Check this out:
https://www.youtube.com/watch?v=1X35-bGWpEY
Cleetus put Leroy the Savage (a twin-turbo, 8-second C5 Corvette death kart) into a wind tunnel and measured cd a bunch, including making cardboard aero. We probably all figured that the new-trend body-less death karts were terrible in aero, but not to this extent! It is very interesting that with the amount of stuff on the nose of that thing that the tail is where they picked up all the gains. I think it's time to grab a bunch of coroplast and crawl under the Cobra...
They were testing at the smaller of the tunnels I was at on Friday. They got a quick tour of what we were doing. They seemed suprised at ther drag of thier car comapred to a stock C5 z06 as well.
Exposed tubes are atrocious for drag. I'll bet that if they had those wheels spinning, they'd have been even more surprised.
Anyone got a summary of their findings? No time for 40 minutes of guys going "oh wow!".
In reply to Keith Tanner :
Yeah. That was annoying.
STM317
SuperDork
7/9/18 9:22 a.m.
In reply to Keith Tanner :
The kart had a cd of .75 when they started, and got it down to .66 by removing the rear wing, and doing a bunch of cardboard work. There's enough dead air at the rear that the chute wouldn't deploy on it's own in a windtunnel simulating 85mph.
A stock C5 had a cd of .33, but had more lift as well.
Keith Tanner said:
Exposed tubes are atrocious for drag. I'll bet that if they had those wheels spinning, they'd have been even more surprised.
Anyone got a summary of their findings? No time for 40 minutes of guys going "oh wow!".
I fast forwarded a bunch but here's what I gathered were the important take away messages:
GM knew what they were doing when they designed the C5 bodywork
A rear diffuser reduces drag and increases downforce
A sloped nose increases downforce with little or no drag penalty
An 80 MHP wind will mess up a cute blonds hair
A vertical firewall with a near vertical windshield with no other bodywork creates a ton of drag
When we did the instrumented tests on my Locost, the rate of acceleration fell off a cliff at either 60 or 80 - I forget which. Exposed wheels and control arms, a flat windshield, exposed roll bar. We didn't have a chance to retest without the windshield.
I suspect - no, I know - that an Exocet is tragic from an aero standpoint.
In reply to APEowner :
Those points are generally true no matter what vehicle is being tested.
In reply to Keith Tanner:
I suspect the accel resopnse for that car is a little different (speed to power reaction), but yes lots of exposed stubby things hanging out in the breeze is usually bad. Look at natures fastest/quickest animals and notice that most of them are not blocky/stubby things, but more sleek and streamlined. Nature has had a few years to experiment...
