Lift — Forces

Aerodynamic force acting perpendicular to the relative wind, generated primarily by the wings. Lift opposes weight and keeps the aircraft airborne.

How it's generated

Lift arises from a pressure difference between the upper and lower wing surfaces. Air flowing over the curved upper surface accelerates, which lowers its pressure (Bernoulli's principle). Higher-pressure air below the wing pushes upward. This pressure difference, acting over the entire wing area, produces the lift force.

Newton's third law also plays a role: the wing deflects air downward, and the equal and opposite reaction pushes the wing up. Both explanations are correct and complementary — a complete analysis of lift requires both.

The lift equation

L = ½ρV²SC_L

ρ (rho)	Air density — decreases with altitude
V²	Airspeed squared — doubling speed quadruples lift
S	Wing area
C_L	Lift coefficient — determined by airfoil shape and angle of attack

Lift is perpendicular to the relative wind, not straight up. In a banked turn, lift tilts with the aircraft — the vertical component of lift now opposes weight, and the horizontal component provides the centripetal force to curve the path. This is why maintaining altitude in a turn requires increasing total lift.

What controls lift

Pilots increase lift by increasing angle of attack (pitch input), increasing airspeed (throttle), or deploying high-lift devices like flaps. Lift decreases as altitude increases (lower air density) or if angle of attack exceeds the critical value, causing a stall.

Related terms

Drag — always accompanies lift; induced drag is a direct byproduct of lift generation
Weight — the force lift opposes
Stall — what happens when angle of attack exceeds the limit
Flaps — increase the lift coefficient at a given speed

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