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Old 08-18-2009, 09:02 AM   #10 (permalink)
raquatrac
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lavoiture - '93 Renault 19 1.9 dT
Diesel
90 day: 56.36 mpg (US)
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Quote:
Originally Posted by tasdrouille View Post
At some point, as the trailing vehicle gets close enough, the Cd of the leading vehicle eventually gets lower than the trailing vehicle. Which means the leading vehicle can benefit more from drafting then the trailing vehicle.
I do not think so. The Cd of the drafter may be higher, but his airspeed is now much lower, too.

If you remember the drag equation, the Cd is power one, but the airspeed is power two. In other words, reducing air speed by 29% [one over square root of 2 is 71%] or halving your Cd have the same effect.
(assuming you can do both reductions independently).

Note, also, that the (awful) vehicle shapes depicted in the figure will tend to produce higher drafting benefits than better streamlined vehicles. It'd be pretty pointless drafting an aerocivic, for example ;-)
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Last edited by raquatrac; 08-18-2009 at 04:08 PM.. Reason: clarified the maths
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