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Refer to figure.
What is the correct combination of letters identifying the airfoils with the corresponding numbers from the CD graphic?
  • A
    1 – a, 2 – d, 3 – c, 4 – b
  • B
    1 – a, 2 – b, 3 – c, 4 – d
  • C
    1 – d, 2 – a, 3 – b, 4 – c
  • D
    1 – d, 2 – a, 3 – c, 4 – b

Refer to figure.
Aerofoils with high camber will produce the highest lift and, consequently, the greatest induced drag.

Aerofoils with greater frontal areas will produce the most parasite drag.

Less lift and induced drag will be produced by thinner aerofoils and shapes with little camber.


Let’s examine each aerofoil:

  • “a” and “d” have high camber.

  • “d” has a larger frontal area (and nose radius), therefore it will produce more drag than “a”.

  • “b” and “c” have little camber.

  • “b” is thinner than “c”. Thus “b” will produce less drag than “c”.

We get the following combinations: 1 – d, 2 – a, 3 – c, 4 – b

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