I am eventually going to have to make tapered, compound curved
fairings to fit between my sliding canopy rails and the coaming that
will be attached to and slide with the canopy. (I am installing the
RX4 engine in a ackro biplane) Nuclear physics and composites are a
couple of my weaker subjects so please give me all the help you can
think up. I have glassed some small fairings and wing butt's but
nothing complicated. I would like light weight, strong and to be able
to make them look as much like metal as possible. I am assuming foam
fillers covered with modeling clay for the final shape and covered
with a couple coats of spray release agents before the layup. I am
considering carbon fiber for strength, weight and thickness but know
nothing about it. If whatever I use works well I will probably do the
canopy to turtle deck fairing with it also.
    Please forward all the possible info starting with the bulk
filler materials right through filling the finished cloth weave to
look like metal. Remember, I am an empty sponge here :))

Also, I have a brand new, never used, engine stand to rotary engine
adapter from Pineapple Racing. $63.10 new I would like $40 plus
shipping. rjechtinaw(at)toast.net
Thank you,
Randy

In comparison to fiberglass, carbon fiber is rather stiff and unruly when
wetted out.  You may want to consider vacuum bagging if you choose to go
with carbon.

Robin


A couple of excellent books, "Understanding Aircraft Composite Construction:
Basics of Materials and Techniques for the Non-engineer" and "Advanced
Composite Techniques" were mentioned here this last year.  Written in actual
English by Zeke Smith, a fellow who, like Paul, knows his stuff and can
explain it plainly to people without an engineering degree.

Among personal revelations I found, where how little material was needed to
make a properly designed panel rigid, the importance of the kinds of core
material (if any) and some understanding of how a composite combines very
stiff, high tensile fiber in a more elastic matrix for a strength and
durability far beyond their individual properties.  Also unforgettable, the
discussion of how very small fibers increase the distance between the
inevitable imperfections in any material to achieve fantastic performance.

It sounds as though you are beyond novice, but there is a thoroughness in
the coverage here that you appreciate in the presents of a sure guide.  I
may be a geek, but I found both books simply fun to read. I opened them for
reference, but just keep reading. I am certain I would enjoy the author's
company in person, and it pleases me to call attention to his work.

Grant

Rotaries!

I've said this before, so I'll be brief: Lay off carbon unless you are a PhD
spacecraft designer working for Boeing. There are too many problems in
design and application for the amateur. Certainly not the beginning amateur.
The amateur will almost certainly not achieve the structural strengths in
practice suggested by the raw specs of aircraft-grade carbon. It may be a
small point, but you can't see through carbon to verify that the layup is
good. The stuff is expensive, too.

It is not common in practical aircraft application that a panel needs to be
especially thin. If a panel needs to be strong in compression and/or
twisting, just make the panel thicker with a thick, cheap, light, foam core
and skin with glass. The final weight per square foot with a thick composite
panel is competitive with thin carbon and a whole lot cheaper and easier to
make.

I recommend my own books, of course, but I'll add Fiberglass & Composite
Materials by Forbes Aird. His viewpoint is racing cars in addition to
aircraft, but he's been there and done that and he treats true compound
curved molds quite well. The price, of course, is that the builder must make
and use a compound mold. For most of us, life is too short to go down that
path.

Often, careful re-thinking of the problem will produce an excellent
compromise design that can use single-curved surfaces or combinations of
such surfaces.

Off-List communication is welcomed.

Zeke Smith    Aeronaut Press