Quote:
Originally Posted by DGthe3
Yes, I ignored that -but with good reason. When a car is said to be producing downforce, the number quoted is the net result of the lift and downforce being generated. In theory, the body shape of the Z06 might be producing say 100 lbs of lift, while the various aerodynamic devices tacked on produce a sum total of 300 lbs of downforce, for a net result of 200 lbs downforce.
Yes, this is expressed in the increased rolling resistance. And as far as the tires & suspension are concerned, it doesn't really matter if its extra mass or aerodynamic downforce thats pressing down on them. So in that respect, you were right before when you said that aero & extra weight were the same.
But at speeds where aerodynamics become important, rolling resistance plays a fairly small role. I'm not 100% certain, but I think rolling res is a constant (based on the normal force at the tire). Aerodynamic drag is proportional to speed squared. So as speed increases, drag will quickly come to dominate over rolling resistance.
Thats right. Create a pressure map, integrate over the surface area and you get a net force either up or down, for lift or downforce respectively.
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Maybe I misunderstand, but it sounds like we are saying the same thing. Adding a person imparts a downward force (mass of person * acceleration of gravity) and negative lift imparts a downward force (pressure differential). Both can be expressed in terms of Newtons (1kg m/s2 = 1 Pa = 1/6,894.8 psi). Both increase grip by the same principle, but negative lift also increase drag but adding a person doesn't really (unless you strap them to the roof
) Does that sound right?