Definition
A unit of torque or moment equal to the turning effect produced by a force of one pound applied at a perpendicular distance of one inch from a pivot point. In weight and balance, inch-pounds express a moment: the weight of an item (in pounds) multiplied by its arm (the distance in inches from the reference datum).
Plain English
It is a way of measuring how much turning or tipping effect a weight has, found by multiplying the weight in pounds by how far it sits, in inches, from a fixed reference point on the aircraft.
Context Anchor
Seen in aircraft weight and balance charts, loading problems, and moment calculations.
Derivation
The unit literally combines the two measurements used to calculate it: inches (the distance from the reference datum) and pounds (the weight of the item). Multiplying them gives the moment, so the unit name simply reflects how the value is produced.
Why Pilots Care
Moment values expressed in inch-pounds are summed and divided by total weight to determine the center of gravity location.
Grounding Statement
A 40-pound bag placed 80 inches from the reference line creates 3,200 inch-pounds of moment.
Intuition Check
Do not read inch-pounds as two separate measurements listed side by side. In this context, it means pounds multiplied by inches to show a turning or balancing effect.
Example Sentence 1
A 50-pound bag of cargo loaded 80 inches aft of the datum produces a moment of 4,000 inch-pounds.
Example Sentence 2
The torque wrench was set to 80 inch-pounds before tightening the propeller bolts.