A CSA article (CSA Newsletter Set/Jul-03.pdf#page=29) specifies that a (not per plans) NACA inlet diffuser needs to double the inlet area and use a 14" radius.
The inlet into the cowl measures 4x15 (60 sq. in).
Increasing the outlet
to 7x18 yields 126 sq in.
Using a 14" radius, the exit is at about 6.5" from the inlet.
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Before trimming, test fit before glassing in flanges and adding a stiffener. |
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| Trimmed off the edges, added a stiffener and a flange to seal against the firewall. |
