I am finishing my G.P. Cub in Koverall, and dope. The problem I have is the covering at the horizontal, vertical stab area is pulling away from the airframe because of the dope shrinking. This is where the tail joins the fuse. Is there any way to repair this? It looks like the longer the dope dries the tighter it gets.
Thank you
Tony

The covering at the junction of the vertical fin and the horizontal stab is never attached to either part to make a sharp, inside corner on the full-scale planes. Take a close look at a full-scale Cub and you will see what I mean. If you meant something different, how about a picture to illustrate what is happening.

BB

I thought that might have something to do with it. I striped the covering off, and recovered the fuse. I didn't run the covering all the way into the corner. After spraying several coats of dope the covering started to lift again. This time I cut a line through the covering the length of the corner. I used ca glue to glue the covering down. Is this a common problem caused by the dope shrinking? The two pieces of covering were never joined in the corner. I was surprised to see it happen the second time. What can I do to repair this, and prevent this happening again?
Thank you
Tony

You are not attaching the Koverite properly. Correctly applied, it will not come loose. I apply it with nitrate dope to the structure. Several coats to the wood, light sanding, then more dope through the fabric to adhere it to the wood. Additional dope to seal the fabric, then paint.

How are you attaching it? Whatever you are doing is not bonding the fabric to the wood.

Edit: I reread your post and see you are using CA to adhere the fabric. That doesn't work. Read the directions on the Koverite, and you will see the easy way to have success with this covering. Good luck.

Three coats nitrate to wood. One coat stixit where needed. Apply fabric, and shrink. Fill weave with three to four coats of nitrate reduced just enough to brush, sanding between coats. Then I applied my base color in several lite coats.
Thank you
Tony

I've had this problem on a few of my planes - the worst offender was the upper side of the gull wing on my F4u Corsairs. I tend to agree that something's up with your installation - definitely need to use separate koverall pieces for the stab / fin, and perhaps you need to give the dope / stix-it more time after installing to dry and setup before you heat shrink?

Regardless, pulling does happen and may be caused by something on the wood, something on the fabric, something on the something, etc. Could also be that you're heat shrinking too much and the dope is proverbial straw that breaks the camel's back.

My long-term solution was to switch to Randolph's non-tautening dope and to get the tautness I need by heat shrinking.

EG

After this experience with dope I am going to try latex, or Nelsons paint on my next project. I love the koverall fabric, but almost lost my happy home from the fumes. I do like the idea of non tighting dope.
Thank you
Tony

Can you post a picture showing what it looks like with the material "pulled away from the airframe"? From the fuse to the V-stab should be a smooth transition and not follow the contours of the fuse exactly. How close to this does it look?

i use .75 oz fiberglass cloth on sheeted areas and only use koverall on open areas. i use stix it under the koverall but shrink it with a iron like monocote. then i paint/cover the entire assembly in Minwax polycrilic, prime then use latex paint (and then Nelson's clear coat). there's more to it than that but that's the basics.

david

The problem is two-fold. 1. you're not applying the fabric correctly. It should be glued with either "Super Seam" or "Poly Tak". A coat of dope isn't enough to hold it as it shrinks. I know, I know. There is someone out there that has used dope for 110 years and it has held. Well, this one didn't.

Secondly, dope shrinks through its entire life, even non-tautening dope! As it shrinks it is pulling the fabric off, or the dope underneath. The fabric is polyester and the best bond is the polyester to polyester bond with either "Super Seam" or "Poly Tak" it's the same stuff.

End of story.

Click on fabric or covering on the above replies.

They are right. The full scale planes don't have the horizontal stab attached to the fuselage, but is supported by tubes that allow the horizontal stab to be moved for trimming the plane. Nitrate Dope will not hold when you allow the fabric to make the 90 degree corner from the fuse to the stab. You can either make a cut joint and finish it off with seam tape as is shown in the photo, or make a fairing that is not covered by the Koverall. I too have used this stuff for years, and I have one model that is close to 15 years old that is covered with Koverall and Sig Nitrate/Butyrate dope. It's tighter now that it was when new. Eventually it will split.

Bill, AMA 4720
WACO Brotherhood #1

I have dope & fabric covered planes some 40 years old that still look good . The secret is I have always used Dave Brown's "Flex-all" plastizer in the dope . This is a product that really works . Give it a try . MAX H. AMA 14958