not geting the plot and my loop is not working

sigma=0.047193;
    V_tip=180;
    W=180;
    Cd_avg=0.01;
    R=2.235;
    Rv=80.529;                              %rotational velocity
    A=pi*R.^2;
    rho=1.225;
                                                     
for Ct=0.004:0.0001:0.005
    Vs=-(sqrt(Ct./2)+((sigma*Cd_avg)./(8*Ct))).*(Rv*R);       %descent speed
    Cd_eq=((2*W)./(rho.*A.*(Vs).^2));                            % equivalent drag coefficient of the rotor in steady descent
end
hold on
plot(Ct,Cd_eq,'r');

Answer 1

[Mathieu NOE]

hello

consider indexing your variables

sigma=0.047193;
    V_tip=180;
    W=180;
    Cd_avg=0.01;
    R=2.235;
    Rv=80.529;                              %rotational velocity
    A=pi*R.^2;
    rho=1.225;

Ct=0.004:0.0001:0.005;
Cd_eq = zeros(1,length(Ct));

for ci = 1:length(Ct)
    Cti = Ct(ci);
    Vs=-(sqrt(Cti./2)+((sigma*Cd_avg)./(8*Cti))).*(Rv*R);       %descent speed
    Cd_eq(1,ci)=((2*W)./(rho.*A.*(Vs).^2));                            % equivalent drag coefficient of the rotor in steady descent
end
plot(Ct,Cd_eq,'r');

Answer 2

[Alan Stevens]

Needs to be as follows:

sigma=0.047193;
    V_tip=180;
    W=180;
    Cd_avg=0.01;
    R=2.235;
    Rv=80.529;                              %rotational velocity
    A=pi*R.^2;
    rho=1.225;
 Ct =  0.004:0.0001:0.005;                                                   
for i = 1:numel(Ct)
    Vs=-(sqrt(Ct(i)./2)+((sigma*Cd_avg)./(8*Ct(i)))).*(Rv*R);       %descent speed
    Cd_eq(i)=((2*W)./(rho.*A.*(Vs).^2));                            % equivalent drag coefficient of the rotor in steady descent
end
hold on
plot(Ct,Cd_eq,'r');

[Sourav singh]

sir i have a question , why did u use " i ". and why u didn't put i with Vs

[Alan Stevens]

i is a commonly used index counter, but it is arbitrary and you can use whatever you like.

You can also have Vs(i) if you wish, then all values of Vs are available at the end of the loop. However, your original code only had Cd_eq being plotted, so that was the only one I put the i into.

[Sourav singh]

thank u sir