Plexiglass canopy view distortion radius.

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Chlomo

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So.. Everybody happy building?
As with aluminum sheet I think there may be such thing as minimum radius for a given thickness of plexiglass(let's say 4mm for example). The radius must be carefully chosen so as not to cause significant distortion in view!
I'm thinking about a semimonocoque aluminum design with filleted rectangular (almost box-like) frontal section.
When viewed head-on the ceiling should look flat except for the fillets so how much fillets should I apply?
 

Matt G.

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A picture would really help, but if I can assume you're talking about a canopy with three flat, planar sides, why not make a frame and use three separate flat pieces? This will be much easier to build, and you don't have to junk the whole thing if one panel gets damaged.
 

Sockmonkey

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A picture would really help, but if I can assume you're talking about a canopy with three flat, planar sides, why not make a frame and use three separate flat pieces? This will be much easier to build, and you don't have to junk the whole thing if one panel gets damaged.
Yep, also since a lot of WWII planes used a setup like that you can just copy whichever one suits your plane best.
 

SVSUSteve

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Evansville, Indiana
So.. Everybody happy building?
As with aluminum sheet I think there may be such thing as minimum radius for a given thickness of plexiglass(let's say 4mm for example). The radius must be carefully chosen so as not to cause significant distortion in view!
I'm thinking about a semimonocoque aluminum design with filleted rectangular (almost box-like) frontal section.
When viewed head-on the ceiling should look flat except for the fillets so how much fillets should I apply?
Just out of curiosity, how fast are you planning on going? If very fast, that thin of a piece of plexiglass may vibrate enough to be annoying especially if directly behind the prop. It could make for an uncomfortably loud cockpit.

I also support the idea of the WWII "greenhouse" canopy.
 

Chlomo

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Just out of curiosity, how fast are you planning on going? If very fast, that thin of a piece of plexiglass may vibrate enough to be annoying especially if directly behind the prop. It could make for an uncomfortably loud cockpit.I also support the idea of the WWII "greenhouse" canopy.
Umn not very fast at about 120mph. I wonder what thicknesses rvs and sonexs use
 

JamesG

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Columbus, GA and Albuquerque, NM
4mm shouldn't be that bad, unless you have a large unsupported section and get unlucky and an annoying resonance sets up in it.

But yes, you would have distortion from going from a straight to a radius-ed corner. Much better to give it constant curve all the way across/round. Like the difference between an F-4 Phantom and an F-15's windscreen.
 
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