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dgorissen / naca

Generate 4 and 5 digit NACA airfoil sections
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Derivative Calculation Mistake #3

Closed alexandroslessis closed 2 years ago

alexandroslessis commented 4 years ago

I think there is a minus missing in the derivative calculation in line 238 (naca5) of naca.py. Without fixing, if the number of points is too large, a discontinuity appears in the max camber location.

dgorissen commented 2 years ago

Apologies I missed this somehow. Probably too long ago but still happy to take a PR if you recall the fix

alexandroslessis commented 2 years ago

I think the derivative variable dyc2_dx estimation should have a minus sign in front. Take a look at the naca 5 digit airfoil calculation here: http://airfoiltools.com/airfoil/naca5digit

Here is a screenshot of the formulae used: derivative_naca5