Definition
The fixed propeller RPM that a constant-speed propeller system maintains automatically once the pilot selects an RPM with the propeller control. The propeller governor senses any change in engine speed and adjusts the propeller blade angle to hold that selected RPM, even as airspeed, power, or attitude change.
Plain English
The propeller RPM the pilot has set, which the system then keeps steady on its own by changing how much the blades bite the air.
Context Anchor
Seen when learning how a constant-speed propeller holds a selected RPM during takeoff, climb, cruise, descent, and power changes.
Derivation
Constant means unchanging. Governed comes from the same root as govern, meaning to control or regulate. So a constant governed speed is a speed that is held steady by a controlling device — in this case, the propeller governor.
Why Pilots Care
Maintaining a selected RPM improves fuel efficiency, engine longevity, and performance across climb, cruise, and descent.
Grounding Statement
If the airplane speeds up or slows down, the governor changes the propeller blade angle to help keep the selected RPM nearly steady.
Intuition Check
Constant does not mean the RPM can never move at all; it means the system is designed to return to and hold the selected RPM. Governed means automatically controlled by the propeller governor, not held only by the throttle.
Example Sentence 1
After setting 2,400 RPM with the propeller control, the pilot watched the tachometer hold that constant governed speed as the airplane accelerated in the climb.
Example Sentence 2
As the airplane climbed and airspeed increased, the governor adjusted blade pitch to keep the constant governed speed unchanged.