Question

Which of the following is the correct thrust balancing equation for thrust producing engines?

(a) FN+D=Wsinγ2+mV̇

(b) FN-D=Wsinγ2+mV̇

(c) FN-D=Wsinγ2-mV̇

(d) FN+D=Wsinγ2-mV̇

I had been asked this question in exam.

The origin of the question is Climb and Descent Performance with Thrust-Producing Engines in chapter Climb and Descent Performance of Aircraft Performance

Answer 1

Right choice is (b) FN-D=Wsinγ2+mV̇

Explanation: The correct thrust balancing equation for thrust producing engines is given by the equation FN-D=Wsinγ2+mV̇ where FN is the normal force acting on the aircraft, γ is the angle at which the force is acting on the aircraft, D is drag produced, W is weight of the aircraft, m is mass and V̇ is velocity.