Windshield to Canopy Fairing - RV-9A Slider

[ksouthar]

I am having difficulty with the windshield to canopy fiberglass fairing. I have partially fabricated this fairing twice now with unsatisfactory results both times.

The issue I am having is with adhesion (actually the lack of adhesion) of the epoxy to the plexiglass windshield.

I have used vinyl tape on the canopy to keep the epoxy from sticking. No problems there. The windshield is masked using the same vinyl tape, two layers thick.

The desired area on the windshield, just forward of the screws securing the windshield to the roll bar, is roughed up using 60 grit paper.

The area is then wiped with a clean dry cloth, then blasted with air to remove any remaining sanding dust.

A layer of epoxy is then applied followed by the first layer of epoxy-saturated cloth.

I allow this to cure for 48 hours.

When I check the adhesion, I find that I can lift the now-cured fiberglass from the windshield with little effort.

This is my second time around. The first time I cleaned the area with acetone before applying the epoxy and cloth. A local aircraft composites shop advised against doing that because it 'slicks up' the surface that was just roughed up. The second time around, done without the acetone, I get the same results.

I am using the ProGlass Epoxy system. Suggestions?

Brian Southard

N355RV

[painless]

Brian:

Can't hlep you regarding your adhesion trouble, other than to suggest using West System epoxy. I have used it on several occasions with no complaints.

Have you considered using an aluminim fairing? There was an article in a past RVator describing how to do it. I was able to make a quite satisfactory fairing using the method described.



I could not make the aft fairing, the one that goes over the roll bar, to my liking so I made that out of West epoxy and made it removable using stainless steel screws.

Just something to consider.


Regards,

[vlittle]

I used West Systems and had no trouble. It adheres very well to scuffed plexi.
Epoxy formulations vary by manufacturer and are subject to quality control problems.

Pay a bit more and go for West Systems. Do a trial layup on a piece of scrap sid-by-side with your ProGlass layup.

You didn't say if you were using precision measuring pumps... they are an absolute necessity. If the ratio is off, you will have problems. They can be purchased at the same place as the epoxy.

Vern Little
9A slider

[Bob Axsom]

I used EZ Poxy from Aircraft Spruce aaand had no problem but I did not conciously try to peel it off after the first layer. I'm guessing here but it seems like you saw evidence of delamination right away - I did not see any delamination from the plexiglass (or anything else). I used the slow cure (24hr) epoxy which I read had the best adhesion qualities. I did buildup around 9 layers before I started working with it. I consider this a real eye catcher so I spent a lot of time on it and it came out very well. I spent one month and two days on the windshield epoxy alone (I know many people have most of their airplane done in that amount of time). After two carefully executed tries I guess you must be very disappointed but all I can suggest is try another brand of epoxy and try again. Images of mine below.

Bob Axsom


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