Four forces are necessary for an aircraft to fly, and understanding them helps you recognize the limitations you must overcome to successfully challenge the bonds of earth. Here’s a basic description of each; you can see the forces in the figure:

  • Lift: Lift is the upward force vector resulting from air movement along both the upper and lower portions of the wing.

  • Drag: Drag is the air resistance that slows down the forward movement of an aircraft. You encounter two types of drag: induced, which is the drag that results from the wing’s developing lift, and parasite, which is the drag associated with the resistance to forward movement.

  • Weight: Weight is the downward force resulting from the gravitational pull of the earth.

  • Power: Power, or thrust, is the force that enables an aircraft to move forward though the air.

    The interaction of these four forces allows the aircraft to fly.
    The interaction of these four forces allows the aircraft to fly.

Your test will feature questions that both directly and indirectly relate to the four forces on an aircraft in a given situation. An example of one such question may include the following:

The four forces that act on an aircraft in flight are
  • (A) Lift, weight, thrust, and drag

  • (B) Lift, mass, propulsion, and resistance

  • (C) Aerodynamics, mass, propulsion, and drag

  • (D) Lift magnitude, mass, thrust, and drag

  • (E) Roll, pitch, yaw, and magnitude

The correct answer is Choice (A).