acdii

In the process of building a B-25 and later a P-61, and will need to glass them both. I am not 100% sure what weight cloth to use on them. My previous builds, a Corsair and P-51 I used .58oz cloth, which I still have plenty of, and also have used to lay up cowls along with using auto store cloth(which I have NO clue to its weight). The .58 seems to be a bit too light to use on the big planes, and think .75 (3/4)oz is what to use, but want to make sure before I order. For making cowls and molds, what weight should I be using? I want to order at least 10 yards for the planes, and maybe 5 yards for molds and cowls.

Last time I got my cloth from ACP Composites, but they are out of stock on the 3/4oz stuff. Also will 10 yards be enough for both planes? They are Ziroli models, 101" and 114". I will experiment with using WBP with the heavier cloth, it worked great with the .5 stuff, and should be good with the 3/4oz stuff, but want to make sure I will be happy with the results before applying it to the finished plane. If not, then maybe use the resin ACP has or go with West Systems.

ETpilot

I have been interested in fiberglassing an airplane. I have never done an airplane and so I have been researching the subject. I can only suggest a couple of interesting videos. The first is an, YouTube, AMA Fiberglassing Tutorial. The second is Pimp your ARF part 1, fiberglassing.




Between both videos, the recommended cloth weight is ¾ or 1 oz. The AMA video suggests 1 oz. cloth purchased from Nick Ziroli Plans. Ten yard roll $30.00. Even including shipping it seems like a good price. I haven't checked other places for price so I could be wrong here.




In the ARF video, the process is using MinWax PoLycrylic. This may be useful since it is a process you would like to use.




As for cowl making, in one thread 2 oz was used for inner layers and ¾ oz for outer layer and final finish. Hope this helps some.


AMA video HERE

ARF video HERE

RBACONS

My Feedback: (3)

3/4 oz cloth. You're only trying to get a good base for paint, not add structural strength. Even 1/2 oz is sufficient except that it can be harder to work with because it is so fine. 10 yds may be a little tight. If I remember correctly, it takes about 6 yds of covering to do a 1/4 scale cub. You've got twice as much plane to cover.

acdii

Thanks, I have done the Corsair in .5 oz and it wasn't too bad, the cloth is very light and easy to move around, so the heavier cloth might work better. Since I have 2 large planes to do, might as well get as much as I can on a roll.

Still haven't been able to determine the weight of that Bondo cloth. Would like to get a few yards of it as well for making more cowls and molds. I also need to get some more heavy chopped mat for molds. Going to try other epoxies as well. Been using West Systems, and it works well, but heard there are even better working ones out there.

RBACONS

My Feedback: (3)

For laying up cowls, depending on the size, you'll want a light layer on the outside (3/4 oz is probably fine) and several layers of heavier cloth. Something totaling on the order of 8 - 12 oz or so depending on the size of the cowl and how much strength and rigidity you need (for example., 3/4 oz, 4 oz, 4 oz, 4 oz). The auto store cloth is generally crappy as it has too open of a weave. Useable but it means more epoxy to fill the weave yielding a heavier, but not stronger, part.

acdii

Yeah, thats what I found, my cowls come out nice, but a bit on the heavy side. I did a recent repair on a H9 P-47 cowl and used Bondo cloth. It came out heavy. On the plus side, the plane needed nose weight. I use .58 cloth for the outer layer, and two layers of the Bondo cloth. So with that said, I think I will order a roll of 4oz cloth along with the 3/4 oz cloth. I may make my own cowls for the B-25, at the very least I will make the gear doors out of glass.

Pylonracr

All good advice. .5 to .75 for finishing, and 2 to 4 ounce for the cowls and molded parts. One thing to keep in mind, you can not use chopped strand mat with epoxy. Mat has a binder in it that is dissolved by styrene, and epoxy does not contain any styrene. You are much better off making your molds with epoxy resin and cloth. If you try to make the molds using polyester resin and mat you run the risk of your parts sticking due to styrene migration through the mold release.

acdii

Did not know about the mat. It has worked fine for my molds so far, havent had any issues, but I tend to mix the mat with the cloth. I chop the mat up into small pieces and it is layered between the fine cloth against the part and the outer layer of heavy cloth. I uses it as a filler.

j.duncker

My Feedback: (2)

for surface finishing I found 3/4 oz cloth much easier to use than 1/2 oz. Especially on larger areas.

After trying different methods of applying the resin I found small foam rollers to be by far the best as they are much less likely to pull the cloth out of shape and you can really work the resin through the cloth. NB WARNING NOT ALL FOAM ROLLERS ARE RESIN TOLERANT! Have a trial first on a test piece.

As others have said most glassfiber mat is not suitable for use with epoxy. However you can get mat that is suitable for epoxy.

If working with mat and especially if you are tearing the mat by hand you MUST wear something to protect you against the short glass strands that will break off. They are a serious irritant.

Pylonracr

Thanks for the tip on the mat. I never knew there was an epoxy compatible one. That will make molds easier for sure. I get tired of laying layers of fabric.

Scott

acdii

Here are two of the molds I made using the auto store mat material. The big one with the sticks is my very first mold. The second one is a later mold for a P-51 lower cowl. The parts came out pretty good. Have to be a little more careful applying the first coat of epoxy, I had some bubbled in the p-51 cowl, but nothing a spot of filler wont fix.