Covering System Options

[R Rinker]

According to the comparison chart posted below, the Poly Fiber covering system is "42" pounds lighter than the Superflite system!! I haven't heard anyone comment on this in the weight reduction ideas, but that is 'huge' with no extra expense or downside. Weights are at the very bottom of chart. "42" pounds!!..really..

[kenryan]

Who authored the chart? I believe Ceconite and Polyfiber are owned by the same company. Could the chart have originated with them?

[danerazz]

At the bottom of the chart it says "Poly-fiber, Inc."

[SheepdogRD]

It would be interesting to see that same chart updated, with columns for Stewarts and Oratex.

[R Rinker]

The note at the very bottom says it was an independent study done by Daryl Hammond PhD. My guess is that Stewarts is the heaviest, although I have no data to support that. Oratex is supposed to be the lightest, but I wonder if it is just lighter than Superflite and not necessarily lighter than Poly Fiber? Could someone do a search for this Daryl Hammond PhD and talk to him how he came up with this?

[kenryan]

Here's a link to the study:

http://commons.erau.edu/cgi/viewcontent.cgi?article=1278&context=jaaer

[R Rinker]

I have to believe the study..it has credibility. Concerning the weight issue, it says.."Although Stits is polyurethane based, it does not contain high solids". Maybe this explains the weight issue. Although some of the differences are close, the Superflite lost its' strength fastest and had the best gloss retention. The Poly Fiber (Stits) has the best strength retention. I just got back from a fabric workshop. It was taught by Gary Hillman. In the workshop we used Poly Fiber which has three options for the color coat - Poly Tone which is not a Polyurethane finish but gives a satin-gloss, Aerothane, which is a Polyurethane finish, and Ranthane which is also a Polyurethane finish. We used the Poly Tone because it is the fastest & easiest for beginners. One comment on the Poly Tone is it is extremely easy to patch since it is not a Polyurethane finish. You can literally put a patch on in a couple minutes. I know that most bush operations it is very common to have to patch somewhere, in the field. You can carry a small patch kit and it's no big deal. With the Polyurethane finishes you have a problem getting that hard finish off to patch it. Gary assured us that the fabic is the same for all the vinyl systems (so that excludes cotton). He said it all comes off the same roll but simply has a different stamp on it. So if you got the roll of fabric from Just with the kit you can use any of the vinyl systems on it, but you do have to use the same system all the way through from glue to color coat. And that is absolutely essential since the components are not compatible between the different systems. Oratex finish is really dull, and for many it is unacceptable compared with the others. He also said the automotive color coats, or finishes designed for aluminum, are too rigid (crack easily), and the additives to soften them do not really work. He had samples of actual fabric taken from airplanes to demonstrate this. All of the polyurethane color coats require fresh air masks and you can't cheat on that. Poly Tone only requires a respirator.

However, the issue of the thread was the incredible 42 pound difference in weight on a J-3 Cub (between Poly Fiber and Superflite) which should be close to the same on a Super Stol. I'm sure that the difference would be even greater for those going for the super wet finish and adding additional coats.

[SuperFly]

To compound on what Roger said here, the flex additives for automotive paints and high filler paints are only intended to increase flexibility for a short time. The flex agents started when manufacturers started using plastic parts on the bodies of cars. ie, plastic painted bumpers. The flex agents only ad flexibility for 30 - 45 days after painting. Then finally gas off completely leaving the paint as brittle as if no additives were put into it. So after painting, and a short cure time, the parts could be installed, upon which they are rigidly mounted to the vehicle and no longer flex. It gives sort of a working time to a painted part. If youve ever seen a plastic bumper on a vehicle when it was not attached, it is pretty darn flimsy. once installed, it is pretty solid. If your not sure, drive you car up to a light pole base, or tree or something, and dent that plastic bumper in. Where it flexes, the paint will crack in little streaks. But I must advise, this will end up being an expensive test...

I had this discussion with a guy who built a beautiful Pitts Model 12, and used automotive paint on it. I asked about the paint, as I was told never to paint fabric airplanes with automotive paints. He said baloney they just want to sell paint, I dont have any issues, blah blah blah. Two days later we were looking at the plane again, and low and behold not one but four large (like 6" long cracks in the paint on the left wing) He was sick. I laughed (to myself, not out loud) because people decided whats best and dont listen to professionals.

I still went for a ride in the airplane... And it was awesome!!! The roll rate is incredible and it climbs like a jet, but I struggled to get past the 30 gallons per hour fuel burn showing on the engine monitor.... and thats 100LL. UG!

[john2]

The note at the very bottom says it was an independent study done by Daryl Hammond PhD. My guess is that Stewarts is the heaviest, although I have no data to support that. Oratex is supposed to be the lightest, but I wonder if it is just lighter than Superflite and not necessarily lighter than Poly Fiber? Could someone do a search for this Daryl Hammond PhD and talk to him how he came up with this?

Hello from Kazakhstan,

Yes I still follow the forum even while at work.

Interesting comment above about the Stewart's being heaviest. One of the reasons I decided to try is was because it was supposed to be the lightest conventional system available at the time. Also I have used the Poly system before and while I liked it ok there is a lot of exposure to MEK etc and I didn't have may brain cells to start off with so I wanted to minimize the exposure to harsh chemicals as much as possible. For me the Stewart's was easier in some ways and more difficult in others. I think now that I have used it one time it would be much easier the next time. I don't have any scientific data to validate Stewart's is lighter, I am only going by what was posted on the forum at Stewart's by Jason Gerard who used to work there.

