Composite construction techniques?
Luke Scharf
bit, but I can't quite visualize the process. Could anyone point me to a
good writeup or illustrated guide to this topic?
Thanks in advance,
-Luke
Larry Smith
"Luke Scharf" <lu...@vt.edu> wrote in message
news:pan.2002.09.04.14....@vt.edu...
See books on the subject by Burt Rutan, Jack Lambie, and Andrew Marshall.
There are others but these are usually on the top of the head of the
composite builder.
Scott VanderVeen
wheel pants. You can look at these pictures if it helps. There are some
good examples of the technique.
http://www.arrow4graphics.com/Vision/vision199builder.htm
Scott V.
"Luke Scharf" <lu...@vt.edu> wrote in message
news:pan.2002.09.04.14....@vt.edu...
Richard
> bit, but I can't quite visualize the process. Could anyone point me to a
> good writeup or illustrated guide to this topic?
Roger Halstead
> bit, but I can't quite visualize the process. Could anyone point me to a
> good writeup or illustrated guide to this topic?
>
In general, (simpelest form) you carve out a shape in Styrofoam (Long Ez and
Cozy) and do fiberglass and resin lay-ups on it. Part of the fuselage lay-up
has been described to me as a lot like wall papering, except it's a lot
heavier and smells worse.
The wings are made the same way with the spar being fiberglass rope and
Eposy resin, layed into a channel cut in the foam
--
Roger Halstead (K8RI EN73)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)
> Thanks in advance,
> -Luke
Luke Scharf
> In general, (simpelest form) you carve out a shape in Styrofoam (Long Ez
> and Cozy) and do fiberglass and resin lay-ups on it. Part of the
> fuselage lay-up has been described to me as a lot like wall papering,
> except it's a lot heavier and smells worse.
Is the fiberglass and resin lay-up(s) done in several distinct layers of
different materials, or is it like wallpapering a room several times? Is
there any sort of layer between the fiberglass/resin layups and the paint?
Does fiberglass usually come in a woven fabric, or do you just lay down
raw fibers?
Thanks again,
-Luke
P.S. I'm going to look into purchasing one of the books suggested on this
topic... :-)
RobertR237
<lu...@vt.edu> writes:
>
>Is the fiberglass and resin lay-up(s) done in several distinct layers of
>different materials, or is it like wallpapering a room several times? Is
>there any sort of layer between the fiberglass/resin layups and the paint?
> Does fiberglass usually come in a woven fabric, or do you just lay down
>raw fibers?
>
>Thanks again,
>-Luke
>
>P.S. I'm going to look into purchasing one of the books suggested on this
>topic... :-)
>
>
>
Yes...
Yes to both accounts. For the most part it's like wallpapering a room with
several layers of paper at one time. In other cases, you may do multiple
sessions of one or more layers each time. You may also in some circumstances
do layups of different materials. It all depends on the specific requirements
of the component being fabricated.
Most of the fiberglass you will be using will be woven fabric but that too can
vary. When constructing spar caps you want to orient all the fibers in a
single direction and thus a woven fabric is not desired. You might however
encase those same single direction fibers in a woven fabric covering. One of
the aspects of composits that makes them so useful it the ability to tailor the
material to the requirements. There are many available forms of fiberglass,
carbon fiber, and other fiber products such as kevlar. Each has specific
advantages and disadvantages. You can mix and match them to the requirements
of your project.
Bob Reed
www.kisbuild.r-a-reed-assoc.com (KIS Builders Site)
KIS Cruiser in progress...Slow but steady progress....
"Ladies and Gentlemen, take my advice,
pull down your pants and Slide on the Ice!"
(M.A.S.H. Sidney Freedman)
Nathan Young
> different materials, or is it like wallpapering a room several times? Is
> there any sort of layer between the fiberglass/resin layups and the paint?
