Use of Filler on Fuselage

[karaka29211]

There are several places on the fuselage where the interaction of components require the use of some kind of filler to create a solid foundation for fabric covering. Front left AL panel and carbon fiber intersection adjacent to fuel selector/Rear Fuel Drain area/Longeron and Alloy Tubing both sides of rear fuselage to name a few.
CC use Bondi in the videos, but Polyfiber advise "No" because of shrinkage and later possible de-lamination of the fiber.
Some suggest the application of anti-chafe tape in susceptible areas to cover the filler before covering will work.
Others say an epoxy filler? is the only answer.
What works?

[c130jake]

I used poly fibers two part epoxy filler. Light weight and designed to be used with their process.

https://www.stits.com/store/superfil.html

Jake


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[David H]

Russell,

This is what I used. worked perfectly:

DSC_0808.jpg

See post 34 on this excellent thread:

http://forum.cubcrafters.com/showthr...n-s-Build-Tips

David

[karaka29211]

Thanks for the reply, I used a very similar West System 105 resin product.

www.westsystem.com/the-105-system/

Very happy with the results, did you apply fabric tape or paint before the fabric blanket?
Cheers,

[jmorrical]

I am finishing last things before I start to cover my fuselage. The EX cover manual says I should use light weight filler putty where needed. I have done the fabric spacer/top stringer left side and the tail fin transition. One other place mentioned is at the end of all stringers.

When I look left and right sides where the two stringers are glued to the aft end of the fuselage and lay a straight edge across both top and bottom longeron to simulate fabric stretched over that area I don't see any need to fill any of those joints. Those joints fall inside the fabric line. My test shows the fabric beginning to contact the stringers very gradual forward of those joints. Fabric wouldn't meet the stringers fully until 2-3 inches forward of the joint. Am I missing something here?

[karaka29211]

No, not missing anything, I think you are fortunate that this is not an issue for you.

I am finishing last things before I start to cover my fuselage. The EX cover manual says I should use light weight filler putty where needed. I have done the fabric spacer/top stringer left side and the tail fin transition. One other place mentioned is at the end of all stringers.

When I look left and right sides where the two stringers are glued to the aft end of the fuselage and lay a straight edge across both top and bottom longeron to simulate fabric stretched over that area I don't see any need to fill any of those joints. Those joints fall inside the fabric line. My test shows the fabric beginning to contact the stringers very gradual forward of those joints. Fabric wouldn't meet the stringers fully until 2-3 inches forward of the joint. Am I missing something here?

[jmorrical]

Just curious. My EX Cover Manual says: Spray Etch Primer (RM 30005-11) on all of the places filler was applied. Let the primer dry, then spray the area with black paint.

Why is the primer needed on the filler?

I can understand priming then painting scuffed steal frame tubing would inhibit rust, but what is the purpose for primer and paint on filler if we're covering the area?

[karaka29211]

Hi Jim,
My original post was around complying with the Covel Manual or the Polyfiber Manual where they differ, to accomplish the same outcome. I am outside the USA and some products referenced in the CC or Polyfiber manuals are simply not available, so an equivalent must be applied.
To address your question, the use of black paint was simply to comply with the manual, I would guess that the filler requires a sealer, before applying Polytak, the real reason- I do not know.

Just curious. My EX Cover Manual says: Spray Etch Primer (RM 30005-11) on all of the places filler was applied. Let the primer dry, then spray the area with black paint.

Why is the primer needed on the filler?

I can understand priming then painting scuffed steal frame tubing would inhibit rust, but what is the purpose for primer and paint on filler if we're covering the area?