I think that there are two groups of race car drivers – the ones with natural god given talent and those that need to learn the proper driving techniques in order to be fast. I would venture to say that less than 1% have the god given talent and the rest of us need to rely on our ability to learn to get the job done. I’m definitely part of the 99%. Also, I’m very consistent in almost everything I do but unfortunately that means that I could consistently be doing something wrong and not know it until someone (or something) points it out. That is where the data system comes in. Analyzing my data has pointed out some things that I should have been doing differently in order to go faster and as a result I believe that the earlier a driver’s techniques are analyzed the better the driver will be.
For example, below is a screen shot that shows some different traces over a given lap at Summit Point Raceway. The 2nd trace is speed and one thing to look for (especially with a new driver) is whether or not the valleys (where the driver is going through the corners) are pointy or curved. They are curved in the pic below which means that I was carrying decent speed into the corner and gradually picking up speed as I go through it. If they were pointy (which mine used to look like) then that could mean that the driver is too focused on braking as deep as he can and fighting the car to the apex which ends up slowing the car down too much. After he gets the car slowed down and into the corner then he mashes the gas to get the car back up to speed again. The result is that the driver who brakes a little earlier than the really late braker and is smoother (and quicker) through the corner is going to turn the better lap time.
Another basic thing to look at is the braking technique of the driver. The proper braking technique is for the driver to brake as hard as he can while the car is going the fastest and then gradually release the brakes as he approaches the corner. Easy to say but not as easily done. When we brake on the streets it is the exact opposite. As we approach a traffic light we initially brake lightly and then brake harder until we bring the car to a stop. So, for most of us that is ingrained in us. When looking at the front brake pressure line in the pic below, my braking technique is not that good and it is something that I continue to work on. When I hit the brakes for Turn 1 ( the first braking point in the chart) my braking technique was a little better because you can see that I hit the brakes hard initially but I eased off of them a little too quickly and had to get back on them again. But the braking for Turn 5 (the one that I have circled) is much worse – I didn’t get on the brakes hard enough initially and then had to increase the brake pressure as I approached the corner. The reason why this is not good is because every time you hit the brakes, the gas, or turn the steering wheel you are transferring weight from one part of the car to another. If the driver can minimize this weight transfer then the car will be more balanced, will feel more comfortable, and will most likely be faster as a result.
The chart below shows a couple of other tidbits of information as well. One, coming out of Turn 6 the car got loose and I have circled the two things that tell me this. I lifted off the throttle very quickly and my steering wheel went the opposite direction very quickly. And two, not long after that corner there is a big lift off of the throttle but my steering input didn’t change. This tells me that the car was probably had understeer through this part of the course. Either of these conditions could be caused by how the driver is driving the car or the set-up of the car but the point is you can’t begin to fix the problem until you know that there is a problem. The driver may or may not remember but the data doesn’t lie!
In the AIM data system, a User Profile is a set of saved charts that can be quickly recalled every time that you open a data set. This means that you can quickly look at certain bits of information without creating charts every time which saves you tons of time. Below is a pic that shows a User Profile which I recall almost every time I look at data. (Btw, on the left, you can see all the User Profiles that I have saved.) The purple line in the top graph shows the longitudinal Gs and the red line is a math channel called Combined Gs which combines longitudinal and lateral Gs. This is a great way to see how well the driver is transitioning from braking to turning. Ideally the car should be slowed down to the point where it will get through the corner at the limit of grip and the car should still be slowing down a little bit as the driver enters the corner. So you should see the Combined G line "springing" off of the Longitudinal G line. If the Combined G line is falling off the back side of the Longitudinal G Line then the driver is over slowing the car. I have highlighted examples of each below.
