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Old 10-10-2006 | 10:24 PM
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Chip_Mull
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From: Granbury, TX
Default RE: finishing with Koverall or equivelant

Stickbuilder, I am very impressed with your AMA number. You must know Charlie Nelson, "Mr. Waco". You are correct in as much as there are as many techniques as there are builders. I don't have the benefit of your experience, I can only go by the manuals and what I have learned over years dealing with the full scale mistakes and problems. By using the same techniques and procedures we can avoid re-inventing the wheel. What we have learned is stay with what has been proven and tested in the labs and don't mix procedures. If you start with dope, stay with dope. Also, if you start with Poly Fiber then stay with Poly Fiber. Dope is manufactured with about 85 per cent MEK and disolved cellulose. MEK is the solvent we use to clean off Poly Tone so it stands to reason NOT to mix the two. The MEK in dope will attack the Poly Tone.

Racer 7696, you asked if you can use epoxy. Of course you can, after you fill the weave of the fabric. And keep in mind epoxy is not designed to be flexible. You see Polyurethanes on full scale aircraft. You see dope on full scale aircraft and you see lots of Poly Tone on full scale aircraft. Never epoxy though. Why? Cause eventually it will crack. There are plenty of people out there that will confess to using epoxy for years and have never had problems with cracks. There are them that have and them that are gonna.

As for the seams, try to place them where they will be the least noticible. Also, if it's a scale project, the seams are covered with the pinked finishing tapes. Finishing tapes are usually all the way around the control surfaces, along the leading and trailing edge of a fabric covered wing, and along the ribs.

Attaching the fabric: http://www.stits.com/RC_Model_instructions.html#tak . Each fabric manufacturer has his own cement to attach the fabric. The idea being to establish a polyester bond. Whether it's Sig Stiks It, Randolphs Super Seam, or Poly Fibers Poly Tak, they are all intended to bond the polyester. The best situation is to have a polyester to polyester bond where the fabric is attached to fabric with one of the fabric cements. Chemically, they are all about the same.

Shrinking... All dopes shrink over time. This worked to our advantage when we were using cotton or silk. Not so good with polyester. The concept is to encapsulate the fabric with nitrate dope and then use butyrate. The nitrate sticks to the fabric and the butyrate sticks to the nitrate.

Covering the fuse with fabric... covering a compound curve can be tricky. But, it can be done. I still contend that on a Corsair it would be better to use fiber glass cloth instead of fabric. Then, I re-read your original post and realized we are talking about a 1/12 scale project. If you're using this as a test bed for different fabric techniques then press on. But, if it's a model to be flown and enjoyed, just paint the fuse without fabric or fiberglass.