Sliding canopy springback

[mburch]

Hey sliding canopy experts - below are a couple canopy questions I sent to Van's, along with their noncommital response. I've searched the archives but I can't find a satisfactory answer. Does anyone have any firsthand experience that they can share that might help guide me?

Date: Mon, 13 Nov 2006
From: Matt
To: Van's
Subject: RV-7 sliding canopy frame

Hi guys,

I've got the canopy frame on my RV-7 slider all fitted - I think - and I have a couple questions before I proceed:

1. I had an issue where the aftmost corner on the right side was rubbing/catching on the top skin when the canopy was slid back. I bent the right rear bow outward and it now clears the skin by a minimum of 1/16" on the right side, 1/8" on the left side. I am assuming that the spreading force of the canopy bubble will tend to increase this clearance, not diminish it, so I don't need to worry further. Is this a good assumption?

2. I got things arranged so that with the canopy tracks and slide rail screwed in place, the canopy will glide smoothly open with very light finger pressure. Then I slightly narrowed the front bow so that the rollers rub with moderate friction against the inboard faces of the tracks. My hope here is that if the plexiglass spreads it back out again, the rollers will wind up in the middle of the tracks and give smooth canopy operation. Is this worth doing or should I put it back to neutral and let things fall where they may?

thanks,
mcb

Date: Wed, 15 Nov 2006
From: Ken Scott
To: Matt
Subject: Re: RV-7 sliding canopy frame

Matt: there will be some springback when the bubble is attached to
the frame, but it is impossible to say how much on a given airplane.

thanks,
mcb
Working on the canopy, ordered the engine today!

[steveciha]

when i did the canopy of my 6a i got the rollers centered in the tracks, then i put the plexiglass on the frame. At that point, the rollers gently contacted the outside of the tracks, and the canopy became more difficult to open.

when i built my 7a i did just as you are thinking of doing. let the rollers gently contact the inside of the tracks. once the plexiglass is set on the frame it will squish down the frame and move the rollers into the center of the tracks. my 7a canopy moves much more easily than the 6a did.

steve ciha

[mburch]

Originally Posted by steveciha

when i built my 7a i did just as you are thinking of doing. let the rollers gently contact the inside of the tracks. once the plexiglass is set on the frame it will squish down the frame and move the rollers into the center of the tracks. my 7a canopy moves much more easily than the 6a did.

Great! That's exactly what I was hoping.

thanks,
mcb