Conference vmszoo::rc

    I've been toying with the idea of a glider wing made of foam,carbon
    fiber,plastic film and a balsa leading and trailing edge. I was
    wondering what others comments would be.
    
    
    My thoughts;
    
    First to start a foam wing would be cut per the norm. THen the wing
    tip would be radioused.(sp) Next would come the glueing of a carbon
    fiber srtip from the center cord of the wing arount the wing tip
    back to the center cord. Bays of foam would be removed creating
    rib sections and a shear wib glued between the carbon strip top
    to bottom. Next a leading and trailing edge strip would be installed
    and then entire wing after centersection joining would be covered
    with plastic film. I would think that the carbon fiber/shear webbed
    truss would carry the load and the foam would be there for shape
    only. COMMENTS??
    
    						Tom

    I've just started to build a 1/4 scale model of the actual plane
    that I am building (Shirl Dickey's E-Racer - a CAFE a/c that is
    somewhere between a Long EZ nad a COZY).  I need a model in order
    to make adequate mods for the weight-and-balance (it's orginially
    a two seater [SBS] and my Mk1 variant is a single.)  Quite a few
    people around the experimental a/c business make flying r/c models
    (a very exhaustive series of tests using 1/4 scale models were used
    for the Wheller Express and the prototype flew unusually close to
    designs because of this.)
    
    Anyway I don't have too much to offer at present although I am using
    a similar layup process that the actual a/c uses.  I haven't decided
    whether to use Kevlar and/or Graphite on any components of the E-Racer
    as of yet nor for the model.
    
    Kevin
    
    P.S. at least the vacuum bagging of the model is practical, as for
    the real a/c I don't know how I'm going to get the fuse into a 19'
    Zip-Lok baggie :-)
    
    

>    P.S. at least the vacuum bagging of the model is practical,

    This triggers a question that has been bugging me for quite some
    time: 

    Can someone please explain the full vacuum bagging process
    step-by-step, assuming the reader knows nothing about it (like me)?

    EX:  1. get a bag and vacuum cleaner  (or whatever)
         2. take the (mumble-mumble) and place in bag
         3. take (mumble) and (fumble-fumble)
         4. ...
                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

    There was a method given by Tom T. how how to foam cores is an early
    note. Its a bit more involved (you need 12 gallon of water)..
    
    As far as mixing the epoxy, the cookbook called for warming the
    epoxy (in their separate bottles) in water. This will make them
    more liquid.. The stuff is then mixed in some throw away container
    and applied to core .
    
    md
    
    

RE: < Note 683.4 by CSTEAM::HENDERSON "Mode-1 for Ever" >

    FANTASTIC!!!  That's exactly what I was looking for.  Thanks.

    However, since I've never seen it done, I still have some
    (potentially stupid) questions...  

    1.  About the motor, you say "Test with a meter for a circuit before
    removing from frame."  When you use the meter, what are you looking
    for, an open circuit?  A short circuit?  What are the common failure
    modes for these motors?  What should the resistance (?) be?

    2.  To make the bag - you just cut 2 sheets of vapor barrier (or
    whatever) roughly the same shape as the wing only oversized.  How do
    you seal the edges?  I realize you said to use packing tape, but do
    you first fold the plastic over a few times or do you just tape the
    edges?  (Or doesn't it matter?)

    3.  When you place the fiberglass arrow shaft in the bag, where does
    this go?  Along the trailing edge of the wing?

    4. You mention "a simple F/G, foam, veneer, sandwich".  Is the order
    actually: wood veneer, F/G & epoxy, then foam?  (Going from outside
    towards the center.)  [Sorry for this dumb question - I just want to
    make sure I've got it right.]

    5.  Can you use this process without the wood veneer for just foam
    and F/G?  Does this give a nice smooth finish on the F/G?  (Or does
    it leave just a wrinkled mess?)

    6.  What other methods (sandwiches) are possible?

    7.  After the wing is done, do you usually leave the foam in the
    wing or do you melt it out with acetone (or whatever) to reduce
    weight?

    8.  What does using vacuum do for you?  In other words, why bother? 
    Can't you do the same thing by just laying the foam, F/G, veneer
    sandwich in the foam cut-outs and weigh down?  What else (besides
    wings) is the vacuum bag process good for?

