36 lines
1.4 KiB
Matlab
36 lines
1.4 KiB
Matlab
function TxDot = T3dxdt(t,x)
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%% Threat is a 240 mm Rocket
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% Compute Rocket xDot = [velocity; acceleration]'
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g = 9.8066; % acceleration due to gravity
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gravity = [0; 0; -g]; % gravity vector
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diameter = 0.24; % missile diameter in m.
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S = pi*(diameter/2)^2; % reference area in m^2
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[acousticSpeed,rho] = getRho(x);
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mach = norm(x(4:6))/acousticSpeed;
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% Transcribed from the provided target-data plots.
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timeCurve = [0 7.5 7.5001 45]'; %seconds
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thrustCurve = [77000 77000 0 0]'; % Newtons
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massCurve = [410 210 210 210]'; % kg
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machCurve = [0 0.5 0.7 0.9 1.0 1.1 1.2 1.3 1.5 2.0 2.5 3.0 3.5 4.0];
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dragCurve = [0.40 0.40 0.43 0.60 0.75 0.87 0.86 0.80 0.74 0.60 0.50 0.44 0.40 0.39];
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machCurveB = [0 0.5 0.7 0.9 1.0 1.1 1.2 1.3 1.5 2.0 2.5 3.0 3.5 4.0];
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dragCurveB = [0.31 0.31 0.34 0.47 0.62 0.78 0.77 0.72 0.64 0.50 0.40 0.34 0.30 0.27];
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if(t<=timeCurve(end-1))
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Cd = interp1(machCurveB,dragCurveB,mach,'linear','extrap');
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else
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Cd = interp1(machCurve,dragCurve,mach,'linear','extrap');
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end
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mass = interp1(timeCurve,massCurve,t,'linear','extrap');
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thrust = interp1(timeCurve,thrustCurve,t,'linear','extrap');
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%Compute acceleration --------------------------------------------
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dragAccel = -0.5*rho*Cd*S*x(4:6)*norm(x(4:6))/mass;% drag acceleration in m/sec^2
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thrustAccel = thrust*x(4:6)/(mass*(norm(x(4:6))));
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accel = dragAccel + thrustAccel + gravity; % total acceleration
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TxDot = [x(4:6);accel];
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end
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