Conference vmszoo::rc

    
    Al, I've been experimenting with Dan Parson's .6 oz cloth and his
    recommended technique using epoxy (Envirotex).  The write-up he
    sends with the cloth covers everything from thinning the epoxy
    to what kind of sandpaper works best.  I followed his recommendations
    to the letter except that I used acetone to thin the epoxy.  On
    a test sample, sanded and  primed with K&B Super-Poxy, I was very
    impressed with the results.  It is true when he says that overlapped
    seams disappear!  I am getting ready to finish my CAP 21
    and will use this covering technique.  I'm glad there's a way
    to glass without the fumes of polyester resin, especially with the
    closed building environment I'm in during the winter months.
    This probably belongs somewhere other than in "ramblings" but you've
    mentioned Dan in here a few times - and I wanted to say I'm a 
    satisfied customer of his .6 oz cloth.
    
    Bill

I made several cowls in my high school days. Sig used to sell a release agent 
and you made a mold out of plaster of paris. I used wax paper and clay in the 
nose to set the final shape I wanted and then stuck the nose into a half gallon
milk carton with a cardboard divider. Pour in the plaster and let dry. Peel off
the carton and split the mold along the divider. Rejoin the mold with the model
removed and coat the mold with release agent. Lay in the strips of cloth and 
resin as you would any fiberglass job and when dry, split the mold again and pop
off/out the piece. Trim off the overlap and sand/finish the outside.

Sig had very complete details in with their glass kit (included cloth, resin,
and mold release agent)

With the new materials now you could also embed carbon fibers in it for strength

    I know someone who taped a block of foam on the firewall, sanded the
    foam to the shape he wanted, and then removed the foam from the
    firewall.  Then he fiberglassed over the foam and when it was cured,
    he melted out the foam from the inside with acetone.  It worked
    nicely.
                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Caster Oil!! "    
                      |_____/

Re: < Note 871.2 by ROCK::MINER "Electric = No more glow-glop" >
                          -< Try Fiberglass on Foam >-

The only problem with Dan's process is the finish is not real great and
requires further finishing to get a good result.

Making Fibre components is quite easy but it needs some experience before you
get the best results. I have made several moulds for cowls, canopies and
fuses etc. using female moulds. Remember the finish of the component is always
as good as the finish on the mould.

The first step is to rough out a plug, that is a make up the shape you want as
the finished article to be. The best material for a plug is a wood called
Jeluton (sp) but cedar is also good and smells lovely. Wood is the hardest
to work and finish. A quick easy method of making the plug is to use
Polyurethane foam; that is the green foam that you can rub with your hand to
shape it. It is best with large objects to block the foam over a wood former to
reduce the movement of the foam.

Once the shape is close but undersize cover the plug in a resin and filler
mixture. With polyurethane foam polyester resin can be used as it does not
attack the foam. Next you just finish the plug including panel lines etc. and 
make up a mould. The mould structure will depend on the object and the shape. 

Glass mat is good enough for the mould construction as you don't care about the
weight.

Once the mould is finished it must be polished, you are then ready to make
your first cowl or what ever.

Its quite a simple process really I have missed a lot of the detail in this
very quick description. Some good books exist that go into it fully, as I
recall RCM do a book on glass work. We in Oz have stores that sell glass/resin
etc to people to make boats. They hire the moulds also. They generally have a
good selection of books but remember they are a bit agricultural when it comes
to technique and their processes need refining to give the best lightest result
for our purpose.

John 

    On a new tangent, but still relating to fiberglass...
    
    I'd like to find a source for fiberglass sheet stock.  This will be
    used in 1/10 scale car racing applications (i.e. chassis, chassis
    components, suspension etc.).  I've been using old pc board scraps,
    but would like to find "virgin" material of more appropriate
    dimensions (such as 3/32 and 1/8 inch thicknesses).  I've laminated
    the scraps in some cases to achieve the desired thickness, but avoiding
    this extra step in the future would be nice!  I'm also having a hard
    time finding scrap pc boards that are long and wide enough for the
    bigger components I want to fabricate.
    
    I've struck out at the Nashua hobby shops I've tried, any other ideas
    on a source would be appreciated.
    
    Greg

    
    I'd try board shops. That is Printed Circuit module shops.
    
    
    Tom

Al,
I've used one can of the Sig resin. I never used K&B so I can't
compare them, but I was very happy with the Sig. The catalyst is a
little plastic bottle that you add a certain number of drops to the
resin and stir. I always used about twice the amount of catalyst they
recommended and it always worked, even set up over CA glue, Red Devil
lite spackle, aliphatic resin glue, and epoxy glue. It's thin and
brushes on easily, starts setting up in 10-15 minutes  (probably
longer if you use the recommended amount of catalyst). When it fires
it fires fast - from the time it starts getting a little stiff until
it's a solid mass in the bottom of the mixing cup is about 2 minutes.
I always used those throw-away foam rubber brushes for it. You can
sand it in a couple hours, but I usually waited overnite. Sands good -
harder than balsa or spackle but much easier than epoxy or CA glue.
Sands with a fine dust, doesn't gum up the sandpaper.

The can lasted me about 3 years, and the end of it was just about as
good as the beginning. The only problem I had was that it started
setting up in the threads of the cap, and I had to use stronger and
stronger pliers to get the cap off. The last time I took the cap off I
had to destroy it, but I also used up the last of the resin then so it
worked out fine.

I'm out of resin now and I plan to get Sig the next time too.

Dave

    eric,
    what kind of epoxy do you use that sands better than polyester?
    i love polyester for its sandability and find epoxy (ne hobby
    or whatever that stuff tom sells) is gummy to sand even days
    later.  its worse when i thin with alcohol (tho admittedly only
    70%).

    Re: last couple, Eric,
    
    I have to echo Kevin's question: indeed, _what_ kinda' epoxy have you
    found that, on its best day, sands better than polyester??  Like Kevin,
    I've found epoxies to be FAR less sandable than polyesters which is
    precisely why I stick to polyester.  Epoxy gums up and ruins more
    sandpaper than I'da believed UNTIL, it cures solid (at long last). Then
    it's so miserably hard I might as well be trying to sand marble.
    
    Polyester, on the other hand, with its bad smell and all, sands quite
    readily, at least for me, using open coat, silicone carbide paper (the
    light gray stuff...it's great!).  No loading up or gumming of the
    paper, feathers nicely, etc.
    
    
    Dave Huge, :B^)
    
    Yer' reputation (for whatever that's worth) is safe, amigo.  I used the
    SIG resin last night to second-coat all the glass-patchwork on the nose
    and it worked fine...behaved just like [good] K&B.  Still, a sock
    full'a sand sounds like a good gift idea. ;b^)  Hey, you can always use
    an extra sandbag in the shop, right.  For those who haven't discovered
    the myriad uses for [various sized] sandbags, you owe it to yer'selves
    to try 'em...once you have, you'll wonder how you ever built without
    them!
    
    
    More Christmas shopping, wrapping, etc. last night (Bah-Humbug!) so,
    again, I didn't get out to the shop 'til later than I like if I hope to
    get much accomplished.  Still, as I said before, every little bit, when
    done regularly, adds up faster than one imagines.
    
    I trimed the glass cloth from the previous night's work, feather-sanded
    the new glass into surrounding original areas, lightly sanded the new
    glass then applied the second resin coat to upper/lower hatches,
    restored nose areas and left cheek-scoop.  By then, it was past 11:00
    so I hung it up...the resin smell was starting to get to me anyway.
    
    But, everything went fine and I think the grafted front-section of the
    cheek-scoop will look OK after all.  Besides, it way past the point
    where it'd be easy to start over on it...by now, I'd have to dynamite
    it off and make one helluva mess in the process so, for better or
    worse, IT STAYS!
    
    Tonight's work: sand second resin coat nearly completely off and apply
    first coat(s) of K&B primer.  Last thing before closing shop, apply
    2 or 4-oz. glass to insides of all repaired areas, i.e. engine
    compartment, hatches etc.
    
    BTW, Eric, no comments about the TV...I don't watch it, just listen 95%
    of the time.  Besides, if it wasn't out in the shop, I wouldn't be
    either...yes, I confess to being a TV addict - love ta' sit in front of
    it and nap in the ol' recliner.  Regarding building speed, I make no
    secret of the fact that I'm a very slow, meticulous builder; I've found
    over the many years I've built models that, the better built they are,
    the better/longer they last and (God forbid) the better they come
    through sudden-stop incidents involving terra-firma.  And don't forget,
    this is a Masters-class competition model were dealing with here, not
    a Panic.  ;b^)  ;b^)  ;b^)  Seriously, the repairs _have_ to be done
    carefully/accurately or the whole model is ruined from a scale
    standpoint so I take LOTS'A time carefully aligning, shaping, etc. so
    the original appearance is restored...this above and beyond building
    [back] in the structural integrity at the least weight gain.

