$6\mathrm{.}5$ From the information generated in Prob. $6\mathrm{.}3,$ calculate the maximum rate of climb for the twin$-$jet aircraft at sea level and at an altitude of $5$ km $.$

$6\mathrm{.}3$ Consider an airplane patterned after the Fairchild Republic A$-10,$ a twin$-$jet attack aircraft. The airplane has the following characteristics: wing area $=47m^2,$ aspect ratio $=6\mathrm{.}5,$ Oswald efficiency factor $=0\mathrm{.}87,$ weight $=103,047N,$ and zero$-$lift drag coefficient $=0\mathrm{.}032.$ The airplane is equipped with two jet engines with $40,298N$ of static thrust each at sea level.