The chart in the bottom middle is another very important one because it quickly shows what the driver is dealing with in regards to understeer and oversteer. This is an X/Y Plot and Lateral Gs are on the X axis and Steering is on the Y Axis. So one side of the chart is left hand turns and the other side is right hand turns. If data points are showing up below the main line on the left side of the chart then this is understeer and if they are showing up above the main line on the right side of the chart then this is also understeer. And likewise if they show up above the main line on the left and below the main line on the right then this is oversteer. The reason why this happens is because if a driver enters a corner and continually puts in more steering input as the Lateral G's increase then he/she will reach a point of diminishing returns and the front tires will not turn the car like they should thus -- resulting in understeer. If a driver enters a corner and the back end of the car begins to rotate more than the front then the driver will have to turn the steering wheel the opposite direction in order to catch the back end. Therefore the lateral G's would still be increasing but the steering input is decreasing, thereby showing the oversteer in the chart. Again, these conditions may or may not be caused by the driver. I actually like a car that has a little bit of understeer and what is shown in the above chart is what I like to see but I'm making this statement based on what I feel in the car and after looking at hundreds of charts from my data.
The XY plot on the bottom left has Lateral Gs on the X axis and Longitudinal Gs on the Y Axis. This is basically showing what is known as the traction circle. Again, there should be a smooth transition between braking, accelerating, and cornering and this chart highlights the smoothness of those transitions and whether or not the driver is getting the most out of the car. It is really a half circle because the G forces from accelerating aren't nearly as great as the ones experienced in braking and cornering. This chart isn't a very good example of what it should look like because there should be fairly straight lines in the center that then curve to each side of the char where the Lateral Gs are the greatest. So, a half circle with a line going from to the top to the bottom would be ideal.
The XY plot on the bottom right has Lateral G Velocity (a math channel that is the derivative of Lateral Gs) on the X axis and has Steering Velocity (a math channel that is the derivative of Steering) and this shows how busy the driver's hands are. In looking at the chart above, there aren't any lines shooting out from the center so my hands weren't especially busy -- which is the way I like it.
In contrast, below is a pic of the same chart from a lap where the car was loose and I was not happy with the handling. And btw, the lap was 1.5 seconds slower than the lap above. Later I had discovered that I had a setup issue which was that one of my rear wheels was slightly toed out. Notice that the chart in the bottom center shows that the oversteer condition was only present in left hand corners and there is more understeer in right hand corners.
Btw, any data system worth its salt when generate a track map that you can look at. I know the lines generated from driving Summit Point so well that I don't have to look at it but here is the map generated by the AIM software. The software will come up with its own corner numbers based on what the car is doing but I have changed those to reflect the actual corner numbers at the track.
Another extremely useful tool is Split Times. The pic below shows all my times from the session with my best time being a 1:16.12. However, it also combines all my best segment times (shown in blue) and combines those to come up with my best theoretical lap time, a 1:15.384. It is impossible to match all of those segment times because chances are if you are much faster in one segment there is a good chance that there you are going to be slower in another. However, it does give you something to shoot for. The other measurement that is a little bit more useful to me is the best rolling lap. This is highlighted in yellow and it starts a lap from somewhere other than the start finish line and combines the segments across two laps to give you your best time. It is possible to have your best time equal your best rolling lap but it isn't very likely. My best rolling lap was a 1:15.983 which was only a couple of 10ths off of my best time so that is totally achievable and definitely something to shoot for especially since I should get faster with this car. In fact this chart has given me some very good insight about how to get into the 15s. If you look at corners 6 through 9 (the carousel at Summit), my segment times were the fastest on the first lap shown. So I obviously did something different on that lap then I did on any other lap. I was able to figure it out using my data but I'm not sharing it. :)
Everything that I have discussed so far still fall in the category of "the basics" and that is really all I can do in this blog. There is just so much to it that anyone that wants to learn more than what I have discussed needs to go to other professional sources, such as John Block and Bob Knox. I do plan on doing one more posting on data analysis and I will discuss some of the things that I look at to see what the car is doing but it will probably take me a little while to get that published. I hope these posts are getting those racers that are following me to want to learn more though! Btw, I'm always happy to answer any questions!
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