On average a cub sized airplane cover and paint job should be about 45-50lbs with Stewart Systems.

That is lighter than what all the other covering systems advertise by 20-40 lbs. I have heard of some of the heavy Solvent based cover jobs getting up to 90+ lbs on cub sized aircraft.

A cub takes about 45 linear yards of fabric which is 90 square yards or 810 square feet. Forget about the scrap you throw away. Each square foot of medium fabric up through color and lets assume there is a 2" tape on every square foot weighs about .75 oz.

810 x .75oz = 607.5 oz

607.5oz / 16oz per LB = 37.9LB for just the fabric parts up through a single color.


Jason

[Rampil]

Very interesting comments so far in the covering debate!

On an engineering basis, i.e., strength (resistance to tearing shear or puncture), weight, UV resistance, repairability,
ease of application, etc., Oratex has it all over the other systems and by fairly large margins.
Only the long term durability question remains to be addressed with more field data, although there are
some planes flying for ten years in Oratex.

Since the lack of STC does not apply to experimental, one wonders why people still are not using it more.

Rinker suggests that lack of a factory-applied glossy coat is a reason for some. The Oratex guys say you can spray glossy topcoats over
the factory matte finish. Strikes me as kind of a weird reason though - do yo really want a SuperSTOL to look at, or to fly like a
aerial dirt bike and get dirty? I know quite a few experts in covering aircraft (as I'll explain below), and many of them (but not all)
just want to stick with what they have been using for decades. It reminds my of the reasons IT consultant used to recommend IBM
PCs to businesses instead of Macs - it was to ensure a steady stream of work maintaining and supporting PCs. They would starve if everyone had Macs. Then there is conservatism - people just don't want to change from what they know. I have a good friend who
has been an outstanding professional pilot for more than 50 years, military, airline, corporate, and has an FAA Wright Brother Award to
prove it. He owns three classic aircraft each over fifty years old and flies them regularly. He won't fly in my Rotax-powered homebuilt
because the engine turns too fast! Facts, data and modern metallurgy are not relevant and don't apply.

I volunteer with a program at my airpark which teaches high school kids to restore and fly classic aircraft (http://www.peachstateaero.com/museum-youth-program/). Since we work on certificated airframes (cubs, champs, supercuts, etc.), and the owner of the museum is the former owner of Polyfiber and Stits, we use polyfiber and ceconite. We get a "very" good price on
the materials and have incredible local expertise! Still, the calibrated irons, the multiple coats of chemicals, brushed and sprayed, etc.,
are just tedious.

I've learned a fair bit about covering and finishing (by doing with the kids), and all I can say is when I get around to building my own Just, its got to be Oratex. My current plane is finished in Dupont Imron with clear coat, but then it's a swoopy fiberglass Europa, and I paid a professional to paint it. I ain't crazy about cyanide, thank you very much!

Cheers,

Ira

[alan]

Hi.

My experience with automotive polyurethane paint flex agents is quite different from the comments posted here. I've covered two kit planes with polyurethane with added flex agents, all purchased from automotive paint stores. I admit I forgot the lesson about the difficulty removing this paint from the first airplane to the second. It was 20 years after all.

When I was preparing to paint our Highlander I saw my old Kitfox II and liked the way it still looked so I did it again. To make a long story shorter, the Kitfox had no cracking paint and the Highlander has none either. With 650 hours and almost 9 years on the Highlander I can honestly say that the only downside to polyurethane on a fabric covered airplane is the difficulty in repairs. I'm not the best fabric guy here nor the best painter but the paint is not cracking at all.

Having said all that, because of the difficulty of repair I would go with Poly Tone if I were to build another. Glossy paint only counts for so much.

Alan

[jak]

Several years ago I striped one of our planes down to bare fuselage and wings we were careful to put every piece of fabric that came off into a trash bag when completely finished we weighed the trash bag. 40 lbs this was with the superflight system , It was all we used back then. The paint job was 3 colors on the plane then. We use 45 yards of material also. The problem with the cracking was with the primer they have a newer formula now and they say it wont crack like the old did. Just saying Jak

[kenryan]

Seems to me that whether the finished weight of the fabric (traditional systems) is 40 pounds or 120 pounds will depend mostly upon the skill of the person applying the coatings and, to a lesser extent, the color(s) chosen.

Just skimming the study, I didn't see anything with regards to how the tested samples were created. Were they all created by the same experienced professional, or were they created by a couple of bumbling scientists in a laboratory?

If Jak says the Superflite fabric on a completed Highlander weighed 40 pounds, I believe him. If you believe the study, the fabric on that same airplane, if it were Polyfiber/Stits it would have weighed 24 pounds.

I'd sure like to know exactly how those samples were created.

Just sayin

[R Rinker]

Jak, do you know if the fabric you weighed was the polyurethane type topcoat Superflite uses now, or an older non-polyurethane type?

[jak]

All I know is it was superflight polyurethane it would have been painted somewhere around 04 with whatever they had then. Jak