What happens to the horizontal component of lift as bank angle increases (with airspeed unchanged)?

What happens to the horizontal component of lift as bank angle increases (with airspeed unchanged)?

• A. Decreases
• B. Remains the same
• C. Reverses
• D. Increases

Answer: (D)

Banking tilts the lift vector, so part of lift goes horizontal to provide the turn, and part must balance weight vertically. For level flight in a turn, vertical balance requires L cos φ = W. As the bank angle φ increases, cos φ decreases, so the total lift L must rise: L = W / cos φ. The horizontal component of lift is L sin φ, which becomes (W / cos φ) sin φ = W tan φ. Since tan φ increases with φ, the horizontal lift component grows as the bank angle increases. With airspeed unchanged, the extra lift needed comes from a higher angle of attack to raise L, so the horizontal component increases accordingly.

Banking tilts the lift vector, so part of lift goes horizontal to provide the turn, and part must balance weight vertically. For level flight in a turn, vertical balance requires L cos φ = W. As the bank angle φ increases, cos φ decreases, so the total lift L must rise: L = W / cos φ. The horizontal component of lift is L sin φ, which becomes (W / cos φ) sin φ = W tan φ. Since tan φ increases with φ, the horizontal lift component grows as the bank angle increases. With airspeed unchanged, the extra lift needed comes from a higher angle of attack to raise L, so the horizontal component increases accordingly.