triumphs
[Top] [All Lists]

Re: accelerating while cornering

To: triumphs@Autox.Team.Net, chansen@exis.net
Subject: Re: accelerating while cornering
From: "Larry Hooven" <dirty_howi@hotmail.com>
Date: Wed, 25 Feb 1998 20:04:23 PST
the odd part of cliffs answer is it's the only one i really 
understand......hmmmm  too much time with a nose in a book instead of a 
gear case i guess...

larry


----Original Message Follows----
Date: Wed, 25 Feb 1998 22:41:20 -0500
To: triumphs@autox.team.net
From: Cliff Hansen <chansen@exis.net>
Subject: Re: accelerating while cornering


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)




______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

<Prev in Thread] Current Thread [Next in Thread>