Bonding fiberglass to underside of canopy - Sikaflex

[rnbraud]

Hello all.

 

I have a question about bonding fiberglass to the underside of our canopy.

 

I came across a product called Sikaflex that the RV guys use to bond there canopies to

a metal frame. It is a two part product which consists of a Primer/UV (Sika 206) protector applied to the

canopy, and an adhesive (Sikaflex 295UV) applied to the metal frame. This is in lieu of rivets or screws.

 

I would like to bond fiberglass to the underside of the Cozy canopy material via a "wet layup". However,

this would leave it exposed to UV radiation. So I am considering laying up the fiberglass over

Sikaflex Primer 206 which has been applied to the canopy which would give me UV protection and adhesion

to the canopy.

 

My question is if anyone knows/speculates/guesses whether this will provide a good/sufficient bond

between the plexi and the fiberglass once it cures?

 

My other option is to use the canopy as a sort of mold by covering the inside with tape to form a mold release,

layup the fiberglass and let it cure. Remove the cured fiberglass, remove the tape from the canopy, apply the

Sikaflex primer 206 to the canopy, apply the 295 UV adhesive to the primer, then replace the cured fiberglass.

 

As you can see the second option is way more time consuming.

 

What are you guys thoughts?

[Lynn Erickson]

Hello all.

 

I have a question about bonding fiberglass to the underside of our canopy.

 

I came across a product called Sikaflex that the RV guys use to bond there canopies to

a metal frame. It is a two part product which consists of a Primer/UV (Sika 206) protector applied to the

canopy, and an adhesive (Sikaflex 295UV) applied to the metal frame. This is in lieu of rivets or screws.

 

I would like to bond fiberglass to the underside of the Cozy canopy material via a "wet layup". However,

this would leave it exposed to UV radiation. So I am considering laying up the fiberglass over

Sikaflex Primer 206 which has been applied to the canopy which would give me UV protection and adhesion

to the canopy.

 

My question is if anyone knows/speculates/guesses whether this will provide a good/sufficient bond

between the plexi and the fiberglass once it cures?

 

My other option is to use the canopy as a sort of mold by covering the inside with tape to form a mold release,

layup the fiberglass and let it cure. Remove the cured fiberglass, remove the tape from the canopy, apply the

Sikaflex primer 206 to the canopy, apply the 295 UV adhesive to the primer, then replace the cured fiberglass.

 

As you can see the second option is way more time consuming.

 

What are you guys thoughts?

You must be doing something that is not in the plans. what or why are you trying to bond to the underside of the canopy? that stuff is used on boat windows and is used on the RV because it is able to fill the gap between the plexi and a poorly fitted metal frame.

[rnbraud]

Hello Lynn,

 

Yes I am considering building the canopy/turtleback a little differently than standard.

 

I had a one-piece canopy blown/made that goes "on top" of the turtleback and covers all the windows.

 

This way the turtleback will be under the full length canopy. Therefore the glass that

is bonded to the canopy would be exposed to sunlight; i.e. no layups on the outside of the canopy.

 

You must be doing something that is not in the plans. what or why are you trying to bond to the underside of the canopy?

[Marc Zeitlin]

I had a one-piece canopy blown/made that goes "on top" of the turtleback and covers all the windows.

 

This way the turtleback will be under the full length canopy. Therefore the glass that

is bonded to the canopy would be exposed to sunlight; i.e. no layups on the outside of the canopy.

So, aside from making the canopy a lot heavier than stock, making it more susceptible to warping due to temperature changes like the Long-EZ canopies are, making it harder to build and making the inside glass layups visible so that it's uglier and exposed to UV, what's the purpose of doing this? Am I missing something obvious?

 

If the object is to give the rear seaters more visibility, the problem in the back isn't being able to look up - it's downward visibility through the strakes, and this does nothing to address that issue.

[rnbraud]

Hello Marc,

 

Thanks for responding.

 

First please note that I am "considering" doing this, I haven't decided yet.

 

The primary reason for considering this approach is appearance.

 

A secondary reason was ease of construction, however, this is turning out to be not the case, duh.

 

Anyway, in considering this approach one of the major problems, from my perspective, is how to best bond the canopy to the turtleback structure.

 

Later.

 

So, aside from making the canopy a lot heavier than

stock, making it more susceptible to warping due to temperature changes like the Long-EZ canopies are, making it harder to build and making the inside glass layups visible so that it's uglier and exposed to UV, what's the purpose of doing this? Am I missing something obvious?

 

If the object is to give the rear seaters more visibility, the problem in the back isn't being able to look up - it's downward visibility through the strakes, and this does nothing to address that issue.

[Lynn Erickson]

Hello Lynn,

 

Yes I am considering building the canopy/turtleback a little differently than standard.

 

I had a one-piece canopy blown/made that goes "on top" of the turtleback and covers all the windows.

