Plastic is used to vacuum-form difficult to shape parts such as cowlings,
wheel pants and surface details such as cowl bumps, engine exhausts, etc.
I feel these parts are much inferior to fiberglass as plastic tends to crack
from engine vibration and many paints will peel off the plastic after a while.
Paints that will not peel off the plastic can melt the plastic unless it is sprayed
on in light coats. Most modelers attempt to spray on one thick coat of
paint even though every set of instructions they've ever read said do not do
that. This can result in the plastic crazing under the paint. What
that means is the solvent in the paint reacted with the plastic in a bad way.
Beaded Polystyrene Foam
Hot-wire cut Foam Plastic
has been used since at least the 60's to make wing cores. The
core is cut from a block of beaded polystyrene foam (not Styrofoam)
using a thin, hot wire (nichrome). The core is then sheeted with
balsa, veneer plywood or a synthetic material.
Built up wings that are
fully sheeted are difficult to make smooth and often the sheeting sags
between the ribs unless the builder is skilled and careful. Foam
cores virtually eliminate this problem. Unfortunately, foam
wings tend to be heavy unless the builder goes to great lengths to
prevent weight build up. Usually this means cutting sections
from the foam so it resembles lattice-work.
Hot wire cut foam has become popular for many other
items besides wings. Entire aircraft are sometimes built from it.
Usually it is used to cut the turtleback on ARF models, but tools are now
available that allow any modeler to cut wings, fuselages and other shapes
Generally used to vacuum form canopies.
A newer material that has become very popular.
It is a relatively
expensive material. However, it is becoming more widely available which
means it should come down in price. It has a very high strength to weight
ratio and is used to make propellers, landing gears and various reinforcement
throughout the model.
Carbon Fiber is not difficult to work with, but the splinters
can be really nasty. You have to be careful to break your habit of running
your hand along the edge of a part after sanding it to feel how smooth it is.
A plastic material made
like corrugated cardboard. It has two outer layers and a
corrugated inner layer. This is another material I have not used,
but it has become popular with manufacturers of "indestructible"
CoroPlast is a heavy material so that
indestructibleness comes at the price of forever having a heavy model.
Apparently it is easy to work with.
This is another material
I have never used because it has a lot of disadvantages both in building the model
and it is flight worthiness. It is only advantage is that it is widely
available and it is inexpensive. It generally does not build into pretty
models, is heavy and has a poor strength to weight ratio.
Oops! I stand corrected. Charles Felton has built many
very attractive cardboard R/C models. Visit his site for
information and tips about building with this inexpensive and easily
I like fiberglass because
it is lightweight, long lasting and the parts can be made thin enough to
replicate features on scale aircraft such as aircraft cowlings. Wood
equivalents generally need to be too thick for scale.
Plastic parts can be
used in these cases, but I consider plastic to be inferior to fiberglass.
Fiberglass is lighter, stronger and lasts longer than plastic.
FoamCor was popular for a while for R/C
planes, but has since faded out. I am not sure why it did not stick around, but I expect that it did not tend to
build into models that were as light as expected. FoamCor's only advantage
over other materials is its lower cost.
Injection molded foam
Manufacturers use molded foam for lightweight models that do
not require any type of sheeting to strengthen it. Normally these are
small models that are electric powered. For higher performance models,
there is often a carbon fiber or wood spar molded into the wing.
Available in sheets from hobby shops and is
often used for scale details in cockpits. It is not used for
general construction due to its weight and tendency to crack.