    9.  Do the full-scale fiberglass planes use a vacuum bag technique?
    If not, how do they do it?

    10.  I'd like to see you do this process sometime.  Where do you
    live and would you be willing to have a spectator?


    I'm very interested in all kinds of composite construction.  As a
    kid, I hung around a small airport that my dad worked at.  During
    the summer, they had a soaring contest that usually drew about 15 of
    the high performance fiberglass ships.  Since that time, I've
    dreamed of building a FULLY scale fiberglass glider that is scale
    right down to the last internal linkage and piece of fiberglass (ie,
    NO wood at all).  The only difference would be that it would have
    servos hidden somewhere.  But, that's still just a dream at this
    point...
                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

        .0 asked for composite materials sources. Here are a few of the
        palces I'm aware of. Aircraft Spruce sells to the EAA (full size
        homebuilt) folks, but some of the stuff is useful for model
        building as well. Their catalog is a great reference. MRL and the
        Model Box are more towards Free Flight, but again the products are
        usable by everyone. Aerospace Composites advertizes in MA, and
        while they seem to have all of the useful productsd, their prices
        are higher than Aircraft Spruce for the same items.
        
        Two excellent references are a pamphlet by Bert Rutan, and Jack
        Lambies Composites book, both available from Aircraft Spruce.
        Lambie is also available from AMA supplies. They both address the
        homebuilt market, but again, much info applies to model building
        as well. 


    Aircraft Spruce & Specialty Co.	Homebuilt Aircraft
    201 W. Truslow Av.			Safe-T-Poxy, fiberglass,
    Fullerton, CA 92632			Kevlar, carbon fiber,
    Orders:	800-824-1930		ceramic, plywood, dope
    Other:	714-870-7551		Composite construction books
    Catalog $5


    Model Research Laboratories		Carbon fiber and sheet,
    25108 Marguerite Pkwy., B-160	Kevlar, Boron, Mylar
    Mission Viejo, CA 92692
    Other: 714-240-8433
    Catalog send SASE


    Aerospace Composite Products	Carbon fiber, sheet, and rod
    P O Box 16621			Kevlar, Safe-T-Poxy
    Irvine, CA 92714
    Catalog $1


    The Model Box			Carbon fiber, Kevlar,
    12 Cook Street			Safe-T-Poxy, Tissue, Kits
    Rowayton, CT 06853			(was NFFS supply)
    Catalog send SASE

    I just ordered the Aircraft Spruce and Specialty catalog, and the
    Lambies book ($17.95)
    
    A. S. & S. only takes Visa/MC.  Grump...
    

    I have a question concerning the use of polyester resin.  What should
    I use for a release agent?  I will be glassing the inside of a scale
    fuse to repair a hole that was cut out for a muffler, and I wish
    to place something over the face to maintain the shape.  I would
    want this coated with a release agent so that I could remove it
    once the patch is cured.

		________
	 /	  __|__  
	=========[_____\>
	/	__|___|__/  BREAK A BLADE,
			    Ken    	

    Hi Ken,
    my friend Cam has done this kind of work many times. He uses car
    wax. Something like Johnson Paste wax works just fine. Stay away
    from the liquid waxes though.
    
    Dan Eaton

Yes, car wax is the accepted material for release agent.  Get one
with lots of "carnuba" (whatever that is), because that's what does
the job.  Johnson's is the usual one.  Lay it on relatively thick.

Also, to make the removal job easier...you DID put some taper in
your mold, didn't you? 

The fiberglass industry  uses a spray-on plastic film, the name of
which slips me now, but before that came into use they used the wax.
Must've been quite a job to wax the inside of a 40-ft boat mold!

    If you're glassing from the inside to fill a hole, and your backing
    is on the outside, then just use a backing made of an old Clorox
    bottle (it's polyethylene, chemical-resistant, cheap, and nothing
    sticks to it).
    
    The spray-on plastic film is polyvinyl alcohol- it goes on liquid
    and then turns into something like Saran wrap, but it peels off
    fairly easily too.
    
    	-Bill
    

>Yes, car wax is the accepted material for release agent.  Get one
>with lots of "carnuba" (whatever that is), because that's what does
>the job.  Johnson's is the usual one.  Lay it on relatively thick.

