Cowling

A cowling is the removable covering of a vehicle's engine, most often found on automobiles, motorcycles, airplanes, and on outboard boat motors.

In aviation, a cowling may be used for drag reduction or engine cooling by directing airflow.

Examples in aviation include the NACA cowling and Townend ring.

Furthermore, turbulence after the air passes the free-standing cylinders is greatly reduced.

After tests in 1932 proved the effectiveness of NACA cowlings, almost every radial-engined aircraft were equipped with them.

The NACA engine cowling on a Curtiss AT-5a .
The engine cowling on a Porsche Carrera GT .