Mylar

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Postby Guest » Fri Nov 26, 2004 3:52 pm

TUT20BG3 was being used on Lazairs before the Falcon was developed.

The TTR20SG4 Tedlar

T- Tedlar
TR-Transparent (Little to no UV blocking properties apparently)
20-thickness (2 mil)
S-Strippable non-adherable release film (oooh this is bad)
G-Glossy
4- High elongation with good formability and good heat sealing properties.
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Postby senna12625 » Fri Nov 26, 2004 5:14 pm

George has just made my point by answering a question I said I had no interest in. There are many, many formulation types for TEDLAR... and he states that ONLY one satisfies his comfort level.

DuPont manufactures 223 different MYLAR or more correctly Polyethylene Terephthalate (PET) Films! To just make blanket statements that MYLAR 'sucks' (corrected spelling), 'it's a poor (corrected spelling) choice', and 'last time i seen it was at THAT PARTY PLACE for BALLOONS (SIC... no attempt to correct this one...) tells me nothing. Without specifics about WHICH film these references are made makes such statements suspect as to the level of experience or expertise the person or persons making said statements posesses. Lets call it material bigotry and move on...

I'm attempting to further educate myself AND the GROUP about an alternative polymer material to supplement the exsisting material choices available. My foray into this endeavor has me somewhat confused... hence my request for technical assistance. If it can't be had here... so be it. I will look elsewhere. I will however share whatever I learn...

Steve
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Postby Guest » Fri Nov 26, 2004 6:54 pm

Quote: "Mylar as a covering material, when ALL aspects are considered, is a MORE desirable product that performs almost as well as the TEDLAR product that just can't be easily had."

On what evidence and experience have you drawn this conclusion ? What aspects make it more desirable ?
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Postby ozzie » Fri Nov 26, 2004 7:45 pm

hi steve. for mylar (and i prefer it) try a fiberglass supplier as they use it for bagging and laminating. i was going down this track with a bit of success until george sold me a roll that he did not need. i have heard that others have used this source before. the tape i am using is foam 3M VHB 4950, double side tape is Tesa 4965. the 2" wide finishing tape is an all weather repair tape by Husky don't have the specs here but it was substituted at the last moment as the original type i ordered was only available in large quanities. i so far have covered the tail with these tapes and are quite pleased with them.the 12mm wide double sided 4965 was so strong on the elevon i shunk it up completly then realised that i hadn't put the 2" tape on. did not peel away at all. i am more than happy so far with the mylar and the tape choices i made. i found that nearly all manufactures of tape have the same specs or that close it does not matter. i am in australia so can't help you with suppliers. good luck and ignore the wombats. Ozzie
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Postby Chappy » Fri Nov 26, 2004 7:52 pm

Hi Steve,

Maybe I can try to help a little more. Both the Mylar and the Tedlar films supplied by Ultraflight were of the stretched variety. When heated, they "shrunk", or more properly described, stress relieved, attempting to return to their original dimensions. They seemed to be stretched more in the long dimension than in the width of the material, but I'm not sure, as I never actually tested it. The later Mylar supposedly had some form of UV protection applied as a coating. I was very suspicious, but the last Mylar I used was much better at tolerating UV than the earliest Mylar I used. It was also much clearer, as the earlier material had a slightly cloudy appearance, although still much better than the Tedlar materials I have used. Both the Mylar and Tedlar I used had some form of lubricant on them straight from the roll, but it didn't seem to keep the adhesives from adhering to the films. Then again, the rubber adhesives used on the Mylar tapes seemed to stick noticeable better than the acrylic adhesives used on the Tedlar tapes, especially in shear. Over heating Mylar tapes caused the adhesive to burn and bubble up. When moisture got into this damaged adhesive, it turned white and powdery. The acrylic adhesive, when overheated, didn't exhibit the same visual signs. but the adhesive was damaged too. It would not "set up", and would get sticky and slip in shear much easier than if not overheated.

Fabric covering is fine, I just really like the look of Lazairs in clear or translucent coverings. I also find real value in being able to see clearly what's going on inside my wings. I think covering. and recovering, is much easier and faster when done in film/tape than when done in fabric/glue/UV block/paints. And I guess I just think our planes are cool because they are so unique looking in see-through films.

The Catto brothers pioneered film covering. They used Mylar on their first Gold Wing Ultralights - that's where Dale Kramer got the idea to use it. Back in the day, it was not unheard of to cover homebuilt hang gliders with plastic shower curtains. Dale covered his homebuilt Super Floater with it. Dale's contribution was to use "glue on a roll" (tapes) rather that the contact cements used by the brothers, and to try Tedlar. They used Plyobond glue, which Dale thought was messy and more difficult to use than tapes.

Twenty-25 years later, it's hard to believe there aren't newer film type materials available that would be even more suitable covering materials for our planes. I'm sure there are people on this list that have the intelligence to research and test these new materials if they decide to commit the mental effort and time to the task.

Many years ago, I played around with Tyvek and it looked like it might have potential, but needed to be glued with something like Plyobond, as tapes didn't have anywhere near enough grip on it. It would also need to be painted, and I never tested whether that was practical.

