Question

An aircraft is climbing with a 20° of climb angle and a 5° of angle of attack having a mass of 11,000 kg and aircraft drag is 9,000 N then determine aircraft lift.

(a) 11453.17 N

(b) 9220.07 N

(c) 11553.17 N

(d) 97385.85 N

I have been asked this question in class test.

This interesting question is from Cruising Performance in chapter Cruising Performance of Aircraft Performance

Answer 1

The correct choice is (b) 9220.07 N

Easy explanation: Aircraft weight=mg=11000*9.81=107910 N.

Engine thrust: From equating the forces we get the following equation: T cos α= D+W sin γ

T=\(\frac{D+Wsin\gamma}{cos\alpha}\)=\(\frac{9000+107910*sin(20)}{cos(5)}\)

T=46082.75 N.

From equating the vertical forces we get the following equation: L+Tsinα=Wcosγ

L=107910*cos(20)–46082.75*sin(5)

L=97385.85 N.