Definition
A dimensionless number that expresses how effectively an airfoil produces lift at a given angle of attack, in given air conditions. It is one factor in the lift equation, alongside air density, airspeed squared, and wing area. The coefficient of lift increases with angle of attack up to the critical angle, then drops sharply at the stall.
Plain English
A number that shows how good a wing is at producing lift at a particular angle to the oncoming air. The number goes up as the wing is tilted more into the airflow, until the wing stalls.
Context Anchor
Seen in aerodynamics, stall, flap, and aircraft performance discussions, especially when explaining how wings make lift at different speeds and angles to the airflow.
Derivation
From Latin coefficiens, meaning 'working together with.' In math and physics, a coefficient is a number that multiplies another value in a formula. Here, it is the number that works together with air density, speed, and wing area to produce lift.
Why Pilots Care
It directly affects stall speed, climb rate, and how wing configuration changes influence handling and safety margins.
Analogy
Think of it like an effectiveness rating for the wing. It is not the total amount of lift by itself; it shows how hard the wing is working to make lift for its size and speed.
Grounding Statement
At the same speed and wing size, a higher coefficient of lift means the wing is producing more lift.
Intuition Check
Do not read coefficient of lift as simply “the amount of lift.” It is a comparison number that removes wing size and speed so different lift conditions can be compared fairly.
Example Sentence 1
As the pilot increased the angle of attack on final approach, the coefficient of lift rose, allowing the airplane to fly slower while still supporting its weight.
Example Sentence 2
Lowering the flaps increased the coefficient of lift, allowing the aircraft to fly slower without stalling.