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Mar 13, 2010, 08:11 PM
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JosePain's Avatar
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Advise needed for Materials on First Lost Foam Fuse


Hello ,I'm thinking on building my first Lost foam fuse ever ,i have already study the technique for the shape and overall structure of the Fuselage ,i can get West Epoxy system resin from a close by West Marine store but i have doubts about the type of fiberglass cloth to use ,any advise please !!
Here are some pictures of the BEDE plans .

Jose
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Mar 13, 2010, 08:39 PM
Composites Kid
Alex.Schweig's Avatar
BD-5 Acrojet!

You'll want to use a medium cloth like 4oz plain weave (surfboard cloth) or 6oz if you can't find the 4oz.

If you can get the 3.1 ounce Satin Weave cloth, it's much better because the weave allows you to conform to tighter radii.

The trick would be to spray the cloth lightly with 3M77 and then wrap the foam in it, trying not to get any voids. After the main layers of cloth are applied (4ounce or 6ounce cloth), you'll want to apply a layer of 3/4-ounce fiberglass as a finishing layer. This will give you a nice surface on which to fill, prime, and paint.

This Joe Cormier photo shows how he applies the glass perfectly:
https://www.rcgroups.com/forums/atta...mentid=3003726

Saludos Jose!
-Alex
Last edited by Alex.Schweig; Mar 13, 2010 at 08:52 PM.
Mar 13, 2010, 08:54 PM
Registered User
JosePain's Avatar
Thread OP
Hi Alex i just look on CST Composites and i can order the 3.1oz Cloth ,you recommend only one layer or 2 layers of 3.1oz ? and then the 3/4oz as finish ?
Thank you .
Jose
Mar 13, 2010, 09:11 PM
Composites Kid
Alex.Schweig's Avatar
Layers... no idea. I haven't made a lost foam fuselage although I've made small parts using the method (servo covers). Depends on how heavy you want the final part to be.

I'd wait for more experienced members to chime in before making a final decision.

Cheers!
-Alex
Mar 13, 2010, 09:16 PM
Dragons, WindMills, all Same
jcstalls's Avatar
Also, before you start laying up you can add desired reinforcement, bulkheads, push rods, servo trays and the like. This way when you are done, you almost are. Great time saver.

You may also want to add getting some finishing resin in addition to your West System laminating resin on the final coats as it sands much easier.

Enjoy,

Jared
Mar 13, 2010, 09:46 PM
Just fly it!
wyowindworks's Avatar
Quote:
Originally Posted by jcstalls
Also, before you start laying up you can add desired reinforcement, bulkheads, push rods, servo trays and the like. This way when you are done, you almost are. Great time saver.

You may also want to add getting some finishing resin in addition to your West System laminating resin on the final coats as it sands much easier.

Enjoy,

Jared
How do you get the foam out of there will all the bulkheads, servo trays, etc. in the way?

Adam
Mar 13, 2010, 09:51 PM
Just fly it!
wyowindworks's Avatar
Quote:
Originally Posted by JosePain
Hi Alex i just look on CST Composites and i can order the 3.1oz Cloth ,you recommend only one layer or 2 layers of 3.1oz ? and then the 3/4oz as finish ?
Thank you .
Jose
I think that lay-up would be too thin. Typically around 18 ounces is the minimum for a sloper.

Adam
Mar 13, 2010, 10:41 PM
Secret clown business
gizzo's Avatar
+1 to that. In my limited experience I always end up adding more glass after the foam is gone, because I just didn't put enough in to start with.+ I think more layers of lighter glass is stronger than 1 layer of heavy stuff.
my 2c
Mar 14, 2010, 01:58 AM
Dragons, WindMills, all Same
jcstalls's Avatar
Hi,
Removed foam dependent. Solvent is the older and often nasty way. I like making a home made kinda flex shaft. Wire twisted with a hand drill to form a flexible shaft type and flare the user end. If short, then just a leather glove to hold it. Longer may need atube bearing length like a plastic push rod housing. Finish cleaning open and visual areas with a Dremel and wire brush.

