canopy moved after completed

[Tom's rv7]

Tip up canopy on rv7a
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I installed a tip up canopy and when the gas struts are not connected the fit between the rear window and the canopy is very good. When I hook up the struts the gap is larger by about 1/8 " I understand there is a lot of pressure from the struts (65 lbs. each) I am hoping when I rivet the top section of the fuselage in front of the canopy and behind the cowling, that this will improve this situation. I don't understand where the flex in the airplane is occurring to make this gap.

 

[Jamie]

Yes, riveting the skin will help a lot. There will still be some movement, however. It's just one of those things. I have seen some folks put delrin blocks on the subpanel to keep the canopy from sliding forward. Also, this is one of those nasty things that will get you. When you think you have that gap juuuuust right between the canopy frame skin and the forward fuse skin, you put those struts on and now your gap is screwed up. I damaged what I thought was a pretty good fiberglass job this way and cracked the canopy skin. Nothing a drill, some superfil/micro won't fix though.

 

[TX7A]

Canopy Movement

Tom,

One thing I learned is to try to do all the canopy fitment with the struts on...as much as you can. I riveted all the sub-panel & ribs in before doing the fitting just to make sure everything was where it was going to be and rigid. I also clecoed the forward skin into place. I am not going to trim the forward edge of the canopy skin until everything is glassed, fitted, riveted, screwed & tatooed! Then, I will trim to get the appropriate gap to the forward skin.
I'm doing a similar thing on the aft end of the plexi. I trimmed it just a "tad" long (~1/16")and once the canopy is final assembled, I will sand it down even with the centerline I have drawn on the roll bar. Then I will cut my rear window and install to match the centerline...minus 1/32".

My canopy will move forward about 3/16" when the struts are on. Where it goes...I haven't a clue. I do believe some of the strut force causes the forward bottom side of the canopy frame to "pooch-out" a little. As much as I tried to get the canopy frame flush with the side of the fuse...the dang thing now doesn't fit as good as I thought it would.

As someone said, there's one heck of alot of dynamics going on with the canopy.

Good luck.