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  #1  
Old 04-17-2017, 05:05 PM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 440
Default Slider C-653 cover strip (or equivalent) necessary for Sikaflex?

Hi All,

I've just finished sikaflex 295UV bonding my slider canopy and windscreen, so I'm now in the process of finalizing the planning for my fairings. I'm planning on making a one piece composite skirt around the slider, however I was wondering how people are addressing the center tube that runs from the front bow to the rear bow? Looking at the specifications for the Sikaflex 209D/N primer, it says that it should be covered with something for UV protection (odd, that for a window application they can't make a primer UV proof), so I am wondering how others are tackling this. I am leaning toward painting a stripe of West G-Flex Epoxy down it, priming with a high build two pack primer, then just top coating with my polyurethane top coat. Let me know if you think I am off base with this one.
Cheers,
Tom.
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  #2  
Old 04-17-2017, 06:08 PM
bugsy63 bugsy63 is offline
 
Join Date: May 2010
Location: Melbourne, Australia
Posts: 51
Default Slider C653 cover strip (or equivalent) necessary for Sikaflex?

G'day Tom,

I didn't put any form of strip over it, but it does live in the hangar. I was somewhat guided by the difficulty I've had in changing windows in yachts. I'm absolutely convinced that there is no greater testament to the tenacity and longevity of Sikaflex than for yacht windows to remain in the baking sun all their lives, then sail to Tassie on Boxing Day then home again, all the while having sails and fittings and crew members thumping down on them and show no signs of leaking or shifting.

As I say, if you've ever tried to change one after this treatment, you'll now what I'm talking about.

Sounds like you sorted out your canopy frame.
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  #3  
Old 04-17-2017, 08:18 PM
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Dbro172 Dbro172 is offline
 
Join Date: Apr 2012
Location: Moorhead, MN
Posts: 937
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Quote:
Originally Posted by tgmillso View Post
Hi All,

I've just finished sikaflex 295UV bonding my slider canopy and windscreen, so I'm now in the process of finalizing the planning for my fairings. I'm planning on making a one piece composite skirt around the slider, however I was wondering how people are addressing the center tube that runs from the front bow to the rear bow? Looking at the specifications for the Sikaflex 209D/N primer, it says that it should be covered with something for UV protection (odd, that for a window application they can't make a primer UV proof), so I am wondering how others are tackling this. I am leaning toward painting a stripe of West G-Flex Epoxy down it, priming with a high build two pack primer, then just top coating with my polyurethane top coat. Let me know if you think I am off base with this one.
Cheers,
Tom.
This is an interesting point that I haven't heard brought up here before. Obviously you have read the product data and pointed out that the "primer" suggests something to cover it from UV, whereas the 295UV is intended to be in direct UV... In most window applications, the sealant, mullion, sill, gasket, etc. will hide the primer from exposure to UV. However this reverse application, such as the top bow of a slider canopy, has the primer directly exposed to sunlight.

In the industry of large building curtain walls, when it comes to sealants, we talk about "adhesion" and "compatibilty". Adhesion means it sticks, compatibile means that neither dissimilar material has an adverse affect on the other, thus degrading the adhesion or service life. In order to obtain the 20 year warranty that many of these sealants offer, one must prove that the application is both compatible and will adhere, through tests. A prudent designer and contractor will also vet the application so as to make sure that the design.... does not expose the primer to UV, in this instance.

Would I be worried; probably not, but doing as you suggest, by masking off a line of paint, on the exterior of the plexi, would be the belt and suspenders approach. Care and maintenance of that paint line might be an issue, so perhaps you wait it out, and if ever there are signs of degradation, you could then put a Bandaid on it... not many RV's are hangared outside, i'd be surprised to see any bad examples out there.
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  #4  
Old 04-17-2017, 08:36 PM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
Posts: 440
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Thanks for your responses guys. I think I may skip it then, given that it will be living in a hangar and when not at home, it will have a canopy cover over it (apart from when flying of course...). Yes Michael, I finished bonding the canopy and the windscreen yesterday. This has definitely been one of the tougher parts of the build thus far. I'll put the slider frame back on the tracks today to see how the two match up, so fingers crossed. I had a friend spec out a one piece skirt layup for me. He said use one layer of 750gsm triax glass on the bottom, a layer of 500gsm carbon uni in the middle running around the entire setup (to give it hoop strength) and another layer of 750gsm triax glass on the top. Total cured layer thickness will be approximately 2mm (0.078"). Seemed a little thick, however he said this would give a good stiff skirt, and that I could taper the edges of it so that it didn't seem to protrude too much. Does this sound like overkill to you, or about on the money?
Tom.
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Old 04-18-2017, 08:32 AM
219PB 219PB is offline
 
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Location: Victoria, Tx
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I used one layer of fiberglass and two layers of carbon fiber. I did the right half and the left half separately. This was for ease of installation and to accommodate the C-679 slide rail seal that I fabricated to go over the canopy slide rail. Below is a picture of the three pieces before application. I put all three pieces together on the table, applied the epoxy and installed on the canopy at one time. More pictures are available on my website link below in the canopy section.



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  #6  
Old 04-18-2017, 05:10 PM
tgmillso tgmillso is offline
 
Join Date: Nov 2012
Location: Launceston, Tasmania, Australia
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Thanks Paul. Your layups look quite a bit thinner than I have proscribed for me. I couldn't find on your log what weight of glass and fiber you were using, so do you remember? I'm starting to think that mine may be complete overkill.
Tom.
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Old 04-19-2017, 05:55 AM
219PB 219PB is offline
 
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Location: Victoria, Tx
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I do not have the exact weights. The bag they came in is gone. Out of the two fiberglass fabrics that I was using it is he lighter one. Very silky and smooth unlike the heavy one that I have. I am sorry that it is not very precise. I know that I have my receipts from aircraft spruce, I just did not document the weights during the build. The layups are very stiff and I do not foresee any issues with it. It is way more rigid than a piece of aluminum and it fits tight to the contours of my fuselage.
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