A wing with an elliptical planform is flying through sea-level air at a speed of 55 m/s. The wing is untwisted, has the same section from root to tip and its loading is W/S = 1000 N/m2 . The 2D lift curve slope is a0 = 5.7. The span of the wing is 15 m and the aspect ratio if 5. Find, a) The sectional lift coefficient. b) The sectional induced-drag coefficient. c) The effective, induced and geometric angles of attack if L=0 = -2 degrees.

Respuesta :

Answer:

Explanation:

a.) To find Secrional liftSectional lift Coefficient [tex](c_{I})=\frac{W}{(0.5*Rho*V^{2})}[/tex]

where Rho = 1.225Kg/m³ (density of air at sea level)

[tex](c_{I})=\frac{1000}{(0.5*1.225*55^{2})}=0.5397[/tex]

b.) To obtain the sectional induced coefficient:

[tex]C_{D} = \frac{(C_{L})^2}{π(AR)}[/tex]

[tex]C_{D} = \frac{(0.5397)^2}{π(5)}=0.0185[/tex]

C.) For the effective angle of attack ∝0

∝0 = [tex]\frac{C_{l}}{m_{0}}\\=\frac{0.5397}{5.7}\\=0.0947rad[/tex]

For induced angle of attack ∝i:

∝i= [tex]\frac{-C_{D}}{C_{L}}\\=\frac{-0.0185}{0.5397}\\=-0.0343rad[/tex]

For absolute angle of attack ∝a:

∝a = ∝0 - ∝i = 0.0947 - (-0.0343) = 0.1290 rad

For geometric angle of attack ∝g:

∝g = ∝a + ∝L given ∝L = -2°≅-0.0349 rad

= 0.1290-0.0349 = 0.0941rad