Hi,
I'm thinking of glassing a model, but I have never done this before, and would like any information and advice to get me through it.
Thanks for the help.
Robert.

Can you give us some more information?

Are you glassing the whole airplane?

Do you wish to use the very light cloth or just paint on resin.

Is the whole airframe balsa covered.

What shape is the fuselage (Lots of compound curves?)

Do you have access to Fibreglass supplies.

Depending on the airframe and the finish required the are several procedures. That is why I have asked the questons.

Ed S

Yes, I will be glassing the whole model, and will use some cloth. The airframe is balsa, with foam veneer wings The plane is very flat, without many curves. Its a simple sport plane, that I want to do first to see how it works out. Its a JBAVIATION SuperSport. www.jbaviation.com so it shouldn't be to hard. I also have access to Fiberglass suplies, so that shouldn't have problems there.

I would suggest the following:

Do not use polyester resin. The hardener for polyester is very dangerous. one tiny drop in the eye and the eye will eventually be useless. You cannot wash it out quickly enough to prevent the damage. Polyester will not cure over some glues. The smell will hang around for weeks.

Use a good quality epoxy resin that is fairly liquid and try to get a fairly slow hardener. Some hardeners start to set up the resin after twenty minutes or so. this is too fast and does not give you enough time to work it. Avoid thinning the resin with anything. It can create cure problems and affects the strength.

Use about 3/4oz glass cloth. this cloth is fairly fragile and will need carefull handling. you will be adding weight to the airframe, but the weight will not be in the cloth. It will be in the amount of resin you leave on the airframe.

I will assume the airframe is sanded to the smoothness of a B.B.

Start with the wing. one side at a time, it is the easiest. I use one piece of cloth for each panel. Cut it with about a 1/2" overlap all round. Lay the cloth on the wing along with any center section glass that is to be applied. So now the whole top of the wing is covered with dry cloth. Mix up the resin and pour some on the centre section. Very carefully. so as not to wrinkle the cloth squeegee the resin through the cloth out to the wingtip. I use a flat piece of 1/16 ply about two inches wide. Then squeegee the resin chordwise. Do this for the whole wing. Smooth the cloth as much as you can and remove as much resin as possible but at the same time thoroughly wetting the cloth. Excess resin can be returned to the cup. When I have finished this part I then lay some toilet tissue (The absorbent type) on the wing for a few minutes to soak up any excess resin, then pel it off. When this has all cured sand off the excess cloth and repeat for the wing otherside.

To give you some guideline. On a 500 sq in. wing with the glassing all finished I have added about 3 1/2 ozs weight.

The fuselage is basicly the same procedure. You will have to decide yourself whether to do it in four strips or one large piece. I would suggest strips for the first time.

You now have a weave finish that has to be filled. Another coat of resin would do this but the weight will really go up. I use a lightweight spackle compound. I get a blob of it on the end of my fingers, dip it into some water and rub it into the weave all over the surface. It is messy and it looks like hell. when it is dry, sand it all of and you are ready to prime.

Ed S

Finished glassing an autogyro with 1\2oz. cloth and water bassed polly-eurothane. I will never use anything else. It went on so easily cleaned up twice as nice. i got the eurothane at "Home Depot" and brushed the first two coats on ... sanded... then sprayed the third on, lightly sanded then primed and painted. Half the cost and half the weight.

-Mustang

Thanks, I will try soon.

I am building a 60 size heritage rc stuka. i wish to glass and paint this model, what tips do you all have for the gull wing to cover it properly, also are there any good websites out on the internet that covers this process, also in an earlier post it was mentioned to use a lightweight spackle to fill the rough weave in when sanded does this stay bonded ok to the glass over time?

The spackle I use is available from any hardware/building supply store. There are a variety of brands. I am currently using Home Hardware's brand. They call it wall repair compound.

I have not had any problems with it not sticking. There is not much left on the wing anyway. Most of it is sanded off. Of course it cannot be wet sanded. I use automotive primer to paint my aircraft and there is no ill affect. Once the primer is on I can then wet sand.

Ed S

An alternative to the spackle is to spray automotive filler primer. This will fill in the weave and any small imperfections. Wet sand the primer off until you see mostly wood, making sure that you do not sand through the glass cloth and that the surface is even and smooth. This adds a negligable amount of wieght because you sand 98% of it off. After that, you apply a lite coat of primer for the paint to adhere to.

I also use the West Marine epoxy resin. It has a pump system so you get the same mixture evertime. Ther also sell a fast and slow cure hardner. I use the slow cure. It gives you about 45 minutes of working time.

Regarding the very good advises, it seems that glassing doesn't require a lot of resin if we want to keep the weight light.

