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airinnova / airfoils

:large_orange_diamond: Object-oriented airfoils (aerofoils) for Python
https://airfoils.readthedocs.io/
Apache License 2.0
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possible mistake in NACA 4-digit series geometry creation #2

Open jsaldia opened 3 years ago

jsaldia commented 3 years ago

it is possible that Lines 131 to 132 of airfoils.py should be changed to p = float(naca_digits[1])/10 m = float(naca_digits[0])/100 to complain with NACA 4-digit series designation

jphkun commented 3 years ago

Hi jsaldia,

I have looked into it and it looks like you were correct. I have implemented the changes in my version, but I want to discuss the results with Aaron before merging the code. If that can help I have compared the results with the ones obtained from http://www.airfoiltools.com/airfoil/naca4digit.

At the moment there is still a significant difference between the module and the website results (error of 1e-2), for extreme cases like a for the NACA9930 wing. Classical NACA profiles like the 00xx, 14xxx, 24xx and 64xx series should be precise enough to work with.

DavidAnderegg commented 3 years ago

This is probably related to this.

When i create a NACA0002 with 125 points in x-direction (cos spacing), i get this (zoomed in on the LE): is But it should look like this: should