Question

A jet aircraft is traveling at 262 m/s in hor-

izontal flight. The engine takes in air at a

rate of 85.9 kg/s and burns fuel at a rate of

3.92 kg/s. The exhaust gases are ejected at

921 m/s relative to the aircraft.

Find the thrust of the jet engine.

Answer 1

Solution :

Speed of the air craft, $S_a$ = 262 m/s

Fuel burns at the rate of, $S_b$ = 3.92 kg/s

Rate at which the engine takes in air, $S_{air}$ = 85.9 kg/s

Speed of the exhaust gas that are ejected relative to the aircraft, $S_{exh}$ =921 m/s

Therefore, the upward thrust of the jet engine is given by

$F=S_{air}(S_{exh}-S_a)+(S_b \times S_{exh})$

F = 85.9(921 - 262) + (3.92 x 921)

   = 4862635.79 + 3610.32

   = $4.8 \times 10^6 \ N$

Therefore thrust of the jet engine is $4.8 \times 10^6 \ N$.