Gee John,
it obvious that you've never been to the EAA museum in Oskosh.8^) When I was
there this summer, Johnson Wax had a special display. The display is a lagoon
and fullsize mockup of one of the amphibious planes used by Johnson back in
the 30's (I think). Johnson Wax was big into exploreing the Amazon basin in
search of a special varity of palm tree. The fronds from the palm were stripped
off and boiled in large pots. The carnuba wax would rise to the surface and
be skimmed off. They had some sample pieces of raw wax there. The stuff is
dark and looks sort of like shiny chocolate.

Dan Eaton

    Can anyone shed any light on this...
    
    Since nosing over on landing is a common problem with my eindecker,
    I tried to reinforce the ABS cowl with a little glass and resin.
    I sanded the inside of the cowl to try to give the resin something
    to adhear to.  All went together fairly well and I gave it plenty
    of time to dry.  It worked fine until is got slightly twisted. 
    This action broke the bond and the glass readily came out.
    
    So, how do you adhere f-glass to ABS??  Should I use epoxy next
    time??
    
    
    Side hint...  I don't know if I mentioned this in the Rhinebeck
    wrap-up.  
    	Are you tired of screwing and unscrewing those little screws
    	to remove and replace your engine cowling on your sport ship??
    	Why bother??  Just use Velco!  It actually works very well at
    	holding the cowling on and it gives some too when something
     	knocks into the cowl....  Just put the fuzz on the fuse and
    	the hooks on the cowl.  So far, the adhesive backing seems to
    	be keeping it on very well.
    
    cheers,
    jeff
    

    I would use Epoxy to glass to ABS.  (Actually, I would use epoxy
    to glass just about anything - I hate polyester)  THis worked fine
    on my Aeromaster cowl.
    
    Charlie
    

Yes, its true, you can't glass into ABS, even with epoxy the joint
is not a true bond.  There is some special epoxy made for plastic
that should work, its commonly available and quite expensive.

I would even question the strength of a CYA bond.  The reason you
can't go into the plastic is the very reason that CYA causes no
harmful long term bond to the skin; the plastic, just as your body
does, contains oils that come from underneath the bond and "float"
it away.

Since I started this note there has been one question that I have wanted to ask 
and hopefully one of my fellow noters would have an answer.

I have a friend who builds wooden boats by the WEST system.  The hulls are made up of narrow
strips of veneer layed over a male mould.  The first layer of veneer is usually stapled to the
plug until one layer is completed.  The next layer is laid on at 90 degrees to the first layer
and laminated into place with the WEST epoxy.  Usually three layers of 1/16 veneer is enough.
Once the hull is popped off the plug , internal bulkheads are added and the result is a very
light and durable hull.

I seem to remember that in the thirties there was a company, Lockheed?, that used a similar 
method of multiple laminations of veneer strips placed ina concrete female mould and then
pressurized with an inflatable neoprene bag until cured?

My question:  I have seen an ad for WEST epoxy in one of the model mags and wondered if they
were using the veneer technique?  Any feedback on this process?  It seems like a great way to
build a composite fuselage on a styrofoam plug.

       --|--             Happy (con)Trails!
        (O)             
________/ \_______       Scott Cox

    SCOTT,
    
    Much of yer' note was lost in the right hand margin...you may want
    to edit and re-enter.  Meanwhile, I can confirm that it was, indeed,
    Lockheed who laminated a fully monocoque wooden fuselage over a
    concrete mold for the Lockheed Vega and Sirius, perhaps others.
    Other than the labor intensity, I see no reason why a similar technique
    couldn't be adapted to model use.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    RE: the last two.
    
    Scott,
    most people have their terminals set up for 80 columns so line lengths
    longer than that are a bit of an inconvience. Not much though.
    
    Al,
    quit picking on Scott. 8^) Enter the command EVE SET WIDTH 132 and
    then do a Ctrl-Z or EXIT. Magically, your terminal will be set to
    132 character mode and you can read Scott's reply with no problems.
    
    Dan Eaton

Plywood composite construction has been traditionally avoided by
the home builder because of the difficulty of getting a 100% bond
between the layers of plywood, and because of the added effort in
making molds.  You must use a vaccuum bag to do it right, and it
must be perfect or it is worthless (well, maybe worthless is too
strong a word for model applications).  I've heard that the
modern glues, such as resourceinal (sp -- I know I've butchered
that one!) greatly improve one's chances of getting a good part.

