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Originally Posted by Hermie
Actually, I haven't been putting too much time into looking up stuff.
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Awww. I was hoping for supporting documentation. The spinning (and flying shortly after the spin) Mazda in the previous thread was an eye-grabber, but from an argument supporting standpoint, it's like arguing that water is bad for you and using the Titanic as your example.
Quote:
Originally Posted by Hermie
I do have a life, and a college career to attend to.
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That deserves an attaboy and a woohoo! I used to teach (before I got in the aero biz) and I have huge respect for anyone who chooses a career in education. To quote Farm Boy (in the Princess Bride again, but at least this time I got the character right), "This isn't as easy as it looks."
Quote:
Originally Posted by Hermie
Besides, it's common sense that lift degrades performance. Why would people that actually work designing cars spend time and money publishing papers stating the blatantly obvious?  |
Hah! Now I know you're not teaching aerodynamics (and if you're teaching any of the sciences, I hope you don't use terms like "common sense" and "blatantly obvious" much in class). I would agree that lift degrades cornering force and braking force, and that at the lower end of the speed spectrum, lift degrades acceleration, but if you set up a car for less than optimum lift, it will degrade high speed acceleration and top speed.
That may not be common knowledge, because in many motorsports (e.g. dirt oval racing, and in the highest power classes, Bonneville) the course is too short or tight to achieve genuine top speed, but elsewhere there's an optimum. The NASCAR guys tune in less lift at the slow tracks than they do at the fast tracks, because at some point (determined by horsepower, speed, and the mix of tight corners to long straights), reducing lift costs more energy than it is worth. It wasn't until the mid-'60s that Formula 1 cars had enough power that top speed wasn't an issue and it was worth getting the lift down to zero (and they've gone way way past that since then, to negative lift, then to negative lift greater than the mass of the car).
Of course, having more than optimum lift costs energy too. Remember "Fastbacks"? The looked fast, they looked like they were pulling the car's wake into the dead water behind the car, but if you look at a car like a wing section with an aspect ratio of about .5, the induced drag from what the airplane folks call tip vortexes was far worse than the pressure drag. But for minimum drag, a car is going to generate lift, and if you go over or under that optimum Cl, you'll increase drag, which will cost you in top speed, in high speed acceleration, and in what matters most on this forum: fuel consumption.