AerodynamicsQuestion 457 of 934

A pilot keeps the airplane clean and waxed. What is the aerodynamic reason?

  1. Dirt disrupts airflow and adds drag
  2. Dirt smooths the airflow over the wing
  3. Wax cuts the induced drag of the wing
  4. Wax adds camber to the wing
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Correct answer: Dirt disrupts airflow and adds drag

Dirt on an aircraft disrupts the free flow of air and increases drag.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 5: Aerodynamics of Flight — Skin Friction Drag, page 104

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Questions last reviewed: 18 October 2026