Paul
For those willing to build with epoxy, I think, the best would be to
purchase directly made sheets to be glued on rib
Not the cheapest way, but by far the quickest giving a superb
result.
https://www.rockwestcomposites.com/plates-panels-angles/carbon-fiber-plate/carbon-fiber-fabric-plate/plate-carbon-fiber-qiso-tri-axial-gloss-matte-48-x-120-x-0-050-inch-thick-options
pascal Virlouvet
Thanks Pascal
I have the wing rib problem decided. This is a Teflon mold .75 inches
thick. The procedure is wet out the fabric and place it over the
center piece hole. Press the rib form into the center mold. the
flanges will be automatically formed. Put it in an oven set to 200
F. Let cure.
Teflon is good to 500 F.
Each rib will be precisely the right size. Cut a hole for the spar
and use sort pieces of carbon fiber angle to bond and pop rivet the
rib to the side of the spar.
This will be much faster then making each ribs out of foam and
covering it by hand with fabric glass or carbon.
Patent applied for :-)
Paul Lamar
Very nice. It seems feasible to do the spar locater hole the same way
at the same time. Cut an X in the hole and put plug in.
Michael Nash
A little problem with that. The dimensions of the spar will vary due
to load on it. Top and bottom will have varying layers of uni.
A list of spar hole dimensions should be mad for all the rib
locations.
Here is a stress diagram for a typical wing load more or less.
Paul Lamar
Paul the point of the built up spar is you can vary the ply schedule
to get the strength you want over the spar with the same outside
diameter or even easier with the box spar. Then all your rib holes
can be the same size for easy molding
Bill Jepson
Yes all the ribs are the same out side dimensions.
If made on a SIMPLE square tube male mold the thickness of the caps
would step down starting at the root rib. You can start with an off
the shelf cured square or rectangular carbon tube.
If all the holes in the ribs are the same size the spar then must be
made in a female box mold.
Lets call it a square tube female mold. How do I lay up inside a 20
foot long square tube? Not possible of course. Or at least extremely
difficult.
OK say I made a rectangular male mold that was tapered in height. The
small vertical dimension was near the root rib where the caps are
thickest.
Could be carved out of 20 ft long blue foam I guess. Could also be
made out of four ten foot long steel or aluminum bent up tapered
channels and welded up.
Kind of tricky getting the right taper. Probably calculate the
proper number of ply schedules and then adjust according to needed
height.
The next problem is cutting the square holes in the rib plies before
saturating and molding. That is not practical. Particularly in
carbon.
Plan B. Makes two part ribs. One front one rear twice the rib lay up
time. That will also work.
Nay.
I would rather cut different size holes in the cured ribs :-)
Lots of options.
BTW the cost of solid Teflon is out of sight.
Garbage bag material can be used as a mold separator with a plywood
mold. The same stuff you use to saturate the fabric. Add a couple
more layers before you put in the plywood mold. Room temperature or
150 F max in oven cure. Otherwise the garbage bag might melt :-) .
The actual plan form I intend to use is that of a C182. The 2/3 span
center section is straight to accommodate the fowler flaps and the
outer panels with the ailerons are tapered so those ribs are not all
the same size. I am doing that for the known excellent handing and
stall characteristics of the C182.
No point in reinventing the wheel and do all that R&D on handling.
Paul Lamar
Paul, Love your ideas, but I would prefer a pusher, remember the
Italian flying Boat, the radiators up front, max cooling.
Milo Burrows
It seems probable a spray on coating that would give the same results as
solid Teflon can be found and a compatible mold release. Even a thin
sheet of Teflon say .020 thick vacuumed molded onto the form would cut
cost. I believe our shop would use a mandrel to layup the main spar with
multi directional layers then in a jig epoxy on the ribs into their
accurate locations and then apply the additional carbon fiber materials
needed per load requirements and attachment brackets. Multi vacuums bag
it and autoclave the entire assembly. This produces a double seal for a
wet wing at the spar holes which can all be the same size and a very
torsionally solid assembly which can be lowered into the female wing
molds before the skin is removed from the mold. Just my thoughts, have a
nice day.
Michael Nash
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