This is a real good read into the understanding what actually goes on when you race a car

He was driving a C4 at the time he wrote it.

Brian Beckman's The Physics of Racing
http://phors.locost7.info/contents.htm

There's downloadable PDF's on the site.

I put it in Corvette Chat since it's worth reading even if you don't race.

something more to add

The local SCCA came up with a handout that's also a good read

http://www.ner.org/sites/ner.org/files/drivingschoolnotes.ppt

But there seems to be a contradiction.

NER SOLO handout last page
Quote:

Physics of Racing, p17
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Reading his later chapters, he's optimizing total time on the track by setting up faster times on the straights.

Since we're dealing with cones and not curbs we can get real close, the smallest radius being dictated by the turning radius of the particular car you drive.

or course since
a=v^2/r
or
v=sqrt(a*r)
you're going a lot SLOWER even though you change direction FASTER

If that leads into another turn, that's not necessarily a bad thing.
If it lead onto a straight, that's another matter, but there's not too many long straights autocrossing.

I found an old Devens National Tour course map

I think I'll punch it into my CAD program and see what I come up with using his calculations

Doing some physics analysis to see if I can improve my times at the autocross.

1st run through is a simple circle.

1 foot/second = 0.682 mile/hour (mph)
lateral G

Assuming:
1 G lateral grip
1 G braking max
and
1 G acceleration, keeps it simple and it matches my 60ft times.

a=v^2/r
a*r=v^2
v=sqrt(a*r)
Gives me the max speed in a turn

c=2*pi*r
t=c/v
Give me the distance covered and the time it takes to cover it.
As predicted the smaller the circle the better for turning direction, though the speed is kept low.



Next up, A SIMPLE SLALOM.

The curve is dictated by how far the cones are set apart, the width of the car, and how close the driver can get to the cone.


I ran three slaloms 25ft, 50ft, and 100ft separation.
with the car's center being 4ft and 3.5ft from the cone @ apex.

As you can see being closer to the makes a big difference.
The distance is about the same, but the speed is higher.


Next up, AN S TURN

I first calculated the distance between the cones as a reference even though you could never make the corner that way, it shows what the absolute minimum distance would be.

Next I used an s-curve to find out what the max radius the element could be taken
This gives the speed that would be used throughout the element.
It also gives the entrance and exit speeds

The car's turning radius gives the path with the shortest drivable distance.
A straight is used to connect the two curves.

The turning radius give the max speed in those two curves, the entrance and exit speeds.
The straight line between is used for acceleration and then braking.

I also ran a curve with slightly wider turns at the corners.

Times are then calculated.

I do plan on adding more to the models

Forgetting Beckman's math not taking into account contact patch area.

This statement struck me as rather odd.

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