Sikaflex Canopy

Hello,

Looking to talk with a -9 or -7 slider builder who has used Sikaflex to bond their canopy. I am ready to do it and want to compare notes and learn from their experience.

Pete
St. Paul, MN

SikaFlex

Hi
To all that are considering SikaFlex for their canopy (tip-up or slider). After doing shear testing with samples of materials (both tip-up and slider) supplied by Van's, we did some testing at Sika. If ANY of the steps are not done correctly (i.e. cleaning, surface prep, priming, application), the test scores are too low. So Van's and Sika are NOT supporting this application. Neither want ANY canopies coming off during flight for obvious reasons.

Frank

Sikaflex 295UV

Hi Pete,

I just finished bonding my canopy to the frame on my 9A slider. I followed the instructions for each of the Sika components to the letter to ensure the best bond possible. I used the Sikaflex 295UV adhesive. The 226 cleaner was used on both the powder coated frame and the plexi. The 209 primer is used only on the plexi. Both surfaces were prepared with scotch brite and cleaned per instructions. I had an application engineer at Sika verify these were the right components to use for bonding plexi to powder coated steel.

I can understand why Van's and Sika will not endorse the use of this method due to the wide variation in mechanical properties depending on preparation. 90% of bonding is in the preparation and care must be taken to ensure a good bond.

I am going to use a belt and suspenders approach by adding a mechanical attachment at the aft upper center portion of the canopy. This will allow for CTE mismatch between the steel and plexiglass (10x!). The fiberglass lip on the windscreen will be a mechanical joint and I will likely make that a little thicker than recommended. I don't see how the canopy can go anywhere using this approach. IMHO

Jim Bray
http://websites.expercraft.com/skytrash/

to resurrect an old thread, is it okay to scuff the powder coat and not actually strip or remove it down to bare metal??

By scuffing the powder coating and bonding to that, you are relying solely on the adhesion of the powder coating to the metal to secure your canopy. Sikaflex will bond extremely well when used per instructions, but be sure that the material you are bonding it to will also stay in place.

In my case I removed the powder coating from the areas I was bonding the canopy to and prepared per instructions. Testing I have seen done has broken the acrylic before breaking the sikaflex bond so I am pretty confident my canopy isn't going anywhere.

My opinion only........

Clive Whittfield

I did not remove powder coating, just sanded to get a good scuffed surface. I made a test piece bonding the plexiglas and a piece of powder coated tubing and was amazed at the bond strength.

Been flying for 2 yrs and 200+ hrs and it still looks good and hasn't left me yet. (But a few critics have told me it will)

Good luck!

A couple of questions for those who have gone before.

I understand how to provide the ~1/8" spacers at the front and rear of the canopy. What did you do on the sides of the canopy? There is not space between the WD-725 side frame and the C-603 side skin to provide the ~1/8" space on either side of the canopy. Advice?

How did you index the Canopy to the frame when you lowered in into the Sika Flex on the frame? Any tips?

Thanks for any help.

whd721 said:

A couple of questions for those who have gone before.

I understand how to provide the ~1/8" spacers at the front and rear of the canopy. What did you do on the sides of the canopy? There is not space between the WD-725 side frame and the C-603 side skin to provide the ~1/8" space on either side of the canopy. Advice?

How did you index the Canopy to the frame when you lowered in into the Sika Flex on the frame? Any tips?

Thanks for any help.

Click to expand...

Have a look at this thread. The link to a Picassa album in post #25 is a good one (the link in the first post is broken). This photo in the album may answer your question. I followed the recipe as depicted in the photos.