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Old Jul 26, 2002, 01:11 PM
Dude, where's My Plane?
JasonJ's Avatar
Green Lane PA USA
Joined Mar 2001
2,167 Posts
Glassing wings,, HELP

Hey guys, I am building a pair of Blue fan fold foam jets, AUW will be somewhere between 32-38 oz. They are for MF-480 with brushless motors. I plan to glass them, the wings will be built up blue foam with CF arrorw shaft sparr.
I have little glass experience, so I dont know how strong its going to be when done, so my question is, Should I sheet and glass the wings, seems like overkill to me, or should I just glass over the foam?
Any tips for glassing the swept wings would be helpfull, do I use one piece or do it in strips? How many layers of what type of glass, ect, ect.
I will be useing WBPU, I have striped the plastic from the foam.
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Old Jul 26, 2002, 01:55 PM
silent flight
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South Wales UK
Joined May 2002
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I've glassed a few wings.

Depends on how much weigth your willing to allow on the covering, but I've covered wings with 2 x layers of glass fibre/exopy then a final finishing coat of epoxy and the wing is as hard as nails. I squeeze out all the excess epoxy out of the glass to keep weigth to a minimum.

Get yourself some medical type latex gloves, epoxy is a nightmare on your hands. I also find it easier to use a spreader rather than a brush to apply the epoxy.

Also thin out the epoxy with epoxy thinners makes the job much easier and your epoxy will go further too.

Hope this helps, good luck

Mike Y
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Old Jul 26, 2002, 02:10 PM
FoamyFactory.com
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USA, TX, Fort Worth
Joined Nov 2001
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Jason,

use .54 or .75 oz glass cloth. You can usualy get it at your LHS. DON'T use anything heavier, as it will add too much weight. Use just the foam and glass. No need to sheet with balsa.

I use 1 piece when covering an F3 foam wing. Cut a piece big enough to cover both sides of the wing with about 1/2" overlap on all sides. Start on the bottom of the wing right at the LE and work towards the bot. trailing edge, fold over the glass and work toward the top LE. Make sure you get all the wrinkles out. You should have about 3/4" overlap now hanging off the LE. Cut that to about 1/2" and wrap it over the LE onto the bottom. The cloth seam should be on the bottom of the wing.

WBPU works great. Not as hard a finish as epoxy, but it works. Use one coat to get the cloth to stick to the foam. Don't worry about putting too much on like with epoxy. Let dry for about 2 hours (more if humid). Lightly sand with 180 to 220 sand paper. Don't sand through the cloth! Then mix up some WBPU with baby powder. Mix it enough powder to make it about as thick as "thin" pancake batter. This will be your filler coat. Brush it on, let it dry. Sand with 220 grit paper. Do it again. This is what I did on the MB339 and it worked great. Oh, BTW, those cheap little foam brushes work the best! If you have any other questions, send me a PM

Tim H.
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Old Jul 26, 2002, 03:09 PM
silent flight
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South Wales UK
Joined May 2002
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Hello Tim

Your Water Based PolyUrathane (WBPU) method sounds intresting, I've used it myself but I didn't do the "filling" coat. How many Poly/baby powder coats do you usually use and do you finish off with a poly only coat?

How many coats of poly in total to get a visually pleasing finish?

thanks

Mike Y
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Old Jul 26, 2002, 03:09 PM
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Colorado Front Range, USA, EARTH, Sol system, Milkyway Galaxy
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You shouldn't use latex gloves with any epoxy, solvent,......

You should use vinyl.

The solvents and epoxy just go through laytex.
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Old Jul 26, 2002, 03:21 PM
silent flight
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South Wales UK
Joined May 2002
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Sorry Dave, you could be right , I just thought the ones I had were latex, they could well have been vinyl, they didn't disolve anyway.

Mike y
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Old Jul 26, 2002, 04:09 PM
Dude, where's My Plane?
JasonJ's Avatar
Green Lane PA USA
Joined Mar 2001
2,167 Posts
Great Info all, thanks!
Tim H, thats the kind of detail I needed!
I guesse its best to apply a base cote of WBPU and wait for it to start to tack up to make it easier to work with, thats a great idea, and I would have never thought of useing the baby powder either.
I do use gloves, I dont know if they are vinyl or latex,, I get them at the paint dept in walmart,,, Ill have to look, WBPU I dont think is as nasty as epoxy resin, but I still dont want it all over my hands.
Well, I have to pick up a few things and will be ready to glass the twins up next week or the week after I hope. I suppose you build the whole bird up and stick your equipment in to make sure every thing is set, then remove it and glass it then??
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Old Jul 26, 2002, 05:38 PM
FoamyFactory.com
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USA, TX, Fort Worth
Joined Nov 2001
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Quote:
Originally posted by JasonJ
Great Info all, thanks!
Tim H, thats the kind of detail I needed!
I guesse its best to apply a base cote of WBPU and wait for it to start to tack up to make it easier to work with, thats a great idea, and I would have never thought of useing the baby powder either.
I don't apply a base coat. Just lay the cloth on the foam and use the brush to fill the weave of the cloth. You will know when it is wetted out when it "dissapears". If you apply a base coat, let it dry then sand lightly. If you try to put on the cloth while it is tacky you will have a fun time...LOL. Like I said earlier. The cheap little foam brushes seem to work the best.

