Chapter 5 | General knowledge

5.2 | DISTRIBUTION OF THE FOUR MAIN FORCES

Various forces act on an aircraft, all of which are related to physical laws. Take-off, descent, or horizontal flight are the result of the four main forces acting on the aircraft.

The main forces are:

  • Lift
  • Weight (gravity)
  • Thrust
  • Drag

For differences in the four main forces the following principles apply:

  • In upward flight the lift is greater than the gravity.
  • In horizontal flight the lift is equal to the force of gravity.

5.2.1      Lift

  • The Venturi effect
L = 1/2 ρ * V2 * Cl * S
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