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

The reason for the whacker is to remove the wax in the finishing
resin.  Resin will not cure in air, so resin without wax is used
for all general purpose glass lay-up.  It doesn't cure
completely, leaving the top surface slightly tacky for further
layup work.

In finishing resin with wax, the wax floats to the top surface of
the work, cutting off the air and allowing the surface to cure. 
As pointed out, this must be removed before painting.

But I bet you already knew that!

Before starting this ramble, does anyone have a copy of Scale R/C Modeler in
their desk drawer?  I need the address for Innovative Model Products in
Lebanon, Tennessee so I can mail off a letter to Claude Baskin, the guy who's
drawing the 1/5 scale MiG-3 for me.  (Yup! I'm pressing him just a bit to give
me some idea when he expects the drawings to be done so I can start building.)

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Seems like I'm just doomed to have resin problems here lately, something I've 
NEVER had before.  Quite frankly, I think it's because of the colder temps in 
the workshop of late.  The resin fires off normally in the cup and gets harder
than a wh*re's heart but, on the surface of the work area, it stays tacky, even
after overnight curing.

I cranked up the heater to 80F room temp and used a Monokote gun to try to ac-
celerate the cure and this worked to a certain extent but the crap remained
tackier than I like.  Needing to get on with it, I sanded the stuff anyway,
treating it like epoxy, i.e. sanding slowly with only moderate pressure to avoid
heat buildup which aggravates the stickiness.  Using this technique, I got it 
ground down satisfactorily, though the resin had a real dull apearance rather 
than the hard, shiney look I'm used to.

Ta' H*ll with it, I thought as I went on and applied K&B primer over the resin/
cloth. The primer behaved normally and I was able to sand the first coat and ap-
ply a second coat before hanging it up last night.  It looks great!  Amazing how
much better things look when you get 'em tied together in a common color.  The
cheek-scoop repair I was concerned about now looks perfectly acceptable and the
overall repair actually looks better than I thought/hoped.  It's gonna' be VERY
tough for anyone to tell it was ever hurt.

Today's my last day at work 'til after New Years and I hope to be able to report
I'm into color and near the end of repairs when I return.  No reason that's not
possible if I don't run into some enormous snag.

I'll close this ramble by including once more, for those who may've missed it, 
my traditional Christmas card for all my notes_file buddies, all over the world.
Please have a safe and joyous one, amigos...it's on the ol' Rat.

	v			  ______
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	   V	     /			  \____________/	 \  /  \________
		    /			   	      /		  \/    
	___________/  			  ||	     /            /     
       /	  /			 \  /			 /
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/	   /				=    =
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			    \	/	=    =	     ||
   _____        _   	   =	 =	=    =      \  /
 |  \  \       / |	   =	 =	=    =     =	=
 |___\__\(o|--/  |	   =	 =	=    =     =	=
<|   _\__\_   ---| ------  =	 = ----	=    = --- =	= ----------------------
 ||______________)	   =	 =      =    =     =	=
 |  /\	      0		   =	 /      =    =     =	=
    O O                	   =	  | | | =    =	   =	=
			   = 	 	     =	   \	=
  			    =		     =| | |	=
(Ol' Yeller Peril)	     =	     			=
			      / | | | |=	       =
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				       =     =
				       =     =
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				       =     =
				       =     =
MERRY "CHRIS-MOUSE"		       =     =		"FELIZ NAVIDAD"
				       =     =		
       from			       =     =	  "PROSPERO ANNO y FELICIDAD"
				       =     =
 "THE DESERT RAT"		       =     =	  Best Holiday Wishes, Amigos!
				       =     =
     Al Casey			       =     =
				    \\\\\   /////	


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    Going back to fiberglass parts. I am making a couple of cowls but I am
    having a bit of trouble in getting the parts out. What is this release
    agent that was mentioned in earlier notes in this topic. I have never
    seen anything advertised to release components from the moulds.
    
    I have tried coating the plaster mould with varnish, followed by wax
    then the fiberglass - but it is still a major task to get the cowl out
    in one piece. Comments ?
    
    Eric();

PVA is the usual release agent used in commercial work.  It is
sprayed on the mold before the gelcoat, or before the first layer
of glass is laid up.  It forms a thin, rubbery kind of film that
will separate from the mold with a little pressure.  This is the
best stuff to use, as wax can be a bit of a gamble as a parting
agent.

Assuming that you have built in some taper to your mold, the best
way to separate the part is to wedge a knife blade around the top
in several places, bending the part away from the mold.

This, by the way, requires that the mold be quite rigid,  that
is, made of many layers of cloth.  This is what makes glass parts
expensive, as you cannot skimp on the thickness of the mold.

Once you have separated the part in several places, it should pop
free. Commercial applications sometimes use compressed air for
this, but I assume that you don't have a compressor big enough to
do the job. 

    
    
        I think I have a problem with polyester resin settin up.
     I mixed about 2 oz of it with the hardener, applied it to the
     glass on my wing (center section) and left it outside for about
     2 hours. Temps were in the 80s. I mixed it in a plastic cup and
     when I checked, It was still very tacky on the wing, even the 
     leftover resin in the cup was/is still very fluid. I checked again
    this morning.. still not set although a little harder on the wing.
    
        Does polyester resin go bad?. Does the catalyst?  with age?
    I admit I've had this resin and hardener for about 10-11 years
    from my boat building days. Is there anything I can do to cause
    this to set-up without removing the gooey cloth and trying again
    
     I also tried the talcom powder trick and it does work!! First time
    I didn't itch all over doin fiberglass.
    
    Thanks for any suggestions
    
    kevin p

Yes, the catalyist has definitely gone bad after that length of
time -- 3 or so years is about max, though I'm using some with
degraded results after 5 years.

Assuming you're using finishing resin, which does harden, and not
layup resin, which does not harden, I'd try a heat lamp for an
hour or so.  If that fails, I'd put some fresh resin/catalyst
down; this should both seal the tackiness and kick off what's
underneath.

If you're using layup resin, then just put down a layer of
finishing resin and call it a job well done!  There's some talk
about all this in the Spray note.

    This seems to be the best place to start this.
    
    Several of the Acton flyers have been talking about fiberglass
    fuselages. Steve Schommer (a non-DECcie regular contest attendee) made
    a HLG fuselage over a male plug and that got me going again. Yesterday
    I picked up some wood to create a plug and give it a try. I'd like to
    get some layup ideas fron people's experiences with fiberglass
    components.
    
    Steve's method is to layup over a male plug and then slit the fuselage
    down the bottom and pull the plug out leaving just a seam on the bottom
    edge. This is done while the fuselage is still somewhat green so as not
    to crack it. Like Steve, I'm going to practice on small fuselages and
    move up to larger ones. I hope to have a Chup style plug done this
    weekend so next week I'll be looking for suggestions on number of
    layers and weights to use. I'll be including carbon fiber in the tail
    boom layup to add strength in this area. This is where Steve has broken
    most of his fuselages. I also hope to use HobyPoxy Smooth and Easy as
    the resin since it sands very nice and is easy to work with and is
    flexible the next day but hardens over the next week (sounds like a
    good candidate for getting the plug out while green). Steve has been
    using Bondo (automotive) resin which he feels has a more predictable
    curing rate and is cheaper by the quart/gallon than most of the hobby
    stuff. I also have some EnviroTex which I'll give a try but that has a
    longer curing time than the HobbyPoxy. I have both so I'll try both
    before going out and buying something new. My initial feeling is
    multiple layers of 2-3oz glass over a 24 hour period. Should I bother
    with a finish coat of .6oz cloth?

    I got my plug done. I didn't have a lot of time so I did a quick and
    dirty with my bandsaw. Unfortunately, I probably should have tensioned
    the blade before I started. Filler works on hardwood too 8^) I wasn't
    too worried about it since it will be inside and what I do over the top
    is what matters. I'll be doing the layup this week and will bring the
    plug to tonight's DECRCM meeting. I've got two coats of latex urethane
    over it and will apply a hard wax to it as a release agent. I used
    1/16: ply for the fin so I'll be able to slip some sheeting into the
    tail if it needs stiffening.
    
    I'm planning on using 3oz glass gloth in several layers with some HEAVY
    mat in the nose, tow hook and finger hole sections. I'm going to use
    HobbyPoxy Smooth and Easy initially and will report back with my
    results.