Mike_Y - I usually just do 2 coats of the Babby Powder/WBPU mix. The very nature of the F3 foam doesn't lend itself to showroom quality finishes. However, if you want a realy good finish, I would say 3 to 4 coats with 220-300 grit sanding in between coats. Then prime it, then paint it. The WBPU filler coat adds next to no weight.

Tim H.
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Old Jul 26, 2002, 07:59 PM
silent flight
Mike_Y's Avatar
South Wales UK
Joined May 2002
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Great info Tim thanks, I'll try it next weekend.

Jason,

I glassed a few mini Zagis to practice on, I installed all the gear cutting holes where I wanted them and then removed all the gear and glassed the wings. I put epoxy in all the servo, Rx, battery bays etc to add strength to these areas as removing all that foam tends weaken the small wings around the centre wing join.

Mike_Y
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Old Jul 28, 2002, 12:48 PM
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Colorado Springs, CO
Joined Nov 2001
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Weight of fiberglass

Tim H.,

Great post! I'm looking at building a slope foamie made from pink foam. I experimented last nite with pink and epp foam and did a patch on both. This morning, rock hard. Will try the WBPU with baby powder this afternoon. My question is, the below fiberglass product I found yesterday from the local automotive parts store didn't have any weight or other technical information on the package. Here is the info from their web site. Is this too heavy? Thanks for your input.

GWebb
Colorado Springs, CO
--------------------------------------------------------------------------------
499 Bondo

Fiberglass Cloth 8 sqft

UPC Code: 076308004996
Unit Weight: 0.025 LB
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Old Jul 28, 2002, 04:35 PM
FoamyFactory.com
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USA, TX, Fort Worth
Joined Nov 2001
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GWebb - That stuff is way too heavy. It's usualy 8oz. cloth. You need .56 or .75oz cloth. The stuff you need to use is almost like tissue paper. Go to your LHS and ask them for the cloth you need. Midwest sells packages of 3 square feet for about 7 bucks. Of course, that's the expensive way to do it. If you know you will be using a lot of glass, the Aircraft Spruce and Specialty is the way to go.

Tim H.
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Old Jul 28, 2002, 08:10 PM
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Colorado Springs, CO
Joined Nov 2001
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Tim H.,
No sooner did I post, went to the local Hobbytown and found .75oz cloth. Your right, much finer weave and of course, lighter.
Now, the baby powder and WBPU measurements. Tim, I don't know how you like your "pancakes", but I like mine really thick.
With a heavy dose of bacon or sausage, on the side. Do you have some ratios, say 3:1 or 4:1 or 1:1 that maybe I could work with?

Thanks in advance,

Greg
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Old Jul 28, 2002, 08:17 PM
FoamyFactory.com
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USA, TX, Fort Worth
Joined Nov 2001
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Gwebb - Mixture is not critical. "Runny" pancake batter sounds about right. I have no idea about the ratio. I just pour some WBPU into a tub then start mixing in BP. You want it thin enough to paint on with the brush. Just don't forget to use the first application of WBPU without baby powder.

Tim
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Old Jul 28, 2002, 08:27 PM
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Colorado Springs, CO
Joined Nov 2001
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Tim,

Thanks. I had did up a little batch (mixing cup/small) and kept putting more and more bp in with no real measures, but one thing for sure, it dried very hard and in only about 50 minutes on my test pieces.

Thanks again,

Greg
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Old Jul 28, 2002, 08:36 PM
Registered User
Colorado Springs, CO
Joined Nov 2001
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Tim,

Not on subject, but....how's the winds out there in Wichita? I'm a sloper by trade, but we've had these crazy Easterly winds coming from your neck of the woods, so I'm disgruntled right now.
Beautiful weather and no where to fly.....so, I'm gonna built a Floyd foamie and see if I can "thermal" something?!? Still deciding on "poly" or not. Still in the drawing mode.

GW
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