To add to this interesting discussion about more g's but slower times, we
have found the same on several occasions. The line does make quite a
difference; however, in your setup for the g-cube, you specify a certain
deg/g for the lateral compliance. If you specify a stiffer number than you
actually have, you will record more g's. Perhaps part of the difference
people are seeing is due to the setup calibration and mounting in the car.
I would like to share with you another number that we have found by
plotting the average g's (average of the g-vector from the start to the
finish of an autocross). The correlation is quite good and shows that an
increase in 0.1 g's average results in 3.0 seconds on a 60-second course.
This 0.1 g's can come from driver ability or from the tires. Further,
tires drop by 0.1 to 0.2 g's as they wear from new to about 25% of the wear
indicators left (I'm referring to racing slicks on a Formula SAE car).
We use this average g's as a metric for evaluating our driving. This might
be something that Byron might want to include in his metrics. Incidently,
at SCCA nationals, we have recorded over 1.1 average g's (with no aero).
Dr. Bob Woods
Faculty Advisor, University of Texas at Arlington Formula SAE
Amod driver
At 12:25 PM 5/6/00 -0400, you wrote:
>GH Sharp responded:
>
>>In a message dated 5/5/00 3:45:14 PM Eastern Daylight Time, Todd wrote:
>>
>>> I've specifically been focusing on being agressive this year and GEEZ
>>> seems to reflect this, but I'm beginning to think I've reached the limit
>>> on how far just raw pushing it can take me.
>>>
>>> My theory is that aggressiveness will take you to a certain level at
>>> which you'll plateau. Only by being smoother can you keep the car
>>> settled and put the power down (in a relatively high horsepower RWD
>>> car) and ultimately generate more grip for better times.
>>
>>There is some truth to that, but more cornering grip and bigger lateral
>>"numbers", regardless of how you obtain them, *may* not be the answer
>>to a faster time. Bob is likely taking a better *line* than you are in
>some
>>places, and getting through certain parts of the course quicker than you
>>even though you're pulling higher "numbers" in those areas. An example
>>would be a slalom in which one driver pulls the maximum lateral g's that
>>the car can generate around every cone, when another driver might be
>>able to negotiate that slalom by running a tighter (and shorter) line
>through
>>the cones which might not necessarily generate the same peak lateral g's.
>>
>>> Thus my corollary is that even though I'm being scored at 99%, that
>>> rating is based on the peak and sustained values I can generate. If you
>>> were to put Bob in my car, his G's would be even higher and thus my
>>> ratings would go down in comparison.
>>
>>If I understand how Geez figures this (Byron or someone correct me if I'm
>>wrong), the usage numbers are based on how closely the driver comes to
>>the peak numbers seen when he drives the car. Therefore lower "peaks"
>>by another driver can actually generate usage percentages similar to those
>>of the first driver, as long as the second driver stays equally close to
>his
>>lower
>>"peak". (I'm not sure I even understood that explanation myself <g>).
>>
>>OK, a friendly wager: I'd bet that if Bob and you had both driven your car
>at
>>Lemoore, Geez would likely have shown your peak numbers as being *higher*
>>in some places on the course than his, but he actually may have negotiated
>>those portions of the course as quickly, or more so, than you. He may have
>>used a line which was straighter in some places than yours, loading the car
>>less (and generating lower Geez numbers) but letting the car use its power
>>to push the car forward, instead of against the cornering loads of the
>tires.
>>Another consideration: that straighter line may also be shorter, so he
>drove
>>less distance to get through the course.
>
>I concur with this. When I started autocrossing in the late 80s I bought a
>g*Analyst and I worked at generating the greatest Gs at every possible
>opportunity. It wasn't until I compared my runs with fellow C/D stocker Jeff
>Perkins that I discovered he ran about the same lap times (or in some cases
>better), but I consistently generated more Gs than he did. Now, mind you I
>was driving a Porsche 944 at the time and he was driving an MR2 so you could
>say the difference was the car. But when I compared myself to Noel, his
>wife, I found that my lap time was slightly faster, but she drove the car
>much more like I did.
>
>What you really need to do is compare your runs to a variety of other
>drivers and see how their style and line may be better or worse than yours
>on that particular day. It would be incredible if we could get hundreds of
>drivers on the same course under the same conditions so we could compare
>various approaches. Topeka '00???
>
>Paul Foster
>
>
>
>
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