AntiGravity
Well Known Member
Hi Guys, this issue has been mulling around in my brain for several days and I'd like some advice on how best to proceed. I'm building a Tom Clark fastback and have a Todd canopy for it. I',m part way through the fitting of the canopy and have the following issue. Please bear with my somewhat rembling description.
The curve of the canopy does not match the modified canopy frame at the rear. The photo is looking up at the edge of the canopy from underneath. The canopy itself is also a little short in height as it sits. I need to push the canopy in to match the frame. In doing so the bottom edge also gets moved downwards to give me the correct fitting along the bottom tube (at the moment it is ?" short of teh required distance). The gap you are looking at is approximately 7/8" between the canopy and the frame. The garden hose spacer for the sikaflex is a fraction over 1/8". So I need to close the gap by ?" or so. This is easy to do with moderate pressure from thumb and one finger, so it doesn't take much.
I am concerned that squeezing the canopy this way might cause issues. Such as, perhaps, the sikaflex bond failing some time into the future, or stresses being setup in the canopy that causes other issues. My initial plan would be to clamp the gap against some 1/8" spacers (which I would fabricate). I would rivet through the spacers *and* sikaflex between the spacers, but just in the affected area on each side of the canopy. Once dry, sika around the spacers if necessary. To my mind, this would aleviate the issue of the bond failing in the future, though perhaps not the 'other stresses' issue.
Problem is, if this is not a suitable way forward then I either need to get a better fitting canopy or modify the canopy frame again. The current modified frame took considerable work and pretty closely matches the lines of the fuselage bulkhead upper; it is the canopy that does't match. This canopy fitting has caused considerable work and many issues, this just being the latest. Hence why progress and motivation are at an all time low at the moment :-(
EDIT: note that this only occurs on each side at the rear of the canopy and is around 8" long, tapering from ok near the bottom edge to 7/8" in the 'middle' of the upsweep to ok again at the top rear. The photo is the left hand side looking up. The front of the canopy still needs trimming some more to bring it down further to meet the frame at the front.
Thoughts?
Picture:
![](/proxy.php?image=http%3A%2F%2Fimg142.imageshack.us%2Fimg142%2F1976%2Fdsc00025mk2.th.jpg&hash=61f7c13f65446716e32ad895fa834bef)
The curve of the canopy does not match the modified canopy frame at the rear. The photo is looking up at the edge of the canopy from underneath. The canopy itself is also a little short in height as it sits. I need to push the canopy in to match the frame. In doing so the bottom edge also gets moved downwards to give me the correct fitting along the bottom tube (at the moment it is ?" short of teh required distance). The gap you are looking at is approximately 7/8" between the canopy and the frame. The garden hose spacer for the sikaflex is a fraction over 1/8". So I need to close the gap by ?" or so. This is easy to do with moderate pressure from thumb and one finger, so it doesn't take much.
I am concerned that squeezing the canopy this way might cause issues. Such as, perhaps, the sikaflex bond failing some time into the future, or stresses being setup in the canopy that causes other issues. My initial plan would be to clamp the gap against some 1/8" spacers (which I would fabricate). I would rivet through the spacers *and* sikaflex between the spacers, but just in the affected area on each side of the canopy. Once dry, sika around the spacers if necessary. To my mind, this would aleviate the issue of the bond failing in the future, though perhaps not the 'other stresses' issue.
Problem is, if this is not a suitable way forward then I either need to get a better fitting canopy or modify the canopy frame again. The current modified frame took considerable work and pretty closely matches the lines of the fuselage bulkhead upper; it is the canopy that does't match. This canopy fitting has caused considerable work and many issues, this just being the latest. Hence why progress and motivation are at an all time low at the moment :-(
EDIT: note that this only occurs on each side at the rear of the canopy and is around 8" long, tapering from ok near the bottom edge to 7/8" in the 'middle' of the upsweep to ok again at the top rear. The photo is the left hand side looking up. The front of the canopy still needs trimming some more to bring it down further to meet the frame at the front.
Thoughts?
Picture:
![](/proxy.php?image=http%3A%2F%2Fimg142.imageshack.us%2Fimg142%2F1976%2Fdsc00025mk2.th.jpg&hash=61f7c13f65446716e32ad895fa834bef)
Last edited: