coefficient of drag

rjmaype · **Posted:** Thu Dec 16, 2010 1:52 pm

I read the new Ford Explorer was designed with a CD of 3.5 to gain a 25 MPG highway rating with a 3.6 gas engine.

Does anyone know the 2005-2006 CD for the CRD?

ihatemybike · **Posted:** Thu Dec 16, 2010 2:23 pm

Think you might have shifted the decimal.

Cars.com
2006 KJ = .42
2010 Explorer = .41

LibertyCRD · **Posted:** Thu Dec 16, 2010 3:32 pm

.35 is pretty darn good. Some people are surprised at which vehicles do well and which don't. For example, in 2006 the Chevrolet 1500 pickup truck had the same drag in the wind tunnel as a Corvette. Pretty amazing how certain lines on a vehicle can make it "slippery" even though it doesn't visually look that way.

ihatemybike · **Posted:** Thu Dec 16, 2010 3:43 pm

Just for S&Gs I looked up my vans.

1985-2005 Astro = .38

UtopiaCRD · **Posted:** Thu Dec 16, 2010 5:43 pm

I'm no aerodynamics engineer, but I do know that th CD is just that -- a coefficient. It is NOT the drag for a vehicle, but just a factor in the drag. You multiply the CD by the frontal area of the vehicle (and other factors) to get the actual drag.

So a 'vette and a truck might have the same CD, but that does NOT mean they have the same drag. The truck has a much bigger frontal area, so it's drag is much higher. Ditto on the van.

tjkj2002 · **Posted:** Thu Dec 16, 2010 5:57 pm

UtopiaCRD wrote:

I'm no aerodynamics engineer, but I do know that th CD is just that -- a coefficient. It is NOT the drag for a vehicle, but just a factor in the drag. You multiply the CD by the frontal area of the vehicle (and other factors) to get the actual drag.

So a 'vette and a truck might have the same CD, but that does NOT mean they have the same drag. The truck has a much bigger frontal area, so it's drag is much higher. Ditto on the van.

Actually you are wrong also.A Chevy pickup has less "drag" then a Indy race car,but the Indy car uses that drag and converts it to downforce.

ATXKJ · **Posted:** Thu Dec 16, 2010 8:37 pm

both

high performance sports cars have high Cd's because of downforce effects
in fact an F1 racer can easily be close to 1 depending on which track it's setup for

and a truck will have 2x the frontal area of a Corvette - so the same Cd will give 2x the drag.

ihatemybike · **Posted:** Thu Dec 16, 2010 10:52 pm

I just stick with the vans being more aerodynamic in my head. Has to be some reason for Grumpy being able to pull off better mpgs than Eugene. :lol:

UtopiaCRD · **Posted:** Thu Dec 16, 2010 11:43 pm

ihatemybike wrote:

I just stick with the vans being more aerodynamic in my head. Has to be some reason for Grumpy being able to pull off better mpgs than Eugene. :lol:

I read once that the old VW Beetle and the VW Bus had the same drag. Anybody who ever drove a Bus against the wind at 65, then down to 60, then 55, then 50... -- knows better.

coefficient of drag

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