Bob Aberle's column in this month's AMA magazine, MODEL AVIATION included an address for a table he created. It compares the weights of different brands of covering materials.


http://webpages.charter.net/rcfu/Hel...IOCWeight.html

Da Rock thanks for that info!
I had as a swag, an estimated weight of an ounce per yard relative to my Sig SE build. Where I am substituting .2 per yard carbon fiber veil as a covering material.

When Monokote first came out there were a number of magazine articles that mentioned covering weight. (back when magazine articles were more than advertising copy for ARFs)

The writers were usually just modelers who had discovered that the new stuff looked lighter, and seemed like it had to be lighter than a full paint job, but had discovered their newly finished scratch/kit built airplane covered in the magic stuff wasn't lighter at all. Or not significantly lighter. So they did what real modelers do and did some simple tests. And reported what they'd done in their next construction article.

And the comparisons were eye opening for most. Because it really seems to most everyone that the plastic films HAVE TO BE lighter than paper or silk and dope.

So I wish his chart had given a bit more test results on the two lines that cover silk. Because silk and silkspan can easily be done such that you've got a decent finish, and the outcome is lighter than Monokote/Ultracote/etc.

BTW, if you look at the chart carefully, you see that he has separated the Monokote weights by "opaque" and "transparent orange". You'll notice there is an appreciable weight difference. Almost half an ounce per yard.

Earlier charts listed many more individual colors. And showed that the color mattered significantly. I showed the chart at the field and almost immediately one of the guys who likes one brand and hate the other went off like a roman candle. Seems he saw a difference in weight between Monokote and Ultracote but didn't understand that the only listings were of different colors. And they aren't a reliable indication of the weight ranges of either brand.

So don't read more into the chart than is there. It's an excellent thing to have, but it's not complete. Aberle is one of the few really excellent "information providers" we have left, and I'd bet big money he would have preferred to offer a more complete chart. But I'm sure he just didn't have the time. You know, the MA magazine is almost worth getting just for his articles and column. Heck, forget "almost"..... it is for sure.

It also appears that people using Koverall or light fiberglass cloth and Minnwax PolyCryllic with latex colors are coming in noticeably lighter than film as well. It also has the added benefit of not producing nasty fumes, so it can be done indoors during winter without problems. It's perfect for gas power, as the latex is 100% fuel proof without additional work and there are no seams to lift over time. There is nothing like a well done painted finish - dope, latex or other paint. It looks SO much better than film and Koverall is way tougher than any film ever thought of. I have a Kadet Sr. wing covered with Koverall and dope that has followed me through 12 years and at least 4 moves and it is still tight, wrinkle free and looks great. Try THAT with film....

Mark

Da Rock,
I was used to using either tissue or silk on my builds in the past. Having just returned to the hobby after many years of absence I tried using plastic thinking it was lighter. After finishing the plane I discovered that such was not the case and trying to do compound surfaces was no easy thing either.
Anyhow, thanks for the timely info on the coverings...

"It also appears that people using Koverall or light fiberglass cloth and Minnwax PolyCryllic with latex colors are coming in noticeably lighter than film as well"

Did I miss something here? Monokote 1.8 oz./sq. yd, Sig Koverall 1.25/sq. yd less adhesive and finish. Can you finish 1 sq. yd with less than 1/2 oz of paint?

Even if it were a little heavier light fiberglass with Polycryllic is worth it, its 10 times more durable.

Hmm, skyloft looks to be even better than light fiberglass cloth, and its cheap to boot. I wonder if you can use it with polycryllic.

It would appear so, at least the light fiberglass cloths will do it (0.6oz and 0.75oz). The Minnwax is water based and leaves very little behind. At the minimum, it is competitive with films and many times more durable. Not to mention looks WAY better when finished.

Mark

Well I am trying to use a bit different method that someone I know that does control line stunt uses. That is using carbon fiber veil over sheathing, the veil itself weighs .2 oz per yard the balsa I am using weighs very little. The more interesting part of this is the strength that it adds to the structure, while plastic coverings add nothing to the strength of the airframe.
Have any of you used this method?

not only does the Minwax polycrilic leave almost no weight behind also painting with latex based paint leaves very little weight behind.

david

Really enjoyed this post,very informative but have a question,new to fabric covering.Last time did it was in the early 60s,silkspan or an old silk scarf and dope!NOw all those modern materials.BUt want try the fabric I see Tower has 7oz but see mention of then using latex paint to cover,thought I had heard somewhere on here that not all latex was fuel proof only certain ones? Have worked with fibergalss resins and sure sounds good if can use the H2O based min wax product sure hate cleaning up that epoxy mess when done!!Have avoided idea of fabric for that reason you make it sound real good!Thanks!!

I use Sig Koverall, on planes such as a Cub that you want the fabric covered look I use Sig Dope to attach the fabric then shrink the fabric. I then apply 4 coats of PolyC to fill the weave. You can still see the weave of the fabric with 4 coats. For a plane that I am trying to simulate a metal finish I apply 6 coats of PolyC then spray high fill sandable primer to finish off the surface then apply panel line and rivet detail. This makes for a very strong, light and durable finish that in my opinion looks better than any iron on covering.
Anthony

Dumb question alert!!!

