Question

1) For a NACA 0008 airfoil at an angle of attack of 5°, with a downward flap deflection of 25°, where the flap hinge point is located at 0.65c from the leading edge where c is the chord length. (5 points)

1. Calculate the lift coefficient using thin airfoil theory.
2. What is the zero-lift angle for 25°downward flap deflection.

Answer 1

Answer :

Given data :

Angle of attack (A)= 5° = π/36 radian

Downward flap deflection = 25° = 5π/36 radian

Location of flap hinge point = 0.65 c

Chord length = c

(a)

According to thin airfoil theory,

Lift coefficiant = 2π(Angle of attack)

So,

Lift coefficient :

(b)

Formula for zero lift angle :

where,

= Zero lift angle

= Downward flap deflection (in degree)

= Lift coefficient

putting all values in above equation, we get

aon solving this, we get

= 19.99°

Thanks