Yes. Multiple layers at the same time. Procedure is to apply a
layer, fill the weave with the minimal amount of epoxy to thoroughly
'wet' the layer, add another layer, and repeat until the layup is
complete... After layups, the weave of the top layer of fiberglass
hardens and is not a suitable surface for painting. This weave cannot
be sanded down, as it would damage the fiberglass. So the procedure
is to fill the weave with a thin layer of (mixed) epoxy and microcells
(very small bits of fiberglass). There are also commercial products
available (PolyFill for example) that work well.
The fill layer is then sanded smooth, pinholes and low lying areas are
again filled and sanded smooth until the wing has only small pinholes
remaining. At this point a few layers of ultraviolet blocking primer
are added. The primer is added in several coats, which fills the
remaining pinholes. The primer is then sanded smooth and cleaned free
of dust,dirt, and oil.
The part is now ready for paint.
> P.S. I'm going to look into purchasing one of the books suggested on this
> topic... :-)
Go a step further. Aircraft Spruce has a 'kit' for about $50 that
includes ~20 pages from Burt's book, styrofoam, fiberglass,
microcells, and epoxy.
Instructions take you from first layup to fabricating a small wing
section complete with spar. The directions on finishing the wing are
a bit weak, so ask back here or do a google search on composite
finishing, and you'll find the wonderful answers other
rec.aviation.homebuilt posters provided when I asked the same
questions last year.
-Nathan
Luke Scharf
> Yes. Multiple layers at the same time. Procedure is to apply a layer,
> fill the weave with the minimal amount of epoxy to thoroughly 'wet' the
> layer, add another layer, and repeat until the layup is complete...
That makes sense. I think I can actually see myself doing this in a year
or two!
> Go a step further. Aircraft Spruce has a 'kit' for about $50 that
> includes ~20 pages from Burt's book, styrofoam, fiberglass, microcells,
> and epoxy.
Is this clean enough that I could do it on a workbench in a carpeted
apartment, or should this really be done in a garage?
Thank you for the insight,
-Luke
Nathan Young
> Is this clean enough that I could do it on a workbench in a carpeted
> apartment, or should this really be done in a garage?
Depends on how much you care about your room-mates and neighbors? The
epoxy smells, (not too bad - but few people like chemical smells in
their living room). Also - the bigger issue - when sanding -
fiberglass/epoxy dust gets everywhere.
A heated garage or hangar is definitely preferable.
-Nathan
RobertR237
<lu...@vt.edu> writes:
Yes, it can be done in a carpeted apartment if you are careful. I have done a
few on the surface of my pool table with some plastic covering it. It's the
sanding that will truely get messy.
RobertR237
(Nathan Young) writes:
>
>Yes. Multiple layers at the same time. Procedure is to apply a
>layer, fill the weave with the minimal amount of epoxy to thoroughly
>'wet' the layer, add another layer, and repeat until the layup is
>complete... After layups, the weave of the top layer of fiberglass
>hardens and is not a suitable surface for painting. This weave cannot
>be sanded down, as it would damage the fiberglass. So the procedure
>is to fill the weave with a thin layer of (mixed) epoxy and microcells
>(very small bits of fiberglass). There are also commercial products
>available (PolyFill for example) that work well.
>
>The fill layer is then sanded smooth, pinholes and low lying areas are
>again filled and sanded smooth until the wing has only small pinholes
>remaining. At this point a few layers of ultraviolet blocking primer
>are added. The primer is added in several coats, which fills the
>remaining pinholes. The primer is then sanded smooth and cleaned free
>of dust,dirt, and oil.
>
>The part is now ready for paint.
>
>
That's the hard way, use peel ply over the layup and save yourself a log of
filling and sanding. The basic issue is that the epoxy will, because of
surface tension, cover the surface of the glass threads in a fairly even
coating instead of floating as an even layer over the surface of the fabric.
This causes the resulting layup to be very uneven on a close up view. It will
require extensive filling to even out the surface to prepare for painting.
