Caddell

The "Track Report" function is powerful when comparing laps. I can see that GK typically (but not always) goes into the corners faster and carries that speed thru. However, I agree with the others that if speed is what you are comparing, typical "measures graph" speed traces are even a better place to look. They will provide a more clear picture of not only "what" happened but "where" it happened.

Were the differences on entry, mid, or exit of the corner? I believe if you look at the data this way it will show that sometimes GK trailbraked harder into the corner and his minimum speed in the corner was much further into the corner but slower. Something he could easily fix and help his laptimes.

The Track Report function is typically used with other channels like shown above. A few of my favorites are comined g's, brake pressure and throttle position.

Van

Rick, what sensors do you have and what system are you using? In Aim's Race Studio, you can set up "profiles" where you can have many data sets displayed at once.

In the example below, I'm looking at RPMs, speed, lateral and longitudinal Gs, and steering angle. Then with some math channels, I can put some neat stuff together.

The top chart is the tire's slip angle - above the x axis is understeer and below the axes is oversteer. Next to it is a gear chart (like what's in the back of an owner's manual) to tell me if I'm using the right gears in the right places.

The middle chart is longitudinal Gs in red and combined Gs in blue - this will tell me how my trail braking is. See the dip in the first corner before the blue ramps up? That's not so good. Next to it is a friction circle - it's pretty good overall (but could be better).

The bottom chart is corner radius. If the lowest part of the valley (tightest radius) is on the left, the apex was late. If the lowest part is on the right, then the apex is early and the driver has to make the exit of the corner a little tighter to compensate.

The chart in the lower right is steering angle and lateral Gs - it also shows over steer and understeer. If the car was perfectly neutral, it would just make a diagonal line. My car has a bit of understeer - at max cornering, I'm turning the steering wheel more.

The more I learn about Race Studio, the more I like it!

RickBetterley

Hi Van
I have the Aim MXL with GPS and a recently added longitudinal accelerometer from Jerry Austin.
Car is 1995 so no OBDII, of course.

HiWind

thanks Matt, Roger, Van - i tried some of those out - not quite sure what they mean tho

Van here's the g sum you showed ... does the high G in last turn show I should be getting more G's in first 4?
To read trail braking , should i look at where orange is rising as G sum still high?


and Matt here's the Lon/Lat A with time delta ....
it seems most of my (black) losses are from accelerating less out of turn 1 and 2 but you can see i brake less hard into 2,4,5.
What else appears?

Van

HiWind, you might be able to visualize that top chart better if you do 3 things - first, display the charts overlapping each other, not tiled; second, "flip" the long acceleration upside down ("reverse channel" check box; third, make the scale on both charts the same amounts.

But, without doing that, I can tell that you trailbraked poorly at the 700-800 mark on the x-axis, you trailbraked well at the 1600-1700 mark, and the turn with the 1.8G peak has some kind of "aid" - like compression from a hill, or lots of camber, to achieve that amount.

I'd also hazard a guess that you're taking T2 too slow. You're back to full throttle so soon, you over-slowed going in.

From your bottom graphs, the green car goes through T1 at a faster speed and pulls more cornering Gs because of it, and gains about .6 seconds on you. However, the green car is on the brakes too early and too hard for T2, and you gain .4 seconds back.

Then you lose it coming out of the turn as the green car accelerates much faster to T3 - you're now 1 second behind. I assume he might have different gearing than you?

You guys are pretty even until the straight to T5, where he pulls away again. At T5, he's on the brakes fast and hard which slows him down more (you can see that in speed and in the time difference), but that lower speed lets him get on the gas sooner and he gets that time back on the straight. When you approach T5, you start off gentler on the brakes, then at the last minute give them an extra stab, and skate through the corner a little faster, but then you can't get on the gas as quickly.

HiWind

Cheers Van and very Nice - t5 is huge camber
I'll try those adjustments again but couldn't get axes to match despite lots of scrolling, dbl clicking, dragging - secret?? I was using overlapped not tiled then.
What about trailb at 12-1300m? Should I be looking to make wide, rounded tops on Gsum?

Matt Romanowski

Just emailed you a way to align laps. The quick dirty way is to click the "snap to" icon (the double ended arrow in between two lines) then click and drag one of the measures on the X axis so they match up.

rkirshner

hi van
i am trying to get a better understanding of how to interpret these graphs . can you tell me why you say the trailbraking is poor at the 700-800 x axis point
thanks

Van

So, at about the 650 point, the braking begins for T2 - and we see the G-force peaks at about 700 on both the long G and combined G charts.

And, at 750, the brake pressure has been released (less long Gs) and, again, we see that in both the graphs. It's this downward spike on the combined Gs - between 700 and 750 - that tells me the trail braking could be improved. When combined Gs climbs without long Gs, it's getting that from lateral Gs. Lat Gs are cornering force.

We can see that there is a point between long Gs and lat Gs where the tires are being utilized for less than their optimum grip. (Because their grip was holding 1.1Gs at 700 and 800, but only 0.9Gs at 750.)

At the 1600 mark, see how the combined Gs climbs with long Gs and at 1650 the combined Gs are still going up - although the long Gs are going down? That's an excellent transition from braking force to cornering force.

I guess the short answer to your question is: when there is a dip in the combined Gs at the transition between longitudinal and lateral force, you're not using the maximum grip of the tires.

ProCoach

Ding, ding, ding! That's a winner!

rkirshner

now i see thank you . what would a typical cause if this be . is it not transitioning from brake to throttle quickly enough ? could this drop in total g be from understeer . i suppose seeing the other channels would make this clear

Matt Romanowski

Not enough trailbraking. Combined G is just another way of looking at the friction circle (or a G-G Diagram). Any dips in combined G on entry into a corner shows that there is traction that is not being utilized.

amso3

Hi Van

I like your math channels and approach. Would you e-mail me screen shots of the math channels? I'd like to study them further. my e-mail is jandsaustin1 at verizon.net, thanks

ProCoach

Several questions there, but the most common cause is braking too early, too much or too long...

My whole business is translating what the data shows into what is going through driver's minds to make them generate the "shape" of their particular trace, and where they generate that trace is part of this analysis!

The typical cause, especially when other corner entry transitions look good (as in this case) is braking too early. Most drivers leave quite a margin, especially where they can't see through the entire corner and subsequent travel path.

The drop in CombG is likely due to the finishing of braking and "rolling up to" the point where the LatG begins to rise. This can be double-checked with an animated playback of the G-G graph (friction circle). This is also why video is a must-have to validate surrounding conditions and add the aural dimension to further validate what is going on.

Unfortunately, most drivers prioritize an arbitrary and often incorrect "start of braking point" and base all their subsequent actions afterwards on that point. In fact, they should begin with "the end in mind," (the transition to throttle coming out of the corner) and work backwards to the beginning of the braking.

This all means NOTHING if the proper execution of fundamental skills is not practiced, which in my experience is where the greatest gulf exists. Few people brake properly and effectively, most "modulate" the brakes not against the "limit" but according to their own estimation of where they need to be at what speed to "make the corner." Bass ackwards, when compared to the pros...

Bingo, this is just additional fleshing out of Van's original observation.

HiWind

Would also love to see the gear one.
I found the G sum was a pre-loaded option in RS2 Jerry - just had to rename the variables from Acc_Laterale to Lateral_Acc