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Carl Bells RV7A N947CB
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Date: 4-14-2008
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Number of Hours: 5.00
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Manual Reference: Dwg 41, 42 & 42
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Brief Description: Canopy frame manipulation
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Well I'm back from Sun & Fun 08 and back in the building saddle. I have decided to take considerable time on the canopy construction for a number of reasons. I saw plenty of pretty RV’s with bad fitting canopies, especially sliders. I also saw many cracked canopies with stop drill holes. This would not be terrible if you could easily replace them, but no such luck and many don’t bother. The worst canopy I saw was on the new Rans S19. It looks like a great little plane and I have heard good thing about its flying capabilities, but they need to come up with a better canopy attachment system, it must have had 3 cracks in it, all at screw attachment points.
Ok, that bring up the next item in my canopy plan, and that is to use Sikaflex for attachment. I have read every article and builder notes on using this system, and although it is leading, perhaps even bleeding edge, it looks like the way to go. On the positive side:
1) If you get a crack which is a much lower probability because there are no holes, it can be cut off and replaced. The Sikiflex flexes and allows for the thermal expansion and contraction reducing stress between the frame and the screws.
2) It will look much cleaner and more professional
3) Builder using this system, and there are many are convinced it is far superior to screws and pop rivets.
On the downside:
1) Long term testing in this environment and application has not been documented, so far only in marine and automotive.
2) There are no mechanical fasteners on the slider other then the latch handle so if it gives way it could mean a really tough time in the air perhaps even catastrophic.
3) Vans does not like it yet because of the above, so it’s up to you.
OK, back to building. As you can see in the pictures below, you have to bend the canopy frame to match the fuselage to make for a good fit. This is not so easy, those square tubes are strong. The jig with the bottle jack will you allow to tweak the curve, just take you time and go slowly. By the way, don’t eve t
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The bending / tweeking jig showing the bottle jack and lever 2x4
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The tube I'm bending to match the fuselage side
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The template- ah finally right on
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