R

rv9aviator

Well Known Member
I am struggling with understanding how to properly fit the canopy frame to the fuselage. From what I've read I am supposed to first get the lower square tubes to fit just inside the shape of the fuselage all the way from the front to be back of the tube. This makes sense so the canopy will follow the same lines and skirt will fit nicely against the outside skin. After I do this I drill a couple of holes in the tracks to locate them so the rollers will run smooth as you move the canopy back and forth. This part is done. Now am I supposed to squeeze the frame sides in 3/8 to 1/2 inch more before I attach the canopy so when it springs out the canopy will come back to somewhere close to where I had it when it worked in the tracks, or do I pull the sides in the 3/8 -1/2 inch with duck tape and simply hold it there while installing the canopy and then when I take the tape off it will spring back the same amount? I have studied other builders websites on this until I'm blue in the face. It was a nasty job getting it to fit as well as it does now and I really hate to start bending it again for fear it won't come back where it belongs.

I have another issue while I'm begging. The rear small dia. bows on the canopy are nowhere near flush with the aft skin. When I lay a straight edge on the aft skin I have about 1/16 gap at the top center but around the curved sides the bows are about 3/8 inch lower than the aft skin when you lay a stright edge on the skin. There is no way to fix this except to cut the tubes and weld in a piece of tubing and reshape the curve which will be a BIG ordeal. Any thoughts?
 
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rv9aviator said:
I am struggling with understanding how to properly fit the canopy frame to the fuselage. From what I've read I am supposed to first get the lower square tubes to fit just inside the shape of the fuselage all the way from the front to be back of the tube. This makes sense so the canopy will follow the same lines and skirt will fit nicely against the outside skin. After I do this I drill a couple of holes in the tracks to locate them so the rollers will run smooth as you move the canopy back and forth. This part is done. Now am I supposed to squeeze the frame sides in 3/8 to 1/2 inch more before I attach the canopy so when it springs out the canopy will come back to somewhere close to where I had it when it worked in the tracks, or do I pull the sides in the 3/8 -1/2 inch with duck tape and simply hold it there while installing the canopy and then when I take the tape off it will spring back the same amount? I have studied other builders websites on this until I'm blue in the face. It was a nasty job getting it to fit as well as it does now and I really hate to start bending it again for fear it won't come back where it belongs.

I have another issue while I'm begging. The rear small dia. bows on the canopy are nowhere near flush with the aft skin. When I lay a straight edge on the aft skin I have about 1/16 gap at the top center but around the curved sides the bows are about 3/8 inch lower than the aft skin when you lay a stright edge on the skin. There is no way to fix this except to cut the tubes and weld in a piece of tubing and reshape the curve which will be a BIG ordeal. Any thoughts?
Click to expand...

Not sure whether you have seen this...if not it might be helpful.
http://www.vansaircraft.com/pdf/canopy.pdf
 
Canopy

I've been working on my 7A slider for three years now. I work on it, get disgusted, then move onto something else for awhile and then come back to it. I would highly recommend cutting the rear bows. It makes it much easier to bend them and get them very close, but not perfect. I would cut it as close to the bottom weld as possible. Leave enough of the bottom bow to slip a piece of smaller tubing in to hold it when welding. You don't need much. Fill with sand and bend to your hearts content. Not a big deal with a good welder. Now the issue is the rear skirts. I'm about to go the fiberglass route. Allready have ruined four skirts. But right now I'm happy wiring and installing avionics. I can always say I intended it to be a open canopy.
 
When putting the bend in the rear skirts do this to get the proper bend.
Put the skirts on and hold them down tightly with tape. Then draw lines on them two inches apart parallel to the longitudinal axis of the plane. Remove and bend at each line over a 4 inch piece of pipe. Works perfect every time.
 
when to adjust frame width

Scott,
I am right now in the throes of fitting the slider frame, and read your "Adjusting the Frame" article in preparation. It is a real help. I found the best way to alter the profile of the tubes was with blocks and a clamp - I screwed 2 wood blocks 8 inches to a foot apart to the bench top near the edge of the bench, placed the tube I wanted to bend behind the blocks, and tightened the clamp on the tube between the blocks using the bench edge as as the other "pull" point for the clamp. One could also use a third block screwed to the bench to put the clamp against instead of the bench edge.
With this method I found I could quite precisely bend the tube as it was easy to direct the bending force to a specific point on the tube and control the force applied.
One question about your article. You suggest how to calculate the distance between the base of both the forward and rear bows, allowing for the inset for the sideskirts and the spreading that occurs when the canopy is attached (1/2" at the front bow, 1/4" at the back). But when does one apply that measurement to the frame? The article suggests that with the frame in place on the fuselage, one should check the bows (front and back), to get the front bow 1/8"-3/16" bigger than the roll bar all the way around, and 1/16"/1/8" inside the turtle deck.
But what about the narrowed measurement to allow for spreading? Is the idea to get the canopy frame perfectly bent and fitted in its final position, without the plexiglass, and not accounting for the spread, and then before installing the plexiglass, bend the base of the front and rear bows inward the required 1/2" and 1/4", so the assembly will (hopefully) spread out correctly? I think that makes sense, and that is pretty much where I am with it now, but before I screw it up....
Thanks,
Bill Brooks
Ottawa, Canada
RV-6A, fuselage in progress
 
C-GRVT said:
Is the idea to get the canopy frame perfectly bent and fitted in its final position, without the plexiglass, and not accounting for the spread, and then before installing the plexiglass, bend the base of the front and rear bows inward the required 1/2" and 1/4", so the assembly will (hopefully) spread out correctly? I think that makes sense, and that is pretty much where
Click to expand...

In a nut shell, yes.

The spreading power of the canopy is mostly concentrated near the bottom of the frame. The canopy is not really able to change the shape of the tubes.
Think of it this way, when you tip the frame up on its side and push on the base of the front bow where the roller attaches, it takes very little pressure (compared to the force required to locally change the shape of the front bow) to change the width of the frame at this point. This is what the canopy does.
So once the frame is fitting well, if you put pressure at this point to reduce the overall width by the prescribed amount, the spreading force of the canopy will return it to the original width.

Hope this helps
 
I never did...

get the canopy frame to fit perfectly on my plane, and it showed once I tried to install the skirts. No way to make the things fit. My solution was to concentrate on getting it to slide correctly, and then forming a one piece epoxy glass canopy skirt, using the aircraft as a "plug". This worked out perfectly for me, and the thing snaps shut like a refrigerator door. I'm not suggesting that you forgo proper canopy alignment, I'm just saying that with the epoxy skirt method, some small amount of irregularity in the fit will most likely not effect the final outcome. I also found out that it is just not that hard to make, and it looks great, and it don't leak!!

FWIW,
Chris
 
Thanks Scott and others

I had read the article from Van's several times and after talking to a fellow member by E-mails several times I have a clear idea on how to proceed. Thanks Todd! I'll check back after I'm finished with a progress report.
 
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