> 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

Paul,

I have always wondered whether doing a lay up on say, formica warped
into a shape onto supportive ribs would serve to layup on (getting rid
of the sanding) and getting much of your foil shape. Say in halves,
upper and lower than bonded together for your complete foil shape.
Terry


That works too for simple curves. I think I would use sheet metal like thin 24 gage sheet steel as that is cheaper and is more likely to be flat than the plastics. Of course it is extra work as you must make female molds for the upper
and lower surfaces of the wing. Assuming it is a Hershey bar wing. If the wing
is tapered it takes four female molds. I would bond the steel to plywood formers
with JB Weld.

Paul Lamar