Definition 1 of 2
Definition
A dimensionless number that represents the portion of an aircraft's total drag coefficient produced by the generation of lift. It varies with the square of the lift coefficient and inversely with the wing's aspect ratio, increasing sharply at high angles of attack and low airspeeds.
Plain English
A number that tells you how much of the wing's drag is being caused by the act of producing lift. The harder the wing is working to hold the aircraft up — for example, when flying slowly — the bigger this number gets.
Context Anchor
Seen in aerodynamics and aircraft performance discussions, especially when studying slow flight, climb performance, turns, and wing design.
Derivation
Induced means 'brought about' or 'caused by' — from the Latin inducere, meaning 'to lead in.' This drag is induced because it is caused by lift itself; without lift, it would not exist. A coefficient is simply a number that lets engineers compare wings of different sizes on equal terms.
Why Pilots Care
It directly affects how much thrust is required to maintain level flight and influences the airplane's best glide speed and range.
Analogy
It is like using a fuel-economy number instead of only saying how much fuel was burned on one trip. The coefficient lets you compare the effect in a cleaner way, separate from one exact speed or airplane size.
Grounding Statement
When the wing has to make more lift, the induced drag coefficient usually goes up.
Intuition Check
Do not read this as total drag, or as drag measured in pounds. It is a no-unit number for only the drag that exists because the wing is producing lift.
Example Sentence 1
As the aircraft slowed on final approach, the induced drag coefficient climbed quickly, requiring more power to maintain the glide path.
Example Sentence 2
Designers reduce the induced drag coefficient by increasing wing aspect ratio.