Any idea of the approximate amount of epoxy resin needed to glass a Top Flite P40 which is a .60 to .90 size plane (68" wingspan) ?
West System sells it by quart, Z-Poxy by 6+6 ounces containers, I don't know what I should order ! This stuff is expensive and I am not keen to waste it on a shelf.

Thanks for your help, Chris.

As a rough estimate for a wing that size a maximum of six ounces total, that is combined resin and hardener. Remember what I said in my original post about setting up time. I have never used Z-Poxy but from what I have read on these Forums it might start to set up too quickly. When I glass my wings I warm the resin with a heat gun to make it flow easier. DO NOT DO THIS WITH A FAST SETTING HARDENER MIX. Believe me, I have experience in these matters!!

I do not use epoxy just for glassing wings. I use it for gluing on wing skins, mixing with micro-balloons for fillets and for making parts. I use the same epoxy for everything. I do have to agree that if this is a one time use then the expense can be a little high.

Ed S

Ed,

Thanks for your quick reply. I initialy planned to use West System 105 + 206 hardener which gives (from their website) about 25-30 minutes pot life. I don't know if it is enough, I planned to mix small quantities at a time but I don't know what happens at the join when the resin starts to cure, does the resin still soak in the cloth even when the cloth gets hard ?

Which brand of resin do you use ?

Is the brand of the glass cloth important ? I found a site (CST) who sells 2y of 0.7oz for 5$ or 10y for 20$, this sounds reasonable.

Thanks again.

oliflyer:

The West Marine resin gives you plenty of working time. The resin will start to set up in the pot before it sets on the work surface. The smaller the pot, or container, you mix the resin in, the faster it will start to set. The reason for this is heat kicks off the resin. It is more condensed in the container than on the work surface, so it kicks off faster. I use the deposible zip lock food containers, not the bags, to mix resin in. If you use the West system, I highly suggest you purchase the pumps, there is one for the hardener and one for the resin. The pumps meter out the proper mixture of resin to hardener everytime. I agree it can become expensive if you are planning to do only one airplane, but chances are that if you try fiberglassing and painting a model, you will never go back to monokote (ultracote) again.

oliflyer:

Oh, by the way, you will need about 4 yards to cover your plane.

Actually, I find the opposite is true. As you pointed out, the chemical reaction is exothermic and so the heat produced speeds up the curing process. If you use a big container, the heat tends to be trapped within and you could get into a thermal runaway situation. I won't tell you how many smoking canisters I've had to haul out to the patio in a rush while holding my breath (the fume is toxic).

Once the epoxy is spread onto the work surface, the larger exposed surface areas help to dissipate heat.

I find 35mm film canisters to be ideal for the West System Quart(resin)/Pint(hardner) pumps. I particularly like the transluscent Fuji canisters as you can see how much you have in them (I like Fuji film better anyways).

25-30 minutes is plenty for fiberglassing. The key is to mix small batches at a time so you are not rushed to use up a buttload of it. West does make a 45min hardner too. It works well too, but I find it takes quite a bit longer to reach full cure strength.

If you haven't already, buy a box of rubber examination gloves. HarborFreight sells them cheap so be kind to your fingers. Epoxy is toxic until cured. FG'ing is a messy business so don't do it over hardwood floors or brand new carpet. If the pieces you're FG'ing are small and/or require handling, build simple jigs or handles to hold them so that both your hands are free to handle the FG and resin. Wear old cloths or an apron.

Lastly, you don't have to use FG. When I lived in CA, I knew a guy that uses women's nylon hose to cover parts of his plane. Don't laugh. It is strong, extremely lightweight, and goes around curves no FG cloth can. I've experimented with some polyester fabric myself and they work reasonably well. The trick is to find the right weave - loose enough to allow the matrix (epoxy) to saturate the voids, but tight enough to offer the tensile strength required.

Oilflyer,

By now you are probably beginning to realise that Glassing airplanes is a bit more involved than at first thought. I guess it can be said that you are now moving to a different level of modelling.

I do not know that I would agree with covering your airplane with panty hose. There is a big lump at the toe end! I have never had a problem with brands of cloth. I have purchased from many sources and it all seems the same. If you mix up enough resin for one wing panel only and work from the centre out the 30 min working time should be OK. Do the same for the econd panel and the 'join' will not be an issue. The first lot will still be wet. The resin will stay wet for a long time after the "working" time has expired.

