> http://www.visionaircraft.com/
 >
 > This is a fantastic idea. Steve Rahm is a genius.
 >
 > Solid composite in the curves and sandwich in the flat sections
 > where you need it. Spray on gel coat. Lay up on glass so there is no
need for
 > sanding. Low cost shipping. Say what you will about the rest of the
design but
 > IMHO this is a major breakthrough in low cost aircraft fuselage
construction.
 >
 > With the right fasteners the same trick could be used for the wing.  > Here is my idea for that. You build the core of the wing with composite
 > coated foam ribs one inch thick and the spar of course.
 >
 > You then layup the wing skins top and bottom on large plate window
glass with
 > foam cores where applicable on the flat parts. You then bend them
over the ribs
 > temporarily. Drill the holes for the drywall anchor screws.
Temporarily install
 > the screws. Remove the screws. Remove the skins. Coat the ribs and
spars with
 > glue and screw down the skins. I call it the drywall anchor techniqueor drywall
 > anchor wing.
 >
 >
 > Paul Lamar

Paul,

Steve Rahm is a genius, and this Vision design is great.
His wing construction method varies from the method you've outlined, but
results in the same type of wing (sandwich top and bottom skins with
ribs and a composite main and rear spar).  Rahm wanted to avoid any
fuel-susceptible foams, and his design does that, as well as being
strong and very lightweight.

I'm not quite following your wing idea.  The foam skin panels can be
bent only as long as there is no  epoxy/fiberglass  on the inner surfaceof the panel, so how would you bend the skins to the ribs and then glass
the inside surfaces of the skins  in your system?  Obviously, if there'sonly epoxy/fiberglass on the outer surface of the skin it will be much
less stiff.

Rahm's  wing design incorporates some additional gusset-like pieces to
provide more bonding surface between the skin that is closed in last and
the ribs.  As you've descried your method, the only bonding surface
between the skin and the ribs (at least in the part you close in last)
is on the edge of the rib, and i think that might be too little (but I'm
no engineer)

I've got a set of his plans, and will start construction soon.  It's the
only composite plans-built conventional (ie.e non canard) designs I'm
aware of.  The plans are actually separate spiral-bound books that walkbuilders through every step.

I think mine will have a 13B in the nose.  It's a little on the heavy
side for this design (Rahm says 300lbs is the firewall-forward limit,
and the design flies great on 100 HP, so this is really overkill), but I
think i can make it work with careful placement of cooling system
components.

Mark Waldron

I propose a one inch thick rib so that would be plenty of surface area for the
skin to bond to. Epoxy bonds are are about 3000 psi.

I would not use a complete sandwich on every square inch of the wing skin. It is
unnecessary as the curvature of the skin provides the necessary panel stiffness except in the large flat areas between the ribs towards the rear of the cord.
There I would use chamfered 1/4 inch thick foam to stiffen those panels.Very similar to the way Steve is doing the fuse. Three layers of ten
ounce glass cloth or carbon would be fine.  The shear strength of the composite
in the plane of the composite would be the same and that is what counts when
it comes to the torsional stiffness of the wing. Also in so far as the skin
adds to the bending strength of the wing. See the new 3D.

Build a section with just two ribs to test the idea.

It might be easy to install a P51 type cooling system since you are building
the fuse. from composites. The P51 type duct duct walls can stiffen the aft fuse. Make sure you use the Kuchemann and Weber trumpet shaped  internal duct curves. A car ram air hood scoop can be used under the fuse. up side down.
 That would help the CG problem and ease the cowl layout.


Another easier thing to do is use the quick and simple cooling system with
a boundary layer splitter plate  aft of the wing under the fuse. From the side
it would look like a P51 duct anyway.

Paul Lamar

Paul, another way to do this is to glass only one side.. [but make it the inside..] then
the foam will stretch in tension on the outside as it's formed to the shape of the ribs..
you can do your close out and skin bond at that point, then do a complete glass wrap
of the exterior [top and bottom right around the "D" section] all at the same time..

Some slitting of the foam may be required around the D section [tight curvature] but
for the most part it shouldn't be nesc.. I was always amazed how flexible a pc
of foam was w/ only glass on one side.. it's only when it gets on both sides that it
get stiff [mind you.. I know you already know this.. :)]

I think the Polywoggen or some such 'older' design did things this way..

Jarrett

Well the problem with that is the time it takes to sand it. I know people
that have spent over a year or more sanding Long EZ or Varieze's.
It tends to get heavy with filler in the low spots.

The big break through here is you lay this up on plate glass and you get
a super smooth finish from the get go. First you spray the glass with
the outer gel coat. Then lay up the cloth and then apply the foam only in squares where it is necessary. Then apply the inner layer of cloth.
This is a super quick way of doing it. Then you ship the parts as a bunch
of perfectly flat panels. No need for a huge crate.

One problem with completely cored wing skins is transferring the torsional shear
load from the inner skin to the outer skin. Do an FEA on a rectangular box with foam sandwich skins and then apply a torque load. That would be a great illustration of the problem. Then do the same thing with cored skins only
in the center of the panel.

Paul Lamar