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Building Tips and technical articles. => Building techniques => Topic started by: Keith Spriggs on February 18, 2007, 10:25:37 PM
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A friend of mine ask me to post this for him. He has built a couple of models recently. He covered each of them with silkspan from two entirely different sources. Ono of them he doped with nitrate and the other one with butyrate. Both of them had the covering split like it was stretched too tight. Any ideas?
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What type (mfg) of dope? They have different shrink rates. Had the dope worked on previous coverings?
Jim
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If it was light silkspan (00) and he used high shrink dope, it could certainly happen.
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Where did the splits occur? In the open bays, or against a "corner" like cap strips, or some other area where it meets the sheeting?
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I am sending these questions on to my friend that had the problem. After I get some answers I will let you know.
Thanks
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As usual I got some of the details wrong. Here is a reply that I got back from my friend when I inquired further
"Only one of the planes has had a problem. The half fast is covered with skyloft and nitrate. The jerkline is covered with two grades of silkspan. Heavy and lite. They’ve both split length wise. Both sides of the wing. Seven in total. This plane is doped with butyrate dope. I used this same can on my oriental profile with absolutely no issues. I removed a piece of covering from the offended wing last night and attempted to tear it by hand, could not. When the wing splits, it omits a obvious pop. As I recall, this is aerogloss dope."
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I have a Bunch of patches on the Sunflyr and Humongous because of Plyspan splitting... Normally as I make that last swipe cleaning it at the Nats... ~^ HB~>
Extremely annoying.... Had used that stuff for a long time with no problems, then splitsville... I am almost convinced that the tissue itself is part of the problem.. But I am also wondering if ultraviolet is getting to it since I use a tinted dope finish or clear... The latest project a NEW!! old timer, which won't be ready for VSC :P is covered with regular weight silkspan and will be getting nitrate as a base, then litecoat with a layer of regular butyrate to shrink a bit... FWIW ;D We will see wha hoppens...
Later
Jim
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I have become a believer in using plasticized dope. You can get nontaughtening from Randolph's. Sig Litecoat is fairly well plasticized, but the Supercoat clear is not. I've really had problems with Aerogloss splitting when not plasticized. I haven't had any problems with Plyspan. I agree that sunlight is a real culprit. The top of the wing is faded and cracking and the bottom is fine. :'( I have not done so, but I really ought to make covers for my airplanes. I think it is a real good idea to keep any airplane out of the sun as much as possible.
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I had that happen to my Smoothie that I had refinished. I used Aerogloss, but I am not sure of the "vintage". I understand that Aerogloss changed a couple times. Don't know what caused it, but sounds like Aerogloss is the common denominator. (??)
Bill <><
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The Aerogloss one can get these days, is NOT the Aerogloss of old. I fixed a crack then refinished the fuselage of an airplane I built in the 60s using the new stuff. It looked good for a while but then developed all sorts of cracks in the paint in the repaired area. Bummer! Has to be related to the current removal of VOCs craze in paint formulations.