OK, Paul Dye and Danny King are replacing cracked RV-8 canopies....is there something that can be done in the build stage to prevent this in the future?
I did mention the surgical tubing "grommets" to a VERY high level Vans Aircraft un-named source a few months ago, and he smiled and said "yeah, that sounds like it might be a good way to do it".
We obviously believe in experimental, but... How often do we see certified aircraft with cracks in windscreens which are not drilled for installation...something to think about.
We obviously believe in experimental, but... How often do we see certified aircraft with cracks in windscreens which are not drilled for installation...something to think about.
Yes, but in another thread yesterday, we had a report of an RV-8 with a Sika'ed canopy (no holes drilled in it at all) that had also cracked....so it is not a panacea.
I believe the ShowPlanes canopy setup does not use a steel frame, only fiberglass. I wonder if the rate of expansion difference is better with that setup.
Plexiglass has a huge coefficient of thermal expansion (about 1/16" per linear foot per 100F), far more than steel or glass/epoxy composite. However, the difference in expansion rates should be less of a problem with an epoxy/fiberglass frame. The glass frame has a far lower modulus than a steel frame, i.e. it can stretch a little as the plexi expands. And it certainly seems to do so.
As for the standard frame and attachment, I think the most important factor is edge finishing, including the inside of the drilled holes. I swear guys, look at those holes with a 10x magnifier and you'll be jaw-on-floor at all the stress risers....and plexi won't tolerate any. A drill and a deburring tool isn't enough. I'd suggest grinding the edge break with a very fine rotary rock, and doing something to slick up the bore.
