Captain Avgas
Well Known Member
I'm interested to know if any builders have deviated from Vans specs on the canopy installation in order to reduce point stresses on the plexi caused by differential expansion between the frame/fasteners and plexi canopy.
I'm building a slider and that's what I'm particularly interested in.
I'm not interested in using Sikaflex. I've researched that extensively and I'm just not comfortable with it.
At this stage I'm inclined to attempt an improvement of the existing system using mechanical fasteners.
Personally I believe that virtually all in-service cracks initiate at drilled holes. That makes sense because the Vans fastener is approx 1/8 and the holes are only 5/32. That leaves a margin of only 1/64 in any direction for the plexi to move before it hits the fastener.
In many installations, due to very slight fabrication inaccuracies, fasteners may already be touching the plexi. Differential thermal expansion between the steel frame and the plexi canopy will therefore cause very high point stresses on the plexi, often resulting in cracks.
Has anybody tried drilling the holes in the plexi to a slightly larger size (say 3/16) and using neoprene o-rings to centralize the fastener in the hole.
Any other successful experiments out there.
I'm building a slider and that's what I'm particularly interested in.
I'm not interested in using Sikaflex. I've researched that extensively and I'm just not comfortable with it.
At this stage I'm inclined to attempt an improvement of the existing system using mechanical fasteners.
Personally I believe that virtually all in-service cracks initiate at drilled holes. That makes sense because the Vans fastener is approx 1/8 and the holes are only 5/32. That leaves a margin of only 1/64 in any direction for the plexi to move before it hits the fastener.
In many installations, due to very slight fabrication inaccuracies, fasteners may already be touching the plexi. Differential thermal expansion between the steel frame and the plexi canopy will therefore cause very high point stresses on the plexi, often resulting in cracks.
Has anybody tried drilling the holes in the plexi to a slightly larger size (say 3/16) and using neoprene o-rings to centralize the fastener in the hole.
Any other successful experiments out there.