Question

The lift acting on an aircraft climbing vertically up is

• A. equal to its weight
• B. zero
• C. equal to the drag
• D. equal to the thrust

Hint:

Lift acts perpendicular to flight path — in vertical climb it has no role.

Answer 1

The Correct Option is B

In aerospace engineering, it is important to understand the forces acting on an aircraft during different phases of flight. When an aircraft is climbing vertically, the situation is unique compared to horizontal flight. Typically, the four main forces acting on an aircraft are lift, weight, thrust, and drag:

• Lift: Acts perpendicular to the flight path in normal, horizontal flight. It is generated by the wings to counteract the aircraft's weight.
• Weight: The force due to gravity acting downwards.
• Thrust: Generated by the aircraft's engines to propel it forward.
• Drag: The resistance an aircraft encounters while moving through air.

In horizontal flight, lift counteracts weight, and thrust counteracts drag. However, during vertical climb:

• The aircraft is moving straight up, so the orientation and contributions of these forces change.
• Thrust from the engines must overcome both weight and any opposing drag to achieve vertical movement.
• Since the motion is vertical, lift force, which typically acts perpendicular to the wings and plane's motion in horizontal flight, becomes effectively zero because the wings aren't angled to create lift in the vertical direction. The engines provide the necessary upward force.

Therefore, during a vertical climb, the lift acting on an aircraft is zero.