 

This way the turtleback will be under the full length canopy. Therefore the glass that

is bonded to the canopy would be exposed to sunlight; i.e. no layups on the outside of the canopy.

if you are going to keep it one piece back to the windows then why have windows? just leave it all clear. if you want to block of some of the open space you can paint the under side of the canopy to look like windows ala the edge of a car windshield. you can by the dot pattern masking to paint that type of pattern. the only reason for the turtle back is because you need to fill the space between the canopy and the engine cowling or there might be a bit of a draft on the back of your neck.

[rnbraud]

Hello Lynn and Marc,

 

I think my idea may have been lost my wording.

 

If you are still interested, take a look at this pic on my website:

 

http://www.maddyhome.com/canardpages/pages/tripleseven/mycanopy.jpg

 

This is the "effect" I am trying to recreate. You can see the substructure under the canopy plexi in the photo. What I am talking about is bonding/adhereing that substructure to the inside of the canopy plexi.

 

Also, the Sika Primer 206 I mentioned is a black colored liquit and is supposed to provide real good adhesion to the plexi. The added benefit is that from the outside it looks like that coating we see on the edges of our cars windshields and windows.

 

From what I read it seems the primer provides a real good bond with the plexi, provides UV protection, and makes for a very nice looking cover under the plexi. My concern is in the bonding of a "wet layup" to this primer which is why I posted the original question.

 

Thanks for your previous comments and I look forward to any and all future comments on this.

[WileEZ]

...take a look at this pic on my website:

 

http://www.maddyhome.com/canardpages/pages/tripleseven/mycanopy.jpg

 

This is the "effect" I am trying to recreate.

Ahh that looks really nice, I like the look!

 

I'm not sure how well Sika Primer 206 will do in this case for a couple reasons:

 

How well it hold while flying, considering the pressure on the canopy.

 

The fact it's black and on fiberglass, will the heat absorption have a negative effect on the underlying fiberglass? (A major reason why so many composite airplane is painted white.)

 

This is a puzzle worth pondering, but I'm sure it's been done.

 

More research needed!

[Big Steve]

Rock:

 

You could do that using the same materials we use to make a standard canopy. would take a lot of before thought. That canopy is going to be really flimsy. My forward hinging canopy is shorter and it wiggles all over the place when it is not bolted down to the fuselage. I like the look. I think you could make it work I just dont know if it would work the way you wanted it to. My .02 STeve build on

[Lynn Erickson]

Hello Lynn and Marc,

 

I think my idea may have been lost my wording.

 

If you are still interested, take a look at this pic on my website:

 

http://www.maddyhome.com/canardpages/pages/tripleseven/mycanopy.jpg

 

This is the "effect" I am trying to recreate. You can see the substructure under the canopy plexi in the photo. What I am talking about is bonding/adhereing that substructure to the inside of the canopy plexi.

 

Also, the Sika Primer 206 I mentioned is a black colored liquit and is supposed to provide real good adhesion to the plexi. The added benefit is that from the outside it looks like that coating we see on the edges of our cars windshields and windows.

 

From what I read it seems the primer provides a real good bond with the plexi, provides UV protection, and makes for a very nice looking cover under the plexi. My concern is in the bonding of a "wet layup" to this primer which is why I posted the original question.

 

Thanks for your previous comments and I look forward to any and all future comments on this.

This is a good look. what if you bond it with epoxy that is colored with black pigment. one of the problems I see , if you still have the split between the canopy and turtledeck is that the plexi will have an exposed edge and if it gets hit with something it will start a crack that will never end. another way is to build it the plans way and paint the structure black with a tinted clear over the black to match the effect of glass over the structure.

[brainfart]

Sikaflex offers such products with different colours. It doesn't need to be black, I've seen, transparent, white and grey and many more. Give them a call or send an email and see what they recommend.

These polyurethane glues and sealants are widely used in construction, car manufacture, transportation, marine etc. One of the advantages is the flexibility. The best glue line isn't necessarily rock hard (like epoxy glues), it's sometimes better to have a somewhat flexible glue because it will take up mechanical stresses better and allow some deformation. I wouldn't call these glues/sealants inferior way to do the canopy bonding at all, whole cars are glued together using them.

 

Regarding the internal canopy structure, I wouldn't lay up wet glass on the Sikaflex unless they specifically tell you to do so. I'd rather build the structure using the canopy as a mold, then take it out and glue it back in using the Sikaflex.

 

Can't hurt to do some experiments and learn more about the canopy to epoxy bond strenght before using it on the actual plane.

[brainfart]

Oh, you already mentioned that as your second option.

It might be more time consuming, but the result should be much nicer, too, since you can take it out and work on it without endangering the canopy.