RE: Note 871.17 by ZENDIA::REITH "Jim Reith DTN 226-6102 - LTN2-1/F02"
>    I'm planning on using 3oz glass gloth in several layers with some HEAVY
>    mat in the nose, tow hook and finger hole sections. I'm going to use
>    HobbyPoxy Smooth and Easy initially and will report back with my
>    results.

    Well, I see we need to change your nickname from:

                "Lead Sled" Reith    to:
                "Flying Brick" Reith.       :-)  :-)

    Gee, "3oz glass gloth in several layers"??!!??!!

    The Merlin layup (from memory) is something like 1 layer of 1.7 oz.
    glass and 2 (or 3?) layers of 1.7 oz Kevlar for the front half and 2
    layers of 1.7 oz Kevlar for the tail boom.  This is for a 100 inch
    span glider, not a HANDLAUNCH!  You'd better start working out in
    the gym to toss your 57 oz. glass fuse. Chup.  :-)  :-)

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    Ballast? I don't need no stinkin' ballast!
    
    I was just getting used to the feel of the hardwood plug 8^)
    
    I'm open to suggestions. I'm just plodding ahead without any data. Like
    I said in an earlier note, I expect a few to be discarded...

>>    I was just getting used to the feel of the hardwood plug 8^)

    I can see it now.  Jim shows up with his new fiberglass Chup.  

    "Hey Jim, why are the servos taped to the outside of the fuselage?" 

    Jim's answer: "Well, there wasn't any room inside for them."

    "Huh?  Isn't this a hollow fiberglass fuselage?"

    Jim: "Rats! I _knew_ I forgot something.  The hardwood plug is still
    inside.  Oh well, at least it's crash resistant."

      :-)  :-)  :-)  :-)  :-)  :-)  :-)  :-)  :-)

    Well, the process began last night. I put cloth on one half of the
    plug. I only did half since I didn't want to be fighting with
    pushing/pulling cloth in the overlap areas. The good news is that the
    cloth will come free of the plug. The bad news is that the cloth
    insisted on coming free of the plug. The cloth was put on a piece of
    plastic and the epoxy squeegeed onto it for a thin uniform coat. Then
    the cloth was put on the plug and wrapped around the edges. I got to
    one end and found the other end lifting around the edges. Back and
    forth I went. Part of this was due to there not being a LOT of epoxy on
    the cloth. I kept going back to it and as the epoxy started setting, it
    laid down better. Tonight I do the other half and then I'll have
    something for the next layer to stick to. Being a Chup, I decided to
    initially try 1.5oz cloth in two layers. I used a piece of 3oz cloth at
    the finger hole, tow hook area and underside of the nose. I'll also run
    a strip of carbon fiber laminate down each side of the boom between the
    layers. I also intend to put the small stab pieces onto the fin in the
    final layup. They always come off so I'll imbed them in the tail. Looks
    like a four night process as it currently stands. Polyester resin and a
    full saturday could probably work but I'm hesitant due to the smell in
    a closed house at this time of year. Time to get the paint box built I
    guess.

    re .21
    >>I put cloth on one half of the plug<<
    
    Which half? Top, bottom, front, back ? 
    
    I assume top half, and you had trouble with the cloth staying at right
    angles as it passed around the corners ?
    
    A fiberglass Chup fuselage will change life on earth as we know it
    today, so it's worth while that we all pay attention to Jim's
    struggles.
    He may save us all a lot of work in the future, except of course
    for Gremlin fanatics, who apparently need only a bit of plastic pipe
    .....or something.
    
    Terry

    
    
      Gremlin fanatics? I resemble that statement!
    
      I still think you guys are barking up the wrong tree. Why not use the
    Gremlin concepts, cut a different foam wing, and have an easy to build
    glider without all the drag of a seperate tail! Or, you can continue
    to lay fiberglass on fuselage plugs, its up to you! :) 
    
                                              Gremlins forever!

    Change life on earth?? Was I muttering in my basement THAT loud? 8^)
    
    I put the glass on one side of the plug wanting the seams to be on the
    top and bottom. The plug is shaped exactly like the built up fuselage
    with rounded corners so the rear is oval `0' not `o'. The tailboom
    thickness is about 1/2" while it's almost an inch high so the top and
    bottom corners are somewhat sharp. This is the area where the lifting
    occurred as well as the wrap around on the 1/16" plywood fin plug
    edges. The wax used as a release gave the glass nothing to stick to
    "around" the corners. This is how we want it AFTER we get done but it
    made it somewhat of a challenge to do initially. I think tonight's
    "other side" will go easier since it has last nights glass to stick
    too.
    
    I had also considered vacuum bagging both sides at the same time but
    chickened out (this time). Any thoughts about doing that with just 4mil
    vinyl supporting the cloth? I figured that this would leave protruding
    seams that would be sanded off between layers. The female mold method
    was looking better and better as I kept having to work the edges last
    night 8^)

    Re: Grem-glider
    
    Without an engine, the fuselage is superfluous. Glider-types already
    put electronics in the wing 8^)

    
     Your the one building fuselages, not me! :)
    

    Regarding the Grem-glider:
    
    You think that concept will REDUCE drag??? Hah! And that 1/16" plastic
    downspout doesn't weigh much, either.
    
    Jim is a Pioneer. Don't discourage him. 

    >> Jim is a Pioneer
    
    plodding along at the frontier of sanity. Making mistakes where few
    dare go... What the #$%@# am I DOING! (I'm leaving now to enjoy the
    Simpsons and play in the epoxy 8^)
    
    Lamar found out that Sealy will sell Pulsar fuselages for $50 including
    UPS. I can cut wings...

    
>>    Lamar found out that Sealy will sell Pulsar fuselages for $50 including
>>    UPS. I can cut wings...

...and will be ordering one tomorrow(Friday.) I'll be practicing cutting foam
wings this weekend for the Predator. First up is a flat 3014 with ailerons.
I'll probably go through a dozen before I get it right. 

-Lamar

p.s. - I can hear the slopes at the Cape calling.............

    Jim,
    	One of my club members is an ex mold maker for plastic injection
    molds.  The type that are used to make plastic bottles and the like.
    He's talked about a new plaster of paris type material that as it
    dries doesn't shrink or crack.  I'll check with him and see what it
    is.  If he's correct and you have a male plug, making the female
    just got a whole lot easier!
    
    Tom

    Lay-up day two.
    
    The second side went on last night. It stuck quite a bit better to the
    opposite side. This has me a lot happier about the prospect of removing
    the plug. I've been putting the cloth on a piece of plastic on the
    table and squeegeeing the epoxy over it. This gets a nice even coat
    with minimal weight BUT it might be too dry for the initial wrap. I
    was thinking that a better lay-up method might be the toilet paper
    method Al Casey described in the "Let us Spray" topic. Tonight, I will
    sand the bumps with a block and then put on another layer (with the CF
    underneath it. Final layer will be saturday morning with final sanding
    late saterday night and sunday morning. Sunday I pop the plug out and
    join the seam that produces. Sunday night I have a Ware club meeting
    and will bring it along for show and tell.
    
    I probably start the process all over again on monday to fix all the
    problems I find by sunday 8^)
    
    One more problem that has come up. If you wrap the entire plug, how do
    you hold it? My thought was to drill a 1/16" hole into the nose and
    tail and use music wire to support it. These holes would be sealed when
    the bottom seam was joined. I didn't do this in this version and I've
    just bewen balancing the fuselage on a board in my vice with a piece of
    plastic over it on the wing saddle. Final report next monday (unless I
    end up working this weekend)

    Re: .30
    
    Yes, please let me know. I've done female molding of cowles and I think
    it would be easier to do. You can layup several layers quickly in a
    female mold.

    
    
                                      Hello Glider's Pilots AND builders
    
    
    
    For the ones who are intersted, I may tell you how to mold fiber
    glass fuselages. For you that do not know me, here is my "builder"
    background: I am a full scratch builder: I have molded 7 fuselages
    up to now. The smaller is a replic of the Graupner RC/UHU (original
    weight is 320 gr; molded fuselage weights 95 gr!). The bigest fuselage
    I molded is 174 cm long and weights 850 gr. It is a replic of the
    SPEED ASTIR IIb and is intended for 4 to 5 meter wings. I also mold
    the canopies, servo protections as well as many other small pieces.
         Keep an eye on topics 871 and 399 and you'll read the whole
    story on HOW TO MOLD!
    
    
                                             Philippe
                                         The Highest Flyer
    
    

    
     DW1
    
        The Grem-glider was not a serious suggestion, but instead, just
    a normal Ba!!busting note as I am sure you know. Keep working on that
    mold - Jim!
    