Jared
Mar 14, 2010, 10:55 AM
Registered User
JosePain's Avatar
Thread OP
i was thinking on installing a center spine ,wing saddle , couple of bulkheads plus the servo tray with the pushrod for the stab as jcstalls recommend .weight is something that concerns me because were i fly the conditions are not optimal but good enough for something in the 30oz range and 40 inch ws.
still confused with the cloth arrangement ,so far this is what i have :

- Foam carved fuz + bulkheads + servo tray + wing saddle and pushrod installed
- Start spraying a light mist of 3M 77 to secure and form the 2 oz glass in place
- Then Stack a 3.1 oz crows foot glass and apply resin
- Use 3/4 oz cloth and resin as finish coat

what you guys think ..??

Jose
Mar 14, 2010, 11:33 AM
Dragons, WindMills, all Same
jcstalls's Avatar
Sounds like a fine plan Jose.

For tools too, pick up a Sureform. Looks like a fine cheese shreader on the working side. Many sizes and shapes. Works fantastic and gives excellent control. Composite store have them if you ordering other materials. If not, you local Auto Parts store just may have some. Auto Body supply stores will have a much better selection as well as fiberglass boat material suppliers. Geared for wholesale to producers, but many will sell retail.

Also, if you have never done one of these before and especially hand carved fuses much less any shapes, I would plan on a practice run first on one.

As far as the best modern techniques, I would count on Adam as from reading lots of his threads this man knows much and appears to be quite a master. IMO

Jared
Mar 14, 2010, 03:53 PM
Registered User
Ward Hagaman's Avatar
Drywall mesh works awesome for sanding foam...
Mar 14, 2010, 04:07 PM
Registered User
Quote:
Originally Posted by jcstalls
Sounds like a fine plan Jose.

For tools too, pick up a Sureform. Looks like a fine cheese shreader on the working side. Many sizes and shapes. Works fantastic and gives excellent control. Composite store have them if you ordering other materials. If not, you local Auto Parts store just may have some. Auto Body supply stores will have a much better selection as well as fiberglass boat material suppliers. Geared for wholesale to producers, but many will sell retail.

Also, if you have never done one of these before and especially hand carved fuses much less any shapes, I would plan on a practice run first on one.

As far as the best modern techniques, I would count on Adam as from reading lots of his threads this man knows much and appears to be quite a master. IMO

Jared
Jose, if you were you I would go straight with heavy glass two layers before you go to the resin. When the resin gets to the point that it is tacky check the fuse to make sure it still looks good on the seams. You can save yourself some time here by pressing the seams together. Have fun and if you have a little practice project to do first I highly suggest doing that first to get use to the process.
Mar 14, 2010, 06:55 PM
by ZIPPER
ZIPPER's Avatar
After you have carved the foam you need to tape it up with packing tape, Zagi style. This will make it much easier to get the foam out and give a better finish to the inside of the fuse.
I do at least 4 layers of 10oz glass, and don't bother with the 3/4oz, you will sand most of it off along with 1 layer of the 10oz. once you have given it a rough light sand then cover it in auto body filler (bondo) and then you will sand most of it off to get your finished shape, try not to sand to much of the glass off or you will need to add extra in the fuse. When you are happy with the finished fuse you then pure petrol in the fuse to dissolve the foam and then pull the tape out.
I wouldn't put the bulkheads or wing saddles in before, they aren't that hard to get in when the fuse is finished and if any changes need to be made they wont be in the way.
Mar 15, 2010, 09:24 AM
Registered User
JosePain's Avatar
Thread OP
Thanks to everybody ,i will start purchasing the materials later this week ,i have some Z poxy finishing resin and 2oz cloth i got long time ago that i can made some testing before the final fuz .
I will post the build thread as soon i'm ready .

Jose


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