# Canopy Stress

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by mladen.k, Aug 3, 2010.

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1. Aug 3, 2010

#### Guest

Hi, does anybody know how to calculate acrylic or polycarbonate molded canopy thickness based on it's area for pressurized tandem 2 seat airplane? Pressure difference is 5psi. I'm not sure if canopy can be made from 1 piece or separate for pilot in front seat and 2nd. pilot in back seat. I understand that you can seal connection point of canopy and aircraft body with inflatable rubber seal so you can pump air inside canopy without leak, but haven't found any information in books or internet about calculating canopy area and thickness. Thanks in advance.

2. Aug 3, 2010

### orion

#### Well-Known Member

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Assuming a blown shape that can be approximated with a spherical loft, the stresses within the material can predicted using the following:

sigma = [q x r]/[2 x t]

where "q" is the pressure over the face; "r" is the approximate radius of the shape: and "t" is the thickness of the shell.

For a more precise calculation though it would be beneficial to actually build a finite element model so you can account for the actual shape and any edge fasteners or other details of shape or mounting that could introduce stress risers or concentrations.

3. Aug 3, 2010

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