"What am I missing? "
Assigning the values to an output array via indexing.
Because you did not use indexing to assign the values to an array your code simply overwrites the previous iteration's values until the final iteration, leaving you with one data value (which is not visible when plotted as the default line has no marker).
This works and plots all of the loop results (only you can check if it is correct):
G = 6.67408e-11; % Universal Gravitational Constant
M = 5.9722e24; % Mass of the earth
R = 6371e3; % Radius of the earth(m)
A = 21*pi; % Area of the rocket
Cd = 0.4; % Drag Coefficient for the rocket
t = 0:1:4000;
h_v = 0:100:5000;
rho = nan(size(h_v)); % <--- preallocate the output array
for k = 1:numel(h_v) % <--- loop over indices, not data values
h = h_v(k);
if (h < 11000)
T = 25.05 - h.*0.00649;
p = 101.29* ((T + 273.15)./288.08)^5.256;
else
if (11000 < h) & (h< 250000)
T = -56.46;
p = 22.65* exp(1.73 - h.*0.000157);
else
if (h > 25000)
T = -131.21 + h.*0.00299;
p = 2.488*((T + 273.15)/216.6)^-11.3888;
end
end
end
rho(k) = p / (0.2869*(T + 273.15));
% ^ use indexing to assign output to an array
end
plot (h_v,rho)
xlabel('height')
ylabel('Density')
Logical indexing may be a simpler approach than using a loop.
