Dear Matlab users,
I am currently writing a code to output air temperature, pressure, and density based on the geometric altitude of an aircraft. The code is below.
What I would like to focus your attention on is my "if" statements. Basically, I have a table of values and equations in front of me which can calculate temperature/pressure/density in specific altitude ranges. What I tried doing in the code is telling the computer that if my altitude (Z) is in a particular range, then execute this formula and assign this value to, say, temperature. However, my first problem is I get a squiggly red line underneath each "Z" value for temperature "if" statements saying "Variable Z might be set by a non-scalar operator", and also the code skips all if statements and only executes the last "if" statement for temperature even if Z is not in that range of the last "if" statement!
Some help/advice would be VASTLY appreciated!
CODE --> matlab%% Comments
% Chapter 1, question 1.5 of "Mechanics of Flight
% H=geometric altitude
% Z=geopotential altitude
% T=temperature
% p=pressure
% rho=air density
%% Input H
H=input('Geometric altitude is: ');
%% Calculating Z
RE=6356766;
Z=(RE*H)./(RE+H);
%% Calculating temperature
if 0<= Z <=11000
T=288.150-0.0065*(Z-0);
end
if 11000<= Z <=20000
T=216.650;
end
if 20000<= Z <=32000
T=216.650+0.0010*(Z-20000);
end
if 32000<= Z <=47000
T=228.650+0.0028*(Z-32000);
end
if 47000<= Z <=52000
T=270.650;
end
if 52000<= Z <=61000
T=270.650-0.0020*(Z-52000);
end
if 61000<= Z <=79000
T=252.650-0.0040*(Z-61000);
end
if 79000<= Z <=90000
T=180.650;
end
if Z>90000
error('Geopotential altitude out of range (max=90000m), please try a lower altitude');
end
%% Calculating pressure
p0=101325;
p1=22632.04912;
p2=5474.881674;
p3=868.0168756;
p4=110.9059745;
p5=59.00074835;
p6=18.21000498;
p7=1.037706534;
if 0<= Z <=11000
p=p0*((288.150-0.0065*(Z-0))/288.150)^(-9.806645/(287.0528*-0.0065));
end
if 11000<= Z <=20000
p=p1*exp(-(9.806645*(Z-11000))/(287.0528*216.650));
end
if 20000<= Z <=32000
p=p2*((216.650+0.0010*(Z-20000))/216.650)^(-9.806645/(287.0528*0.0010));
end
if 32000<= Z <=47000
p=p3*((228.650+0.0028*(Z-32000))/228.650)^(-9.806645/(287.0528*0.0028));
end
if 47000<= Z <=52000
p=p4*exp(-(9.806645*(Z-47000))/(287.0528*270.650));
end
if 52000<= Z <=61000
p=p5*((270.650-0.0020*(Z-52000))/270.650)^(-9.806645/(287.0528*-0.0020));
end
if 61000<= Z <=79000
p=p6*((252.650-0.0040*(Z-61000))/252.650)^(-9.806645/(287.0528*-0.0040));
end
if 79000<= Z <=90000
p=p7*exp(-(9.806645*(Z-79000))/(287.0528*180.650));
end
if Z>90000
error('Geopotential altitude out of range (max=90000m), please try a lower altitude');
end
%% Calculating air density
rho=p/(287.0528*T);
%% Displaying results
disp('Temperature: '); disp(T);
disp('Air pressure: '); disp(p);
disp('Air density: '); disp(rho); |
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