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  #11  
Old 10-12-2018, 09:47 PM
WingRock WingRock is offline
 
Join Date: Aug 2015
Location: Davenport, IA
Posts: 16
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Quote:
Originally Posted by sjhurlbut View Post
I’ve sikaflexed all my canopies. As long as pressure is reasonable (and it will be at sides) your gap is fine. Sika flex is definitely hold it if applied correctly. I made a chin up bar with it years ago.

One thing I would recommend is a couple clecoes to prevent the canopy moving while drying as mentioned in another post. You can get away with 2-4 clecoes on entire canopy to hold it. Ensures perfect alignment. Put the clecoes near where you have a spacer so it doesn’t pull canopy in too close
Steve,
Thanks for the info. I will definitely use some clecos to prevent movement as I final trimmed my canopy to size already and can't afford movement.
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Davenport, IA
RV8 Tail and QB Wings done, deep into QB Fuse
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  #12  
Old 10-12-2018, 09:58 PM
WingRock WingRock is offline
 
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Originally Posted by cdeerinck View Post
You probably already know this, but here goes:

As you clamp the sizes, the top will try to go up. To not to honor your cut line as if it is a given. Keep readjusting the clamps until the canopy drops to contact the rollbar top and size, side rails, and back. When you do that, the pressure to squeeze it together is not very much at all.
Chuck,
Each time I clamp, I start with one at the top center of the frame to index the canopy to the same spot on the frame, then move to the back and clamp from the rear forward. I hope that this is achieving the same thing that you are describing, getting full contact all the way around to get down to the trim line.

Thanks for sharing your experience!
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RV8 Tail and QB Wings done, deep into QB Fuse
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  #13  
Old 10-13-2018, 02:53 AM
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EdH EdH is offline
 
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Location: Bristol, UK.
Posts: 176
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We had the same gap at the sides of our -8 canopy which we glued on.

Managed to do it without making holes or using clecos, just referenced centre marks at the very front and back (one clamp at the front), then clamped at the same side spots every time. The canopy settled to a natural position after that.

Also, we made a timber frame to hold the canopy while it was off the aircraft that matched the way the assembly fitted on the fuselage. The frame also had a solid back stop so the perspex ended up in the same fore/aft position each time.
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  #14  
Old 10-13-2018, 11:07 AM
SHIPCHIEF SHIPCHIEF is offline
 
Join Date: Mar 2008
Location: Seattle
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Just a warning:
I SIKA'd my RV-8 canopy, and at about 50 hours TTAF it cracked at the base of the hoop around the back. It cracked at the weld where the two side bars come together and a single tube goes aft. This seems a common crack point, on RV-4s as well.
The crack was on the left side, so maybe the pull of the canopy latch, and a local stress riser, like a weld bump touching the plexi, or a flaw in the edge of the plexi?
The crack went straight up. I used Acrilifix, but did not remove the fiberglass skirt to glue the original point, so it cracked again, and longer, nearly to the top.
To keep flying, I used a cut-off wheel and cut the canopy straight across and down to the starboard side. I did this to prevent the crack growing forward or aft, and eliminate any built in stress.
Then I made a Targa strip, put it through a sheet metal slip-rolls for a perfect fit, and SIKA'd it on. I didn't invent this, I saw it on an RV-4.
I was going to get a Todd's canopy, but he passed on just about then...and the canopy repair has kinda grown on me...
The take away here is to know about this common crack point and try to reduce the likelihood of it happening to you.
Or, failing that, to know of acceptable repairs.
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  #15  
Old 10-14-2018, 05:46 PM
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Blain Blain is offline
 
Join Date: Mar 2013
Location: El Dorado Hills, CA
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Quote:
Originally Posted by SHIPCHIEF View Post
Just a warning:
I SIKA'd my RV-8 canopy, and at about 50 hours TTAF it cracked at the base of the hoop around the back. It cracked at the weld where the two side bars come together and a single tube goes aft. This seems a common crack point, on RV-4s as well.
The crack was on the left side, so maybe the pull of the canopy latch, and a local stress riser, like a weld bump touching the plexi, or a flaw in the edge of the plexi?
The crack went straight up. I used Acrilifix, but did not remove the fiberglass skirt to glue the original point, so it cracked again, and longer, nearly to the top.
To keep flying, I used a cut-off wheel and cut the canopy straight across and down to the starboard side. I did this to prevent the crack growing forward or aft, and eliminate any built in stress.
Then I made a Targa strip, put it through a sheet metal slip-rolls for a perfect fit, and SIKA'd it on. I didn't invent this, I saw it on an RV-4.
I was going to get a Todd's canopy, but he passed on just about then...and the canopy repair has kinda grown on me...
The take away here is to know about this common crack point and try to reduce the likelihood of it happening to you.
Or, failing that, to know of acceptable repairs.
Scott, did you use spacers to allow for gap between frame and plexi?
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  #16  
Old 10-15-2018, 07:09 PM
WingRock WingRock is offline
 
Join Date: Aug 2015
Location: Davenport, IA
Posts: 16
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Thanks for chiming in Ed and Scott. A very mysterious part of the build for me. Were it not for this great forum, doing something like gluing on a canopy would be a lot of trial and error.
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RV8 Tail and QB Wings done, deep into QB Fuse
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  #17  
Old 11-02-2018, 09:11 AM
Pman Pman is offline
 
Join Date: Nov 2013
Location: Geneva, Illinois
Posts: 43
Default Spacers/crack?

Quote:
Originally Posted by SHIPCHIEF View Post
Just a warning:
I SIKA'd my RV-8 canopy, and at about 50 hours TTAF it cracked at the base of the hoop around the back. It cracked at the weld where the two side bars come together and a single tube goes aft. This seems a common crack point, on RV-4s as well.
The crack was on the left side, so maybe the pull of the canopy latch, and a local stress riser, like a weld bump touching the plexi, or a flaw in the edge of the plexi?
The crack went straight up. I used Acrilifix, but did not remove the fiberglass skirt to glue the original point, so it cracked again, and longer, nearly to the top.
To keep flying, I used a cut-off wheel and cut the canopy straight across and down to the starboard side. I did this to prevent the crack growing forward or aft, and eliminate any built in stress.
Then I made a Targa strip, put it through a sheet metal slip-rolls for a perfect fit, and SIKA'd it on. I didn't invent this, I saw it on an RV-4.
I was going to get a Todd's canopy, but he passed on just about then...and the canopy repair has kinda grown on me...
The take away here is to know about this common crack point and try to reduce the likelihood of it happening to you.
Or, failing that, to know of acceptable repairs.
Scott, hoping you might share more info regarding the crack you experienced in your RV8 canopy......, wondering if you incorporated “spacers” when gluing your canopy?

It would be helpful if you can share with us the size and type of spacers used?
Specifically for the RV8 canopy frame, the aft area of the no rivet weldment, maintaining a gap (approx. 1/8”) between the plexiglass and the frame would seem to help reduce the stress and the likehood of cracking. I’m curious to know if you used spacers and still wound up with a crack?

Thanks, Mike P
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