SonexBuilders.net

Sika Adhesive...…….Canopies

The comment about using Sika adhesive for the canopy is NOT the total answer. The RV crowd have been getting mixed results with that method. There was a "posting" on www.vansaiforce.net only a couple months ago of an RV-7 tip up canopy with a 6" long crack starting at the bottom right side and going up. This was before the airplane ever flew. The same results happened to an RV-8 last Fall on a "low time" airplane that used Sika adhesive. There were NO holes or screws in either of these canopies.

I have done 4 RV tip up canopies over the last 30 years and have never used Sika adhesive and have never had a crack on any of those canopies. I think the problem is builders do not pay enough attention to "edge finishing" of the plexi. You need to be fanatical about getting a smooth, rounded edge.....I use a "scraper" and then finish off with emery cloth (320 and then 400). Of course you want to use "plastic drills" to drill the initial holes and then up-sized with a ONE FLUTE dull step drill. This is to avoid those "spider web" cracks radiating from those attach holes......they will come back to haunt you sooner or later.

My Onex canopy turned out very well and I do not expect any surprises in the future.

Gordon...…….Hummel 2400...…..Onex

My first canopy was also bonded in place with Sika. No holes in it anywhere, no notch for the latch either. Still when went out to the shop morning after it was installed, had three cracks. Thinking I must have scratched or nicked the inside when sliding it into the lower angle that trapped it. Second canopy was Todd's, 7 years now with unheated winter storage, and some hot summer days. No sign of cracks. Cracks were about 4 - 5 inches long, stop drilled them and put that canopy in storage, also unheated, no further progression of those cracks.

David A.

Had some requests on how i did my canopy on my swingback with no cracks. Here's a video on what I intend on the B-model.

https://www.youtube.com/watch?v=W9V1-LWadqk

fastj22 wrote:Had some requests on how i did my canopy on my swingback with no cracks. Here's a video on what I intend on the B-model

Did you use any sealant in the channel to hold canopy in the slot? Thanx billy

Rofomoto wrote:

fastj22 wrote:Had some requests on how i did my canopy on my swingback with no cracks. Here's a video on what I intend on the B-model

Did you use any sealant in the channel to hold canopy in the slot? Thanx billy

I did use RTV on the A-model. I don't think I'll use anything on the B-model. Just don't think its necessary.

Did the canopy on the Super Bee today. The weather was very warm, 90+. The canopy felt rubbery compared to my old A-model.
I used a Harbor Freight oscillating tool with a cutting blade. With little force, it basically melts a cut. Worked like charm. No fear of cracking. Located and drilled the holes through the canopy upsized to 3/16 to give some room for the plexiglass to move. Then counter sunk them for the called out washers. I ran a random orbital sander over the edges with a 220 grit to take out any risers. Leaving it attached for a week before I take it all apart again to paint the frame and reassemble. Probably put a drop of thread locker into the frame with a toothpick before final assembly. They say thread locker can crack the glass, so keeping it away as best as possible.

One thing I noticed when sitting inside, between the lowered seat, the new seat angle and the bigger cockpit, I have at least 3 inches of headroom where the A-model was a tight fit with a headset.

Oh, and using the milled frames for the windshield and canopy, no porpoise nose. The lines really flow. Well done Sonex!

5 minute epoxy applied with a toothpick (just barely anything at all) works really well. No worries about the loctite gassing off and reacting with the plastic either.

Jeff