WingedFrog

WingedFrog

Well Known Member
After trimming the end of the fiber arm of the canopy, I had the misfortune to have a different result on right and left side due to a slight difference in positioning of the trimming template. The right side shows a gap of about 1/8 of an inch through which you see the cavity that is behind the arm (see:http://4.bp.blogspot.com/-lVbvXqkvkLI/T6GO2PCf2WI/AAAAAAAAAvc/8Kuq4cRoHsk/s1600/right1.jpg . The left side covers the cavity completely without any gap (see:http://3.bp.blogspot.com/-t5xSUNn0bFo/T6GOXc3T2UI/AAAAAAAAAvM/uiJyg3phdoI/s1600/left1.jpg
I just visited a friend who built his -12 and his trimming shows the gap on both sides. I am curious to hear from the builders about this mystery.
Interestingly, there is no guidance in VAN's instructions on this matter (unless I missed it).:confused:
More pictures are available on my builder's blog.
 
Good News Bad News!

After trimming the end of the fiber arm of the canopy, I had the misfortune to have a different result on right and left side due to a slight difference in positioning of the trimming template. The right side shows a gap of about 1/8 of an inch through which you see the cavity that is behind the arm (see:http://4.bp.blogspot.com/-lVbvXqkvkL...600/right1.jpg . The left side covers the cavity completely without any gap (see:http://3.bp.blogspot.com/-t5xSUNn0bF...1600/left1.jpg
I just visited a friend who built his -12 and his trimming shows the gap on both sides. I am curious to hear from the builders about this mystery.
Interestingly, there is no guidance in VAN's instructions on this matter (unless I missed it).
Click to expand...
Ok, the good news is after your final trim so that when you open the canopy it doesn't hit anything the cavity is not completely covered at the very front. You can see on the link below when you have your canopy open that if not trimmed back enough the edge of the canopy will bind against the glare shield, see those scratches.:mad:Thats the way Vans designed it. :rolleyes: See this thread link for final pictures of my finished canopy before paint was sprayed.
http://www.vansairforce.com/community/showthread.php?t=68154&highlight=canopy
Also you need to trim the top part of the canopy where the first 100 degree angle is moving from front top to rear so that you can remove the screw that is just hidden on my second picture on the thread link. Look for it along the top edge, the screw head is half way covered. I had to trim mine back after I took the Picture.:) Both screws on both sides needs to be exposed. That way if you need to remove the glare shield you can take out all the screws without removing the canopy.;)
The bad news is from your pictures you may need to rebuild that edge up with some fiberglass and flox about one inch in front of that screw on the right side. I would trim both sides slowly down according to my pictures on the link before adding to the edge. After trimming it maybe so close that you may not have to worry about it. I cant tell you how many times I sanded and then reinstalled my canopy then removed it and sanded again untill I got to the final Picture you can see on the thread.:mad: Because the directions are not perfect these things happen and sometimes its trial and error when building. When you reach another question mark in the directions go to somebody's online log and look how he did it.:rolleyes:Hey, Just wait till you get to Skyview. Remember building an airplane is and adventure.;) Good Luck!
 
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WingedFrog said:
After trimming the end of the fiber arm of the canopy, I had the misfortune to have a different result on right and left side due to a slight difference in positioning of the trimming template. The right side shows a gap of about 1/8 of an inch through which you see the cavity that is behind the arm (see:http://4.bp.blogspot.com/-lVbvXqkvkLI/T6GO2PCf2WI/AAAAAAAAAvc/8Kuq4cRoHsk/s1600/right1.jpg . The left side covers the cavity completely without any gap (see:http://3.bp.blogspot.com/-t5xSUNn0bFo/T6GOXc3T2UI/AAAAAAAAAvM/uiJyg3phdoI/s1600/left1.jpg
I just visited a friend who built his -12 and his trimming shows the gap on both sides. I am curious to hear from the builders about this mystery.
Interestingly, there is no guidance in VAN's instructions on this matter (unless I missed it).:confused:
More pictures are available on my builder's blog.
Click to expand...

Jean-Pierre,

You will need to trim a bunch more so there is no interference. Yes, You will end up with some gaps. And, as mentioned, you want access to all of the deck screws without having to remove the canopy. See my blog,

http://www.martysrv12.blogspot.com/2009_06_01_archive.html

After trimming you may have to build up the area on the backside just forward of the right bolt.
 
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Thanks, Marty and John always helpful as usual. I should have looked at the blogs first, this bad feeling of messing my trimming got me lazy, I guess!;)
 
WingedFrog said:
Thanks, Marty and John always helpful as usual. I should have looked at the blogs first, this bad feeling of messing my trimming got me lazy, I guess!;)
Click to expand...

And be very careful when opening the canopy the first time. Is easy to crack the fiberglass if there is an interference.
 
Investigation result

After reviewing builders sites, I have saved a collection of pictures of the different trimmings found for the canopy's fiber around the pivot bolt. See:
http://vieilleburette.blogspot.com/2012/05/canopy-fiber-trimming-continued.html
My conclusion is that there is a great variation, mostly due to the lack of guidance and clear picture in the documentation. This does not seem to be a problem, though and this additional freedom allows to correct errors more easily.
 
2 cents worth

I too had the same dilemma and went searching for pictures to see how the pivot area was trimmed to avoid damage. Glad to see the collection of photos for guidance. Those are helpful! :D
 
Hold the washers

From the first time I lifted the canopy on its hinges I have had issues with this part of the aircraft. The variety of end results shown in the photos bear this out. My canopy is still not sitting snug when it?s down, and the forward gap is one of the few ugly places on the airframe. IMHO this is one place where Vans designers seemed to give up before they properly sorted out the geometry.
My advice is to not paint the canopy frame till you are totally satisfied with the fit. If needed, flare the bottom fwd edge of the frame by grinding away material inside, and add more resin/cloth layers. You don?t want to solve this problem by simply adding more washers ? you will just create a bigger rainwater entry pathway.
Why the lower front end of the arm is not radiused, and the side skin changed to a matching curve instead of a square cut out, I cannot fathom. But that would mean a change in the pattern for the side skin.
Maybe those clever blokes producing streamline fairings could come up with a neat little piece to fill the gap here.
Rod
 
No fat cheaks!

Pics 4, 6, & 7 are not of finished canopies. Those will bind when the canopy is opened. This is one thing you really want to spend some time working on. If you make the canopy wide enough to slip over the front glare shield skin when you open it then it looks like chipmunk cheaks. To really make it look good then you need to sand the outside down to blend it in with the curve of the fuselage. Kind of like the first pic. Like the yellow one.
 
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