Cd #s without area taken into consideration are meaningless.. It is CdA that
matters
Dave
> -----Original Message-----
> From: owner-land-speed@autox.team.net
> [mailto:owner-land-speed@autox.team.net]On Behalf Of John Burk
> Sent: Tuesday, January 25, 2005 5:41 PM
> To: land-speed@autox.team.net
> Subject: Aerodynamics
>
>
> Excerpts from the 1998 book "Aerodynamics of road vehicles":
>
> The front half of a streamlined shape has a minor effect on its
> drag.
> A shape that had a Cd of .25 and 4" ground clearance
> would have a .26
> Cd if it was 2 1/2" off the ground and .35 Cd if it only had 3/8"
> clearance .
> If the nose of a car is on or below center the drag will
> be the same
> and the low nose has down force - If the nose is above center it
> will cause
> lift and have more drag .
> Very little air getting under the car causes lift , a little more
> clearance gives down force and if there's more air getting under
> , it causes
> neither .
> The lower the Cd the lower the wind noise .
> A streamlined shape will have the least drag if the largest cross
> section in the middle and if the length is 6 times the diameter -
> The drag is
> only a little higher if the length is 8 or 9 times the diameter .
> Bulges like in a hood , if shaped well cause very little drag .
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