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//All the quantities are expressed in SI units
p0 = 30*101000; //reservoir pressure
T0 = 3500; //reservoir temperature
R = 520; //specific gas constant
gam = 1.22; //ratio of specific heats
A_star = 0.4; //rocket nozzle throat area
pe = 5529; //rocket nozzle exit pressure equal to ambient pressure at 20 km altitude
//(a)
//the density of air in the reservoir can be calculated as
rho0 = p0/R/T0;
//from eq.(8.46)
rho_star = rho0*(2/(gam+1))^(1/(gam-1));
//from eq.(8.44)
T_star = T0*2/(gam+1);
a_star = sqrt(gam*R*T_star);
u_star = a_star;
m_dot = rho_star*u_star*A_star;
//rearranging eq.(8.42)
Me = sqrt(2/(gam-1)*(((p0/pe)^((gam-1)/gam)) - 1));
Te = T0/(1+(gam-1)/2*Me*Me);
ae = sqrt(gam*R*Te);
ue = Me*ae;
//thus the thrust can be calculated as
T = m_dot*ue;
T_lb = T*0.2247;
//(b)
//rearranging eq.(10.32)
Ae = A_star/Me*((2/(gam+1)*(1+(gam-1)/2*Me*Me))^((gam+1)/(gam-1)/2));
printf("\nRESULTS\n---------\n(a)The thrust of the rocket is:\n T = %1.2f x 10^6 N = %6.0f lb\n\n(b)\nThe nozzle exit area is:\n Ae = %2.1f m2\n",T/1e6,T_lb,Ae)
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