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I did my cowl first but either order should be ok.

I did my canopy first and think its fine to do so. Just get the forward bow as high as you can and be very careful not to trim too much from the lexan forward windscreen, and you'll be fine.

Good luck,

--Noel
Sonex #1339

Is it okay to do canopy before cowl?

I wouldn't recommend that. In my opinion, to get the front of the plane looking nice I think its important to get a straight line from the cowling above the prop hub to the top of the canopy bow.

I took a piece of the canopy trimmings and applied heat from a hair dryer, in search of a way to relieve the canopy stress at the hinge and latch hook attachments. I held the 1" x 20" piece in an roughly six inch radius and applied heat with an old Conair hair dryer on high. After about 5 minutes the plexiglass was not resisting as much to the bend and took a slight set to the six inch radius.

It wasn't very scientific but proved the point that it could be changed to a new radius. Now how much did that change the specs? Will it be more brittle, more prone to cracking, less flexible? Any engineers out there who could tell us?

I then tried a higher watt heat gun and was easily able to bend the test strip to a one inch radius.

My thought is to hold the canopy tight against the frame sides with, say a 1" dowel rod and apply heat to the area directly behind the dowel rod, in an attempt to put a slight bend or at least enough heat to make that area "relax".

I know it sounds kind of risky with an expensive canopy. Perhaps someone with an old cracked canopy might be able to investigate how difficult this would be. Another reason this is called experimental.

All thoughts welcome.

Watch this, well worth your time:

http://www.eaavideo.org/video.aspx?v=1925319079001

Hi darick,
How did the heat do to the optics, still clear?

WaiexN143NM
Michael

I tried a heat gun to get my first canopy to fit better. The back of the canopy was extending beyond the turtledeck about 1/4". I tried heating is and bending it in. Unfortunately I discovered that it shrinks slightly from the heat.

The heat also removed the nice, natural, looking curvature of the canopy, and messed up the optics...I got it way too hot.

Maybe a hair dryer would be ok, but my first canopy became a hot mess. The more I tried to fix it, the worse it got.

I didn't just blindly hit one spot with the heat gun. I was careful to only heat the area for a few seconds at a time.

Thanks Jeff, I watched the video.

Michael, on the small piece I tested the optics did not change. If you are in Tucson, I may be visiting the area in the fall.

Good, the EAA really does have some nice videos.

To add to Paul's comment on the plexiglas shrinking with the heat gun, he may have experienced the heat gun removing the moisture from the plexiglas. It is well documented that plexiglas changes dimensions with changes in moisture. The changes are usually said to take a days when exposed to the natural humidity changes, but I think the heat gun can speed up the process. The change in dimension from humidity is one of the reasons the mounting holes are to be drilled oversize.

http://www.plexiglas.com/export/sites/p ... rbtion.pdf