information may be out of date.