RCU Forums

RCU Forums (http://www.rcuniverse.com/forum/)
-   Questions and Answers (http://www.rcuniverse.com/forum/questions-answers-154/)
-   -   *Fiberglass (Gel-coated) fuse* (http://www.rcuniverse.com/forum/questions-answers-154/3592657-%2Afiberglass-gel-coated-fuse%2A.html)

Zippi 11-27-2005 02:57 PM

*Fiberglass (Gel-coated) fuse*
 
I have seen a few planes advertised on the net that say they have a fiberglass "Gel-Coated" fuse. Just exactly what is a Get-Coated fuse? Are they any good. Here is one example.
http://akmodels.bizland.com/cmp_chipmunk_120.htm

carrellh 11-27-2005 04:46 PM

RE: *Fiberglass (Gel-coated) fuse*
 
Gel coat is a smooth shiny surfacing material on the glass. Not sure what it's actually made of. Gel coat is often colored and is usually the finished surface on boats. For full size boats and race car parts the gel coat is sprayed into the mold first and then the fiberglass goes in and it all cures together. I'd guess model parts are made about the same way.

Zippi 11-27-2005 05:19 PM

RE: *Fiberglass (Gel-coated) fuse*
 
Sounds like a good process.

ORIGINAL: carrellh

Gel coat is a smooth shiny surfacing material on the glass. Not sure what it's actually made of. Gel coat is often colored and is usually the finished surface on boats. For full size boats and race car parts the gel coat is sprayed into the mold first and then the fiberglass goes in and it all cures together. I'd guess model parts are made about the same way.

carrellh 11-27-2005 05:47 PM

RE: *Fiberglass (Gel-coated) fuse*
 
The fiberglass fuselages can look really good. My brother has a Kyosho AT-6 and it has lots of 'scale' details molded in (panel lines and various bumps and indentations) the fiberglass, so it's a really good looking model.

If the fiberglass gets damaged you usually lose the beautiful finish unless you really have the right stuff [and the talent] to properly do the repairs. Also, repairing glass is different than repairing wood and covering.

Zippi 11-27-2005 06:10 PM

RE: *Fiberglass (Gel-coated) fuse*
 
Do you know if the horizontal stab and vertical fin are epoxyed into the fiberglass or into wood? Never had a fiberglass fuse before.

ORIGINAL: carrellh

The fiberglass fuselages can look really good. My brother has a Kyosho AT-6 and it has lots of 'scale' details molded in (panel lines and various bumps and indentations) the fiberglass, so it's a really good looking model.

If the fiberglass gets damaged you usually lose the beautiful finish unless you really have the right stuff [and the talent] to properly do the repairs. Also, repairing glass is different than repairing wood and covering.

JohnW 11-28-2005 02:03 PM

RE: *Fiberglass (Gel-coated) fuse*
 
Gel coats are typically some form of catalyzed resin, probably polyester. When talking about model plane composite parts, they are used as the outer coat. One potential problem with composite parts is they can pinhole at the surface when made, which makes finishing more difficult. The pinholes can be solved, but it is easier if they don't exist in the first place. A gel coat is sprayed into the mold like paint, which creates a pin hole/defect free outer surface to the part, at least in theory. The composite layers are then laid on the gel coat. When the part is removed from the mold, you end up with a "perfect" outer surface. Gel coats can come in any color, but are typically white for finished parts.

As for quality, I cannot speak for the plane or company in your link as I am not familiar with either. However, in the modeling world, composite parts are typically premo, and in the composite part world, gel coated composite parts are at the top. This is not to say that a gel coated composite part will be of high quality, or that a more traditional wood build is not of high quality. But in general, if the company took the time and invested the cash to make a gel coated composite part, the quality is probably very high.

Not sure what you mean in your last post about fin/stab being epoxied into wood, etc., but I'll take a stab at it anyway. Wings, fins, stabs, etc. can be all composite, but typically they are more traditional in build, such as sheeted foam or built up. An all composite airframe would be more common on a quickie racer or glider. Most others will have balsa/foam parts that attach to the composite fuse. These can be attached in various ways, either with mounts such as wing tubes, etc., or directly glued to the fuse. I can't tell for sure by looking at the pic, but I believe the plane you have the link for looks like the fin/stab glue to the fuse. The wing looks like a bolt on.

Cheers.

