Analytical Studies on the Effects of Cooling Flows on Light Aircraft Drag

A source-paneling body analysis computer program was modified to permit arbitrary panels to be opened to receive or exhaust cooling air flow. It was found that exhausting the cooling air into concave regions such as before the windshield or behind the canopy resulted in decreased drag, probably because of the streamlining effects of the airflow. This suggests that the drag of single-engine light aircraft could be reduced by redesigning the cowl to entrap air below the propeller axis and exhaust the cooling portion of it (but not the engine exhaust) through flush ports in front of the windshield.