NASA_atmospheric_model.m

% MATLAB script for running NASA's standard atmospheric model calculations

clear all; 

N           = 700000;       % Altitude [m]
T(1)        = 25 ;          % Temperature in C
p(1)        = 101.325;      % Sea level atmospheric pressure [kPa]
rho_h(1)    = 1.2;          % Sea level desnity [kg/m^3]

%points      = [100000, 1200000];     % Array of points in 

% Setting up things
h = 0:N-1 ;


% Main calculations loop
for t = 1:N-1
    if h(t) <= 11000
        T(t+1) =  15.04 - 0.00649.*h(t );
        p(t+1) =  101.29 .*((T(t) + 273.15) /288.08).^5.256 ;
    elseif 11000 < h(t) && h(t) <= 25000
        T(t) = -56.46 ;
        p(t+1) = 22.65.*exp(1.73-0.000157.*h(t));
    else
        T(t+1) = 131.21+0.00299.*h(t);
        p(t+1) = 2.488 .* ((T(t) + 273.15)/216.6).^-11.388 ;
    end
    rho_h(t+1) = p(t) ./(0.2869 * (T(t) + 273.15 ));
end

% Plot the variation of the temperature with altitude above the planet
figure(1)
whos
plot(T,h)
grid on
xlabel("Temperature [degC]")
ylabel("Altitude [km]")

% Plot the variation of the density with altitude above the planet
figure(2)
plot(h./1000, rho_h)
grid on
legend Density
xlabel("Density [kg/m^3]")
ylabel("Altitude [m]")

% Plot the variation of the pressure with altitude above the planet
figure(3)
whos
plot(p,h )
grid on
ylabel("pressure [kPa]")
xlabel("Altitude [km]")