It's all in the details
Almost any smooth amorphous automotive shape will show decent aero, but windshield rake angle is a significant factor. Beyond this it's all in the details. That's why modern cars have flush mounted glass and reveal moldings and tightly integrated bumpers versus pre seventies energy crisis designs.
A few years ago Road and Track had an article on automotive aero. They included a table of features that allowed one to estimate the Cd of a car. I didn't try this with the Corvette, because it is a bit different than a sedan, but I ran the numbers for my Cosworth Vega. A Vega hatchback coupe has a decent overall shape, but the glass and doors are recessed and the drip rails and bumpers hang out in the breeze. I computed 0.45, and I'd bet big bucks it's within 30 points (a point is .001) of the real number. A Saturn coupe is around 0.35
In 1989 as I was doing final prep on my MBZ 190E 2.6 to start the Silver State Classic Challenge (the Nevada open road race)the crew of a 944 gridded several places ahead of me chucked as I removed the mirrors and taped up most of the grille and body seams. I wanted to tape up my navigator's door but he refused unless I was willing to tape up my door and crawl in through the sunroof.I told the Porsche crew I figured it was worth a good three MPH. They chuckled again. It was probably about 10 miles down course when we first recognized the black 944 about about 1000 yards out. As I pulled up within a car length I noted that we were making 132 and estimated the 944's speed at 129, a three mile per hour difference. It was like walking past a parked car. My navigator gaves them a "thumbs up" as we cruised on by and I remarked that maybe next year they'll tape it up. Gimme five minutes and a roll of duct tape and I'll take at least 20 points of the drag coefficient.
Duke
Almost any smooth amorphous automotive shape will show decent aero, but windshield rake angle is a significant factor. Beyond this it's all in the details. That's why modern cars have flush mounted glass and reveal moldings and tightly integrated bumpers versus pre seventies energy crisis designs.
A few years ago Road and Track had an article on automotive aero. They included a table of features that allowed one to estimate the Cd of a car. I didn't try this with the Corvette, because it is a bit different than a sedan, but I ran the numbers for my Cosworth Vega. A Vega hatchback coupe has a decent overall shape, but the glass and doors are recessed and the drip rails and bumpers hang out in the breeze. I computed 0.45, and I'd bet big bucks it's within 30 points (a point is .001) of the real number. A Saturn coupe is around 0.35
In 1989 as I was doing final prep on my MBZ 190E 2.6 to start the Silver State Classic Challenge (the Nevada open road race)the crew of a 944 gridded several places ahead of me chucked as I removed the mirrors and taped up most of the grille and body seams. I wanted to tape up my navigator's door but he refused unless I was willing to tape up my door and crawl in through the sunroof.I told the Porsche crew I figured it was worth a good three MPH. They chuckled again. It was probably about 10 miles down course when we first recognized the black 944 about about 1000 yards out. As I pulled up within a car length I noted that we were making 132 and estimated the 944's speed at 129, a three mile per hour difference. It was like walking past a parked car. My navigator gaves them a "thumbs up" as we cruised on by and I remarked that maybe next year they'll tape it up. Gimme five minutes and a roll of duct tape and I'll take at least 20 points of the drag coefficient.
Duke
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