Guys,
After having a covering failure recently on my silk covered El Diablo I started wondering if maybe silk wasn't the best fabric for covering our models. I think maybe the failure was due to the silk being to light weight (old K&S silk somewhere around 4.5 mm i.e. 1/2 oz per sq yd). Having done another ship in 6 mm (roughly 3/4 oz per sq yd) using a dry application method with CA as spot pins (like doing MonoKote with the iron spotting down the covering as you pull it tight) I wondered if maybe another fabric would be stronger and less prone to failure from simple mishandling (gorilla hands picking up the ship after a flight).

Has anyone used other fabric materials like rayon, nylon, fiblerglass? With the dry application approach any material that the paint (substrate/filler/finish) will adhere to should work fine. The reason is that with this approach (my thanks to Charles at CFC Graphics for introducing this method to me) should work with other materials is you pull the material tight as you apply it and don't rely on it water shrinking. I used it on my new Barnstomer and it worked great the first time I tried it. Another big advantage was being able to apply the covering inside with no dope smell going through the house or having to be out in the summer sun down here in FL.

Best,   DennisT

The freeflight guys do tissue over mylar, because their strengths are complementary -- the tissue adds rigidity, the mylar adds puncture resistance.  Apparently the mylar also makes the tissue fill with dope much faster.

It ought to work similarly with silk.  I have not tried it so you'll be a pioneer.  Do a web search, or get onto Hippocket Aeronautics forum and look around -- that's pretty much exclusively a stick & tissue free flight & small RC forum.

Hi Dennis,
I’ve used Sig Koverall on C/L models that turned out really well.  Also I tried using a product called Thermal Span that work great (about the same as Polyspan.

Later,
Mikey

Isn't Koverall kinda heavy?

Mike,
Who sells the Thermal Span? Doing a Google search didn't turn up any sellers. Please let us know.


Best,   DennisT

I just finished a partially sheeted foam wing with Thermal Span.  Looks very good.  What I like about Thermal Span is that it has no grain.  It is as strong in the chord wise direction as span wise.  I think Thermal Span adds quite a bit of torsional strength due to this feature.  Polyspan is easily torn when pulled in the chord wise direction. 

Other than that, it is just like polyspan.  Attach with dope, shrink with heat, fill with dope.  It has an external surface and internal surface.  Like polyspan, it will fuzz up if you do not get about five coats of clear dope on it before sanding.

The specs say it weighs 0.9 ounces per square yard.  A roll of 14 inches wide X 16 feet long is about $14 plus shipping.

I went through a period where I tried a bunch of stuff. I've tried Rayon, Taffeta, various silks, and a pile of other stuff. Most was either too heavy or not strong enough.  The best was a synthetic silk I tried.  Light and very tear and puncture resistant.