Definition
An imaginary straight line drawn from the leading edge to the trailing edge of a propeller or rotor blade's airfoil cross-section at a given point along the blade. It is used as a reference line for measuring blade angle and analyzing the aerodynamic behavior of the blade.
Plain English
A straight reference line running from the front edge to the back edge of a propeller or rotor blade, used to describe and measure how the blade is shaped and angled.
Context Anchor
Seen in propeller, rotor, and airfoil shape discussions, especially when describing blade design, inspection, or repair limits.
Derivation
Chord comes from the Latin chorda, meaning 'string' or 'cord' — the same root as a bowstring stretched straight across an arc. A propeller or rotor blade has a curved airfoil shape, and the chord is the straight line drawn across that curve, just like a string drawn across a bow.
Why Pilots Care
Blade chord directly affects lift, drag, thrust, and structural strength of the propeller or rotor.
Analogy
Think of placing a ruler straight across the blade from its front edge to its back edge. That straight ruler measurement is the blade chord at that spot.
Intuition Check
Chord does not mean a musical sound here. It means a straight measurement across the blade from front edge to back edge.
Example Sentence 1
Propeller blade angle is measured between the blade chord and the plane of rotation.
Example Sentence 2
A wider blade chord provides more thrust at low speeds but increases drag.