function [CL CD] = LiftDragCoeff(aoa)
%
% PURPOSE: Find the coefficients of lift and drag where the angle of attack
%          (AOA) may be greater than stall for Reynolds numbers in the range
%          20k-60k.  This is table look-up with a cubic spline interpolation.  
%
%          aoa is in radians.
%
% REFERENCE: "Aerodynamic Characteristics of Seven Symmetrical Airfoil
%            Sections Through 180-Degree Angle of Attack For Use In
%            Aerodynamic Analysis of Vertical Axis Wind Turbines"
%            R.E. Sheldahl, P.C. Klimas SAND80-2114  
%
% FIRST AUTHOR: 
%
% CHANGE LOG:
%
%
% In keeping with the chart, aoa is in degrees.
%
  persistent Daoa DCL DCD;
  if( isempty(Daoa) )
      
   [num,txt,raw] = xlsread('LiftDragCurves.xls',range)
      
   for i = 2:2:length(txt)
    Re(i/2) = str2double(txt{1,i}(regexp(txt{1,i},'[0-9]')));
   end  
   Daoa = num(:,1);
   DCL = 
   
  end
  
  %Convert aoa to +/- 180 degrees.
  aoa = rem(-175