Definition
Weights attached to the propeller blade shanks or hub of a constant-speed propeller, positioned so that centrifugal force acting on them tends to rotate the blades toward a higher (coarser) blade angle. They work in opposition to other forces in the propeller hub to control blade pitch.
Plain English
Small weights mounted on the propeller that, as the propeller spins, get flung outward and twist the blades toward a flatter bite of the air or a steeper bite, depending on the design. They are part of how the propeller automatically changes its blade angle in flight.
Context Anchor
Seen when studying constant-speed or controllable-pitch propellers, especially how the propeller changes blade angle.
Derivation
From 'counter' (against) and 'weight.' The name describes the function: a weight placed to act against another force. In a propeller, the counterweight uses centrifugal force to push back against the forces that would otherwise drive the blades toward a fine pitch.
Why Pilots Care
They provide a mechanical backup that increases blade pitch if oil pressure is lost, protecting the engine from overspeed.
Grounding Statement
As the propeller spins, the counterweights are pulled outward and that outward pull helps rotate the blades toward a higher angle.
Intuition Check
Counterweights are not just there to balance the propeller. In this context, they are part of the system that helps change blade angle.
Example Sentence 1
When oil pressure to the propeller hub is lost, the counterweights drive the blades toward the feathered position.
Example Sentence 2
Loss of oil pressure allowed the counterweights to drive the blades toward coarse pitch and prevent engine overspeed.