The hidden *real* drag coefficient

[j-c-c]

Originally Posted by JulianEdgar

I've had a couple of cars with four-wheel steer, and I read a really excellent article on this the other day.

I think yawing down the road would upset all the visual / mental cues that a driver knows to control the car eg if it is skidding.

If maybe when one turns their head to adjust the radio, or chat, and promptly changes lanes or runs off the road, I would think a fixed yaw would matter little once the driver made the adjustment for cross wind drag benefits.

[aerohead]

Originally Posted by aerohead

I'll look. Seems like it was Ford Motor, or SAE that mentioned it. They understood that driving in the REAL world involved a statistically-averaged, annual, 7-mph crosswind component and the wanted manufacturers to reflect that in their testing results submitted for new car certification.

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I'm not finished searching my archive, but I believe that the SAE transitioned into crosswind-averaged drag coefficients with
SAE Paper# 780337, 'Realistic Effects of Winds on the Aerodynamic Resistance of Automobiles,' by Bain Dayman, Jr., Jet Propulsion Laboratory, California Institute of Technology ( CALTECH ), Pasadena, California, USA, February 27-March 3, 1978; which looked at yaw conditions from, negative 5-degrees, up to positive-30-degrees yaw, computer modeling a 'wind-averaged' wind spectra, at 360-degrees effect on CITY, HIGHWAY, COMBINED cycle fuel economy.
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SAE Paper# 881874,from Texas Tech University, is one of the first documents I collected which presents coefficients of aerodynamic drag as a function of degrees yaw, at zero, 2-degrees, 5-degrees, 10-degrees, and 'wind averaged.'