airshow incident

Dave Krall CFII said:
How fast will your survival knife get through that thickness of plexiglass?
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Assuming it has the right features, not long at all. The purpose is not to cut the plexiglass, but to crack it. It needs a "pointy" part (possibly on the back of the hilt); the blade is of little use. Slam it once, reposition and slam it again on one of the resulting cracks. Repeat once or twice more, and you should have a big enough hole.

It's not mass or sharpness, it's the concentration of the force that counts.

If it's Lexan, of course, you're out of luck.

Ron Wanttaja
 
I have looked closely at our canopy, and concluded that we are screwed if we end up inverted after an off-field landing. That plexi is thick, and I doubt I could generate enough force to crack it, given the limited swing possible,

Of course, one should not underestimate adrenaline.
 
There's a video out there done by a guy with a canopy that had been screwed up and couldn't be installed. He used a few different escape tools. My recollection is that the edges were not supported as they would be in a real condition but the video encouraged me to get an escape tool for my plane. A drywall saw would be good to have but where do you stop....
 
wanttaja said:
Assuming it has the right features, not long at all. The purpose is not to cut the plexiglass, but to crack it. It needs a "pointy" part (possibly on the back of the hilt); the blade is of little use. Slam it once, reposition and slam it again on one of the resulting cracks. Repeat once or twice more, and you should have a big enough hole.

It's not mass or sharpness, it's the concentration of the force that counts.

If it's Lexan, of course, you're out of luck.

Ron Wanttaja
Click to expand...

What is the difference and advantages between the two?
 
Dave Krall CFII said:
What is the difference and advantages between the two?
Click to expand...
Lexan is very resistant to cracking, unlike Plexiglass. If you're going to cut or drill Plexiglass, you need special blades and bits, but Lexan can be cut and drilled with ordinary tools.

Plexiglass resists fuel and chemicals better, and scratches and flaws can be polished out more easily, but it does tend to crack. Not a problem for well-designed installations, but it is an advantage if you're trying to break through it in an emergency.

Ron Wanttaja
 
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