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% % DOUGLAS A - 4 E / F SKYHAWK [ LONGITUDINAL ] M = 0 . 6 ; rho = 2 . 3 7

%% DOUGLAS A-4E/F SKYHAWK [LONGITUDINAL]
M =0.6;
rho =2.3769*10^-3;
a =1116.45; %all unit in english unit, speed of sound
uo = M*a;
S =260;
c =10.8;
b =27.5;
AR =(b^2)/S;
Ix =8090;
Iy =25900;
Iz =29200;
g =32.174;
m =17578/g;
Q =0.5*rho*(uo^2); %dynamic pressure
alpha =0;
e =0.8; %oswald efficiency
CL =0.1268; % from calculations
CD =0.037; % from calculations
%% Lift Coefficient Derivatives
CDu =0; % for jet assume zero
CTu =0; % for jet assume zero
CDo = CD; % assume same
CLo = CL; % assume same
CDalpha =0.1; %from graph
CLalpha =3.6; %from graph
%% Longitudinal Stability Dimensionless Drivatives, not follow NELSON but dr document
CXu =-(CDu+2*CDo)+CTu
CXalpha =(CLo-((2*CLo*CLalpha)/(pi*e*AR)))
CZu =-(((M^2)*CLo)/(1-M^2))-2*CLo
CZalpha =-(CLalpha+CDo)
CZalphadot =0.82; %assume equal to CLalphadot
CZq =0; %assume since no graphs exist
CZdeltae =0.4; %CZdeltae=-CLdeltae
CMu =0; %assume 0 due to low speed flight
CMalpha =-0.39; %CMalpha to CMdeltae taken from graph
CMalphadot =-1.3;
CMq =-3.9;
CMdeltae =-0.6;
%% Longitudinal Stability Dimensional Derivatives
Xu =(CXu*Q*S)/(m*uo)%checked
Xalpha =(CXalpha*Q*S)/m %checked
X
Xw =(-(CDalpha-CLo)*Q*S)/(m*uo)
Zu =(CZu*Q*S)/(m*uo)%checked
Zw =(-(CLalpha+CDo)*Q*S)/(m*uo)
Zalpha =(CZalpha*Q*S)/m %checked
Zalphadot =(CZalphadot*c*Q*S)/(2*m*uo)%checked
Zq =(CZq*c*Q*S)/(2*m*uo)%checked
Zdeltae =(-CZdeltae*Q*S)/m %checked
Mu =(CMu*Q*S*c)/(uo*Iy)%checked
Mw =(CMalpha*Q*S*c)/(uo*Iy)%checked
Mwdot =(CMalphadot*Q*S*(c^2))/(2*(uo^2)*Iy)%checked
Malpha = uo*Mw %checked
Malphadot = uo*Mwdot %checked
Mq =(CMq*Q*S*(c^2))/(2*uo*Iy)%checked
Mdeltae =(CMdeltae*Q*S*c)/Iy %checked
%State- Space Matrix
format long
A =[Xu, Xw,0,-g;
Zu, Zw, uo,0;
Mu+(Mwdot*Zu), Mw+(Mwdot*Zw), Mq+(Mwdot*uo),0;
0,0,1,0]
B =[0;
Zdeltae;
Mdeltae+(Mwdot*Zdeltae);
0]
C = eye(size(A))
D = zeros(size(B))%zero matrix
[num, den]= ss2tf(A, B, C, D,1)
numu = num(1,:)
numw = num(2,:)
numq = num(3,:)
numtheta = num(4,:)
t =0:0.01:20;
impulse(A, B, C(4,:), D(4,:),1, t);
title('Longitudinal Pitch Attitude (\theta) without Controller');
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