[LettersFromFlyoverCountry]

Between the time of the original fitting -- decades ago, it seems -- of the canopy on my 7A tip-up, and now, a pretty good sized gap on the side has appeared.

It almost doesn't matter why at this point -- slightly misdrilled "ears", a different fit and riveting of the subpanel after it was originally clecoed...whatever... doesn't matter anymore. It doesn't fit that well; that's the the reality and it's time to move on.

But I'd like to close the gap appearance from the outside and I think adding some fiberglass along the side is the way to do it. So I'm looking for any advice here from people who have gone this route, what type of glass was used, number of layers etc., and any lessons you've learned from the process.

 

[Bob Kuykendall]

...But I'd like to close the gap appearance from the outside and I think adding some fiberglass along the side is the way to do it. So I'm looking for any advice here from people who have gone this route, what type of glass was used, number of layers etc., and any lessons you've learned from the process.

I'd do most of the filling with a dry epoxy/microballoons slurry, sand to contour, and then finish with a ply of 6 to 9 oz glass (7725 drapes well).

Microballoons are just that; tiny hollow glass spheres. A mix of epoxy and microballoons is what composites workers use instead of Bondo because it is lighter. You buy microballoons from Aircraft Spruce or composites supply places.

In some Vans literature, it is suggested that "Aerocil" is a brand name for glass microballoons. It is not; Aerocil is a brand name for fumed silica, sometimes known as Cabocil. That is an entirely different epoxy filler known not for lightness but for hardness and brittleness. It is used to make an epoxy paste that is thixotropic, that is, it doesn't sag or run when applied to a vertical surface. Epoxy with enough cabocil in it feels and acts just like axle grease.

Thanks, Bob K.

 

[PaulR]

Gap on sides

Bob,
I had a pretty large gap in mine also when I got back to it. I did a lot of research and found a couple really good examples and I copied them.

I laid 4 layers of glass about 3 inches wide. I started them just below the line of screws that hold the canopy to the side rails and offset the layers by about 3/16" to start the taper. I put three layers of duct tape on the sides of the fuse then a layer of packing tape on top of that. I laid this all up on both sides with the canopy closed and locked. When it cured, I ran a plastic credit card under the layup to pop it loose. I cut it to the same length as the front and rear skins so it looked like it "belonged". Then sanded and am now ready to fill and finish.

I will suggest that you use really course sand paper on the aluminum and be particularly careful about cleaning it before laying up the glass. (Don't ask)

I don't have the pictures available here at work, but I'll put them in a public folder this evening if you'd like. I think mine looks good finished this way.

I've opened and closed it a lot since doing it and it works well.

Bob, check your PM's

 

[hydroguy2]

Check with Brantel, he had a fair gap along one side if I recall correctly. He added a very nice fiberglass skirt to hide things.

 

[Snowflake]

Are you talking about a gap at the front corners of the canopy? You might want to check for cracks in the weldments at the hinges. That's what I found on my RV-6, and it turned out to be the result of extremely poor welds along these joints. A photo of one of the cracks with some more discussion is on this thread:

http://www.vansairforce.com/community/showthread.php?t=76250

Which reminds me, I should go back and post photos of the repaired frame.

 

[Bugsy]

I did 4 plys of glass and built it into a glass fairing over the top of the tipup. About 1 inch overlap. I layed 2 layers of 10 mil tape on the fuselage to creat a gap. The gap i figured would avoid any catching canopy doesnt close perfectly and i will put felt under the skirt to seal the gap when closed.