I know some serious tires will give you "stick" like slicks all spun up and stuff...

but what about normal sports cars?

they can pull latteral G's in excess of 1 due to downforce and all-

but what about when you floor it and slam on the brakes?

 

Well, after some quick math:


9.8 m/s^2 * 1 mile / 1600 m * 60 s / 1 minute * 60 minutes / 1 hr = 22.05 miles per hour per second. So, basically, if your car goes accelerates from 0-60 in less than 3 seconds, you pull more than one 6, and same with deceleration. You obviously pull a lot more Gs with stopping than with accelerating, unless you're a freak with Brembo, Wilwood, or Baer everything on a stock 2.8 L.

 

You are "limited" to 1G only if you assume the tire/road contact patch is subject to pure friction. In fact, there is mechanical interference between the tire tread and the paving material, and now the "limit" is the shear strength of the tire compound. Throw down some "traction" compound, and you are now actually using an adhesive to eliminate slippage even further. Top fuel dragsters can reach peaks of 8G's on launch.

 

According to Dragstrip2000, my car pulls 1.2g's off the line. I don't have an enertia meter to see if it's true but that 1.2g's is only briefly. As the car accellerates, g forces drop off as the torque curve gets closer to the top. By the end of the 1/4 mile I'm only pulling 0.27g's.

Use the above formula to calculate the G forces. A top fuel dragster travels the first 60' in about .85 of a second. It's supposed to be between 5-6g's on launch for them however when they pull the chute at 330 mph, they can pull 8g's decellerating.

 

well the chute is different. that doesnt't involve friction with the ground

 

F1 cars generate far more than 1G of downforce. I once read that in max downforce configuration they exceed 1G at ~60mph. Which means they could drive upside down as long as they maintained at least that speed! That has nothing to do with friction, of course. But it is still cool.

Rich

 

Yes, tire/road friction coefficient (C of F) can exceed 1g as Injuneer said. The mechanism is complex.

Acceleration (+ or -) depends on the C of F and "normal" load, or the load downward on the tires. Here is where aero downforce helps. With 3 times the weight of the vehicle pushing down on the tires and a 1.5 C of F traction force can be 4.5 times weight so with enough power accelerations can greatly exceed 1 g.

As far as braking goes, aero downforce at high speeds also creates aero drag which is a braking force. An F1 car has about 2 gs of aero braking when the driver lifts at 180 mph or so.

 

A reliable source once told me that Einstein was once asked about how fast a dragster might be able to go. His reply was 9s (had to do with 1 G). He neglected to consider traction. Add a wing and look where we are today.

 

That may have been Roger Huntington who also said 150 was the limit in the quarter. He had to retract those statements as the times/speeds were exceeded.

Albert died in 1955 when best ETs were just into the 10s. He also wasn't a "gearhead":

"You cannot love a car the way you love a horse. The horse brings out human feelings the way machines cannot do."--A.Einstein

 

Could be.

Oh, I would never poke fun at Albert.

What's even more cool is how easy it is to go fast today. I just met a guy at work the other day who loves drag racing. He can remember just like it was yesterday when Big Daddy was breaking records running 9s. Now a days a 9s car is pretty common.