How does an augmentor system increase cooling airflow over a reciprocating engine?

How does an augmentor system increase cooling airflow over a reciprocating engine?

• A. It uses a larger radiator.
• B. Augmentors use exhaust gas velocity to cause airflow over the engine so that cooling is not entirely dependent on the prop wash.
• C. It slows down the propeller to increase airflow.
• D. It adds coolant to the engine.

Answer: (B)

An augmentor increases cooling airflow by using the energy of the exhaust to pull extra air over the engine. The exhaust gas is directed through a duct or nozzle around the cowling so that its high velocity creates a jet that entrains ambient air and drives more air across the cylinder fins. This adds to the airflow produced by propeller wash, which is especially important at low airspeed or high power when normal ram air might not be enough. In air-cooled engines, cooling is accomplished by air flowing over the fins, not by radiators or liquid coolant, so adding coolant or a larger radiator isn’t applicable. Slowing the propeller would actually reduce the available cooling airflow.

An augmentor increases cooling airflow by using the energy of the exhaust to pull extra air over the engine. The exhaust gas is directed through a duct or nozzle around the cowling so that its high velocity creates a jet that entrains ambient air and drives more air across the cylinder fins. This adds to the airflow produced by propeller wash, which is especially important at low airspeed or high power when normal ram air might not be enough. In air-cooled engines, cooling is accomplished by air flowing over the fins, not by radiators or liquid coolant, so adding coolant or a larger radiator isn’t applicable. Slowing the propeller would actually reduce the available cooling airflow.