Question 3:

A 1/12th scale model of an aircraft was tested in a wind tunnel under sea level standard conditions. The following data was

obtained.

Air Speed

(m s ¹)

10

15

20

Angle of attack

(degrees)

0

2

4

Lift

(N)

9.9225

37.20938

92.61

Drag

(N)

0.8153723

2.156077

4.690329

Pitching moment

(Nm)

-2.20813

-5.86508

-12.0209

The wing area of the full sized aircraft is 97.9 m² and the wing aspect ratio is 6.5. What value does the coefficient of moment

about the aerodynamic centre have?