Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83 based; site hou2h.UUCP Path: utzoo!watmath!clyde!floyd!harpo!ulysses!mhuxl!houxm!hou2h!an From: an@hou2h.UUCP (A.NGUYEN) Newsgroups: net.auto Subject: Drag coefficient Message-ID: <325@hou2h.UUCP> Date: Fri, 2-Mar-84 13:02:54 EST Article-I.D.: hou2h.325 Posted: Fri Mar 2 13:02:54 1984 Date-Received: Sat, 3-Mar-84 23:23:03 EST Organization: AT&T Bell Labs, Holmdel NJ Lines: 25 . A Cd of say .35 means the vehicle has 35% of the aerodynamic resistance of a barndoor of the same frontal area. Notice that low Cd alone does not mean less drag. A Mercedes with a .35 Cd would still have more drag than a Civic CRX of the same Cd, because of the former's larger frontal area. Streamlining isn't just making a swoopy shape (see Porsche 928.) The object is to smooth the airflow around the vehicle. Details are important (see Mercedes Benz.) Competitive swimmers shave their body. Aircrafts use paints that present a smoother surface to the air rushing by. Aerodynamic effects increase with velocity squared. Double the speed and air resistance is quadrupled. Aerodynamic resistance is the major power consumer above 30-40 mph approx. Because of this, streamlining is the most sensible way to improve performance (gas mileage, acceleration from higher speeds, top speed, etc, see Honda Civic CRX.) Less power used to punch a hole in the air means more power left to accelerate you from 50 to 70 mph for that quick pass (left lane hogs take notice!) Au Nguyen