                                                         DW2 
    

    I look forward to your methods. Here's how mine worked out:
    
    Friday night I went home and put on the second full layer of glass.
    After talking with Dan Miner, I decided to try wrapping both sides with
    one piece. Mistake one was not sanding more between the coats. This
    would have avoided some of the voids I ended up with. Wrapping around
    the bottom worked pretty well and I even managed to get the top to
    overlap and behave. Saterday morning I started to sand the fuselage on
    the plug. Due to not sanding between coats, this was a long process. I
    was hopeful about plug removal since I managed to pop the fin free from
    the plywood plug but I had to get to work so I couldn't do it all. Work
    ran late, I met my family on the way home, and finally got into the
    shop about 10pm. Going into the shop tired, is a BAD idea (mistake 2).
    I slit the fuselage down the bottom center only to find out that the
    release agent, didn't. I spent an hour and a half peeling the fuselage
    off with it ripping vertically (the full length CF laminate worked as a
    stop strip) in several places. At about 11:30pm, I put it on the bench
    to be dealt with in the morning (although my initial feeling was
    rolling it in a ball and sending it towards the trash).
    
    Sunday morning I went down with an idea. If I put plastic over the
    bottom of the fuselage plug, I could repair the rips and, hopefully,
    salvage something from this. With the vertical rips, it wasn't stiff
    enough to align and patch in one operation. I did this and then went
    about my other househodl duties. I ended up going to my club meeting
    without it and when I came back last night, I again headed to the shop.
    I managed to get it back off the plug and taped it together enough so I
    could patch the bottom seam. This morning I went down and did some
    light seam sanding and checked the alignment and strength. It will
    probably turn out fine but there's still a lot of TLC needed to get it
    ready to put radio gear into. I should be done with it by next weekend.
    
    Lessons learned...
    
    Use a good release agent. I've heard car wax is a better agent than the
    wax I used. I'll try that next.
    
    Cloth application. do the entire plug with a single piece if possible.
    Put the cloth on the plug and brush the epoxy onto/through it. Putting
    the cloth on plastic and squeegeeing the epoxy on it, makes the glass
    too dry to adhere to the plug/other layers.
    
    Sand the glass between layers. If there are irregularities, they will
    become voids in the final fuselage and will weaken it.
    
    Do most of your final sanding on the plug (with a block). This will
    support the fuselage while sanding. Be careful not to sand areas too
    thin.
    
    Personally, I think I'll go with 3oz cloth for the initial layer and
    then 1.5oz cloth for the final.
    
    Would I do it over again, learning from my mistakes? Yes, I intend to.
    There are still mistakes I haven't made yet! 8^)

    To keep this string going with yet another physically and emotionally
    draining saga......
    
    Yesterday I finally got started on the Weston 570 bagging. My
    Kevlar shears arrived (they work !) and I had no more excuses to delay.
    
    Did only one stab half, until I see how all this new, to me, stuff will
    work.
    The mylar sheet was painted ~2 weeks ago with auto lacquer which will
    transfer to the glass surface during bagging, I hope.
    
    A piece of .75 oz glass cloth was layed on the mylar first and wetted
    out with West System epoxy. It was squeeged less than usual to allow
    enough epoxy for wetting out the 1.7 oz. kevlar cloth which was layed
    on top of the glass cloth. 
    
    The Kevlar wets out nicely and can be squeeged very easily since you
    don't have to worry about pulling threads, snagging or bunching up.
    The West epoxy flows well, better than E-Z Lam, but hard to see being
    very clear.
    
    With everything wetted, the mylar, being taped along the top rear
    edges, is folded over the core, alignment set carefully, and into
    the bag she goes.
    
    I used the ASC vacuum hose fitting and their plastic snap lock bag
    closures on both ends of the bag. Only way to go, reduces bag
    prep time to 1 min., eliminates sticky caulk, and allows bags to
    be reused with no cutting of bag ends to remove finished product.
    
    One observation; The Weston pre-calibrated 5:1 pumps that deliver
    the correct ratio of resin/hardener put out about 5 times more than
    you need to do both stabs, with just one stroke. Therefore, for
    small amounts you should use the weighing method to avoid wasting
    epoxy.
    
    ALSO..the pot life in one stroke quantities at a room temp. of
    70 degrees is <40 minutes. How much less I don't know, but I
    went back to check on things after it had been in the bag for
    40 minutes, and the left-over epoxy in the cup was HARD AS A ROCK.
    I broke an X-acto blade tip testing it.
    
    The epoxy in the bag was still liquid/flexible as far as I could tell
    by flexing the edge of the kevlar projecting out at the edge of the
    cores.
    
    The directions on the can hint at this characteristic. Apparently
    there is a critical mass that causes it to really kick fast.
    The cup was very warm, never had a laminating epoxy get hot like that.
    
    Turned off the pump this morning, the stab is still in the bag. Tonight
    I see how well the paint transfered to the glass. This is the only
    part I have doubts about.
    
    Terry

    Never had any moulding experience, but I have tied a few bandages
    before, around assorted human appendages...
    
    Now, wouldn't a strip, say 2" wide, and thin enough to take on the
    contour of your fuse plug, wrapped around with some overlap, followed
    by brushing on the epoxy, be the way to go? Using a non-strip piece of
    cloth will not make it hug the curves, IMHO.
    
    'nuf speculation, let us await the word from the master builder -
    Phillipe Clement.
    
    ajai
    

    I rushed home last night and with trembling hands opened the bag and
    withdrew the stab half. Apprehensively I peeled off the mylar. It
    peeled off more easily than when not using paint on the surface.
    
    I saw white on the top and red on the bottom of the stab. Finally the
    mylar is free ! AND ?
    
    Well, it's not perfect but a heck of a lot better than I expected.
    Actually the surface finish on top is nearly perfect. The white lacquer
    transferred completely to the glass. Only a thin border around the l.e.
    of the mylar that wasn't in contact with the core had any paint left
    on it. The surface of the stab was smooth, void and scratch free.
    
    The bottom red surface wasn't as good. The paint had separated on the
    top layer, in a swirreled, curved pattern that had me baffled as to
    its cause. The stab is covered ok, but the pattern is visible,
    and some paint remained on the mylar.
    
    Three things I'll try on the second stab half to improve things:
    
    Wax the mylar with auto paste wax, as a mold release. This will
    help fill the scratches and doesn't interfere with paint application
    if multiple thin coats are applied.
    
    Use 4-5 light coats of paint , rather than 3 as previously.
    And use white tinting paste in the epoxy to give a brighter base.
    
    Don't overlap the kevlar beyond the edges of the core, and make sure
    the t.e. of the core is butted against the taped rear mylar joint.
    This eliminates a lot of post-bagging trimming.
    
    
    I can see how with a little more practice this will beome a viable
    technique and free me at last from the tyranny of how to paint/finish
    a bagged wing.
    
    Tonight I repaint the already waxed mylar, and tomorrow night I
    bag the other stab.
    
    Terry

    Well, when you can't figure something out, ask someone who has. Last
    night I spent about half an hour on the phone with Steve Schommer.
    Steve is responsible for my current fiberglassing binge. Steve is
    producing wonderful fuselages in (you won't believe it) 45 minutes!
    
    Here's some background. Steve is a wood craftsman by trade and does
    show quality work. freehanding a fuselage plug out of cherry with a
    drawknife is nothing. He also has some Corvette auto body background so
    is VERY familiar with polyester resins.
    
    Get the plug the way that you want it and give it a coating of hard
    auto wax. Next apply poly vinyl alcohol (a release agent available from
    boat repair suppliers) to the entire plug. At this point I should
    mention that Steve mounts the plug on his lathe and doesn't remove it
    until done. Once the PVA has set up he applies a coat of wax over this.
    During this time, Steve starts cutting his cloth to size. with a 45
    minute time to complete, this needs to be done ahead of time. He
    recommends using 3oz cloth for everything except possibly the tail fin.
    He lays up the cloth from the nose to the tail overlapping the nose
    several times. He does the layup a side at a time. His layup is usually
    a 3" band around the nose, a band from the nose tip to 8" back, another
    strip from the tip to overlap the boom some amount, and finally the
    boom and fin overlapping the wing mount area. This gives you 9oz on the
    nose, 6oz in the main fuselage and 3oz on the boom.
    
    Next, he starts mixing resin. Like I said, he's done a lot of this. He
    sets up his resin to kick in about 7 minutes. He initially gives the
    entire plug a gelcoat. End to End, both sides, everywhere. When this
    starts to tack up he starts laying the 3" pieces of cloth on with more
    (fresh) resin over it. When this starts tacking, the 8" piece goes on,
    then the main fuselage and finally the boom and fin. Work with the
    cloth and get the edges to lay down flat. His feeling is that the
    faster the kick, the less you have to play with the edges. Once
    everything is layed up, he gives the entire thing another gel coat.
    Once this has kicked, he sands the fuselage still on the plug all the
    way to 600 grit wet. He then splits the fuselage down the bottom and
    the plug practically leaps out of the fuselage 8^)
    
    Important points he stressed were not handling the plug after the
    release agent had been applied. Not handling the layed up areas until
    they were kicked (causes voids). And my biggest mistake, use a good
    release agent.
    
