Question

A thin straight wing with no twist has thin cambered airfoil with a0 -0.035 rad and aspect ratio of 8. The wing is put at an angle of attack of 0.1 rad. Applying the fundamental lifting line equation for this wing at two different spanwise locations using two odd-term Fourier-sine series expansion for general circulation distribution I'(0) 2bV2£4, sin n0 yields the following set of equations: a 3.69.413.74 A-a0 a 6.73.4-3.624 -a0 a. From this analysis, determine the lift coefficient of the wing b. Determine also its induced-drag coefficient

Answer 1

Putting $\alpha$ = 0.1 and $\alpha_{L=0}$=-0.035 in above 2 equation, we can solve for A1 and A3.

0.065 3.69A1 13.74 A3 0.065 6.73A -3.62.A3

A1= 0.0106. A3=0.001867

A)

Cr = TAR(A,)

AR=8. A1=0.0106

putting these values in above equation

C0.266 L

B)

C (1+ δ) CDi πAR An 2 5-Ση: Αι n-3

A1= 0.0106

A2=0

A3=0.001867

A4=0 .....

Therefore

A3 5 n 3(20.092 A1 A1 An n-3

C(1) CDi TAR S = 0.092 AR 8 CL 0.26

CDi= 0.002937