Fix viterna extension bug where polar data is repeated if alpha_low = -alpha_high

Author: abhineet-gupta

pyFAST/airfoils/Polar.py

@@ -539,6 +539,8 @@ def extrapolate(self, cdmax, AR=None, cdmin=0.001, nalpha=15):
         # -90 <-> -alpha_high
         alpha5 = np.linspace(-np.pi / 2, alpha5max, nalpha)
         alpha5 = alpha5[1:]
+        if alpha_low == -alpha_high:
+            alpha5 = alpha5[:-1]
         cl5, cd5 = self.__Viterna(-alpha5, -cl_adj)
 
         # -180+alpha_high <-> -90