    Other hints about fuselage design included shaving the plug so that
    another layer of cloth can be added in a weak area without changing the
    external shape of the fuselage (the layers can show on the inside 8^) 
    Thinning a boom to make is stronger and lighter. I had to hear this
    twice so I'll try to explain it a little. A thicker layer will be
    stronger. A smaller diameter will be stronger. a smaller diameter will
    be lighter. So if you need to strengthen the tail boom but got the
    weight about right, shrink the diameter and add a little more cloth and
    you'll end up at about the same weight but stronger. Anyone that's seen
    Steve twang his old Raven last year can appreciate how strong his tail
    booms are. He says that after you've broken the fuselage a few times
    you get a feel fo where it's weakest and can redo some of the layering
    to compensate.
    
    Another point he made was that he felt that cloths lighter than 3 oz
    were too closely woven and didn't wet out properly and lead to dry
    areas and voids. He felt that you might be able to get away with 2oz
    cloth but in general you needed the strength of 3oz anyway. Boat
    builders suppliers will carry most of the stuff you need to get the job
    done. There's a couple of these places down on Rt20 in Millbury that I
    intend to check out. Another possibility is an autobody place that
    handles Corvettes.
    
    Ajai,
    
    I asked him about the bandage wrap method and he said that he's used it
    and has actually used the lathe to do it. He doesn't like it as much
    due to the overlaps foarming ridges and requiring too much sanding.
    He's used it to make fishing poles and it does work nicely for tapering
    the layers there.
    
    Now to get some PVA and try again 8^)

    
    I called the club member who used to be a mold maker to find out the he
    is again a mold maker.  Seems he was called back to work from his
    layoff.  Tonight my club's meeting so I should see him there and I'll
    ask him about he mold making material. 
    
    I've seen fiberglas insulatiing material that was a woven tube of glass
    that was placed over a pipe.  I wonder if it's available in different
    weights and could be used in lay-ups.
    
    Tom

    Hmmm! Something doesn't jive here, Jim.
    
    For a given wall thickness, larger the dia of a tube, the stronger it
    gets, contrary to what you state. If I remember right, the strength of
    a tube is proportional to the 4th power of its diameter.
    
    Incidentally, this is one reason why Canondale, a bicycle company,
    makes 'fat tube' bicycles, that are super rigid. They use aluminum
    instead of Alloy Steel, to compensate for the extra material a fat tube
    bicycle will use.
    
    OK about the bandage idea needing more sanding - I was [intesely]
    looking at the conformability aspect of getting the cloth to hug the
    plug :), with minor hassles like sanding being taken care of by
    using cheap third world labour.
    
    ajai

    Since I ride a Vitus I'm obviously qualified to jump in here 8-) ,
    but maybe Jim/Jim's source is talking about perceived stiffness,
    ie, what it feels like when simply flexed in the hands, as opposed
    to actual measured bending resistance which does the 4th power
    thing, as I also vaguely recall.
    
    Terry

    I think that there are two separate things to consider. One is
    stiffness, and the other is strength. 
    
    Stiffness can be measured by how much something flexes when a certain
    amount of  force is applied to it. Larger diameter tubes are stiffer
    than smaller diameter tubes.
    
    Strength is how much stress something can take before it breaks.
    
    Having said this, here's my guess.
    
    Say your tailboom is a single layer of cloth and is a certain diameter.
    It has a certain stiffness and a certain strength. If you made it 2/pi
    the diameter and used the same weight cloth, then you could have two
    layers. My guess is that it would a much stronger and probably just
    about the same stiffness.
    
    Of course this is just a guess ;-)
    
    	Marty

    I think Marty is closest of all of you. Like Gremlin wings, there has
    to be some give to absorb the impact. The strength is wanted sideways
    so that when the plane comes in contact with something, the whipping of
    the tail doesn't break the boom. We are trying to maximize the strength
    for a fixed weight. Therefore the smaller diameter generates a thicker
    wall with the same amount of material (read weight). Obviously there is
    a point where this falls apart because you want a hollow center to have
    the parallel walls providing support.

    Took the second stab half out of the bag last night. Wow! a perfect
    one this time. Both sides were smooth, shiney, no funny patterns in the
    paint. The auto wax on the mylar may have contributed to this, but at
    any rate the wax doesn't affect the paint application.
    The quality of the paint job is far better than any I have ever achieved
    or could achieve no matter how fancy the painting equipment, and the
    upshot is that it is so darn easy to get these results.
    
    This weekend I start bagging the wings, which being in three panels
    will take all week to finish. The drill is:
    
    Cut and paint the inner surface of the mylar for a given panel.
    Wait 24 hours for the paint to dry.
    
    Bag the panel, maintain vacuum for ~12 hours and leave the panel in the
    bag for another ~8-10 hours.
    
    Remove panel from bag, trim, clean paint residue (on a good procedure
    there isn't any) from the mylar.
    
    Repeat steps for next panel.
    
    
    When I get some time I'll experiment with enamal vs. lacquer,
    flourescent paint, lapping the cloth front to back vs. back to front
    embedding trim strips in the epoxy and any other Euro tricks I've
    heard of. 
    
    Terry

>>    flourescent paint, lapping the cloth front to back vs. back to front
>>    embedding trim strips in the epoxy and any other Euro tricks I've
>>    heard of. 

    Terry, please explain this "lapping the cloth" thing further.  I
    can't picture what you're talking about.  (Here we go again.  :-)

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    What I do is cut the glass and kevlar cloth in one piece, lay it on the 
    mylar then fold it over the t.e. of the core. So I should have said
    folded over rather than lapping the cloth.
    
    This makes a nice thin, sharp t.e. but the two ends of the folded over
    cloth are now at the l.e. and you have to deal with that. Weston
    does it by simply running a strip of tape over the exposed ends,
    spanwise.
    
    I was thinking if I folded over the cloth from the l.e. then the open
    ends would be at the rear of the wing.
    
    The only problem I see with this is that I'd have to hinge the mylar
    sheets with the masking tape at the l.e., and I don't think that 14
    mil mylar is flexible enough to conform to the small l.e. radius
    of most foam stabs or wings. This would mess up the cloth to core
    adhesion as well as the paint transfer.
    
    Using thinner mylar might be the answer but I don't have any feel for
    how thin it should be, and too thin means running the risk of wrinkles
    and warps on the surface.
    
    Of course using a separate glued on l.e. would eliminate the problem
    but that's not Weston's way, and besides I know that leading edge-less
    wings are done all the time, successfully, so why not by me too ?
    
    Terry

Terry, don't try to make the seam at the T.E, it will never work, your right 
you'll never get the mylar to go around the L.E.  Ron Watts has tried it.  The
best way to do it is to lay a 1-2" wide piece of say 3oz on the L.E (lengthwise)
wait for this to start to set a little bit, or you could tack it down with UFO
if you wanted, or maybe use some 5min epoxy, you just dont want it to move 
around alot.  Then go ahead and bag the skins like normal, then when you are
finishing (sanding ) down the seam on the leading edge you wont have to worry
about going too far and getting into the foam, you can then basically fair
the top/bottom skin into the l.e patch that you put down.  Works like a champ!

Also, dont fully tape the T.E the whole length of the mylar, just tape it 1"
from each end and then a piece of tape say every 4-5" will be fine.

    Hmmm, this sounds like a good idea. You're saying that the spanwise
    l.e. strip goes on the foam first, and the top/bottom pieces overlap
    it ? 
    
    This is the way that makes the most sense to me, and the paint transfer
    method could still be used. Tacking it with UFO seems the best way
    also.
    
    Okay, I be getting some 1" glass tape at the hobby shop tonight, saves
    having to cut long narrow strips with all the fraying and loose ends
    waving around.
    
    I've taped the mylar both ways but prefer full length taping as it
    keeps excess epoxy from oozing out into the bag.
    
    
    Also, I forgot to mention that I added white tinting paste to the
    epoxy on the second stab, and the difference is quite noticeable.
    Makes the white whiter and the red redder.
    
    Terry

Yes, that is what I meant..   Your statement about epoxy oozing out of the T.E
is a concern, if it is oozing out it is excess, let it go!!!  if it pools at the
T.E then it may not be true to the foam planform, or may not give a nice razor
sharp T.E.

