Originally Posted by chuck65
I know this will stir up quite a debate and let me state from the beginning that I really like the looks of our spoiler and the fact that it deploys at 60 and retracts automatically, I question the functionality of it.
The Crossfire's spoiler is functional. It's 80 lbs @ 80 mph functional, if Chrysler is to be believed. I'm sure our rear diffusers have something to do with it too.
Originally Posted by chuck65
On a fast track such as Indy, Formula 1, and even sprint car tracks, you need to have a spoiler on the rear and the front of the vehicle. Pushing down on the back only lightens up the pressure on the front and leads to steering problems. Also notice that at the comparatively slower speed of the sprint car you have much larger spoilers.
I believe Indy and Formula 1 cars use wings, not spoilers. Second, front wings are required on F1 cars because the rules prevent the use of underbody aerodynamics (raised footboxes are required, etc.)
You assume, incorrectly, that pushing down on the back of a car leads to steering problems. Pushing down on the rear of the car with 80 lbs applies very little lifting force to the front of the car because of the lever arm. Imagine the car as a see-saw pivoting around the rear axle. Our rear spoiler is less than a foot from the rear axle yet the front wheels (and about 90% of the car's weight) are a little less than 8 feet away. Basic physics will tell you that the lifting force on the front wheels will be a maximum of 10 lbs, and when you take into account that 10 lbs of lifting force acts on more than 2500 lbs, you hopefully see that the steering is, for all practical purposes, unaffected.
Originally Posted by chuck65
In the case of going for top speed on a relatively straight course wouldn't the spoiler act as a drag to air flow and affect the top speed and make the front end light and affect steering?
The spoiler acts as a drag to airflow, but does so in exchange for downforce. There is no free lunch. In this specific case, the more downforce you make with the spoiler, the more drag is necessary to create it. The efficiency of our rear spoiler is unknown. This is known as a lift-to-drag ratio.
Yes, our top speed would be reduced due to the increased drag. A small price to pay for that rock solid feeling you get in our cars at unmentionable speeds, in my opinion.
No, it will not affect steering. The DC Engineers did a great job making sure that the existing steering system took the rear downforce into account.
My name is sonoronos and I love engineering.