Fabric tension warning ????

Fabric and covering. Fabric, dopes, paint and everything associated with the coverings on our planes.
Post Reply
pmanton
Posts: 121
Joined: Sat Oct 29, 2011 07:42
Location: Indian Hills Airpark Salome, AZ
Contact:

Fabric tension warning ????

Post by pmanton » Wed Oct 16, 2013 18:21

Don't take the fabric above 300 degrees. These Champ wings are flimsy as can be , they are not Citabra construction. All the systems that use Dacron shrink in 3 levels 250,300, 350. The Champ wing will not take 350. It is to be treated like the Ultralites

I found this warning on another board. There were no comments about it.

I have never heard of this. Can this be true? The wings have withstood tightening dope in past years, especially with the newer heavy ribs I can't imagine that 350 degrees would be a problem.

Comments please.

Thanks

Paul
Salome, AZ

MikeB
Posts: 3248
Joined: Wed Nov 17, 2004 15:07
Location: Western Wisconsin
Contact:

Re: Fabric tension warning ????

Post by MikeB » Wed Oct 16, 2013 19:01

My L16 (Champ) wings were rebuilt with new .032 ribs, spars and new leading edge (.022 ??) I'm pretty sure I took it up close to 350 degrees. The only problem that I had was the butt rib got bent in a little which appears to be a normal problem due to lack of support in that area but the wing farings cover it anyway. If I had to do it over again I'd try to stiffen the butt rib up a bit. Might be a different story with .020 ribs and .016 (original) leading edge. The other problem area seems to be the tip rib on the aileron bay. I've seen all kind of fixes on there to try to keep them from bending in. Originally I think they came with a wood support screwed to the rib. I wound up using wood plus a piece of aluminum angle iron...that helped a lot.

Mike

Paul Agaliotis
Posts: 2440
Joined: Wed Dec 08, 2004 16:49
Location: San Martin, California
Contact:

Re: Fabric tension warning ????

Post by Paul Agaliotis » Wed Oct 16, 2013 19:28

Paul,
I don't believe the statement is accurate. The fabric needs to be installed to allow the heat shrinkage. Generally the fabric is too tight before shrinking, this comes from habits when installing cotton. It shrinks only about 10% and is bidirectional, Dacron shrinks about 30% and is omnidirectional. If installed correctly the shrinking of the fabric is the same. The Citabria might tolerate over-shrunk Dacron better than the Champs, but it's never been an issue.
Paul
Mailing Adress : Paul Agaliotis 2060 E. San Martin, San Martin,Calif. 95046

Champ Dreamer
Posts: 185
Joined: Wed Mar 19, 2008 21:14
Location: Colorado Springs
Contact:

Re: Fabric tension warning ????

Post by Champ Dreamer » Thu Oct 17, 2013 14:31

I don't believe this is correct. Polyfiber reminds us that the untreated fabric should be installed loosly. I saw a homebuilt wing where a guy stretched the fabric nice and tight, then glued it. When he shrank it, it bent the trailing edge beyond use. After he ripped the fabric off and fixed the trailing edge, I helped him lay up the fabric and shrink it. 2 final passes at 350 and no problem. I had no problems with 350 on my Champ. Personally, I would follow the manufacturer's specifications before relying on an internet post.

Brian Walker
'46 7AC/DC flying daily !!!!

pmanton
Posts: 121
Joined: Sat Oct 29, 2011 07:42
Location: Indian Hills Airpark Salome, AZ
Contact:

Re: Fabric tension warning ????

Post by pmanton » Thu Oct 17, 2013 16:13

That agrees with what I thought. PolyFiber specifically mentions that their STC requires 350 degrees for certified aircraft.

Paul
Salome, AZ

MikeB
Posts: 3248
Joined: Wed Nov 17, 2004 15:07
Location: Western Wisconsin
Contact:

Re: Fabric tension warning ????

Post by MikeB » Thu Oct 17, 2013 16:57

If I remember correctly Poly-Fiber says to leave a 'pull up' of about an inch loose or at least certainly not tight. The Superflite manual says a 'snug fit' but not tight (whatever that means). I suspect if you have a real weak member: the outboard of the rudder fin is a good example and you installed it too tight it would probably deform the light tubing. The rest of the aircraft is pretty substantial other than the aileron bay tip ribs. There is a brace available for that but it still takes some additional bracing to prevent the tip from bowing in as the fabric is tightened. Also if you look at a lot of Champs and Chiefs, the butt end of the horizontal stabilzer usually has a outward bend. I guess it probably makes them look 'original' :? .

Mike

dikholder
Posts: 173
Joined: Fri Sep 14, 2012 18:12
Location: North Pole AK
Contact:

Re: Fabric tension warning ????

Post by dikholder » Sat Oct 19, 2013 23:51

I am using Stewart Systems on my Sedan. The Stewart manual refrers to using lower temps on the lighter fabrics 101 ect which they say are often used on experimentals, aerobatic aircraft and antiques. I went 350 on my Sedan with 102 fabric, my iron is cheap, so anything hotter than that scares me.

Dik Holder
N1441H The Queen of the Berry Patch

Post Reply

Who is online

Users browsing this forum: No registered users and 1 guest