Definition

1. Noun:
   • A type of aircraft or marine propeller: A variable-pitch propeller is a propeller whose blades can be rotated around their long axis to change their angle (pitch) relative to the airflow or water flow. This adjustment allows for optimal performance under different operating conditions, such as during takeoff, climb, and cruise.

Usage

• The term is used specifically in aviation and marine engineering contexts to describe a propeller system where the blade angle is not fixed.
• It is a compound noun. When used, it typically refers to the entire propeller mechanism, not just the act of changing the pitch.

Examples

• Noun:
  • The new aircraft was equipped with a variable-pitch propeller for greater fuel efficiency.
  • Adjusting the variable-pitch propeller allows the pilot to maintain optimal engine RPM.

Advanced Usage

• The concept is central to understanding propulsion efficiency. A pilot or operator can "feather" a variable-pitch propeller (set the blades parallel to the airflow) to reduce drag in case of engine failure.

Variants and Related Words

• Constant-speed propeller: A specific, common type of variable-pitch propeller that automatically adjusts blade angle to maintain a constant engine RPM.
• Propeller pitch: The angle of a propeller blade relative to its plane of rotation.
• Feathering: The act of adjusting a variable-pitch propeller to a very high angle to minimize drag.

Synonyms

• Adjustable-pitch propeller: A direct synonym emphasizing the adjustable feature.
• Controllable-pitch propeller (CPP): A term more common in marine engineering.

Related Phrases

• To change the pitch: This is the action performed on a variable-pitch propeller.
• Propeller governor: The device that often controls the pitch in a constant-speed variable-pitch propeller system.

Noun

1. propeller for which the angle of the blades is adjustable