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I recently purchased a flying Sonex, the build quality is good but it has a two stop drilled cracks in the canopy, as I did not build this aircraft how difficult is it to replace the canopy without cracking it. I have built several RV's so have worked with perspex before and am in the process of building a B model so could ship a new canopy with my next sub kit order. My fear is that I do not want to go through this process to end up were I started, a cracked canopy.

How big are we talking here? Is it really worth it just to have a crack free canopy? I have some significant cracking caused by a bit of a mishap, but they have been reinforced and aren't getting bigger. I'm not going to change it until it needs it. I would suggest the same. I built mine pretty easily without cracking it. It is possible. But it is a lot of work. My opinion only, leave it and enjoy flying.

Paul Johnson wrote:how difficult is it to replace the canopy without cracking it. .

I was gentle with my canopy and did not crack it, so I'm not sure what it takes to actually crack it. I did do it myself, so it was often being carried gingerly on/off the fuselage with just 2 hands, meaning it was subjected to a bit of flex but never cracked. I used dull drill bits and did most of my trimming using an abrasive (scotchbrite) pad in an angle grinder to "melt" the material off. I also kept a heater under the canopy when possible to keep it warm as I worked with it.

I checked my log and it took me a little under 20 hours of work to trim, drill, and rivet/screw my canopy to the frame. Those hours do not include building the frame/latches etc for the canopy which you probably won't need to do. Using your old canopy as a template it might take you less time to get the trimming done.

Here a blog post I made for my canopy: http://www.rynoth.com/wordpress/waiex/2 ... -trimming/

Thank you for your comments, the two cracks are on the hinge side and are stable, I could remove the hinge and add aluminium strip to cover them or a more simple idea would be to cover them with a couple of stickers.

Hi Paul,

I agree with Ryan on this. With the newer "Sonplex" material that the factory now uses to create their canopies (with some "plastic" in the mix), the chances of you cracking a new canopy is less now than with the older material. It's up to you if you want to go through with it, but if you decide to, heat is your friend. Just like Ryan mentioned, if you can keep the canopy really warm (sunshine and/or heaters are your friend) that will minimize your chances of another crack.

You may have good luck if you can drill off and/or unscrew your old canopy and reuse the same frame; regardless it will take a lot of time to trim and the fit the canopy to finish the work.

Best of luck whatever you decide to do!