Perhaps using CYA carefully as you wrap the layers might remove
the need for a vaccuum bag.

Owen Kampden (sp), who was active in the late '60s and the '70s,
has used thin (1/32) plywood molded in one layer around a form
extensively in his designs.  In Owen's models, he cuts a pattern
out of wood for a fuse.  This pattern has both sides and the
top turtledeck, but no bottom.  He then glues the formers to one
of the fuse sides and using water or amonia to soften the wood,
wraps the rest of the pattern around to form the whole fuse.     

At least one of his designs, the Windsong, a glider (not the one
available today), formed the lower part of the aft end of the
fuse with this method.  This model had a beautiful oval fuse. 

I do not think he used this method for anything else but the fuse
as he was a strong advocate of foam, and specified that material
for wings. 

This looks like a good place for this.

I was thinking for glider bodies, smaller gliders, of making a very light weight
fuse out of 1/16" balsa and small balsa stringers, reinforcing with thin
CF mat, and then a layer or two of woven kevlar and a layer or two of glass.

Any comments?  The wood would stay, and normal bulkheads would be used (probably
1/16 or 1/8 ply for HLG).

Chad

    Re: -1
    
    The current crop of successful HLG designs tend to use 1/16 slab
    sided balsa fuselage with 1/64 ply laminated to the balsa from
    the trailing edge forward.  Brian Agnew's Vertigo is an example.
    
    I have experimented with stab construction using 1.7 oz. kevlar
    sandwiched between 2 pieces of 1/16" balsa.  IT CAME OUT TOO
    HEAVY!!!!!!!!!!!!!!!
    
    The drawback to slab sided construction is the joints between
    fuselage top and sides are at 90 degrees, plus the bulkheads
    act as stress risers.  This is why fuselages using these
    methods tend to break on hard landings.
    
    A round or oval shaped fuselage is much better at absorbing shock
    regardless of the construction material.
    
    For the ultimate in light weight and simplicity, use balsa and ply.
    If you want a stronger fuselage that is equal in weight, carve a
    plug out of wood(basswood, pine, etc) and coat with epoxy.  Sand 
    smooth, apply release agent, and layup glass/kevlar over the plug.
    After the resin has cured, slit along the bottom of the fuselage
    and remove the plug.  Use a strip of glass to laminate the fuselage
    back together along the slit.
    
    A simple method for one-off fuselage construction is to carve the plug
    out of blue foam, layup with glass, and then melt the foam out with
    mineral spirits.
    
    A complex method would be to create a female mold from your wooden
    plug or existing fuselage abd use Rohacell, glass,carbon, kevlar,
    etc. to layup the finished product.
    
    Until you get away from the 90 degree angles, the composites don't
    help all that much.
    
                                                         Regards,
    
                                                         Jim

You can easily get rid of the square angles by putting triangle stock
in the corners and then sanding the corners away.  This is what the
RIDGE RUNT instructions say as well as Thornburg in his "Old Buzzards
Soaring Book."  Anyway, I am trying to avoid carving plugs :-)

Too bad about the weight on your experiment -- I'll take that into consideration
in my experimenting.  Not that I'll start the experiments until summer or
fall -- schedule is already filled :-)

Any other thoughts?  Lighter kevlar?

Chad

    RE: -1
    
    Although triangle stock allows "square" edges to be rounded off
    for a more pleasing visual effect, and does add some strength
    because of the larger surface area to accept glue, you are still
    dealing with 90 degree "butt" joints.
    
    The inherent lightness and smaller moments of HLG's give a lot
    greater immunity to damage, lending themselves nicely to the
    use of balsa.
    
    Of course lighter cloth reduces weight.  I have covered many
    glider fuselages with .6 oz glass cloth and ca or laminating
    resin.  Unfortunately it did not seem to add a great deal of
    strength to the structure.
    
    A monocoque structure, free of bulkheads, allows stress to
    be absorbed by the entire structure.  I can vouch for this
    principle based on the horrendous landings my Arcus and
    Calibra have absorbed.  Much less punishment has resulted
    in my built-up fuselages splitting in half!
    
    
                                          Regards,
    
                                          Jim
    

The free flight and Wakefield guys have been using rolled balsa fuselages 
for years. I would think that that would work for HLGs. You might be able 
to make a usable boom out of rolled 1/64 ply.