    Didn't mean to imply that it was oozing all over everthing and pooling
    up and all that bad stuff, just that the full length tape keeps
    the bag from sticking to the core assembly when I push the core
    up against the edge of the bag, as is necessary when clamping
    the t.e. between strips with clothes pins.
    
    This second stab that I completed last night has such a sharp t.e.
    that it's almost dangerous. Thought I cut my thumb on it once,
    but no blood so guess not. 8-)
    
    Terry

    I agree with Mark.  Do not try to fold the mylar over the leading
    edge.  For those of you who read this and think it _can_ be done,
    please try it with a "dry" layup (no epoxy) and then apply vacuum. 
    What happens is that the mylar forms a wrinkle along the leading
    edge and you end up with the same (or worse) problem than you had
    going the other way.

    Besides, it seems that the current "best" planform (read: "the
    planform that is in fashion this year") is the Schumann planform
    with a straight trailing edge.  This begs for the tape hinge in the
    mylar to be along the trailing edge.

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    Now I'm confused.  If the sequence plans on a sanding of the multiple
    layer leading edge, then how does the paint-the-Mylar technique (which
    I heard of from Tom Kiesling last summer) jibe with the expected
    sanding? 

    Personally, I don't plan on any l.e. sanding.
    Last night I put one of the wing outbd. panels in the vacuum bag, and
    used the fiberglass tape along the l.e. It was a pain getting it
    to stay in place as the wing was slid into the bag, but that was
    because I had tack glued it only along the l.e
    
    Next time I'll glue it farther back on the wing and put tension on it
    around the l.e. 
    
    Tonight we'll see how this larger panel comes out. 
    Weston says to use tape along the l.e. to avoid the problem of how
    to get paint on the l.e. radius. I used chrome trim tape on the l.e.
    of the stabs and it looks ok, and adds extra visibility.
    
    Another solution is to use a separate l.e. edge piece which could be
    sanded and painted before bagging but this defeats part of
    the "one step and you're done philosophy" and doesn't fit
    well with the Weston style cores which aren't cut to accept separate
    l.e.
    
    Terry

    Thank you for entering that. The printer is busy as I type in this
    reply.

    I read your entire method and am very interested in trying it. My only
    problem right now is that it is too cold to do the polyester resin work
    in "a well ventilated area". When spring comes I will probably give it
    a try.
    
    In section B.III.1 (and referenced in B.III.2) you talk about trimming
    the excess fiberglass with an Xacto and PVC. I do not understand which
    side of the mold the cut is taking place. Do you have the PVC inside
    the fuselage as backing or are you cutting from the inside?
    
    I think that method two is probably the method that I would personally
    try first. The current fuselage designs in the USA are using nose cones
    to hide the radio access. This is generally done using the fuselage as
    a male mold. This would mean that you would have a fuselage WITHOUT a
    canopy opening to glass the centerline joint. All work would have to be
    done through the tail. I sense that this would be very difficult.
    
    Anyone have a handy English/metric conversion table handy to go from
    grams/meter^2 to ounces/sq foot?

    The conversion factor for grams per sq. decimeter to oz./sq ft.
                                            ^^^^^^^^^
    is ~3.08. 
    
    To convert from meters, the intuitive solution is left to the student
    ;^)
    
    Terry

>Remove the silicone glue under the work plate and push on the original until

How do you remove the silicon?  I use silicon a lot (servo mounts, hinges, etc.)
and I haven't found any convenient way of removing it.

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    So, the 100 gm/sq meter = 3oz cloth (3.08 8^)
            200             = 6oz cloth (6.16)
        and 300             = 9.24oz cloth (for making the mold)

    
    
    RE .57
                                                  Hi Gliders Builders
    
    
    For the fuselages with a nose cone protecting the radio, I don't
    see where the problem is. I suppose that at the end, you have your
    glider in TWO different pieces: the fuselage it self AND the nose
    cone. So why not to mold them separately. Doing like that you will
    have a well situated aperture to fiberglass the two halves. Don't
    you? Can you figure out how an RC/UHU is small? I have molded 5
    of them without too much difficulties. However I have to admit that
    this kind of work is apparented to gynecologic medecine ...
    
    
                                                      Philippe
                                                  The Highest Flyer
    

    My only concern was that doing the fuselage half mating with only the
    tail as an interior access might be difficult. My comment about the
    nose cone was simply to point out that the nose was fully enclosed by
    design so there would be no canopy opening to smooth the fuselage seam
    through. All access would be through the tail.
    
    My thoughts were more similar to proctology but we are "birthing" a new
    fuselage through this procedure 8^)

RE: Note 871.63 by ZENDIA::REITH "Jim Reith DTN 226-6102 - LTN2-1/F02"
>    My only concern was that doing the fuselage half mating with only the
>    tail as an interior access might be difficult. My comment about the
>    nose cone was simply to point out that the nose was fully enclosed by
>    design so there would be no canopy opening to smooth the fuselage seam
>    through. All access would be through the tail.
    
    Jim, it seems to me that you've been sniffing too much polyester
    resin lately.  :-)

    With or without a nosecone, you still need a "hatch" style cutout in
    the fuselage to install the radio.  Thus, the 2 halves of the
    fuselage can be joined by reaching in through here.  THEN, when
    you're done, you mold the nosecone from a _different_ set of molds. 
    (You could just use the male plug and layup the nosecone directly on
    that.)

    Summary of my (blurry?) "vision" of how to build with nosecone is: 
        - build male plug without hatch cutout.  (Full rounded fuselage)
        - make female molds, leaving approximate area for hatch cutout.
        - mold 2 fuselage sides, attach sides through hatch area of molds.
        - re-use male plug to make each nosecone.

                       _____
                      |     \
                      |      \                          Silent POWER!
      _        ___________    _________   |            Happy Landings!
     | \      |           |  |         |  |
     |--------|-  SANYO  + ]-|  ASTRO  |--|              - Dan Miner
     |_/      |___________|  |_________|  |
                      |       /           |     " The Earth needs more OZONE,
                      |      /                       not Castor Oil!! "    
                      |_____/

    Actually, it's Poly Vinyl Alcohol 8^)
    
    Steve Schommer just molds the nosecone over the finished fuselage (with
    release agent applied) to get the perfect fit. The nose needs to be
    completely contained for this to work (you cut the access after the
    fact).
    
    The male plug used to produce the female mold would work just as well
    since the mold is presumably an exact image of this so you would be
    able to do the same thing with that. Problem solved.
    
    Another thing I was considering was plywood wing rod reinforcements. In
    the female mold case, it would be very easy to install these before
    joining the halves. In the Male plug method I've been playing with,
    I've been considering "letting" them into the plug and NOT applying
    release to them so they become part of the inside surface.
    
    Radio through the tail? Hell no. I'm just going to strap it on the
    outside since I can't get my fuselage to release from the plug! I
    should have my Chup fuselage at next month's DECRCM meeting. The
    initial effort is just about finished after fussing with it far too
    much. It stiffened up after I repaired the splits and seems quite
    servicable with a gelcoat yet to be applied. I'll be trying another one
    this weekend now that I have some real release agent.

    
    RE .64                           Jim
    
    
         Indeed, Dan is right. My explanations were not very clear:
    The nose cone and the fuselage should be molded separately in two
    DIFFERENT molds.
    
                                                         Philippe
                                                     The Highest Flyer
    
    

    Well, fuselage two is now complete. I got some poly vinyl alcohol on my
    way home wednesday and on saturday, I built another fuselage. This one
    used polyester resin (the Bondo stuff just to try it) since the weather
    was warm enough to open all the windows to air things out. I still need
    to figure out a better way to tack down the edges of the overlapping
    pieces but it went better than the first. I found that preheating the
    polyester resin with my heat gun (since my basement was in the 50's)
    allowed the resin to kick in the 7-10 minute range as predicted. I used
    1.5oz cloth (50 gm/sq meter) and did several layers. The fin didn't
    come out very well this time. If I do use this fuselage, I'll probably
    cut the fin off at the base and glue in a normal wooden one.
    
    The Bondo resin is worlds better than the K&B stuff. No waxy feel and
    it kicked nice and fast and predictable. I picked up a quart set for
    $10 at a local discount store (The Fair). It's very sandable too.
    
    Other experiments this weekend included trying to use standard 30
    minute epoxy as a resin. This turned out to be too rubbery and not
    sandable. For my winter projects, I'll be using epoxy laminating resin
    and will save the polyester for the backyard next spring. I'll bring
    the initial two fuselages to the DECRCM meeting next week. They'll be
    useable as slope soaring fuselages but are probably too heavy for HLG
    (5-6oz)
    
    Practice makes perfect and the layup is the hardest thing to master but
    it's getting easier.
    
