Three vertical forces act on an airplane when it is flying at a constant altitud

Question

Three vertical forces act on an airplane when it is flying at a constant altitude and with a constant velocity. These are the weight of the airplane, an aerodynamic force on the wing of the airplane, and an aerodynamic force on the airplane's horizontal tail. (The aerodynamic forces are exerted by the surrounding air, and are reactions to the forces that the wing and tail exert on the air as the airplane flies through it.) For a particular light airplane with a weight of 6610N , the center of gravity is 0.32m in front of the point where the wing's vertical aerodynamic force acts and 3.63m in front of the point where the tail's vertical aerodynamic force acts.

Explanation / Answer

The CG is ahead of the centre of lift of the wing, so the force on the wing tries to rotate the aircraft nose down. That means the tailplane has to counter that tendency.

Consider the centre of wing lift as the fulcrum of a class 1 lever.

If the aircraft were headed to the left, the anticlockwise torque will be (6610 x 0.32) = 2115.2N/m.

To counter this, the tailplane needs to apply an equal torque clockwise.

2115.2/(3.63- 0.32) = 639.03323N. force down on tailplane.

(3.63 x639.03323)/0.32 = 7249.0332N. force on wing. Note this is aircraft weight plus force on tailplane.

a) 7249.0332N.

b) Upwards.

c) 639.03323N.

d) Downwards.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.