Forces in Flight

081-08-01Pablo Asensio Martínez2026-04-011 min

Straight and Level

  • Lift = Weight ($L = W$)
  • Thrust = Drag ($T = D$)
  • (Technically, the tail load must also be considered for moment equilibrium).

Climb

  • Thrust > Drag: Thrust must overcome Drag PLUS the rearward component of Weight ($W \sin \gamma$).
  • Lift < Weight: Only a component of Weight ($W \cos \gamma$) is supported by Lift. The rest is supported by Thrust.

Descent (Glide)

  • Thrust = 0 (or Idle).
  • Weight Component ($W \sin \gamma$) acts as Thrust to overcome Drag.
  • Gliding for Range: Fly at $V_{MD}$ (Max L/D ratio).

Turning

  • To turn, we bank the lift vector.
  • Vertical Component: Must equal Weight ($L \cos \phi = W$).
  • Horizontal Component: Provides Centripetal Force ($L \sin \phi = CPF$).
  • Load Factor ($n$): The ratio of Lift required to Weight.
    • $n = \frac{1}{\cos \phi}$
    • Example: 60° bank = 2.0g ($1 / 0.5$).