    

    I finished fuselage #3 this weekend. I went back to the HobbyPoxy
    Smooth and Easy as my resin. I did this one a little differently. I
    started the fin by laying small strips over the fin leading edge to lay
    a foundation for the edge and to simplify wrapping this edge. I then
    used 3oz cloth to do the wing saddle area and the underside of the
    nose. I also reinforced the rear of the canopy area. I used my heat gun
    to push the epoxy and thin it for brushing. This made it tack up faster
    and allowed me to overlap it with the next layer. All layers were put
    on with the resin first followed by the cloth with the heat gun
    thinning the resin so it saturated the cloth from underneath. Excess
    was spread with the brush as the cloth was flattened/stretched. I used
    the bandage method Ajai asked about and found that it held the edges
    down much better but there will be some extra sanding before the final
    gel coat. I did the entire fuselage in overlapping small pieces and it
    worked much better than trying to tack down one continuous piece. I
    split it off the mold this morning and will put on the gel coat tonight
    and bring it to DECRCM tomorrow night. The original fuselage has been
    touched up to the point where it will be servicable for a slope ship
    (read heavy) and this one seems to have ended up the lightest of the
    three. Next attempt will be a 2 meter fuselage for the Rude B*tch
    replacement.

There have been a few comments elsewhere in this file about the current series 
of articles in R/C Soaring Digest on fuselage mold making by Jerry Slates 
(editor of RCSD) I called RCSD last night about advertising copy formats and
Jerry answered. He was very personable and we got sidetracked onto his series
that just started in the 1/93 issue. I asked about the material used in the 
mold making, due to an inability to use polyester resin in the winter and was 
pleased to hear that the mold and fuselages will be completely done with epoxy.
Having found that out, I will now start to lay out a plug to follow along with 
his article. Perhaps we can discuss this in this topic if there's interest?

    Count me in as one interested in learning to layup fuselages.
    
    I feel a little less urgency than before, because I have just
    ordered a Kevlar F3E fuselage from Modellhaus in England. There
    are no other sources I know of to get this type of fuselage.
    
    I have dabbled a little bit with this already and can make one
    good suggestion at this time.  A large part of the project
    involves carving a plug.  I have found pre-made hardwood tapered
    table legs available at lumber yards/hardware stores for $5 apiece.
    They are the perfect size for the tailboom of a glider.  You need
    only attach a piece of basswood, balsa block, etc. and carve the
    "pod".  This saves a lot of time!  A foam fin is then glued to the
    boom and the whole thing is coated with laminating resin and
    faired/smoothed.  You now have your plug.
    
    From what I have read and experienced, fiberglass is ok for sport
    flying, with extra layers built up around known stress areas.
    Kevlar, Carbon, Spectra, etc. can be substituted where absolute
    light weight and strength are desired. Rohacell is now being used
    in fuselage molds to further lighten and stiffen the structure.
    
    The Trabi F3E fuselage I ordered weighs 130 grams in Kevlar and 220
    grams in fiberglass.  The owner of Modellhaus says the fiberglass
    structure is slightly stronger.
    
    Molding makes a lot of sense for competition glider designs, where
    the design criteria is always the same- light weight, strength, low
    drag.
    Once you have your mold, you can make fuselages fast and cheap.
    
    I think molding will slowly make its way into powered flight, as
    high quality balsa becomes increasingly difficult to obtain.
    
    
                                                        Regards,
    
                                                        Jim
    

A few more things Jerry said:

I asked him if he had done any wings. He said he hadn't, yet. It was something 
he expected to try in the future. 

He said we should feel free to call him if we needed help along the way. As I 
said before, very personable.

He said he's done about a hundred fuselage molds. He feels the process to build 
a mold takes about 40 linear hours work (there is some waiting to cure in there).
Pulling a fuselage from a mold can be done in about 6-8 hours IF an oven is used 
to cure the epoxy. He generally leave fuselages in the mold 24 hours. He said 
you can crank 4-5 a week when you're on a roll. He was doing about 400 wings a 
year and 4-5 fuselages a week back when he was also working fulltime. We related 
a few stories on that point 8^)

Thanks for the tip on the table legs. I expect to turn things down on my lathe 
initially. I will probably use basswood for my plugs due to the positive results 
I've heard of from carvers I know.

    If you are planning to use a bolt on wing, you can sand the wing
    mount area of the plug with a template made from the intended
    airfoil which will be used.
    
    Cut a blue foam core(about 12") using the the wing center section airfoil.
    Laminate a piece of 6 oz. fiberglass to the bottom of the core, making
    sure to wrap the glass up around the leading edge.  After the glass
    has hardened glue a piece of 80 grit sandpaper to the bottom of the
    airfoil using 3M-77 cement.
    
    You now have a custom airfoil sanding block to sand the wing mounting
    area of the plug to the airfoil shape.  This will insure a nice
    clean transition between the finished wing and fuselage.
    
                                           Regards,
    
                                           Jim 
    

If this is a limited use sander, why not just "press" the sandpaper into the 
epoxy and avoid the fiberglass step?

    Re: -1
    
    If your plug is foam or balsa you could probably get away without
    using the glass.  If the plug is basswood/pine the glass stiffens
    the core, so you can apply more pressure without crushing or dis-
    torting the foam core when sanding.
    
    Most high quality fuselages have wing fillets molded in to allow
    a good transition.  This has been true of the plug in wing fuselages
    I have purchased from Bob Sealy and Multiplex.  The Algebra fuselage
    did not have wing fillets.
    
    Reducing parasite drag by using fillets, sealed hinges, etc. is
    probably not critical on a Thermal Duration design due to the
    low airspeed.  
    
    Wing fillets seem difficult to make(particularly for airfoils with
    substantial camber and thin trailing edges), but add a nice
    aesthetic(sp?) touch and promote laminar flow at high speed.
    
    
                                                  Regards,
    
                                                  Jim

    why not borrow the original from a friend, wax it up, and away you
    go... I've seen a few Alpina very..look-a-likes..
    
    Anon.

Part of the effort is to sell them afterwards and the other part is to do 
something not available.

RE: 871.69

>Having found that out, I will now start to lay out a plug to follow along with 
>his article. Perhaps we can discuss this in this topic if there's interest?

Yeah Jim, keep the info coming. Not that I'm interested in building a glider
fuselage but I am in the process of makeing a plug for a helicopter fuselage.
Did you know it takes a 4 x 8 x 1 sheet of blue foam to make a plug for a
1/8 scale Huey fuselage? 8^) Neither did I until I was done. The plug still 
needs more work before I can seal the surface and wax it. One of these days.

Something you might want to try is using paper mache. There was an article in 
Model Aviation last year describing the method. Basically you use strips of 
brown paper bag soaked in carpenter's glue as a replacement for the cloth/epoxy.
I tried it on the tailboom of a plug I gave up on and it worked well. It also
got me over the "gee, I hate to use a bunch of cloth/expoxy and have it not 
work"  excuse for not trying. 

I'm not clear on this. What component does the paper mache become after you've 
layed it up? The male/female mold or just to prove the plug will release?

RE:
>I'm not clear on this. What component does the paper mache become after you've 
>layed it up? The male/female mold or just to prove the plug will release?

Jim, for the test plug I used it to make a female mold off of the wooden plug.
I didn't take things any further than that. When I finish my Huey plug I'll use
paper mache to make a female mold. With that done, I'll try laying up the
fuselage with paper mache to see how that works. If everything goes well then
I can layup a fiberglass fuselage in the paper mache female mold.

There's a couple of nice features to using this stuff. It's cheap. The cost of
the materials is just the cost of the glue. The bags come home from the grocery
store every week. It's not terriably hazzardous. There's no objectionable
smell and the glue could even be good old white glue if you wanted. 

How do you plan on hardening the paper mache surface (or do you consider the 
glue/paper to be hard enough to take a mold from)?

Will you just wax and prep the paper mache surface?

RE:
>How do you plan on hardening the paper mache surface (or do you consider the 
>glue/paper to be hard enough to take a mold from)?



Jim, what you do is cut up a brown paper bag into aout 1 inch strips. Soak these
in a 50/50 mix of carpenters glue and warm water and then cover your plug with 
them. The guy who wrote the article said you didn't need to worry about 
overlaping pieces causing a rough finish but I went ahead and butt jointed 
the pieces as much as I could on the first layer next to the plug. Then I added 
about three more layers and let it dry for a day. When I popped the mold from 
the plug the interior of the mold was as perfect as the exterior of my test plug
was. 8^)  The glue fills up the gaps. The mold surface is sealed by the glue and 
hard. On my test mold I just used plain old Elmer's white glue. I think the
Elmer's carpenter's glue the guy recommended would work even better.

>Will you just wax and prep the paper mache surface?

