Oratex
- Thread starter skysigns
- Start date
CubCubCub
Registered User
Ozzy in Japan
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!
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
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.
Speedo
FOUNDER
TN
Wait, are you suggesting that other coverings actually stiffen the airframe?
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
The tail might resonate more or less with lighter or heavier fabric? Maybe??
Gordon Misch
MEMBER
Toledo, Wa (KTDO)
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 -
CubCubCub
Registered User
Ozzy in Japan
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.
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CubCubCub
Registered User
Ozzy in Japan
I know that, there could be lots of reasons. This Cub is a 150.
CubCubCub
Registered User
Ozzy in Japan
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?
Steve Pierce
BENEFACTOR
Graham, TX
CamTom12
Registered User
Huntsville, AL
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.
CubCubCub
Registered User
Ozzy in Japan
That seems like a fair concern. It would definitely be a problem if the fabric fails in flight!
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.
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.
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