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Which effect does a decreasing airspeed have on the induced drag during a horizontal and stable cruise flight?

  • A

    The induced drag will increase.

  • B

    The induced drag will collapse.

  • C

    The induced drag will remain constant.

  • D

    The induced drag will slightly decrease.

Parasite drag is made up of all the forms of drag that act on any object that moves through a fluid. It is made up of

  • skin friction drag,
  • form drag,
  • interference drag.

Parasite drag is produced even when lift is not produced, and induced drag is caused when the airplane’s airfoils produce lift.

Induced drag, on the other hand, is the section of lift that acts parallel to the relative airflow, due to the limited length of the wing, and the effect of three-dimensional aerodynamics.

When an aircraft is decresing airspeed in horizontal level flight in stable conditions, the Lift must remain the same to remain at the same level, knowing the Lift formula:

  • L=CL 1/2p V2 S

V2 decreases then CL must increase. Therefore, the angle of attack needs to increase meaning higher induced drag and decreased parasite drag.

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  • Austro Control