Best canopy method poll
 

I'm seeing a lot of stories about cracked canopies and as I'm about to decide which route, it would be really helpful to anyone at this point to get a better idea of the best way to install a long lasting crack resistant canopy.

Please note how long your crack free canopy has been in service. Thanks

You might want to see this old thread
 

http://www.vansairforce.com/communit...opy+crack+poll

I did this poll a long, long time ago. It asks a different question than you, aiming more at when one is likely to get a crack vs. what method will reduce that likelihood. What I found though was that if you make it through the build without cracking, your likelihood of having a crack goes way, way down. Also, this was before the period in which sikaflex was being widely used, suggesting that Van's recommended method works pretty well.

Long and short, I wouldn't stress about it too much.

Ugh
 

Ugh "Long and short, I wouldn't stress about it too much."

Bad Pun. I am really interested in results of poll.

Riveted the canopy as per plans over 25 years ago. No cracks as yet.

Thanks guys. And the best summary / source so far is here: http://www.matronics.com/wiki/index....ng_Your_Canopy
Thanks to Rob Prior for compiling all that info!
I think I'm getting a better handle on the basics now.

My plans called for screws and nuts, no rivets installed.

Rivets with no cracks approaching 12 years, 1000+ hours.

Sikaflex, 10 years, 500 hours, no cracks, solid as a rock.

Hit the wrong button. Sikaflex and no cracks. 400 hours

Sika
 

400 hrs, 5yrs no cracks.

Twelve years and 2150 hours on rivets before it cracked on a 75-degree day. New canopy installed with Sikaflex. I'll let you know how that turns out.

Riveted tip-up canopy built per plans and no crack after 10 years.

I did all the canopy work during a hot and humid New England summer, made sure it fitted well with no forcing needed, drilled oversized holes per the plans and used the special bits recommended to avoid any micro cracks that could grow into future cracks under thermal and mechanical load cycling.

Now I have probably gone and jinxed it :)

Jim Sharkey

I live in North Dakota where the temps can swing 130 degrees between winter and summer. I chose to go with the sikaflex bond for that reason. No problems so far. And no, I don't even think about flying when it's -30.

Thanks
 

Thanks all! I hope we can keep gathering datapoints on this -

Of those responding:

11% of those using Sikaflex got cracks
19% of those using rivets got cracks.

Still a fairly small sample, but very useful. The comments are helpful too, thanks!

RV8. Proseal and screws. 15 years, 1500 hours, -20 F. to 110 F. NO CRACKS

5% for Sikaflex
 

I believe it's 5% for Sikaflex since Olyolson and Cjammes mistakenly clicked on Silaflex cracked. See posts 9 & 11.

Both - Sika front 2/3rds, rivets rear 1/3rd
 

I did both.

Tip up canopy was Sikaflexed, no cracks, 1150 hours in 8 years.

Area over baggage compartment (RV7) was srewed as per plans. Cracked the first winter, crack emanated from a screw and propagated 3 inches or so. I've seen several other RVs that had a crack in exactly the same place, leading me to conclude that this crack might be less builder related and more internal stress related. Wish I had sikaflexed my rear canopy.

What type of rivets did you use?

The plans recommend screws in the roll bar and screws/washers/nuts around the aft perimeter.

Wish I could vote seven times
Built seven different RVs using Sika only. Not one crack yet

Sikaflex
 

Not in service. Maybe four months.
Personally, I believe cracks propagate from stress risers and polishing edges and holes helps prevent but I'm no Engineer nor did I stay at Holiday Inn. Check my blog for a write up on Sika.

My mistake, meant to say screws as per plans. It's been awhile.

Sikaflex on my RV-7 slider. First flight in 2009 and 1400 hours.

Sikaflex on my RV-14 tip-up. First flight will be on Tuesday.

Not going to tempt fate by responding to this pole:)

Oblong holes
 

RV-3B, tip-over
10 years no cracks.
Rivets
Note that rather than drilling the holes oversize I expanded them fore-aft to allow for thermal expansion/contraction against the alum frame.

Finn

The aluminum frame is a big plus...coefficient of thermal expansion closer to plexiglass, as compared to steel.

Best method? Compared to steel or aluminum, best to bond acrylic into a glass/epoxy frame, preferably one with the fibers at +- 45 to the plexi edge ;)