West Systems is a top quality resin. However I stopped using it because some of the other applications I have needed a longer working time. Even Wests extra slow hardener is not suitable for me. I use MGS brand, it is available from CST Technologies. It can use two hardeners, slow and fast, The fast is the same as West, the slow will give about 6 hours working time. The two hardeners can be mixed for a custom cure time. If you have yet to purchase your resin it might be worthwile enquiring.

www.cstsales.com

Ed S

Ed,
I believe I received advice from you in another forum about 3 months ago. I ended up buying the APC vacuum bagging kit and resin. I intended to use this to glass my all wood build-up plane. I noticed when I put the wing within the bag (without resin for trial purposes) and turn on the pump, there are depressions in the wing skin formed between the ribs of the wing throughout its length. So, my question is if bagging is really ment for foam core only or can build up wings use this method as well? Does the wood "spring back" even after the resin has cured giving the original smooth contour?

I have never glassed over a built up sheeted wing, so Icannot answer your question. I would rather not take the chance. Even without vacuum bagging your wing I think you will end up with the indentations. When you sand the skin the skin will push away between the ribs and not on the ribs. It is very likely you will sand just the high spots on top of the ribs.

Ed S

Yikes! I'm surprised your built-up wing didn't just implode. You must have built it well. At sea level, the standard atmospheric pressure is 14.7 pounds per square inch.

Now some folks do hollow out portions of their foam core wing to save weight prior to sheeting and vacuum bagging, so I suppose it is possible to VB a built-up wing if you add in enough ribs and cross braces. Still, I wouldn't do it.

One major advantage with VB is that you could skip the sheeting and epoxy carbon fibre cloth directly onto the foam core. You'll have to sandwich a sheet a mylar plastic on top of the epoxy to impart a straight and smooth surface. Hi-peformance sailplane builder do this alot to get a strong, thin wing section with sharp (read efficient) trailing edges - not to mention beautiful with the shiny carbon fibre weave.

rmkearbey:

Are you planning on glassing a built up wing or a foam wing? If it is a built up wing, glassing it will not cause depressions between the ribs nor will sanding as long as you do not take off too much wood. When you sand the sheeting, I assume the sheeting is 1/16th, you want to lightly sand it, just enough to smooth it out. Use a lite weight filler if needed. Try to get the sheeting as smooth as possible without removing too much wood. There are many post on the process. Do a search and you should find lots of info. If you need more info I will be glad to assist or you can post a question in the warbird section. All the warbird drivers use glass their birds using the same are similar techniques.

Volfy,
I was very careful to make sure that my wing didn't implode!!! Your post sent chills up my spine!

I have glassed it just fine with a credit card and brush. It looks really good and I kept it really light. No problems with the depressions. Sanded everything with a sanding bar thinking of the problems you mentioned ahead of time. I'm very excited to see some primer on her. Thanks to all.

Hey Mr Ed Smith,

I know this is an older thread but hopefully you will come across it. I was hoping you could elaborate a bit about glassing the fuselage. You mention using one or four peices. I am a bit intimidated about the upcoming glass project I will have on a topflite Spitfire. The vertical and horizontal stabs will be fixed inplace on the fuselage. Is this going to make it tougher or is this situation standard issue.
Ilearned alot from your previuos posts in this thread, thank-you in advance
Jody Haddow

Jody,

You are right this is an old thread but since I posted my questions I went through the process a glassing then I can give you some feedback. I was initially a little anxious but the result is nice and even if it is a bit messy I really enjoyed it. I don't know the Spitfire structure but as a TF kit I think it is closed from the P40. The horizontal and vertical fins are fixed to the fuse too and I don't remember this phase as a big pb. Nevertheless it is not a big flat surface as a wing then you gonna spend some time "struggling" (not really) with the curves on the tips but the 3/4oz glass cloth is so light that is follows the curves very well.

This was my first experience with glassing, I applied the very good advises I found in the forums (thanks again guys) and some websites and it worked well.
If you havent't yet, visit the very usefull site with pictures:
http://www.arts-hobby.com/fiberglassing.htm

What else could I say ?
- Cut all the cloth first
- Think twice before starting a batch of epoxy (checklist, tools, cloth,...) and think how to deal with difficult parts before starting.
- If you use West System, work fast but don't rush, it has a good working time

Good luck, Chris.

Thank-you for the reply Chris.

So how many peices did you use to cover your P-40.
a) The wing (one peice for the top and one for the bottom)?

b) Fuse (one peice for each side, two for the top and bottom of the horizontal stab, two for both sides of the vertical fin).

I am just geussing. Maybe it would be better to treat the fuse as a top and bottom rather than two sides.

So many questions.

Jody Haddow

I don't remember how many pieces but for the P40 I proceeded as mentionned below:

- 4 for the wings (I started with a wing bottom, just in case ;-))
- 2 for the fuse (1 each side), you will probably decide to use an additional piece if you want to make it easier with the joins of the fillets and the bottom but don't worry the cloth is so thin that you will barely see the joins. But again it really depends on the shape of your fuse.
- 4 for the elevator
- 2 for the vertical fin

Chris.