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-   -   Lord Adhesive vs. Weld-On Update (https://vansairforce.net/community/showthread.php?t=104739)

Aerosport1 10-08-2013 06:58 AM

I do have a small crack about 1.0" on the top of the wind shield. And it only cracked because I did sand almost all the way thru the glass cloth. I took the chance and decided not to repair it with fiberglass. It was more of a test than anything. You do not see it unless you are up on the wing. That being said if you sand thru the cloth or do not use enough glass or go without it will crack.

Geoff

Chalkie 10-10-2013 07:35 AM

Quote:

Originally Posted by Bill.Peyton (Post 814410)
I want to add that I did pull tests using the Sika adhesive. The substrate broke apart and the joint never failed In any of the test panels I created during the bonding process.

To date I know of ONE Sika glue failure of an RV-6A tip-up canopy; the builder did NOT use the Sika 209N Plexi Primer; did not even scuff the Plexi. He glued the shiny Plexi to the structure and the glue joint failed on the shiny surface. Hardly surprising. :confused:

Remember the article in Sport Aviation, 'Why do we still drill holes in Plexiglas?' I wrote that article and am glad to see that Sika has caught on with others. Initially I did not think this was a good idea in an RV-10, but now considering the problems being experienced by others, perhaps it is.

Last year, I bought an RV-10 from a friend's estate, the aircraft had 25 hours on it and had stood in the blazing sun in Botswana (semi-desert) for about a year. All windows showed signs of cracks in the paint and filler around the edges of the Plexi. The windows had been glued in with Sika 295UV. I laid up 5 layers of 160g fg cloth cut on a 45degree bias around the edges of the Plexi, to tie it to the structure. I have noticed bulging of the (flexible) filler I added between the Plexi and the lid. No cracks in the paint yet; too soon to say as I have only done another 50 hours so far.

My suggestion would be to cut and prepare all Plexi in the RV-10 'lid' and make the fit as accurate as possible to leave about a 1/8" (3 to 4 mm) gap around the perimeter. (Between Plexi and the Lid) then bond the Plexi in with Sika and do not paint over the Sika. Now when the Plexi expands or contracts, the Sika will take up the movement. The Sika can be sanded once cured to leave a smooth dull surface. If there is no paint, then it cannot crack. No fg fairing at front lower joint of windscreen, just the sanded Sika fillet.

One builder in the RSA has done this (7 years ago) and I will ask him to send some pictures to post here.

Bill.Peyton 10-10-2013 04:05 PM

The method you describe is how I had intended to install the windows. I should have stuck to my plan!


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