Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 Fluke 8/7/84; site fluke.UUCP Path: utzoo!watmath!clyde!burl!ulysses!mhuxl!houxm!houxz!vax135!cornell!uw-beaver!microsoft!fluke!marauder From: marauder@fluke.UUCP (Bill Landsborough) Newsgroups: net.cycle Subject: Re: Aerodynamics of large vehicles Message-ID: <1787@vax4.fluke.UUCP> Date: Wed, 15-Aug-84 15:34:55 EDT Article-I.D.: vax4.1787 Posted: Wed Aug 15 15:34:55 1984 Date-Received: Fri, 17-Aug-84 00:41:47 EDT References: <1502@proper.UUCP> Organization: John Fluke Mfg. Co., Everett, WA Lines: 17 Keywords: wind currents,trucks (configuration) You are right about shapes of the trucks and the turbulance they create. I have learned that the worst are big, tall, and square corners all the way around, especially the back of the trailer. The front first creates a high pressure area which pushes everything away from it. Then the back, being big and square, creates a large vacuum area which sucks everything back into it. The real condition which sets up the "big blast" when you are riding by is when the wind is blowing from your left side and the oncoming truck breaks that wind with a monsterous blast of pressure then vacuum. Your riding along leaning slightly to your left against the normal crosswind when the truck goes by and triples the velocity. You counteract by leaning harder to the left just as the truck gets by and the vacuum pulls you violently to the left. It becomes tough to stay in your planned lane when the cross wind is around 30mph and the trucks speed is at 70! This is real common on two lane highways in the deserts. Oh well... just tuck down and hang on!