$4\mathrm{.}2$ Calculate the specific thrust and the TSFC of a single$-$spool turbojet engine having the following peculiarities:

Cruise velocity of $280\frac{m}{s}$ at altitude of $7000$ m

Intake efficiency of $93\%$

Compressor pressure ratio of $8$:$1$ and efficiency of $87\%$

Burner efficiency of $98\%$

Pressure drop in the combustion chamber of $4\%$ of the delivery pressure of the compressor

TIT of $1200$ K and efficiency of $90\%$

Mechanical efficiency of $99\%$

Nozzle efficiency $95\%$

Fuel heating value $44,000k\frac{J}{k}g$