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Sikaflex for -14A Canopy

rockitdoc

rockitdoc

Well Known Member
Sponsor
I have found many, many threads, spoke and visited at least to one expert (thanks Larry L) regarding gluing a canopy to the frame in RV-3's, 7's and 8's using Sikaflex. After cracking my first canopy while trimming it I am going to glue mine to the frame. Fewer holes means fewer places for cracks to start. But, I have not found any discussion or descriptions of doing this to a -14. While the overall process may be 'similar' for the -14, small differences between our birds can be significant when going 'off-script'. So, does any one know of a thread or any other description of how to do this successfully on a -14?
Thanks, in advance, as usual.
S
 
Well, I don't have an answer to your specific question (a thread that use Sikaflex on a 14) but just in case you are not aware of, the canopy of a 14 comes in two pieces and very little trimming is required. I have also known of canopy that has used Sikaflex that cracked so gluing the canopy does not guarantee of not cracking.
 
Bavafa said:
Well, I don't have an answer to your specific question (a thread that use Sikaflex on a 14) but just in case you are not aware of, the canopy of a 14 comes in two pieces and very little trimming is required. I have also known of canopy that has used Sikaflex that cracked so gluing the canopy does not guarantee of not cracking.
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Thanks. It's not the trimming I am concerned about. I went up that learning curve after cracking my first canopy using the incorrect trimming method. Ugh.

But, drilling the many, many holes, polishing each one and then screwing and riveting the whole thing together gives me chills. Not the good kind. Anyway, I know, if done correctly, there are many planes out there without cracked canopies that were drilled and screwed. But, the gluing method, as long as stress risers are not introduced, which could lead to cracks, as well, seems like less risk.
 
rockitdoc said:
Thanks. It's not the trimming I am concerned about. I went up that learning curve after cracking my first canopy using the incorrect trimming method. Ugh.

But, drilling the many, many holes, polishing each one and then screwing and riveting the whole thing together gives me chills. Not the good kind. Anyway, I know, if done correctly, there are many planes out there without cracked canopies that were drilled and screwed. But, the gluing method, as long as stress risers are not introduced, which could lead to cracks, as well, seems like less risk.
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Understood. If you did end up going the drilling route, use the drill bit for plexiglass. The one that TAP plastic sells are by far the best. They don't have a numbered drill bit but they have them in 1/8 and 5/32 and they do a phenomenon job.
 
SikaFlex on RV14 canopy

rockitdoc said:
So, does any one know of a thread or any other description of how to do this successfully on a -14?
S
Click to expand...

Search for "KeithB" posts- he used Sika on a -14.

"BruceH" also has a very well-documented site, https://www.overthehills.com/RV-9A-Project/Finish-Kit/Canopy/ and his approach to the 9A is very relevant to the 14.
-Look very closely at the clamps he made (borrowed?) for the canopy rail.

Keith and Bruce are both very helpful.
 
One thing to consider, if it has not already been mentioned, is the QB fuselage has, at least, the rear window holes already drilled. I can’t remember about all of the canopy holes, and I’m not sure if that is true for the slow build fuselage.
 
MED said:
One thing to consider, if it has not already been mentioned, is the QB fuselage has, at least, the rear window holes already drilled. I can’t remember about all of the canopy holes, and I’m not sure if that is true for the slow build fuselage.
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It is true for both slow build and QB as well.
 
rockitdoc said:
But, the gluing method, as long as stress risers are not introduced, which could lead to cracks, as well, seems like less risk.
Click to expand...

Possibly, but at this point we don't really know.

Since the number of Sika installed canopies is rather low when compared to the total number of RV's that have been completed and flow, it is fully possible the crack failure ratio of Sika'ed canopies is no different than it is for ones that were fastened in a traditional manner.

Not trying to talk you out of it, just offer a broader perspective.
 
Sika for the win for me. Love the black targa strip look on the roll bar and rear canopy. Another tip I got on VAF I liked was paint the inside of aluminum in the baggage compartment with a black strip so you don't see a bunch of sealant sloppily squeezed in between the rear canopy and aluminum. It both looks better imho and I worry (a little) less about temp changes. The gap between the front and rear canopies changes noticeably between negative temps and after sitting on the ramp in 100 degree weather. There needs to be some give as the canopy and aluminum are most definitely not expanding and contracting at the same rates. No cracks yet after 200+ hours.
 
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rvbuilder2002 said:
Possibly, but at this point we don't really know.

Since the number of Sika installed canopies is rather low when compared to the total number of RV's that have been completed and flow, it is fully possible the crack failure ratio of Sika'ed canopies is no different than it is for ones that were fastened in a traditional manner.

Not trying to talk you out of it, just offer a broader perspective.
Click to expand...

Thanks Scott.
Any thoughts regarding drilling the holes slightly larger, then using rubber 'grommets' around the screws to cushion the metal to plastic contact?
 
mountainride said:
Sika for the win for me. Love the black targa strip look on the roll bar and rear canopy. Another tip I got on VAF I liked was paint the inside of aluminum in the baggage compartment with a black strip so you don't see a bunch of sealant sloppily squeezed in between the rear canopy and aluminum. It both looks better imho and I worry (a little) less about temp changes. The gap between the front and rear canopies changes noticeably between negative temps and after sitting on the ramp in 100 degree weather. There needs to be some give as the canopy and aluminum are most definitely not expanding and contracting at the same rates. No cracks yet after 200+ hours.
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Did you fill the prepunched holes in the canopy and rollbar with epox/flox before gluing on the plexi?
 
I used the screws in the aft side of the rear canopy. It is bonded with sika on the rollbar. The front canopy is bonded on the sides and aft. The forward side of the front canopy is per plans.
 
Best read the very well written Van's instructions and stay exactly 'ON-script'. I drilled and polished all the holes and it all fit nicely. I was so proud of my work I thought I would make it slightly better... I added a little dab of Lock-Tight to each screw and it looked great when I was finished! Two weeks later, 80% of the holes had tiny cracks. Heartbreaking. NO LOCK-TIGHT on the screws.

I replaced the canopy with a new one and followed the direction to the letter. Three years later exposed to extreme heat and cold, not one crack Yet....

The canopy plans on the 14 are far easier than other Van's models.
 
jdmrv7a said:
I added a little dab of Lock-Tight to each screw and it looked great when I was finished! Two weeks later, 80% of the holes had tiny cracks. Heartbreaking. NO LOCK-TIGHT on the screws.
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You are not the only one to discover this. I recall one poor fellow had to replace his twice because of residual lock-tight left in the threaded holes. Van’s may have even added a statement to Section 5 about this. NO LOCK-TIGHT!
 
Search for "KeithB" posts- he used Sika on a -14.

"BruceH" also has a very well-documented site,

Keith and Bruce are both very helpful.
Click to expand...

Thanks for the kudos.

When I assessed using Sikaflex and asked around, the biggest concern expressed to me (including by Vans) was that of going off-plans. And this is true - you will need to develop your own protocol/plans, so if you are not detail-minded, or not confident, it can be a minefield. However, pioneers have gone ahead - Bruce H is one and I leaned heavily on Bruce’s blog to create my detailed protocol (thanks, Bruce). With that caveat, I’m very happy with my Sikaflex install (now 800 hours and almost 5 years old) and will repeat on my new build without concern.
 
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