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  #1  
Old 08-22-2018, 09:39 AM
sjhurlbut sjhurlbut is offline
 
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Default RV8 Fastback Canopy - hysol/sika?

About the fasten canopy to Showplanes fastback fiberglass frame. I 've used Sikaflex on 4 airplanes and really like it. Plans recommend Hysol (Loctite EA9430) but I think Sikaflex looks better when finished. Website says it compatible.

Anyone use Sikaflex (295UV) on canopy/fiberglass?
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  #2  
Old 08-22-2018, 12:36 PM
Berchmans Berchmans is offline
 
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Default Sika

I use Sika Flex for the entire canopy both windscreen and bubble on my RV8. 180 hours since first flight in 2013 without any issues. No holes drilled in any of the plexi...I should note that I have the standard Vans frame, not a fastback
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Last edited by Berchmans : 08-22-2018 at 06:41 PM.
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  #3  
Old 08-22-2018, 01:03 PM
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DanH DanH is offline
 
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Sika is a fine choice for attaching plexi to a metal frame. However, the SP fastback has an all-composite frame, in which the plexiglass is bonded to a fiberglass flange, then laminated into a sandwich with several piles of fiberglass from the outside. Use the Hysol!
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  #4  
Old 08-22-2018, 01:40 PM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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Dan,

Sika 295 UV is marketed as a plexi/lexan bonding agent for use in marine applications, with 'GRP' being the 1st substrate listed in the installation instructions.
https://www.jamestowndistributors.co...nehandbook.pdf

FWIW...
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  #5  
Old 08-22-2018, 02:34 PM
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DanH DanH is offline
 
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The issue is not Sika's adhesive strength.

The issue is Sika's cured hardness. Sika 295 is Shore A 35. 9430 is Shore D 75.

Now consider the exterior laminate plies. Use West 105 as an epoxy example, at Shore D 83.

So, if one were to bond the plexi to the GRP frame with Sika, then do the exterior glass plies with a laminating epoxy, the epoxy bond would be forced to carry almost all the operating load. Although the canopy would not blow off, the probable result would be delamination of the exterior plies from the plexiglass....after which the Sika would become the load path.
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  #6  
Old 08-22-2018, 02:48 PM
rv7charlie rv7charlie is offline
 
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Got it. Mine's a -7 tipup (obviously aluminum frame), and I just used the Sika to fair in the windshield area instead of using fiberglass. Would the -7 tipup guys have the same issue you describe, if they use 'glass to fair in the windshield?
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  #7  
Old 08-22-2018, 05:00 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by rv7charlie View Post
Got it. Mine's a -7 tipup (obviously aluminum frame), and I just used the Sika to fair in the windshield area instead of using fiberglass. Would the -7 tipup guys have the same issue you describe, if they use 'glass to fair in the windshield?
Yes.......
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Last edited by DanH : 08-22-2018 at 05:02 PM.
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  #8  
Old 08-23-2018, 09:28 AM
Scott Hersha Scott Hersha is offline
 
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I used Pro Set from the Gougeon Brothers (West System). It is a structural adhesive that is compatible with all West System epoxies - in fact it will wet out cloth if applied correctly. According the a technical expert I spoke with at West System, it was the recommended thing to use for this application. In fact he told me it is what the entire SpaceShip 1 was put together with. It has a long pot life, so you have time to work with it during assembly and it's a thickened epoxy, like G-Flex, also from West System, so it won't run out of the canopy frame/plexi joint. I built my FB as per ShowPlanes instructions and it was quite easy. You can lay up the overlying plies of fiberglass at the same time you bond the plexi since it's compatible and it makes the installation pretty seamless. Cure time is 24-48 hours depending on temp/humidity.
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  #9  
Old 08-23-2018, 09:45 AM
David Paule David Paule is offline
 
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G/flex is not recommended for acrylic.

Dave
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  #10  
Old 08-23-2018, 10:19 AM
Scott Hersha Scott Hersha is offline
 
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I didnít say to use G-Flex on the canopy, I said use Pro Set, which is recommended on plexi and has the same consistency as G-Flex, which you may be familiar with. It makes proSet easier to apply than some other west systems epoxies.
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