aircraft stability in matlab

To analyze aircraft stability in Matlab, we need to create a mathematical model of the aircraft and simulate it under different conditions. The model typically includes equations for the aircraft's motion, aerodynamic forces, and control inputs.

Here's an example code snippet to simulate the stability of a simple aircraft model:

main.m
% Define aircraft parameters
mass = 1000; % kg
CD0 = 0.05; % drag coefficient
CL_alpha = 0.1; % lift coefficient
gravity = 9.81; % m/s^2
wing_area = 20; % m^2
wing_span = 10; % m
tau = 0.1; % time constant for control input

% Define initial conditions
initial_altitude = 1000; % m
initial_velocity = 50; % m/s
initial_heading = 0; % degrees
initial_pitch = 0; % degrees

% Define simulation time and time step
t_end = 100; % seconds
dt = 0.01; % seconds
t = 0:dt:t_end;

% Define control input function
delta_e = @(t) 2*deg2rad(sin(0.1*t));

% Simulate aircraft model
altitude = zeros(size(t));
velocity = zeros(size(t));
heading = zeros(size(t));
pitch = zeros(size(t));
altitude(1) = initial_altitude;
velocity(1) = initial_velocity;
heading(1) = deg2rad(initial_heading);
pitch(1) = deg2rad(initial_pitch);
for i = 2:length(t)
    % Compute aerodynamic forces
    lift = 0.5*CL_alpha*wing_area*velocity(i-1)^2;
    drag = 0.5*CD0*wing_area*velocity(i-1)^2;
    
    % Compute gravitational force
    weight = mass*gravity;
    
    % Compute control input
    delta_e_i = delta_e(t(i-1));
    delta_theta_i = delta_e_i*exp(-dt/tau);
    
    % Compute aircraft motion
    altitude(i) = altitude(i-1) + velocity(i-1)*sin(pitch(i-1))*dt;
    velocity(i) = velocity(i-1) + (-drag-weight*sin(pitch(i-1))/mass)*dt;
    heading(i) = heading(i-1) + velocity(i-1)*cos(pitch(i-1))/altitude(i-1)*dt;
    pitch(i) = pitch(i-1) + delta_theta_i*dt;
end

% Plot aircraft motion
figure;
subplot(2,2,1);
plot(t,altitude);
xlabel('Time (s)');
ylabel('Altitude (m)');
subplot(2,2,2);
plot(t,velocity);
xlabel('Time (s)');
ylabel('Velocity (m/s)');
subplot(2,2,3);
plot(t,rad2deg(heading));
xlabel('Time (s)');
ylabel('Heading (deg)');
subplot(2,2,4);
plot(t,rad2deg(pitch));
xlabel('Time (s)');
ylabel('Pitch (deg)');
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In this example, the aircraft model is a simple point mass with a drag and lift force. The control input is a simple function of time that is used to control the pitch angle of the aircraft. The simulation results are plotted to show the altitude, velocity, heading, and pitch of the aircraft over time. By adjusting the model parameters and control input, we can analyze the stability of the aircraft under different conditions.

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