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Sika without fiberglass?

Noah

Noah

Well Known Member
For those who used Sika on their canopy, did you fiberglass in the front intersection or did you strictly use Sika (no glass / epoxy)? Reports are that the Sika sands nicely and is easily shaped with 120 grit sandpaper which allows for a nice fairing at the front intersection; other reports are that the canopy gets a lot stiffer after the addition of fiberglass at the front intersection.

My concern is that the stiffness might be insufficient without the glass, and also that the strength of the epoxy is significantly higher than the Sika. Any comments??
 
I did fiberglass on the front.. saw a plane that had Sika all around -- unfortunately, it didn't look good... Sika was painted over, and the paint cracked (exactly what I expected).. So I would not recommend Sika up front...
 
glass over sikaflex

Radomir;
I used sika on my canopy intending to paint over it but was concerned about what paint to use being the sika is so flexible. Should I decide to glass over the sika how many layers of cloth is recomended & how are the two properties compatable with expansion -contraction and adhesion ? thanks, Nevin
 
I was going to only sika the bow and use the tabs with rivets under epoxy on the front. I ended up using screws because the 1/8th inch bead across the bow made the canopy sit just a hair too high.

Anyway, I think epoxy is the way to go around the front. Sika will soften if painted over, so don't paint it.
 
I used fiberglass...

I did my slider using Sikaflex all around, with a custom-made fiberglass skirt. On the windshield, I Sika'd the plexiglas to the bow, and used epoxy filler and tabs to hold the plexiglass to the fuselage deck, then glassed over the epoxy to create the transition from plexiglas to deck. I didn't put any screws or rivets any where in my wind screen, and rivets only along the rear bow of my slider to hold the skirt on.
 
Sika and glass. Looks great.

Noah said:
For those who used Sika on their canopy, did you fiberglass in the front intersection or did you strictly use Sika (no glass / epoxy)? Reports are that the Sika sands nicely and is easily shaped with 120 grit sandpaper which allows for a nice fairing at the front intersection; other reports are that the canopy gets a lot stiffer after the addition of fiberglass at the front intersection.

My concern is that the stiffness might be insufficient without the glass, and also that the strength of the epoxy is significantly higher than the Sika. Any comments??
Click to expand...

On my bird, we sikaflexed the canopy and windscreen. I couldn't figure out how to eliminate the screws on the side skirts, so they are there,but no other holes in the canopy or windscreen.

Used a bead of sika to hold the windscreen in place (with clamps until it dried), then laid up fiberglass for a really clean and smooth transition.
At the rear, I put mold release on the fuselage and laid up fiberglass skirts directly onto the canopy. Very, very nice transition.

She'll be back in the air this week. Pictures to follow.
 
sika w/o fiberglass

I used the sika to form a fillet/transition from the plexi to the canopy frame. I applied superfil over this to refine and smooth the fillet.

No closeups handy, but I'm pleased with the result so far.

web.jpg
 
Sika and glass

I did most of the fillet with Sika, but added a couple of layers of thin cloth (the stuff called deck cloth) and filler for the final touch. Hopefully the cloth will prevent cracking - so far it has. Mine is a tip-up.
 
I Sikaflex'd my RV7 tip-up canopy and elected to fibreglass the front transition. Despite using Sika 295 UV, with the plexi primer it still needs to be covered and protected from UV. Additionally it is near on impossible to sand Sika to a smooth finish. Across the rear edge of my tip-up (Fwd section) I fabricated a fibreglass shroud that snugs down flush with the rear section when the canopy is closed. This covers and protects the Sikaflex beneath these areas from UV light as well as stiffening considerably the entire tip-up. Happy to post pictures if someone is interested. Also wrote an article for local Aussie Sport Aircraft Assoc magazine if anyone would like.

Cheers and happy building,

Greg
 
Tabs?

BigglesRV7A said:
Happy to post pictures if someone is interested. Also wrote an article for local Aussie Sport Aircraft Assoc magazine if anyone would like.Greg
Click to expand...
Love to see 'em!

Dakotahawk / Lostpilot - What do you mean by "tabs"??? :confused:

Dhall Polo- How will you protect the Sika from UV?
 
???Tabs???

The plans call for a couple of smallish (maybe 1/2" x 1" aluminum) tabs riveted to the forward deck and pressing down on the windscreen. These tabs then get 'glassed over when you are making the fiberglass transition from windscreen to front deck. I may have put in about 5 tabs spaced along the front lower edge of the windscreen/deck.

They don't really do anything after the glass is done - they just hold the plexiglass windscreen firmly against the front deck while you are glassing over them.

Sorry, I don't have the plans nearby to tell you where to find reference to the tabs, but if you look at the plan for the windscreen installation, there is a reference to it there, or else in the instruction manual.
 
CLIPS!

DakotaHawk said:
The plans call for a couple of smallish (maybe 1/2" x 1" aluminum) tabs riveted to the forward deck and pressing down on the windscreen. These tabs then get 'glassed over when you are making the fiberglass transition from windscreen to front deck. I may have put in about 5 tabs spaced along the front lower edge of the windscreen/deck.

They don't really do anything after the glass is done - they just hold the plexiglass windscreen firmly against the front deck while you are glassing over them.

Sorry, I don't have the plans nearby to tell you where to find reference to the tabs, but if you look at the plan for the windscreen installation, there is a reference to it there, or else in the instruction manual.
Click to expand...

I can see why I missed these. They are not in the drawings or in the instructions, except for an obscure photo on Pg. 9-19 which says: "Small clips of .040 aluminum can be used to hold the windshield in place. These are blind rvieted to the forward deck and simply buried in the fiberglass faring".

Thanks again for the feedback. Good to know about these.
 
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