NACA DUCT

I'm guessing that the blurry image tacked onto this post was what the original dust jacket for this book looked like but since it's fuzzier than my hairy back it's useless for the cause. Thus, I'll use it anyway. Perhaps a definition will suffice, ye?

NACA DUCT

an inlet duct named for the National Advisory Committee for Aeronautics, the U. S. agency that did extensive research into the design of inlet ducts with minimum drag for jet engines. NACA ducts are used extensively on racing cars and some production cars such as the Lamborghini Espada to efficiently feed air to the engine for breathing, for cooling the engine and cockpit and for forcing air through water and oil radiators. 

And you thought you were THE pansophist!

from The Road & Track Illustrated Dictionary by John Dinkel