What is cowl flaps?

Answer 1

I don't know why your question is in diet and weight loss, but I'll give you the answer in aeronautical terms.

Cowl flaps are a little different in comparison to trailing edge flaps. Normally you will see cowl flaps on multi-engine airplanes such as the Piper Seminole. Cowl flaps will be located underneath the engine Nacelle (the housing for the engine). The cowl flap looks like a box scoop that hinges from the front bottom of the nacelle and opens towards the back of the nacelle. The reason for a cowl flap is for engine cooling and to some degree increasing drag. Engine cooling is most important for takeoff, because the engine is working the hardest during this time. On takeoff usually the cowl flap is open, during cruise it is closed or open depending upon the temperature of the cylinders. On landing the cowl flaps are normally closed because the engine is barely working and the airflow into the engine would cool the engine too rapidly. The cowl flap handles are normally located beneath the throttle controls, and have normal operation of "open" "intermediate" and "closed."

Hope this was the answer you were looking for.

~Gamut