Interesting DRAFTING article
10-23-2006, 03:49 PM
#1
Race Director
Thread Starter
Interesting DRAFTING article
note, DRAFTING, not Drifting UGH!
November Racecar Engineering has a nice wind tunnel analysis of 2 stock-ish cars. While it is fairly easy to understand that the following car gets a nice toe, they lead car gets quite a boost as well, and they put number out there for us to see.
Basically, at 4" apart, the lead car gets a 20% reduction in drag, while the following car gets a 35% reduction in drag. This allows both cars to get away from any other cars running alone, but the following car gets that sweet slingshot effect we love to see in Formula One (I guess NASCAR as well, although I don't watch it).
When you extend the distance to 8", the lead car still gets 15% reduction, and the 2nd car 20%.
What does this mean in real numbers? Well, using a pretty generic bit of data (Cd=.2, frontal area 18ft ft) at 200mph, the 4" draft would give the lead car a 40HP advantage, and the following car a 75HP advantage over the cars running in clean air.
Obviously, most of us don't drive 200mph, but if you ever get the chance, try and get one of your buddies to tag along to boost you mpg!
November Racecar Engineering has a nice wind tunnel analysis of 2 stock-ish cars. While it is fairly easy to understand that the following car gets a nice toe, they lead car gets quite a boost as well, and they put number out there for us to see.
Basically, at 4" apart, the lead car gets a 20% reduction in drag, while the following car gets a 35% reduction in drag. This allows both cars to get away from any other cars running alone, but the following car gets that sweet slingshot effect we love to see in Formula One (I guess NASCAR as well, although I don't watch it).
When you extend the distance to 8", the lead car still gets 15% reduction, and the 2nd car 20%.
What does this mean in real numbers? Well, using a pretty generic bit of data (Cd=.2, frontal area 18ft ft) at 200mph, the 4" draft would give the lead car a 40HP advantage, and the following car a 75HP advantage over the cars running in clean air.
Obviously, most of us don't drive 200mph, but if you ever get the chance, try and get one of your buddies to tag along to boost you mpg!
10-23-2006, 06:43 PM
#3
Team Owner
but I think gas is cheaper than bumpers & fenders even at the high price it was. 
When I was a 19 two of us were on a 200 cc single cylinder motorcycle tucked in behind a box truck doing about 70 MPH. You could feel the draft but it was a bit suicidal to be 2 feet off the back of the truck. Nice read thanks!
