Cooling Systems

021-10-05Pablo Asensio Martínez2026-03-241 min

Air Cooling Principles

  • Mechanism: Reciprocating engines (especially in GA) are typically air-cooled.
    • Uses Ram Air from the atmosphere to cool cylinders.
    • Source: Propeller slipstream and aircraft forward movement.
  • Cylinder Fins:
    • Cylinders have external fins to increase the surface area in contact with the cooling air.
    • Improving heat transfer.
  • Cowling: Used to direct airflow efficiently over all cylinders (front and rear) and reduce drag.

Cowl Flaps

  • Definition: Movable flaps (usually at the bottom/rear of the engine cowling) that regulate the amount of air flowing through the engine compartment.
  • Function: Control engine temperature by regulating airflow.
    • Open: Increases airflow $\rightarrow$ Decreases engine temperature. Used during high power/low airspeed operations (e.g., Takeoff, Climb).
    • Closed: Decreases airflow $\rightarrow$ Increases engine temperature (or prevents over-cooling). Used during low power/high airspeed operations (e.g., Descent, Cruise) to prevent shock cooling and reduce drag.
Written and reviewed by

Pablo Asensio · 2026-03-24

Aeronautical engineer. Passed the thirteen EASA ATPL(A) theoretical knowledge exams studying from these very notes. Writes and reviews each topic against the Part-FCL Learning Objectives.

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