One winter I was able to rescue some metalized, red Mylar from a commercial Christmas display. I used it to cover the tail of my old Series 1. It was quite stunning in appearance. It was, however, not the best choice in the long run, as it failed in only a couple of years. There were several reasons for that I think. It was only 150 mills thick. Metalizing and/or coloring Mylar is done by post processing, and (at least back then) was done by companies other than DuPont. The coating process utilizes some heat in the process. Some, if not all, of the stretch was relieved out of the film. When attached to our planes, there wasn't a whole lot of shrinkage possible, so you ended up applying more heat than usual. Also, the metalized film reflects heat back at you. It just made it much easier to cook the tapes when attempting to tighten up the covering. Uncoated Mylar is very good at absorbing UV radiation. You can easily witness this in a Mylar covered Lazair that's been left out in the sun for extended periods of time. The top wing covering can become very weak, and actually fail and blow off the wing in flight. This happened to a friend's Lazair I was following one time. I thought he was throwing out foil pieces as he flew along. When we landed, I mentioned it to him. We looked at his plane, and he had lost the top panels on both wings behind the engines. The lower surface was like new, and since he couldn't even tell the panels were gone in the flight out, he flew his plane home with the missing panels, and had no problem at all (I'm NOT advocating doing that!). Anyway, the point being that the metalized coating, because it doesn't allow any UV light to penetrate through it, reflects the UV light back up through the material where it can do even more damage. The thinner material I used just rotted too quickly. Ultraflight also covered a factory demonstrator in silver metalized Mylar, and they told me they had the same problems that I experienced with my red covering. It was, however, AWESOME looking! It looked like the whole plane had been dipped in chrome.

I wish I could come up with the specs on the Mylar and Tedlar supplied by Ultraflight way back when, but I just don't know them ;-(

Chappy
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Postby ozzie » Fri Nov 26, 2004 8:29 pm

whilst we are on the covering topic last weekend i bought some ripstop material to do the wing tips and glued it on then shunk it it looked good and came back after a cup of coffee and it was all loose again.(bugger). with all the recovering going on at the moment can anyone give me a lead on what to search for. i am now thinking of just using mylar on the tips has anyone used mylar or tedlar on the tips before. i don't foresee any probs here but no doubt shorty has something to say hey
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Postby senna12625 » Fri Nov 26, 2004 8:59 pm

Now we have a discussion!!! Thanks Chappy!

I've learned a little more in my pursuit...

These polymer films are made from powder and it has not proven possible to simply heat the powder to melt it and produce a useful film. DuPont talks about the use of "latent solvent" to dissolve the powder at temperatures typically above 100º C. They then allow the solution to coalese into a film before the solvent has completely evaporated. It is extruded while still hot and cast on a perfectly smooth surface. When a sufficient amount of solvent has evaporated to allow the film to be self-supporting, it is passed through a series of rollers that first elongate it in the longitudinal direction and then in the transverse direction. The longitudinal elongation is performed when the film has a 35 to 70% latent solvent content. Longitudinal stretching can amount to 50-500% and is done at elevated temperatures of 20 to 100 C.

The transverse stretching is done while the solvent is about 13%. It is also performed at higher temperatures of 60 to 150 C. The same 50-500% elongation can be acheived during the transverse stretching. (Chappy this may account for your comment regarding the films ability to shrink more in the longitudinal direction... it could be due to the difference in the solvent content at the time of the stretching OR the higher temps the transverse stretching takes place at. Your heat source may of needed to be higher to get the transverse shrinkage. Of course the limiting factor is the burn tolerance of the tape adhesive and I suspect the heat needed to allow the equivalent transverse shrinkage exceeded the burn tolerance limit of your tapes.)

Once stretching is complete the film is allowed to dry. It is at this point considered a bi-axially oriented film.

Steve
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Postby xgary » Fri Nov 26, 2004 10:04 pm

shorty says : take your Mylar and go make some balloons.


Mylar is a waste of time and money

Go see John nagy and buy his TEDLAR


Mind you he has not told What the SPEC is for it .


As far as your comments about discussion seena , when you start talking techie shit outta your ass....... it comes to mind that you are living in fantasy land.

EARTH CALLLING SEENA

MYLAR SUCKS == POOR DECISIION BAD CHOCIE

CAPICE `` ?


But Hey you will not find better guys here to advise you of the merits either way.

Shannon

George etc I will not incude my self as I am a child ish jerk but I a ma jerk with an opinion that does not come from the toy box but from decades of aviation under my belt.

Go ahead call me what you like and i will give you a big FINGER AGAIN .

LOLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL


btw in all serious nesss MYLAR Will work but do you water ski ?
If so this will work tooo

LOL
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Postby xgary » Fri Nov 26, 2004 10:22 pm

George, you got a scanned part of a pdf file ? or the pdf ?

send it to me

new addy they gave me shortnaked@lazair.com

and i will figure a way to post it.
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Postby xgary » Fri Nov 26, 2004 10:24 pm

hey i just noticed the green google adds on top of these post got mylar on it

another one say double sided foam tape and another says carton selaing tape.

looks like problem solved.

Adds do the shopping

every time i refresh page i get new adds
lol hillarious

u can cover your bird from adds

lol
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