Fiberglass vs film weight question
01-09-2008, 05:50 PM
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Fiberglass vs film weight question
I'll try posting this here first, since the scale guys seem to be the 'glass masters.
How much extra weight does glass and paint add vs (insert brand here) of film covering? The airplane is a 60 size plane, ws of 64", a length of 54", and will be powered by a Saito 100. I realize that a lot of variables will come into play, but as a generality, will the difference in weight be enough to worry about?
Also what weight glass will be the best? I know the procedure, just not the fine points. Gotta learn sometime!
The airplane for reference: http://topnotchkits.com/index_files/TN_Kit5.htm
How much extra weight does glass and paint add vs (insert brand here) of film covering? The airplane is a 60 size plane, ws of 64", a length of 54", and will be powered by a Saito 100. I realize that a lot of variables will come into play, but as a generality, will the difference in weight be enough to worry about?
Also what weight glass will be the best? I know the procedure, just not the fine points. Gotta learn sometime!
The airplane for reference: http://topnotchkits.com/index_files/TN_Kit5.htm
01-09-2008, 06:36 PM
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RE: Fiberglass vs film weight question
Using 1/2 oz or 3/4 oz fiberglass cloth and using a watercase polyurethane vs Ultracote - the glass AND paint will add ABOUT an additional 6 - 8 oz. beyond the film weight
Using 1/2 oz or 3/4 oz fiberglass cloth and using a fiberglass resin vs Ultracote - the glass AND paint will add ABOUT an additional 10 - 12 oz. beyond the film weight.
There are a lot of variables here - how many coats of polyurethane/resin, how many coats of primer and paint, etc.
The basic difference between a waterbase polyurethane glass job and a resin glass job is that the poly has ABOUT 50% - 60% of the weight of a resin job, but only about 60% of the strength/hardness of a resin job. To me, the pluses for the poly are ease of application, NO FUMES, easy sanding, NO FUMES, soap and water clean up, NO FUMES and did I mention that you can readily use the poly indoors because there are NO FUMES
.
Bottom line - glassing produces a supurb base for painting and detailing, however it is a fair amount of additional work and typically will add several ounces to the wing loading of the plane.
Using 1/2 oz or 3/4 oz fiberglass cloth and using a fiberglass resin vs Ultracote - the glass AND paint will add ABOUT an additional 10 - 12 oz. beyond the film weight.
There are a lot of variables here - how many coats of polyurethane/resin, how many coats of primer and paint, etc.
The basic difference between a waterbase polyurethane glass job and a resin glass job is that the poly has ABOUT 50% - 60% of the weight of a resin job, but only about 60% of the strength/hardness of a resin job. To me, the pluses for the poly are ease of application, NO FUMES, easy sanding, NO FUMES, soap and water clean up, NO FUMES and did I mention that you can readily use the poly indoors because there are NO FUMES
.Bottom line - glassing produces a supurb base for painting and detailing, however it is a fair amount of additional work and typically will add several ounces to the wing loading of the plane.
01-09-2008, 09:00 PM
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RE: Fiberglass vs film weight question
I dont think it add's much extra weight at all if you follow a couple of steps to keep it light.
When I glass I finish my final sand, make sure there are no cracks for epoxy to seep into, and I brush the wood with my draftsman brush (this creates a little static for the cloth to tack to). I then lay the .75oz cloth over the wood making sure there are no wrinkles. I mix up a 1-2 oz. of epoxy (I use pre mixed finishing epoxy..20min.) and quickly pour it over about a 2ftx2ft or half a wing area. Here is the KEY to glassing very light.....as soon as you pour out the epoxy, use an old credit card or a straight piece of balsa to squeegie (sp?) it over the area and then squeegie OFF AS MUCH OFF AS YOU CAN!
All you are trying to do is get the cloth to attach to the wood. Use paper towels too. But as soon as the epoxy starts to tack STOP! Continuing will only pull the cloth and cause wrinkles. After it has dried for a couple hours, mix up another oz of epoxy and put a second coat on, squeegie it around and again try to squeegie as much off as you can. You actually end up catching most of it back in the cup. Let dry, cut cloth where it hangs off the edges of the wing with a razor blade and lightly sand.
The other key is the primer, put it on as much as you want, but sand it down till it is 90% gone, then one light coat of primer and sand with very fine sandpaper (always wet sand primer).
The last key to keeping it light is to find a paint that has strong pigments. Model master oil based paint is real good, so is krylon. It seems like I hardly spray any on and it is rock solid coverage.
** NEVER use Rustoleum or paints that have to go on real thick, this does add a lot of weight.
You will be limited painting a glow engine plane. Lustercoat (sp?) works good (I glassed a couple of .60 size warbirds), but some colors have lousy pigment....the white, blue and olive drab are good...if they still make it, but the yellow SUCKS! If you have to use lustrecoat, you will need to put a couple coats on, just dont go crazy with clearcoat etc....it isn't necessary. It has been a few years since I used it, it is best to test it first to see how strong the color is and how much paint you have to spray on.
I fiberglassed a 101" stuka, painted it and it came in at 26pounds with a sliding canopy and a bunch of other extra's. Most stuka's I have seen are 31-32lbs. I dont know how much my method of fiberglassing saved weight, but I am sure it was a big part of it. I have been flying it for 8yrs with no problems. Definitely use the epoxy 20min. finishing resin (almost every hobby shop has it), I have seen others use different stuff and the heat made it bubble up (although it was probably because they didnt know how to use it).
