Tedlar Testing

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Postby Ray » Wed Jul 07, 2004 3:32 pm

Im one of the new Lazair owners, with a series 1.

The one I have was never flown, and stored in its trailer in AZ for the last 20 years.

Im wondering if there was a simple test for the tedlar strength.

I will have to replace the tapes in any case as they seem to be loose in areas.

I have a sample that I tried hard to poke my finger through, and it only stretched and would not break.

It seems like the Tedlar is extremely strong and tear resistant.

Any one know how I could test its strength....and what test it should pass?

Postby Guest » Sun Oct 09, 2005 10:57 pm

I know this is a controversial topic.

I am simply relating my experience here.

Peter Corley was flying at a Sun N Fun and had the second upper panel of mylar pop open on the right wing. He heard it happen but the Lazair flew fine and landed safely.

Upon review of the situation I decided to come up with my personal method of determining when the covering had become too weak to fly safely in low G situations as had just occured.

The torn mylar was obviously degraded, no visible indication. The mylar pieces were quite easy to rip by hand, non-degraded mylar is not.

It was apparent that the turbulence of the prop wash initiated the failure.

The mylar had to come off. The obvious test to me was to slap the center of a panel with my hand. The results were interesting. Every top panel eventually borke with a slap. The root panels seemed to take less force but a simple, firm slap was all that was required to pop the panel.

We tried this on the lower panels and none would break, even with slaps that were quite aggressive.

Sooo, that became my personal basic test I did on any unknown Lazair I flew.

I also make sure tapes have not been pulled by overheating and that they are not lifting.

By the way, we turned the event at Sun N Fun into a Lazair recovering clinic and had a large group of bystanders involved. I think this event actually increased sales as people saw how controllable the lazair is and easy to recover. It took only a few hours to do both wing tops and we kept flying without a hiccup.


Postby rayjb60 » Tue Oct 11, 2005 10:06 am

Thats great info......strange thing is that I also had that very same thing occur on mine now that its flying.

I had used some other tape that seemed to have great grip on the inner 2 bays top side that I recovered.

Sure enough the tape lifted in flight and gave me quite a scare since it made lots of noise.

All that happened was the 2" of tape along the leading edge of one bay lifted up and made a horrible buzzing....Im surprised that the air pressure did not blow out the entire panel, so I replaced all that bad tape that I had used and now its fine.

seems that the top surface of the wing takes a lot of turbulence from the prop wash.....Im thinking it could use a couple extra lines of tape chordwise to help dampen the covering vibration on the inner 2 bays behind the engine.

By the way Dale thanks for the greatest ultralight ever....I have been oggling the Lazair since I was in my early 20's when I lived in Ontario.

I found this site and was surprised to see the Lazair still going strong, found a 90% complete kit in Arizona and now at 45 Im flying a Lazair in California.

I also saw you a couple times in the late 90's while I was a SOSA member.

Now I also have a Monerai Sailplane out here at Lake Elsinore....I have yet to fly it.....have to convert my Canadian Glider license to a US ticket and get current again.

Planning for a 2006 Soaring season, Im finishing up some improvements to the Monerai control system to take out the extra play.

<H5>Nothing is impossible...Even the word tells you Im-Possible!!!</ H5>
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