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Can't connect all the dots with a line

Asked by Kevin Tai on 29 Oct 2019
Latest activity Commented on by Kevin Tai on 29 Oct 2019
Hi there, still learning here. I have a small question where how do I connect all the points with a line? I can't seem to get it even after using different functions.
Any help is greatly appreaciated!
c = 0.2;
Re = 386639;
V = 27.78;
b = 0.8:0.02:1.2;
alpha_Lmax = 17.2;
alpha_Lzero = -4.3;
C_lmax = 1.508306;
C_lzero = 0.4527213;
c_d0 = 0.01188282;
rho_0 = 1.225;
rho = 1.202;
R = 287.057;
mew_0 = 1.789e-5;
mew = 1.7284e-5;
alpha = 0;
v = 1.4370e-5;
a_airfoil = C_lmax/(alpha_Lmax-alpha_Lzero);
for i = 1:length (b)
a_wing = a_airfoil/(1+(57.3*a_airfoil)/(pi*0.7*(b(i)/c)));
C_L = a_wing*(alpha-alpha_Lzero);
L = 0.5*rho*(V^2)*b(i)*c*C_L;
C_Di = (C_L^2)/(pi*0.7*(b(i)/c));
C_D = c_d0 + C_Di;
ratio = C_L/C_D;
plot (b(i),ratio,'x')
hold on
end
grid on
xlabel('Span (m)')
ylabel('CL/CD')
title('CL/CD vs Span')

  2 Comments

Rik
on 29 Oct 2019
This time I edited your question for you. Next time, please use the tools explained on this page to make your question more readable.
Oh thank you very much. There's more for me to learn here it seems cause this is my first question posted to here.

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1 Answer

Answer by Rik
on 29 Oct 2019
Edited by Rik
on 29 Oct 2019
 Accepted Answer

Store the ratio in an array:
%rest of your code
ratio=zeros(size(b));
for i=length(b)
%rest of your code
ratio(i) = C_L/C_D;
end
plot(b,ratio,'-x')

  1 Comment

Thank you very much!

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