 

http://www.sikaindustry.com/ind/ipd-marine/ipd-ma-products.htm

[steve]

i have read that some have cut out and replaced our canopy in just a few hours (Evey 10 years?), will this new look be able to be replaced ?

[rnbraud]

Hello Lynn,

 

I will post a complete plan in a subsequent posting, but as to this problem, I plan to warp the aft edge of the canopy with fiberglass layups, inside and out, ala Long EZ Canopy. This should fix the problem.

 

Later.

 

This is a good look. what if you bond it with epoxy that is colored with black pigment. one of the problems I see , if you still have the split between the canopy and turtledeck is that the plexi will have an exposed edge and if it gets hit with something it will start a crack that will never end. another way is to build it the plans way and paint the structure black with a tinted clear over the black to match the effect of glass over the structure.

[rnbraud]

Yep, I got a response back from them which said the same thing. Seems while curing, the epoxy will give off chemicals which will weaken the bond with the primer. They suggest plexi, primer, adhesive, "cured" fiberglass.

 

Later.

 

Sikaflex offers such products with different colours. It doesn't need to be black, I've seen, transparent, white and grey and many more. Give them a call or send an email and see what they recommend.

These polyurethane glues and sealants are widely used in construction, car manufacture, transportation, marine etc. One of the advantages is the flexibility. The best glue line isn't necessarily rock hard (like epoxy glues), it's sometimes better to have a somewhat flexible glue because it will take up mechanical stresses better and allow some deformation. I wouldn't call these glues/sealants inferior way to do the canopy bonding at all, whole cars are glued together using them.

 

Regarding the internal canopy structure, I wouldn't lay up wet glass on the Sikaflex unless they specifically tell you to do so. I'd rather build the structure using the canopy as a mold, then take it out and glue it back in using the Sikaflex.

 

Can't hurt to do some experiments and learn more about the canopy to epoxy bond strenght before using it on the actual plane.

[rnbraud]

i have read that some have cut out and replaced our canopy in just a few hours (Evey 10 years?), will this new look be able to be replaced ?

I would think it would be no more difficult then current design. Further, check back with my new approach based on the LongEZ/Rutan/Melleville roll-over approach. Then it would be very EZ.

[rnbraud]

K, here is my current plan:

 

1. Cut my "mega" canopy to match the normal Cozy canopy cut-line; i.e. the aft canted edge.

 

2. Mount canopy on fuse and jig it in place. Temporarily install temporary upper firewall piece

 

3. Stuff blue foam in the area between the canopy and the firewall.

4. Shape the foam to follow the contour of the Canopy to the firewall. Keep in mind the engine cowling shape.

 

5. Apply release tape to foam, mask off canopy plexi, and apply normal turtleback layups on foam area only. Let cure.

 

6. Add multi-layer (# TBD) layup to aft edge of canopy on the exterior about 2"-3" wide ala Long-EZ canopy.

 

6. Proceed with normal Cozy Canopy construction for foam and outer layups.

 

7. Build jig to hold the Canopy and fixed mini-turtleback shell in place. Remove from fuse and flip over.

 

8. Apply 1-inch strips of normal turtleback foam to the inside of the rear/fixed mini-turtleback and apply normal plys to the inside of the mini-turtleback.

 

9. Proceed with normal Cozy Canopy construction for the interior fiberglass layups.

 

10. Add multi-layer (# TBD) layup to the aft edge of canopy on the interior about 2"-3" wide ala Long-EZ canopy.

 

11. Build-up normal Cozy drip-rail attached to mini-turtleback.

 

Next steps may occur here or after installing Front Hinged Canopy hardware and seeing how rigid the canopy is.

 

If canopy is sufficiently rigid, the following will be done.

12. Add roll-over structure in a similar fashion as detailed in the Long-EZ/Rutan/Melville instructions. The sub-structure will resemble Dennis Passey's design which I call the "T-Top" structure. Kids, if you don't know what a T-Top is, Google "Smokey and the Bandit"!. The primary benefit of this approach is that the roll-over sub-structure is not bonded to the plexi,

but is a seperated from it by about 1/8"-1/4" away from the plexi; i.e. not touching.

 

If the canopy is not rigid enough, then the following will be done.

12. Build up roll-over structure as in Long-EZ/Rutan/Melville instructions, except no separation from the canopy. Not bonded. Let cure and remove.

 

13. Trace outline of roll-over structure to inside of canopy and apply Sika-Flex primer where the roll-over structure will touch the plexi

according to application guidelines. Either White or Black, not sure.

 

14.Bond roll-over structure to canopy with Sika-Flex 295 UV adhesive.

 

15. Connect roll-over structure to canopy edge layups and possibly incorporate Long-EZ/Rutan/Melville roll-over attachments to seatback and longerons.

 

I will update the list as this progresses.

[emteeoh]

Ya know, I'm sure this will look pretty cool from the outside, but I wonder how good it will look from the back seat...