Friday, February 24, 2012

The “Tenths” and Their Appropriate Use on the Track

I was lucky to stumble upon this fantastic Track Wisdom series of advice written by private racing coach Peter Krause in response to popular threads on various high performance driving/racing bulletin boards. My favorite write-up was on the “Tenths” and their appropriate use on the track. As you will find out below, the real fun starts at 6/10s!


*** The "Tenths, and their appropriate use on the track...", an excerpt from Peter Krause's Track Wisdom series.

When I describe "tenths,” or the system of assigning a relative speed, level of concentration or demonstration of car physics on-track to someone, it usually follows these definitions.

3/10 is driving on a flat, straight and level road with no distractions.

4/10 is driving on a gently curving Interstate with low traffic density at a higher rate of speed than at 3/10.

H-3 Interstate highway, Oahu

5/10 is driving quickly, but efficiently and at the speed limit on the street, more concentration required due to more "hazards" present.

6/10 is a standard DE lap or an out lap early on in a race weekend, for me. The purpose may be to re-familiarize myself with the race track, enjoy a relaxed lap or just "cruise" around and, in particular, designed to take NOTHING out of the car. This is also the level of driving quickly on the Interstate with a fair bit of traffic at higher speeds.

7/10 is a more aggressive DE level, designed to begin to "move the car around" and just a little more taxing on the car. Also, 7/10 can be an out lap later on in a race weekend, usually the result of greater confidence and familiarity. Relatively wide variation in lap time depending on traffic and concentration.

8/10 is an easily sustained level, requiring high levels of concentration, generally attained after the first few laps of a race or enduro when the dust settles and you slide into driving quickly and accurately, but are not locked in a battle that is external to you and your car. The car is sliding, but only at the beginning or the end of a corner and not at all corners and not on all laps. Generally laps are within .8-1.5 seconds apart and relatively consistent. This is the level I am most comfortable taking people around the track. Plenty of "headroom" and margin for error or changeable track conditions.

9/10 is driving pretty hard, but is sustainable, repeatable and the driver is still relatively accurate in their placement of the car. The car is now sliding much of the time, the driver is focused on catching someone or staying ahead of someone but is maintaining control and discipline of their own mind and of the car. At this point, the driver is using most of the width of the road, but not much curbing, and is focusing on drawing large arcs with the path of the car. The rhythm is such that the lap times are generally within .2 -.8 seconds apart, barring traffic or mistakes. This is my limit for one or two "hot laps" with someone riding with me.

9.5/10 is driving hard. More sliding, slightly quicker laps still than at 9/10. Less margin for error, a lot more work being done by the car. The driver is now "guiding" the car on a path selected well in advance. The car is sliding from turn-in, through the apex and is using the entire width of the paved track, plus the inside curbs. Cannot generally be sustained for more than five or six laps. I would not drive a car at this level with a passenger in it...

10/10 is when the skill level of a substantially experienced and supremely confident driver meets the competence level of the car nearly perfectly. The car is sliding nearly the entire lap. Slip angles of 7-12 degrees (DOT radials, less on radial slicks) are sustained through the entire length of most of the corners. The entire width of the road, plus the inside and outside (if available) curbing or pavement extensions are used, every corner, every lap. The previous lap is at 9 or 9.5/10 so that the "hot" lap is started at the greatest possible speed and with the highest possible concentration.

Typically, I drive 10/10's for one or two qualifying laps and my first few laps of the race to build a "gap" to the rest of the competition. I also drive 10/10's to experiment with changes made to the car or to evaluate tires in practice, not to mention putting in a "flyer" to achieve the psychological advantage of being on or near the top of the time sheet <grin>.

I may not drive 10/10’s more than a few laps during the weekend, but I pick and choose the time to do it. I feel like the car and I are balanced on a tightrope and I am constantly making tiny little corrections to adjust its trajectory, with each correction making a difference... I'm not sure this level can be sustained more than two or three laps at a time. In order to be successful at the highest level of most organized competition, you must be able to drive at this level.

11/10's is when your talent runs out! <very big grin>


Author: Peter Krause

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