Good luck, either way you go, send me some pics!
Patrick
There are few pics and videos of my planes at
www.putfile.com/pahtreek
When I glass I finish my final sand, make sure there are no cracks for epoxy to seep into, and I brush the wood with my draftsman brush (this creates a little static for the cloth to tack to). I then lay the .75oz cloth over the wood making sure there are no wrinkles. I mix up a 1-2 oz. of epoxy (I use pre mixed finishing epoxy..20min.) and quickly pour it over about a 2ftx2ft or half a wing area. Here is the KEY to glassing very light.....as soon as you pour out the epoxy, use an old credit card or a straight piece of balsa to squeegie (sp?) it over the area and then squeegie OFF AS MUCH OFF AS YOU CAN!
All you are trying to do is get the cloth to attach to the wood. Use paper towels too. But as soon as the epoxy starts to tack STOP! Continuing will only pull the cloth and cause wrinkles. After it has dried for a couple hours, mix up another oz of epoxy and put a second coat on, squeegie it around and again try to squeegie as much off as you can. You actually end up catching most of it back in the cup. Let dry, cut cloth where it hangs off the edges of the wing with a razor blade and lightly sand.
The other key is the primer, put it on as much as you want, but sand it down till it is 90% gone, then one light coat of primer and sand with very fine sandpaper (always wet sand primer).
The last key to keeping it light is to find a paint that has strong pigments. Model master oil based paint is real good, so is krylon. It seems like I hardly spray any on and it is rock solid coverage.
** NEVER use Rustoleum or paints that have to go on real thick, this does add a lot of weight.
You will be limited painting a glow engine plane. Lustercoat (sp?) works good (I glassed a couple of .60 size warbirds), but some colors have lousy pigment....the white, blue and olive drab are good...if they still make it, but the yellow SUCKS! If you have to use lustrecoat, you will need to put a couple coats on, just dont go crazy with clearcoat etc....it isn't necessary. It has been a few years since I used it, it is best to test it first to see how strong the color is and how much paint you have to spray on.
I fiberglassed a 101" stuka, painted it and it came in at 26pounds with a sliding canopy and a bunch of other extra's. Most stuka's I have seen are 31-32lbs. I dont know how much my method of fiberglassing saved weight, but I am sure it was a big part of it. I have been flying it for 8yrs with no problems. Definitely use the epoxy 20min. finishing resin (almost every hobby shop has it), I have seen others use different stuff and the heat made it bubble up (although it was probably because they didnt know how to use it).
Good luck, either way you go, send me some pics!
Patrick
There are few pics and videos of my planes at
www.putfile.com/pahtreek
01-11-2008, 10:03 PM
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RE: Fiberglass vs film weight question
For a .60 size plane I'd recommend the water-based poly-C on .6 oz. fiberglass cloth. This has adequate strength for a plane this size. I find the poly-C much easier to use than a resin or epoxy. Most important to seal the wood with DEFT or some other sealer before using poly-C so you don't get any warpage.
01-11-2008, 10:12 PM
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RE: Fiberglass vs film weight question
Thanks for all the info guys. I'm researching my options, and haven't even ruled out film, but the lines of this plane just beg to slick and smooth. I just don't know if I can get it with the first try. That's the main drawback I'm seeing so far with the glass. I screw up a little with film, I peel it off and redo it. Screw it up with glass, and I'm screwed. Tell me if I'm wrong.
01-12-2008, 08:17 AM
#7
RE: Fiberglass vs film weight question
Don't be afraid of glass,,, Just remember less is best,
The only way to remove extra or mistakes it to sand it of
Up side to glass and paint?
more scale like appearance, doesn't rip or peal off
Down side,
Heavy, harder to make repairs
I would guesstamate light glass and paint would add at least 1lb to that plane over Iron on, probably more
The cloth and the film are just about equal in weight
But, Figure every ounce of fluid (paint, resin) you use adds at least an ounce of weight to the plane
For a scale project, I'd go for it, if it just a daily basher, Film
The only way to remove extra or mistakes it to sand it of
Up side to glass and paint?
more scale like appearance, doesn't rip or peal off
Down side,
Heavy, harder to make repairs
I would guesstamate light glass and paint would add at least 1lb to that plane over Iron on, probably more
The cloth and the film are just about equal in weight
But, Figure every ounce of fluid (paint, resin) you use adds at least an ounce of weight to the plane
For a scale project, I'd go for it, if it just a daily basher, Film
01-12-2008, 09:42 AM
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RE: Fiberglass vs film weight question
A few years ago I removed some 2oz glass on the wing of a BT 75"corsair. I used a hot air gun and started pealing it up a little at a time until it was all removed. Replaced it with .75oz with a pretty decent weight savings. Just my opinion, I wouldnt do .60 sized planes in glass. Seen a lot of those at swapmeets that were just too heavy for their wing area. A light glass job CAN be done, but not usually on your first attempt. My glass jobs only get one coat of reson then light weight spackling mixed with water to a milkly consistancy then rubbed in with fingers. Sands easy and gives a great matt finish for warbirds.
Edwin
Edwin
