Traction circle diagrams (data aquisition)
Hey gang
Thought you might be interested in some traction circle diagrams from my racecar. These are from race laps so you they are not always "perfect laps" i.e. some transitions or curves are stressed or cars are in the way and so on.
Gelleråsen: Link to Google video
Knutstorp (you know, the twisty one with the elevation changes): Link to video
Sturup: Link to video
Kinnekulle: Link to track video
Another lap from Kinnekulle, note the difference in the line indicated. Guess what that is...
Anyway, I thought you might be interested and might be a nice discussion starter.
Thought you might be interested in some traction circle diagrams from my racecar. These are from race laps so you they are not always "perfect laps" i.e. some transitions or curves are stressed or cars are in the way and so on.
Gelleråsen: Link to Google video
Knutstorp (you know, the twisty one with the elevation changes): Link to video
Sturup: Link to video
Kinnekulle: Link to track video
Another lap from Kinnekulle, note the difference in the line indicated. Guess what that is...
Anyway, I thought you might be interested and might be a nice discussion starter.
Last edited by Mats on Tue Oct 16, 2007 10:13 pm, edited 1 time in total.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-
- Verde
- Posts: 1552
- Joined: Mon Nov 29, 2004 7:06 pm
Thanks Greg. Yeah, as you know hard data is paramount when you are trying to figure out what is happening.
Basically you only need a stopwatch to realize that the correlation between what you think is fast and what really is fast hovers around zero.
Next step is to get some software that creates a virtual dash to overlay on my videos, that will be interesting. Get one of those g-bungycord-diagrams as thay have in the F1 broadcasts and tach/speedo.
I was a bit suprised to see in my logs that my speed at Kinnekulle when I turn in under the bridge on the straight is actually over 160Km/h, I was quite certain it wasn't over 140Km/h (remember, I didn't have a tach until recently).
About the plots in my first post, the idea is to use all the available grip during the transition from braking to cornering, ideally you want the plot to follow one of the circles. For instance, if I can brake and corner at 1.2g the plot should go from full brake, follow the circle to 1.2g at full cornering. That means that you will have to release the brakes at a perfect rate during the turn-in, not an easy task (but the F1 drivers seem to be able to nail it every turn...)
The tracks we drive are seldom just corners with a straight leading up to it though, usually there are a lot of stuff going on at the same time and that's why you can see strange loops from when I brake in a long corner for instance.
The "weirdness" in the last graph is from a lap where I actually go from the left hander under the bridge to the loong right hander without going straight in between, the braking have to be squeezed in there somewhere and that's why you see the large hump with the little twist on it.
Basically you only need a stopwatch to realize that the correlation between what you think is fast and what really is fast hovers around zero.
Next step is to get some software that creates a virtual dash to overlay on my videos, that will be interesting. Get one of those g-bungycord-diagrams as thay have in the F1 broadcasts and tach/speedo.
I was a bit suprised to see in my logs that my speed at Kinnekulle when I turn in under the bridge on the straight is actually over 160Km/h, I was quite certain it wasn't over 140Km/h (remember, I didn't have a tach until recently).
About the plots in my first post, the idea is to use all the available grip during the transition from braking to cornering, ideally you want the plot to follow one of the circles. For instance, if I can brake and corner at 1.2g the plot should go from full brake, follow the circle to 1.2g at full cornering. That means that you will have to release the brakes at a perfect rate during the turn-in, not an easy task (but the F1 drivers seem to be able to nail it every turn...)
The tracks we drive are seldom just corners with a straight leading up to it though, usually there are a lot of stuff going on at the same time and that's why you can see strange loops from when I brake in a long corner for instance.
The "weirdness" in the last graph is from a lap where I actually go from the left hander under the bridge to the loong right hander without going straight in between, the braking have to be squeezed in there somewhere and that's why you see the large hump with the little twist on it.
Mats Strandberg
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-Scuderia Rosso- Now burned to the ground...
-onemanracing.com-
-Strandberg.photography-
GTV 2000 -77 - Died in the fire.
155 V6 Sport -96 - Sold!
-
- Verde
- Posts: 1552
- Joined: Mon Nov 29, 2004 7:06 pm
You are right about the correlation about what you think is fast, and what really is fast. When I drive the Fiat 600 up through second gear to 8000rpm and go through a corner with some leaning and a little oversteer it feels so fast it's downright scary. Then I look down at the speedometer and realize I am really not going very fast.
I wasn't really looking at the transitions on the traction circles. That's more of a driver's skill measurement than anything, now that I am looking at it it looks like you can really drive that thing. I will watch the video soon.
Looking at the cornering and braking limits shows the car can really corner. It pulls 1.2Gs of lateral acceleration over and over. I know that's with race tires on a race track, but still...it's impressive.
I wasn't really looking at the transitions on the traction circles. That's more of a driver's skill measurement than anything, now that I am looking at it it looks like you can really drive that thing. I will watch the video soon.
Looking at the cornering and braking limits shows the car can really corner. It pulls 1.2Gs of lateral acceleration over and over. I know that's with race tires on a race track, but still...it's impressive.
-
- Verde
- Posts: 1552
- Joined: Mon Nov 29, 2004 7:06 pm