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To micro the fairing seems and pull fasteners or not

snoop9erdog

Well Known Member
All,

What is the consensus....to add a layer of peel ply and then micro slurry over the fiberglass fairing joint/seems and pull fasteners or get the fit as tight as you can and forgo the aforementioned and leave it a true metal plane?

For those of you who took the time to get a smooth transition (or not), would you do it again if you had it to do again?

I'm debating the whole thing....I want my fairing transitions to look nice but not at the expense of overly excessive weight or excessive time that continues to delay the "get it done" mentality.

Worth it or not?
 
It is a personal preference.

I built a metal airplane because I wanted a metal airplane. I did not do extra work on fiberglass seams. I wanted people to know where my metal work stopped and fiberglass began.

I wish I had the patients and time to do away with the fiberglass and do metal for all the fiberglass parts.
 
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I agree with Gary, but most all metal cowls and fairings I have see where not well executed. I did make my own metal windscreen fairing, three times until I got it right, but it looks good and it will never crack as it is a separate piece(s).
As Gary stated, it is a personal preference. I have seen way too many cracks in the composites right where the “gap” would have been had they not filled it. I have also seen some very nicely done transitions that didn’t crack and probably won’t. I prefer the “separate piece” look, just like most production aircraft.
If you are going to fill the transitions, don’t skimp on prep.
 
I have seen a number of RV's with the seams glassed over and most of them developed cracks along the seams.

All I did was to fill the tops of the pull rivets.

The only places I used platenuts and screws were the rudder bottom and wing tips. If I were to do it again, I would attach the wing tips with piano hinges, but only after determining if they were lighter.
 
10-4

Appreciate the comments. I like Bills approach of just filling in the pull fasteners. I have a couple seams though that don't fit flush and down and pillow slightly which bugs me...so gonna have to tweak the fit some more.
Gonna due the piano hinch tips as well. Already got the extra hinges.
 
I filled the seams in the H stab tips on my 6, as the original builder of the emp did a poor job. 3 years and 550 hours, no cracks. However, the seams on my 10 I did and the look respectable, so no filler. It is a professional look and doesn't detract from the plane in my opinion.

Filling pulled rivets is not easy, unless you fully cover the entire strip of rivets. You often see bleed through/imprinting around the high points and it requires 2K filler and blocking to get rid of it.

Larry
 
I glassed mine on - glassed, not filled.

I used 2 oz cloth and followed the advice of one of the original CA surfboard shapers gave to me when I built a sailplane in the 70's and feathered it in at 1 inch to the oz.

I believe the cloth layer is the secret here, rather than relying on a filler only.
 
Just as Gill said above, you need to use glass tape, not just filler.

Not necessarily true.

Stabilize the joint by bonding with a structural adhesive and setting the fasteners while wet. Scuff and fill the joint with wet micro, sand slick. Done.

That experiment went together about 12 years ago. Been flying 8 years and a fuzz under 800 now. Check it on the HBC line later this month.

Reality says there are more factors than just glass fabric or none...brittle or ductile paint, for example.

To the OP's questions. Do or don't fill the seams. Either is acceptable. Build the lower rudder fairing as a removable part; a few screws and #6 nutplates. Do not surface fill or otherwise add mass aft of the hingeline unless countered by equal added mass forward of the hingeline. That dictum is automatic for the elevators, as they are to be statically balanced after paint.
 
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Nobody will question anyone?s quality of construction when you can see it and inspect it. I will always question what I can?t see.
Who am I? Nobody.... Build the airplane YOU want.

If your going to bury your seams, make sure you know what your doing. I have seen some real messes pop up years later. Not everybody is Gil and Dan.
 
Feedback

Ok after installing a thin fiberglass strip over the rudder tip joint (fiberglass to aluminum), then applying a thin layer of 410 microlight and sanding..........

If I were to do it over. I wouldn't. I'd work with the fairing edge shape alone and get the joint fit as tight as possible to the aluminum and then be happy with that joint.

While I like my results.....I spent an enormous (too much in my opinion) amount of time sanding and applying, then sanding again, then applying small amounts , then sanding some more. But if you are anal then don't do it because you can go on and on and tweak and adjust and tweak some more ....and then more. And even then, you could do more to get it better. Always. And sometimes more and more is not better.

I like my results...but now I'm worried about one location eventually cracking over time with vibration,etc.

In my opinion it's not worth it. I watched a few 12s come in en route to Oshkoshish and they hand standard vans recommended joint seams with great paint jobs and they looked fantastic. Not at all an eye sore.

The remaining of my empennage and wing tips and all fairings will be done this way.
 
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Anxious for some additional replies on this thread. Working on this right now. Have all the fairings cleco'd in place and need to decide how best to proceed. I've decided not to glass the lower fairing on the rudder due to balance concerns.

So why am I going to do the others? After looking a RV's at OSH, I just have to. Love those clean lines. On the other hand, if poorly done....not pretty.

My questions are:

  • Glass against the skin and bridging the seam to the FRP?
  • Build up a little mirco and embed the glass into mirco and on to the FRP? (think elevator counterbalance tips)
  • How much glass (cloth) on either side of the seam?
  • How far to transition (easy on the FRP side tough to know on the aluminum side)
  • If properly prepped, will the micro adhere to the aluminum (West Systems)?
  • If using epoxy and POP rivets (as per Dan H) will West Systems 105/206 work?
 
Anxious for some additional replies on this thread. Working on this right now....
[*]How far to transition (easy on the FRP side tough to know on the aluminum side)
....
[/LIST]

As I mentioned earlier - a tip from a surfboard shaper.

Blend in at 1 inch per oz of cloth weight on a flat surface - which is basically the metal side on all of our joints.

On the molded glass side it's not critical, just blend in to the curvature.
 
My experience

Anxious for some additional replies on this thread. Working on this right now. Have all the fairings cleco'd in place and need to decide how best to proceed. I've decided not to glass the lower fairing on the rudder due to balance concerns.

So why am I going to do the others? After looking a RV's at OSH, I just have to. Love those clean lines. On the other hand, if poorly done....not pretty.

My questions are:

  • Glass against the skin and bridging the seam to the FRP?
  • Build up a little mirco and embed the glass into mirco and on to the FRP? (think elevator counterbalance tips)
  • How much glass (cloth) on either side of the seam?
  • How far to transition (easy on the FRP side tough to know on the aluminum side)
  • If properly prepped, will the micro adhere to the aluminum (West Systems)?
  • If using epoxy and POP rivets (as per Dan H) will West Systems 105/206 work?


Jayhawk Reflex,

I mixed up west systems 105/206 and brushed onto the seam a 1" glass tape (very smooth) over the seam. Worked great. Then came back 24 hrs later and mixed up another batch of epoxy with 410 microlight filler (west systems product) and applied with a credit card over the seam. Gave another 24 hrs to cure....then went to town sanding.
I recommend you sand slowly and have patience....because if not, before you know it you've sanded down too much in one area compared to another...and down to the tape. So then you apply a little more and start the iteration once again.
The most challenging part was the sanding and feathering into either the aluminum or fiberglass side. Can be done to perfection but takes a lit of time and patience in my opinion. Oh yah I used electrical tape placed 3/8" beyond the glass tape on each side of seam and used that as by boundry to mesh into the aluminum and or fiberglass.
Good luck. Actually there is no luck involved. You'll have to make your own luck. But it's possible. Maybe your method will be easier than mine.
Cheers.
 
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