A Boeing 747200 has four engines whose thrust is up to 24400

A Boeing 747-200 has four engines whose thrust is up to 244,000 N each, a wing Ares of 510.95 m^2, an angle of attack of 2.4 degree and corresponding lift and drug coefficients of 0.52 and 0.0331, respectively If the gross flight weight is 2, 833, 500 N, what is the crusting speed at an altitude of 12 km where the air density is 0.303 kg/m^3?

Solution

solution:

1)here weight of plane is equal to lift force for crusing speed,hence we have that

Fl=Cl*.5*density*V^2*A

2833500=.92*.5*.303*V^2*510.95

V=199.46 m/s

hence cruising speed is V=199.46 m/s

2)where drag at this crusing speed is

Fd=Cd*.5*density*V^2*A

Fd=.0331*.5*.303*199.46^2*510.95

Fd=101944.4022 N

where maximum thrust is

T=244000*4=976000 N

hence percentage of thrust use in overcoming drag is

%=Fd/T*100=10.44%