The peel ply does the same thing with the epoxy but since it is on top of the
glass fiber and it's weave is so much finer, it pulls the epoxy to an even
layer slightly above the glass fibers. When the peel ply is removed, it leaves
a surface that on close examination will have a lot of tiny points standing
above the main surface. This provides and great bonding surface for the next
layer of fiberglass if required or can easily be sanded to provide a paintable
surface without the need for filling.
Roger Halstead
"RobertR237" <rober...@aol.composit> wrote in message
news:20020906225631...@mb-mb.aol.com...
I haven't used peel ply, or rather don't have any photos of such....Yes I
do.
I just shot a series on a Glasair Super II being built. I don't have them on
my site yet, but should shortly. BTW, at the front of his hanger is a
LongEz which is built in the manner you were describing.
Admittedly I'm working on a kit, but many of the techniques are the same.
I'm using Vinyl Ester Resin instead of Epoxy, but you still add
catalyst...still saturate the cloth...etch.
My builders diary http://www.rogerhalstead.com/glasair3.htm shows a number
of techniques for working with fiberglass and resin. It is NOT building up
over a carved core, but once you have the first layup done there isn't a
really big difference.
Page three probably shows more than the other two, but so far there are
three pages with lots of photos and I'll be adding more to page 3 in a day
or so. Page 4 is going to show up before much longer.
If you can find an EAA chapter nearby ask about the type of construction you
are looking at. I'll bet you find several.
>
> The peel ply does the same thing with the epoxy but since it is on top of
the
> glass fiber and it's weave is so much finer, it pulls the epoxy to an even
> layer slightly above the glass fibers.
Some use a small roller to help even things out once the peel ply is in
place.
When the peel ply is removed, it leaves
> a surface that on close examination will have a lot of tiny points
standing
> above the main surface. This provides and great bonding surface for the
next
> layer of fiberglass if required or can easily be sanded to provide a
paintable
> surface without the need for filling.
>
Does Poly Ester work like that?
--
Roger Halstead (K8RI EN73)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)
>
Corky Scott
Hmmm, went to Google and typed in "moldless composite construction"
and got many hits. There are video's available as well as a number of
books. There probably is a website that explains it in detail but I
didn't have the time to look at every one.
The simple explanation is that you carve a block of foam to the shape
you want and then overlay that with fiberglass. I made a kneeboard
that way, sized to fit my thigh and it had rings for the straps bonded
to it.
When you build a wing using moldless construction, you hot wire it
using templates at both ends and carve out a groove for a spar and use
specific types of fiberglass with carefully thought out weave
directions.
Then you sand and fill and sand and fill and sand and fill and .....
Corky Scott
Serge
Spruce. It includes several different foams, different glasses, fillers, epoxy,
and a book.
Serge
Peter Dohm
I had better luck with search words on Google, mostly by knowing what had not
worked, and used "moldless composite aircraft" which makes less sense. That
gave a book list on http://www.corsair82.com/corsair/reference/reference.html
as well as a book by Ron Alexander linked on the EAA site.
When I get around to starting my own project, I will almost certainly use
Burt Rutan's "Moldless Composite Homebuilt Sandwich Aircraft Construction"
which I understand includes much of the material in the original Vari-Ez and
Long-Ez construction manuals.
The EAA store does sell the Rutan book and may also have all of the others
in the Corsair82 reference list, plus the Alexander book. Interestingly,
I was unable to find it on their increasingly stylized web site; but that
made me curious enough to call.
An important point, before you get to far into sanding, filling, and more
sanding. Do as much as possible *before* applying the slurry and glass!
It's easier, faster, lighter, and stronger. Back when he "went on tour"
between the introductions of the Vari-Ez and Long-Ez, Burt Rutan phrased
it (to the best of my recollection) as: "the more time you spend finishing
the foam, the less time you'll spend finishing the airplane". A sheet of
plastic (visquene, etc) can also be used over the last layer of glass to
further reduce the need for finish sanding -- I've heard the technique
attributed to Ron Alexander, so it may be in his book. Vacuum bagging also
appears to be a good enhancement, but I have no experience using it as yet.
I hope this helps.
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