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BillSchlatterer

Well Known Member
Sponsor
I'm wondering what those that glassed over cowl rivet lines used and how much of the cowl rivet lines did you really cover?

It seems to me that you can cover all the way out to the hinge edges and then fight getting the edge straight again or just barely cover the rivet line and maybe you won't get a line that shows where the glass lays between the rivet line and the edge?

I have some 1.8 oz glass and I was considering going not quite to the edge and then just fill and sand lightly with one layer of the light glass. I really don't want to mess with the edges again as they are just about right but I don't want to have a bump where the rivet line is covered?

Any thoughts, comments, help from those that covered them would be appreciated.

Then again, the rivet lines are very flush and the hinges are glued in and shouldn't move so is it really worth the trouble?

Thanks Bill S
7a Finishing


PS. Pondering is what passes for thinking in Arkansas,... just happens a little slower :)
 
BillSchlatterer said:
Then again, the rivet lines are very flush and the hinges are glued in and shouldn't move so is it really worth the trouble?
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No, it's not worth the trouble.
The prepreg. material your cowl is made of is very hard and stiff.
As long as your cowl is installed without any preload on the hinges they will hold up great...even if you hadn't bonded them to the cowl.
 
rvbuilder2002 said:
No, it's not worth the trouble.
The prepreg. material your cowl is made of is very hard and stiff.
As long as your cowl is installed without any preload on the hinges they will hold up great...even if you hadn't bonded them to the cowl.
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I agree - you are meant to see the rivets on an RV and marvel at their flushness:)

Seriously though it will just add weight, work and expense for no real benefit. Light and simple is the Van's way.

Jim Sharkey
 
Assuming the rivet heads are flush or just a fuzz below the surface, one or two wipes along the rivet line with epoxy and a squeegee (no glass fabric) will flush and seal it nicely. Just block sand it flat, then start your weave fill and paint prep.
 
Glassing rivets

I might get some VAF bashing, but yes I put a fiberglass strip over the rivets. I never even heard of this until I talked to a multiple Lancair builder. I think it was 10 plus Lancairs. Of course they use carbon fiber. A little out of my budget. I used 5.6 oz 2 inch fiberglass tape and trimmed it to 1 1/2 inches. I positioned the tape about 1/8 to 1/4 inch to the edge of the cowling. I then sanded, filled and feathered the edges of the tape. I also covered the rivets on the wheel pants and gear fairings. I didn't take much time at all. Most of the smoking rivets I have seen on RV's have been from the fiberglass areas.
 
The bottom rear two hinge installations were inadequate

rvbuilder2002 said:
No, it's not worth the trouble.
The prepreg. material your cowl is made of is very hard and stiff.
As long as your cowl is installed without any preload on the hinges they will hold up great...even if you hadn't bonded them to the cowl.
Click to expand...

The two bottom hinge installations popped rivet heads after some flight time was accumulated. Went to next size larger dia rivets and they started "working" also. I came up with another installation using screws. Had I covered the heads with fiberglass it would have been difficult to detect the failure and to drill them out in the traditional way.

Bob Axsom
 
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two ways to do this, you can sqeeze the rivets the normal way, than take a grinding burr and grind it in just a smidge and than put filler over the top. Or you can take the hole for the rivet and pt a taper cut with a cutter and let the rivet set in just a smidge, now comes the tricky part, how to set the rivet with it set in just a we bit, simple, take your revit sqeezer and put a flat die on one side and take a dimple die for the #8 screw and put that on the side for the rivet head, very carefully sqeeze the rivet, with flat die twards the back of the rivet and the nobed die for the dimple die set on the rivet head. Walla you have an incased rivet.
 
Bob Axsom said:
The two bottom hinge installations popped rivet heads after some flight time was accumulated. Went to next size larger dia rivets and they started "working" also. I came up with another installation using screws. Had I covered the heads with fiberglass it would have been difficult to detect the failure and to drill them out in the traditional way.

Bob Axsom
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Which cowl do you have Bob...the gel coated Polyester one or the epoxy one?
 
Although I have a tail dragger without the nose gear slot in the cowl I was still planning to add some extra mechanical fastening on the inboard ends of the lower cowl hinges to prevent them "peeling" due to flex, vibration and buffeting there. They are the only open edges on the cowl to bulkhead joints so they pick up peel loads. The rest of the joint is mainly in shear which is much easier for 3/32 rivets in fiberglass to react.

Does anyone have pictures of how they fastened this area?

(btw - Fiber glassing or filling over the rivet heads is for cosmetic reasons only and probably hinders detection of structural problems in the long run - just my 2 cents.)

Jim Sharkey
 
jsharkey said:
Although I have a tail dragger without the nose gear slot in the cowl I was still planning to add some extra mechanical fastening on the inboard ends of the lower cowl hinges to prevent them "peeling" due to flex, vibration and buffeting there. They are the only open edges on the cowl to bulkhead joints so they pick up peel loads. The rest of the joint is mainly in shear which is much easier for 3/32 rivets in fiberglass to react.

Does anyone have pictures of how they fastened this area?

(btw - Fiber glassing or filling over the rivet heads is for cosmetic reasons only and probably hinders detection of structural problems in the long run - just my 2 cents.)

Jim Sharkey
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You could say the same about painting your airframe, cosmetic reasons, hinders detection of structural problems, point is it's your aircraft, if you want to hide them go for it. I believe in seeing rivets in an aluminum airframe but fiberglass is different. I've never seen a rivet in a Lancair or a Corvette. I chose to hide the rivets in all the fiberglass parts but have seen many RV's with them exposed and they looked fine.
 
Plan A is the "easy way" with an option later :)

Man, just the "counsel" I was looking for. I think maybe I wanted someone to talk me out of it,... at least for now. Great advice on both sides so I think I'll do the easy thing but leave the option open for later. ;)

I had already planned to fly it one season before painting and now I think I'll save the 20-30 hours, flush them up and epoxy and prime and see if it seems important this time next year. If it does, it's not too late and if not,.... well, it puts me a lot closer to flying.

It seems like there is an almost unlimited amount of "things" which are on the bubble, add lots of time, and then in the end, might not matter.

Gotta get this thing in the air, it's killing me just looking at it being "almost" there!

Thanks for the help

Bill S
7a Ark
 
It is Not Gel Coated

rvbuilder2002 said:
Which cowl do you have Bob...the gel coated Polyester one or the epoxy one?
Click to expand...

It was the "new" (when I ordered my finish kit in the late 1990s) non gel coated cowl. I do not know the actual materials it is constructed from but it has a honeycomb core except at the edges. Mel replied when I was working through this problem that it is a common problem which I assume he experienced also. His kit is older so it must be a gel coated version from earlier times.

Bob Axsom
 
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