Question

A wing-body model is tested in a wind tunnel with a flow of 100 m/s at standard sea-level conditions.
The wing area is 1.5 m2
and the mean aerodynamic chord length is 0.45 m.
Measurements of lift force, L, and moment about the center of gravity, M CG are made using the wind tunnel force
balance.
B1(a) When the lift is zero, the moment about the center of gravity is measured to be, MCG = −12.4 Nm .
At another angle of attack, the force balance measurements give, L = 3675 N and MCG = 20.67 Nm .

Q1-- Calculate the location of the aerodynamic center, and the moment coefficient about the aerodynamic center.

Q2-- A lead mass is added to the rear of the model which moves the center of gravity rearward by 20% of the mean wing chord. Calculate MCG when L = 4000 N.

Answer 1