GATE Aerospace Engineering Practice Quiz

Question 1

For a finite wing of aspect ratio AR and Oswald efficiency factor e, the lift-curve slope a is related to the 2D airfoil lift-curve slope a0 by which expression in incompressible subsonic flow?

Accepted Answer

a = a0 / (1 + a0/(pi e AR))

Question 2

Compared with an infinite wing using the same airfoil section at the same geometric angle of attack, a finite wing generally produces lower lift coefficient primarily because

Accepted Answer

the finite wing experiences induced downwash that reduces effective angle of attack

Question 3

A finite wing has airfoil lift-curve slope a0 = 2pi per rad, aspect ratio AR = 6, and e = 0.9. What is the finite-wing lift-curve slope a (approximately)?

Accepted Answer

4.60 per rad

Question 4

For a wing with fixed span and flight speed, if the total lift is doubled while the span efficiency factor remains unchanged, the induced drag will

Accepted Answer

increase by a factor of four

Question 5

A wing has aspect ratio AR = 8 and Oswald efficiency factor e = 0.8. At lift coefficient CL = 0.8, what is the induced drag coefficient CDi?

Accepted Answer

0.0318

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