If I were going to pull a male mold from the female test mold I'd just was it
up and start the layup. I just remembered one advantage to this method over
cloth/resin. My friend Cam said all you needed was wax for a mold release vs
wax and PVA.  As far as doing any prep work on the mold, hmmm, that doesn't 
sound like fun but you can sand the paper mache and wood fillers ought to 
work ok. I guess the best thing is to follow the advice of my friend and make 
the surface of the plug as perfect as you can make it so you don't have the
mess around on the inside of the mold. 

. 

Sounds like a cheap way to try it out. I'll probably give this a try before 
mixing up $20 worth of epoxy. Another benefit to it is that if the mold 
sticks, it can be sacrificed for the sake of the fuselage inside. I don't 
need more to do in the shop (I happen to have a certain HLG fuselage plug...)

I've been having conversations with the Slates at RCSD and mentioned the paper 
mache method to Jerry (who is doing an series on fiberglass fuselage molding in 
the current issue(s)). Jerry thought that for "one of" molding it might work out 
ok but it wouldn't stand up to more than a few pulls. He did think that it might
be a reasonable way to test a "plug" when developing a fuselage style/shape and 
wanting to test build one before putting in the effort on a full blown mold.

Just another datapoint.

    I thought I would report on a couple of my experiments:
    
    Applying .6 oz glass directly to blue foam with CA resulted in
    excellent adhesion.  I tried 3 oz glass and it did not adhere
    very well.  Apparently the thin CA cannot encapsulate the larger
    fibers of the 3 oz. glass.  Apparently adhesion is a problem with
    blue foam using any method due to the closed cell makeup of the
    foam.
    
    I tried Plastikote spray, colored polyurethane on a filled obechi wing.
    It worked well and the coloring eliminates the need to dye the wing.
    At $3.99 per can its worth looking at.  The color selections were kind
    of weird, but I found a deep maroon that looks ok.
    
    I am going to try experimenting with maple veneer instead of
    glass.  This will allow the use of a separate glued on leading edge
    and wingtips which can be shaped with a sanding block to the airfoil.
    I have read that these veneeers work well due to being closed grain,
    unlike obechi.
    
    I am learning a lot but still do not have a complete NACA0009 stab
    for my Arcus and Calibra.
    
    At my own pace I will be experimenting with molded stab construction.
    
    Just wish I had more time!
    
                                            
                                                      Regards,
    
                                                      Jim

Two things:

First, read the section early in the January 1993 RCSD about the 
comparison of NACA-0009 and SD8020 stabs. Apparently there is a larger 
"deadband" (area of insensitivity) in the NACA airfoil. The SD8020 
avoids this for the same general sizes/speeds.

Secondly, Stabs make an excellent testbed for hollow core composite 
construction. Small size and symetrical shape allow you to test/develop
without a left AND right mold.

The new RCSD arrived last night and I spent most of the night on the 
couch going through it and through the 3rd part of the fiberglass 
fuselage making. In my other hand was the new FiberGlast catalog that 
arrived with the fiberglass and kevlar tapes I ordered. If anyone 
called for a catalog back when Jeff put in the note about them (like 
I did) there is a new catalog and the prices are about 10% higher.

One of the things I really liked about the article in RCSD was the 
method used to join the two fuselage halves. Neat and simple and done 
at the time of the initial layup. Basically, you only trim flush half 
the edge of the part during layup. The other half gets left with about 
1/4"-1/2" sticking up. If you trim the top edge of the left half then 
you trim the bottom edge of the right half. You put the molds together 
offset so the stuff sticking up is inside the hollow part and then you 
slide them into place and the stuff sticking up is rolled into place 
finishing the seam. Stand it on the nose and any excess resin that you 
didn't remove will migrate forward lightening the tail. He made it 
look/sound so easy.

Everything Jerry used for the layup is available from FiberGlast. I 
know, I had the catalog in hand as I read the article 8^)

I'm thinking about making a static display aircraft model. I'm not sure how
best to fabricate some parts such as a nose cone. Fiberglass layup (which I've
never done before) seems promising, from reading these notes.

A question: for a non-load-bearing application such as a static model's nose
cone, gear doors, etc., what is a typical thickness of a fiberglass part? Or,
how thin can it be without being fragile? It would need to take handling OK,
but not need to deal with impacts or aerodynamic loads.
						-- Tom

>    <<< Note 871.87 by LHOTSE::DAHL "Customers do not buy architectures" >>>
>                -< Thickness vs. Strength of Fiberglass Parts? >-
>
>I'm thinking about making a static display aircraft model. I'm not sure how
>best to fabricate some parts such as a nose cone. Fiberglass layup (which I've
>never done before) seems promising, from reading these notes.
>
>A question: for a non-load-bearing application such as a static model's nose
>cone, gear doors, etc., what is a typical thickness of a fiberglass part? Or,
>how thin can it be without being fragile? It would need to take handling OK,
>but not need to deal with impacts or aerodynamic loads.
>						-- Tom

I think it would depend a lot on what size this model will be.
If it has a wing span from 40" to 100" then I agree with the last reply.

It also depends on what it is a model of and what kind of spinner the
full scale has.  If you making a LARGE model of a plane that has a polished
aluminum spinner - then you should make one our of aluminum.

Basically I agree with the previous reply - make a foam plane then after
you've already committed to completion go ahead and glass it.

Buy lots of sand paper and prepare for a few evenings of 40 grit followed
by a few evenings of 60 grit followed...100,200

Of course if the plane only has a 10" wing span - forget fiberglass.

P.S.  This is the RC notes file.  We can't imagine all that work and
      never flying it!

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

RE: <<< Note 871.89 by KAY::FISHER "The higher, the fewer" >>>

>I think it would depend a lot on what size this model will be.

So many things I don't think to mention! The project would be a 1:10 scale
F-18 Hornet. My idea is to build it up according to how the real airframe was
built (fuselage frames etc.) and leave it without skin except for a few areas
such as the nose radome, gear doors, airbrake surface, etc. Thus I would not be
making a shell/skin for the entire surface. The radome would be on the order of
five or six inches long.

>P.S.  This is the RC notes file.  We can't imagine all that work and
>      never flying it!

I couldn't imagine all that work and totalling it in a crash. Incidentally, are
there other conferences related to model making?

Back to fiberglass. How does one deal with compound curves, and avoid wrinkles
and folds in the cloth?
						-- Tom

>So many things I don't think to mention! The project would be a 1:10 scale
>F-18 Hornet. My idea is to build it up according to how the real airframe was
>built (fuselage frames etc.) and leave it without skin except for a few areas
>such as the nose radome, gear doors, airbrake surface, etc. Thus I would not be
>making a shell/skin for the entire surface. The radome would be on the order of
>five or six inches long.

Sounds impressive - if you get a good start on this you should bring it to
one of our DECRCM meetings in the winter for show and tell - sounds like
we would all like to see your progress.

>>P.S.  This is the RC notes file.  We can't imagine all that work and
>>      never flying it!
>
>I couldn't imagine all that work and totalling it in a crash. Incidentally, are
>there other conferences related to model making?

No - your fine here - I was just kidding.  There is a Plastics note file that
tends to specialize in static - but a plane this large probably belongs
here as you will be using techniques on a scale with RC planes.

fyi - DOLPHN::PLASTIC_SCALE_MODELING

>Back to fiberglass. How does one deal with compound curves, and avoid wrinkles
>and folds in the cloth?
>						-- Tom

Hmmmmm - others feel free to jump in and correct me or add details.
It depends on the type and weight of cloth you choose.  Some cloth
works better on compound curves that others (types of weave).

For an exercise in terror - call Aircraft Spruce and Speciality and get their
catalogue - runs about $5.00.  In the catalogue they will describe all
the different weaves and their advantages and disadvantages.  The simple
way out is - thin (light weight (.6 oz cloth)) is pretty compliant
and an normal trick is to dust it with 3M spray contact cement (3m77).
Let it set up for 5 minutes then apply the cloth and it will stick down
even tho there are some compound curves.  This does not seem to effect
the ability of the epoxy or resin to wet out and the bond seems just as
good.  If you have trouble slice the cloth and overlap pieces.  

There are some excellent notes no how to fiberglass deep within this notes
file.  Check out note 11.1 for a list of notes to check for a list of notes
to check...

Those written by Al Casey (who got the package quite a while back) should
be taken as gospel.  

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

For fiberglass and resins, I'd recommend Fibre Glast Developments Corp. 
I've used them before and they carry everything you need to go from idea 
to molded part. Their catalog is free and well worth it 1-800-821-3283. 
They have all kinds of weaves and weights and explain what works well 
for what. They also carry all the resins and tools and release agents 
and...  everything!