Are the Minwax PolyC users saying to use the polyc to apply the fiberglass, or as a finish after the glass/resin is applied?

I use PolyC to finish off Sig Koverall,
I have seen guys use PolyC to apply and finish off fiberglass.
Anthony

The ones I have seen use the PolyC instead of resin to adhere the fiberglass cloth or Koverall to the airframe. PolyC is clear, so there would be no point in putting it over resin/glass. The resin leaves a harder finish, but the PolyC is still much more durable than a film finish.

For whoever asked about latex paint, AFAIK none of it is glow fuel proof. It is gas proof, so if you are using gas engines, latex is the perfect finish. For glow use, you do all your color/trim painting then shoot a coat or two of a fuel proof clear. Unfortunately, those ARE toxic and stink a lot, so that needs to be done outside or in a paint room/booth.

Mark

The bottom line here is Koverall without paint weights about 1/2 oz less than Monokote , it's hard to image it will ever come out finished less than Monokote. As far as .6 oz cloth there's really no comparsion because cloth requires full sheeting while Monokote can be installed over open bays, nothing weights less than air. Each covering method has it's own merit. I would bet even the above average modeler would find it difficult to produce a fabric or glassed model weighting less than the Monokoted version.

Thanks CubNut and mmattockx. Appreciate the response. I'll keep an eye on this thread and if anyone is interested, I'll post weights...bare airframe, polyc and glass, and then painted.

The open bay vs. fully sheeted arguement only applies if you are building models that aren't fully sheeted. Since I like pattern planes, it isn't much of an issue for me a lot of the time. But it is true that air is pretty hard to beat on the scale. Every method has it's place. Film is good for smaller, lighter weight sport models. For bigger stuff, especially scale planes, fabric and paint are hard to beat. I am currently building a Mojo 40 and would never consider anything other than film for it. I am also designing a 40% Cassutt racer at the moment and wouldn't consider anything other than Koverall and PolyC for it. Horses for courses as it were.

Mark

For most of the planes I have built, I have pretty much been able to ignore the differences in covering weight, except maybe for some of the 1/2A or smaller, such as indoor microfilm or smaller outdoor rubber FF. In fact, I have some covering film for indoor from Micro-X that is supposed to be light than microfilm.For most of the sport planes, or even some of the competition planes of over about 350-400 sq in area, a couple ounces in covering weight is pretty much irrelevant, at least to me.

What I miss most is the nearly mirror-like finishes that used to be possible using silk or silkspan and pre-EPA Aerogloss dope. With about 15 or 20 coats, lots of sandpaper, polishing paper, rubbing compound, and elbow grease, one could get a finish bright and clear enough to see one's own reflection, almost good enough to shave with. I've never seen any film covering that can give that.

As I get older, I just seem to go more for speed of finish,and am less concerned with some of the details.

When this thread came up, I had a link to a different chart on weights, but I couldn't find it. Now I did...

http://winshiprc.tripod.com/painting_techniques.htm

Scroll down to find the chart. It shows white Monokote being 7.3 g/sq.ft. and Koverall at 4.3g/sq.ft. I believe this is where I had the idea that Koverall was around 1/2 the weight of Monokote and that finished Koverall could be done for less than film. YMMV

Mark

Mark,
If painted properly I can not see the paint weighing over 2 grams a sq ft worst case, so I would tend to agree that koverall is lighter than Monokote. so ok it is not half but rather 60% of the weight it is still lighter and the painted finish will look better. The veil I am using is .2 oz per Sq. yard (9 Sq feet) so that means that the carbon fiber veil is roughly .6 grams per Sq ft so a painted surface using that as a base should weigh less than 3 grams per ft that should make the total weight of finish of my airplane come in at less than 54 grams (less that 2 oz total for the airframe). The total weight of my finish should come in at a bit less than 1 Sq yard of monokote, and have a lot nicer more durable finish.

Thanks for the update on the material weights, I feel a lot better about going this route now...

I covered a control line model I built in 1968 originally with some of the original Monokote. Plane felt very heavy, and also had a hefty tendency for the covering to go baggy. Plane weighed almost 50 ounces. I recovered with a product called Silron (blend of silk and rayon) and Aerogloss colored and clear. Ended up with a much more attractive finish that held up until the fabric started powdering about 6 years ago. Plane weight with the dope/fabric was 46 ounces, almost 4 ounces lighter, and better looking and more trouble-free. Of course, shortly after recovering, there was a recall on the Monokote, because the original manufacturer couldn't hold the tolerances in production quantities. TF had to change vendors. I still have a couple scraps of that era, and you can definitely tell the difference. I recovered the wings and tail in current Mono, and now weigh 47.5 ounces. Of course, I have also had to rebuild the nose are a couple times in the last 40 years. Not all my landings are smooth, or even parallel with the ground.

More recently, I built a Lanzo Stick for SAM RC competition. Originally covered with the current Mono, had troubles with sagging and with the adhesive losing it's grip on the underchambered wing. Recovered with layer of SG grade white silkspan with a outer layer of lightweight colored tissue and clear dope. That 9' span 1384 square inch wing lost almost 7 ounces of weight. No more sagging, no more lost airfoil shape.

Scroll down a little futher and note the weight of dope finishes, Monokote wins the battle.

That's relative regarding dope and silk.

somegeek