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Thread: Oratex

  1. #1
    skysigns's Avatar
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    Oratex

    looking for advice the last 3 cubs i covered in stewarts thinking about oratex on my next cub
    is it a good idea for a working cub

  2. #2
    nanook's Avatar
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    I'm planning on using it on a working cub, would like to attend a workshop and play with the stuff first though.

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    CubCubCub's Avatar
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    Hi Skysigns. I'm no expert on the matter and this is just an observation so take it for what it's worth. A Super Cub came in for a 100 hrly the other day. This Cub was recently recovered in Oratex (it was covered in cotton.....was getting tired!). I am not sure about the figures but speaking with a mechanic that was involved with the recover, he said the empty weigh decreased with Oratex so that's good. However, watching the back end of the aircraft when it is on the ground at idle, my impression is that the entire back end flex's (twist's) allot more than other Cubs covered with either Polyester of Cotton. I think the Oratex is more flexible than the regular coverings. Whether this will translate into structural fatigue later on remains to be seen. Perhaps others have had more experience with this? Apart from that, a friend of mine said it seems fairly puncture resistant and if it gets a dent (stretched), just grab the iron and warm it up again and you are good to go. Anyway, just my 2 cents worth!
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    Gordon Misch's Avatar
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    I just finished covering my landing gear with Oratex. It is definitely different to work with than Stits or Stewarts, but following the directions closely gave a decent result. It certainly is nice that once it's on and shrunk it's done! I think, however I could do a nicer looking job with Stits or Stewarts, the only other systems I've used.
    Gordon

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  5. #5
    Speedo's Avatar
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    Quote Originally Posted by CubCubCub View Post
    Hi Skysigns. I'm no expert on the matter and this is just an observation so take it for what it's worth. A Super Cub came in for a 100 hrly the other day. This Cub was recently recovered in Oratex (it was covered in cotton.....was getting tired!). I am not sure about the figures but speaking with a mechanic that was involved with the recover, he said the empty weigh decreased with Oratex so that's good. However, watching the back end of the aircraft when it is on the ground at idle, my impression is that the entire back end flex's (twist's) allot more than other Cubs covered with either Polyester of Cotton. I think the Oratex is more flexible than the regular coverings. Whether this will translate into structural fatigue later on remains to be seen. Perhaps others have had more experience with this? Apart from that, a friend of mine said it seems fairly puncture resistant and if it gets a dent (stretched), just grab the iron and warm it up again and you are good to go. Anyway, just my 2 cents worth!
    Wait, are you suggesting that other coverings actually stiffen the airframe?
    Speedo

  6. #6
    nanook's Avatar
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    Watching the tail shake on a cub, would not be a valid assessment tool for the fabric! The big prop/180hp., especially so.
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  7. #7
    Eddie Foy's Avatar
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    The words are flexes and twists. If that is the case, it's not the coverings fault.
    "Put out my hand and touched the face of God!"

  8. #8
    Gordon Misch's Avatar
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    The tail might resonate more or less with lighter or heavier fabric? Maybe??
    Gordon

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    Marty57's Avatar
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    Just a quick question or observation; but is Oratex now certified? If it's on a working, certified Cub than wouldn't it need to be certified?
    Marty57
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  10. #10
    Gordon Misch's Avatar
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    Marty, I thought it had fairly recently received STC approval, but I can't seem to find a reference now. Somebody here will know for sure -
    Gordon

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  11. #11

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    Quote Originally Posted by Gordon Misch View Post
    Marty, I thought it had fairly recently received STC approval, but I can't seem to find a reference now. Somebody here will know for sure -
    http://www.betteraircraftfabric.com/news.html

  12. #12
    CubCubCub's Avatar
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    Quote Originally Posted by Speedo View Post
    Wait, are you suggesting that other coverings actually stiffen the airframe?
    Like I said, it's just an observation so take it for what it's worth. I tend to think it could. IMHO, structure's flex more prior to being covered than after they are done. I think if you cover something with a heavier weight material, it would naturally be more rigid. My feeling is that the Oratex is a more flexible covering. The Cub I commented about had it's structure checked over prior to recovering with Oratex and all appeared to be fine.
    Last edited by CubCubCub; 08-28-2017 at 07:58 PM.

  13. #13
    CubCubCub's Avatar
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    Quote Originally Posted by nanook View Post
    Watching the tail shake on a cub, would not be a valid assessment tool for the fabric! The big prop/180hp., especially so.
    I know that, there could be lots of reasons. This Cub is a 150.

  14. #14
    CubCubCub's Avatar
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    Correct me if I am wrong, but generally speaking, isn't one of the reasons that an older aircraft that was originally designed to be covered with cotton, needs to have approval (STC) prior to being recovered with a 'modern' covering, is because the resulting rigidity of the structure changes due to the difference's in strength/flexibility of the 'modern' covering?

  15. #15
    Steve Pierce's Avatar
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    Is there a comprehensive list?

    FAA STC Approval!

    Latest STCs include PIPERS, some AERONCAS and STINSONS. Don't forget our STCs for all Maules and Huskys!! We also have Field Approvals for Cessna 120/140s!
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  16. #16
    CamTom12's Avatar
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    Quote Originally Posted by CubCubCub View Post
    Correct me if I am wrong, but generally speaking, isn't one of the reasons that an older aircraft that was originally designed to be covered with cotton, needs to have approval (STC) prior to being recovered with a 'modern' covering, is because the resulting rigidity of the structure changes due to the difference's in strength/flexibility of the 'modern' covering?
    I don't think a stretched fabric covering provides enough tension to be considered semi monocoque.

    I think coverings require STCs because there's a big concern for fabric failure when your lifting surface is made of fabric.
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  17. #17
    CubCubCub's Avatar
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    Quote Originally Posted by CamTom12 View Post
    I don't think a stretched fabric covering provides enough tension to be considered semi monocoque.

    I think coverings require STCs because there's a big concern for fabric failure when your lifting surface is made of fabric.
    That seems like a fair concern. It would definitely be a problem if the fabric fails in flight!

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  19. #19

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    When RC modelers switched from water shrink paper to heat shrink polyester, there was a noticeable decrease in stiffness as there was no tautening nitrate applied. How tautening are the modern liquids? I would think the big difference would be when we stopped using nitrate on ceconite. I wouldn't think there would be much difference between two heat shrink polyesters if there's no liquid tautening these days.
    P.S. When shrinking, use a calibrated thermometer. Old steam irons need to be cranked just above the synthetics range, slightly into cottons. It's not like you're going to let the iron sit there motionless. Now you've got tension.
    Last edited by Skywalker; 08-29-2017 at 06:35 PM.
    What's a go-around?
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