Finite Wing Terminology

Question 1

Taper Ratio Eq

Answer 1

λ = ct/cr
ct = tip chord
cr = root chord

Question 2

Explain the phenomena of induced drag

Answer 2

Air flows around the wing tips, from an area of higher pressure on the upper wing (bottom of the wing) surface to area of lower pressure under lower wing surface (top of the wing)

Generates trailing wing tip vorticies

Leading to downwash on the inside, strongest close to wing tips

Question 3

Effective angle of attack Eq

Answer 3

αeff = α - αi
αi = induced angle of attack: the change in orientation of the air velocity experienced by the aerofoil due to the downwash

Question 4

Lift Curves for Infinite, finite w/ winglets, and finite wings

Answer 4

Cl vs α graph
The lift curve for the infinite wing has the largest gradient
Finite wing w/ winglets has a lower gradient
Finite wing has the lowest gradient

They all originate from the same point and the only difference is the gradient

Question 5

Drag Polar for infinite & finite wings

Answer 5

CD vs CL graph
Infinite wing - shallow +ve parabola crossing the y-axis
Finite Wing - an exponential esq. graph that starts to the right of the y axis.
As AR decreases the graph becomes steeper