Edgar Perez 11-28-2005 04:16 PM

RE: *Fiberglass (Gel-coated) fuse*
 
Is there an easy fix for cracks in the gel-coat?

carrellh 11-29-2005 12:02 AM

RE: *Fiberglass (Gel-coated) fuse*
 

ORIGINAL: Zippi

Do you know if the horizontal stab and vertical fin are epoxyed into the fiberglass or into wood? Never had a fiberglass fuse before.

The Kyosho AT-6 has a very small wood stick at the top and bottom of the slot the stab goes in. The stab is built up balsa so there is wood epoxied to wood.

The fin is molded as part of the fuselage. There is a balsa stick that looks a lot like a popsicle stick that gets epoxied into the opening in the back of the fin. This gets slotted for the rudder hinges.

I do not know how other manufacturers do it.

N1EDM 11-29-2005 12:57 PM

RE: *Fiberglass (Gel-coated) fuse*
 


ORIGINAL: JohnW

A gel coat is sprayed into the mold like paint, which creates a pin hole/defect free outer surface to the part, at least in theory. The composite layers are then laid on the gel coat. When the part is removed from the mold, you end up with a "perfect" outer surface. Gel coats can come in any color, but are typically white for finished parts.
When you use Gel Coat, do you let it harden first, before laying in the glass (I'm presuming that you do). And if so, how thickly does one spray a Gelcoat finish?

I'm thinking that you would spray in a coat of gelcoat, then let it dry/harden. Afterwards, you would lay in glass cloth and stick it in with epoxy resin.

Or, is there some other method. I've always been curious about this, but no one has ever answered my questions about how to lay it up..

Thanks,

Bob

oscar2005 11-29-2005 05:15 PM

RE: *Fiberglass (Gel-coated) fuse*
 
marine tex is made for repairing cracks in gel goat.there are two typs of fiberglass fuselage there is polyester that uses the gel-coat and then there is epoxy.polyeaster continues to cure for a long time after manufacture,are heaveir than epoxy and more brittle,epoxy is more expensive and subject to pinholes.epoxy fiberglass is usually a light olive green color polyester with gel coat can be any color,white,green blue etc as dye can be added to the gel coat.when laying up a fibeglass fuselage with polyester resin,after spraying in the gelcoat layers of gloth are apllied that are saturated in laminating resin,this resin stays tacky even when cured to allow for more laminations,hold the cloth in place.the last layer is done in finishing resin which cures hard.

JohnW 11-29-2005 05:28 PM

RE: *Fiberglass (Gel-coated) fuse*
 
I've done a fair bit of home composite work, making plugs, molds, parts, etc. I've also done a fair bit of research on gel coats, enough to decide It's not worth the smell, mess and headache at home. I've never personally used a gel coat... but I can pass on what I think I know, if ya know what I mean. I can tell you from personal experience that you can produce high quality composite epoxy parts without the gel coat.

From my understanding, with a gel coat, you spray and then lay your first layer of cloth when the gel coal is mid cure, i.e. slightly tacky. Typically when making composites, you never want any layer to fully harden before you apply the next layer. Doing so (i.e. letting a layer fully harden) can create problems with the chemical bond between resin layers. However, this procedure may vary depending upon your layup resin, i.e. epoxy vs. polyester vs. vinylester. I believe there are some compatibility issues between the gels, which are typically polyester. This may limit layup resins and techniques. As for thickness, I believe final thickness can be any depth, but per coat thickness may have issues related to painting if too thick/thin, such as sag, wrinkles, etc. In general, I believe something in the area of 15 mil per coat sounds about right, but I've had a few professional made parts that have a thickness of 1/4" in sharp corners. I assume the gel coat was allowed to pool in these areas to reduce the bend radius such that cloth layup was easier.

Other methods... I've had good luck with straight epoxy. I warm my first layer epoxy to 110F before I mix. This shortens the pot life to about 30 minutes on the epoxy I use, but the epoxy is super thin at this temp. The only defects I get are very small pin holes, and even these are few in number. Of course, you have to finish/paint the part. But you generally need to paint gels too, esp at the seams, and all white is too boring for me so other areas get paint too. Recently, I tried brushing a mold with a thin layer of epoxy as the "gel coat." I had no luck getting this to flow, but I believe it was related to the mold release I was using. I plan on trying that again with PVA release agent or possibly wax only. I'd also like to try a paint in the mold technique if I can find the time. I'd think the paint would act as the perfect model "gel coat." Light weight, finished part, basically flawless, etc.

Cheers


All times are GMT -8. The time now is 12:27 PM.


Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.