Where it could make a difference is in height variations between the start
and finish lights. As Dennis Laczny of Raceamerica points out, it
requires at least 1/2 inch of solid object to trip the sensors he uses.
Assuming that he's got about the best you can get, let's do some
calculations.
As I mentioned, at 30 mph, a car is traveling 44 ft/sec. That's 528
inches/sec, or 0.528 inches per millisecond. Lets assume that the start
and finish lights vary in height by 3/4 of an inch. Car one crosses the
start line and his front bumper blocks the beam, triggering the timer.
Going through the course he crosses the finish line but that beam is 3/4"
lower. That lower beam just misses his bumper and hits the front of the
body work which is 2 inches behind the bumper. His time is now increased
by 4 milliseconds. Car 2 does the same thing but his bumper cuts the beam
at both the start and finish. His time is 0.002 seconds better than car
1. In this example, car 1 crossed the finish line in a faster time but
minor variations in equipment robbed him of the win.
My proposal is to recognize that we can't be that accurate and round times
to 0.01 seconds which represents 5 1/4" at our typical speeds. The rules
already have a tiebreaker procedure - you take the next best runs and
compare them. That would reward the consistently fast driver.
Just some food for thought. Only once would it have affected me. When I
lose it's usually by a much wider margin like this past Sunday. The #1
guy drove well, I drove poorly in places and my times prove it.
glen
================================
Glen E. Thompson
glen.thompson@worldnet.att.net
'89 Mazda RX-7 GTUs
-----Original Message-----
From: owner-autox@autox.team.net [mailto:owner-autox@autox.team.net]On
Behalf Of Craig Blome
Sent: Tuesday, October 05, 1999 1:14 AM
To: Glen E. Thompson; autox@autox.team.net
Subject: 1/100ths (was Re: Autocross Timing)
I'd be for at least discussing it. We haven't
established so much as a standard height for timing
lights AFAIK, which is bound to result in some error
among various types of car. Yes, I'm aware the error
is in the same direction in the start and finish; but
there is some slop in the distance a car travels from
launch to the start lights, and the resulting
variances in speed through the start could be worth
thousandths or even hundredths over a 60 second
course.
Of course, most sports don't add the results of two
days of competition. I don't remember whether that
makes the odds of a tie higher or lower...
Aww what the hell, hundredths ain't gonna get me any
closer to Gary Thomason's time. :)
Craig Blome
--- "Glen E. Thompson"
<glen.thompson@worldnet.att.net> wrote:
>
>
> Which brings the question of whether we want to try
> measuring times to
> that accuracy. If two drivers are tied to the
> hundredths, can we be
> really sure that one beat the other? At an average
> speed of 30 MPH on a
> course, a difference of .001 second relates to 0.53
> inches. If side by
> side, could you tell which one won? In Rocky's
> Mirrorkana, I'm sure it
> would be declared a tie. Yet in most events we
> would call one of them a
> winner.
>
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