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Re: Excess G forces in auto racing



It would seem to me that the higher banking keeps the 'g-forces' more
vertical (for the drivers) which should be easier for them to handle than
the high 'gs' on flatter tracks which tend to severely stress the
neck/spine. Running INDY at 220 mph around a 9 degree bank has to be more
stressful on the body than 235 mph on a 24 degree bank. Again, as Hugh
states, we need the radius of the turns to do meaningful calculations.

Rick

(I have no problems with g-forces when driving the IRL/F1/NASCAR circuits.
Of course I never leave the front of my computer when doing so. ;-)

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Professor of Physics
Saint Mary's College
Notre Dame, IN 46556
rtarara@saintmarys.edu

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----- Original Message -----
From: "Hugh Haskell" <hhaskell@MINDSPRING.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, April 30, 2001 12:10 PM
Subject: Re: Excess G forces in auto racing


Ray Rogoway wrote:

Great story in the news and on the web today. CART (Championship Auto
Racing
Teams) drivers refused to race in the Firestone Firehawk 600 at the
Texas Motor
Speedway because of a new track. The track is banked at 24 degrees
and the cars
travel over 236 mph. During practice sessions they got up to 236.9 mph.
See
www.cart.com and click on the second story. The San Jose Mercury News has
a
longer article and includes a graphic showing the Texas Motorway bank a
24
degrees, the Michigan speedway at 18 degrees, and the Indianapolic Motor
Speedway at 9 degrees.

Great warm-up exercise for the class to calculate and compare the
"g" forces on
the three tracks.

I thought it would be, too, but the story in my paper didn't give any
data on the radius of curvature of the various portions of the track.
The article did say that accelerations of up to 5 g had been
recorded. I made some reasonable assumptions about radii and came up
with about 3 g at 24 degrees of bank. Maybe we could use the 5 g
result to calculate the maximum radius of curvature. Doing that, and
assuming that the 5 g they are talking about is directed
perpendicular to the car, gives a maximum radius of curvature of
about 115 m, or about a third of the radius of an equivalent circular
track. This was about half the radius I assumed based on the
statement in the story that it was a 1.5 mile long oval track.

The people who operate these tracks are not stupid. I find it
difficult to believe that they had never bothered to calculate the
accelerations involved in making turns at the speeds these cars are
capable of. They decided to increase the bank to 24 degrees so that
the cars could make the turns at maximum speed, which certainly
implies to me that they had calculated the friction force necessary
to keep the cars on the road at that speed, and that calculation is
almost the same as the acceleration calculation. Why were they
surprised when the drivers reported the effects of high-g
accelerations?

Hugh
--

Hugh Haskell
<mailto://haskell@ncssm.edu>
<mailto://hhaskell@mindspring.com>

(919) 467-7610

Let's face it. People use a Mac because they want to, Windows because they
have to..
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