Ah, seems to be the evening to spout off about anything but
Triumphs. Maybe 'cause my *&!%! parts aren't here yet....
The simple answer is that accelerating while in a curve helps
the car negotiate the curve by moving the car towards understeer
(in a manner of speaking.) Braking while in a curve moves the car
towards oversteer. So you should slow down before entering the
curve, then accelerate through the curve (but not 'till the back
wheels come loose :-)
If you want the long answer keep reading. I've tried to interpret
the math in useful terms. Please don't let the following paragraph
stop you.
Vector analysis of the motion of a particle along a curve
results in the following expression for the acceleration
vector A acting on the particle:
A = (s' )T + (s^2 K) N,
where
s' is the rate of change in the speed of the particle
T is the unit tangent vector
s^2 is the square of the speed
K is the curvature
N is the unit normal vector
These two vectors, (s')T and (s^2 K) N, add together to get the
acceleration acting on the car.
Assume for the sake of example that you're turning
left, like at Indy (I can dream can't I). Since N always points
towards the center of curvature, it points directly left over
the driver's door. T always points straight ahead over the hood.
If s' is positive (goosing the gas) then A points toward where you
want to be (ahead and to the left.) When s' is negative (braking),
A points behind and to the left, where you were, not where you want
to go. A picture in this case would be worth most of the preceding
457 words.
See, 15 years of math and a PhD is useful for something besides
adding up the cost of all those parts.
At 10:49 AM 02/26/98 +1100, you wrote:
>
>Rich,
>
>At 11:53 25/02/98 +0000, you wrote:
>>I always understood it that it was best to keep your boot down when going
round
>>a corner so that you got the negative camber of the rear wheels, this
will give
>>you better grip, because as the body rolls, the outside wheel will become
more
>>upright, if you think about it, if the wheels are upright to start with,
then
>>they tilt over a bit, then you are getting similiarites to positive camber.
>
>The centripetal force (between the road and the tire) is responsible for the
>camber change. One reason for accelerating is that doing so transfers weight
>from the front to the rear wheels, improving their grip. There may also be
>2nd-order effects I haven't read about. Someday I'll have to get out my
>Classical Mechanics textbooks and suspension books, install Mathematica on
>my PC, and produce the definitive treatise.
>
>Allen Nugent
>Graduate School of Biomedical Engineering
>University of New South Wales
>Sydney 2052 Australia
>
>
Cliff Hansen
chansen@exis.net
1966 TR-4A CTC 64615L (Hibernating for front end work)
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