Lemming

Then go to https://rennlist.com/forums/showthre...ferrerid=23673

quickxotica

I think the best way to implement Data Aq sharing on Rennlist (which would be awesome) would be to create a new sub-forum under "Perf & Comp" called "Data Aquisition Sharing" -- then have a Mod create one thread for each major track and then lock out new threads. That way each track can have one (and only one) thread where people can share/discuss data files. New threads for new tracks could be added by request to the Mod only.

And in addition to posting up pictures of your "squiggly lines", people should upload their actual raw session files too.

I would be willing to help contribute to this effort if everyone thinks its a good idea.

Lemming

I like the idea of a subforum, just not sure that we have enough interest.

Seth Thomas

If you are correct in a car that is understeering then it is driver induced in each of the turns you listed. A general statement from the Traqmate data about the handling of a car needs this information before the person on the internet reads it and starts making changes to his/her car for an input they induced in the car. A suspension change or upgrade will not remedy this situation.

ProCoach

+1 Agreed. Overpowering the tires.

This is where video can eliminate a lot of guesswork and why every seriously meaningful remote interpretation has to include scrutiny from several different collection media, as well as several different logging criteria.

Veloce Raptor

+1 to all the above

Van

That data was from a few years ago... Here's a screen shot from last fall.

Similar traces on the toe and heel of the boot. I haven't thought that the car understeered - so I'm going to attribute it to driver line/technique (or lack of technique)!

I'm all for sharing data - especially if it can help improve my driving!

quickxotica

Re: the signs of understeer in the Lat G's trace. I'm confused. I would have expected the Lat G's to fall off over the course of a turn whenever you are taking a slow-in-fast out line, because as you unwind the wheel and add throttle you are repurposing tire grip away from turning and using it for acceleration instead. This would show as a declining Lat G' trace coincident with an increase in Long G's. If what you say is right, how would you distinguish this from understeer? Just by checking video?

Please educate me because I am pretty new to this stuff (and I haven't gotten to the Lat G chapter of Chris Brown's book yet).

Larry Herman

Note in sector 7, the lateral G's fall off significantly while the longitudinal G's (acceleration) stay constant. This is the toe, and a big understeering turn for a lot of cars. "Trading lateral G's for accelerative G's" is occuring with the front tires, causing a reduction in lateral G forces, indicating understeer.

If the car was drifting (read oversteering) then the rear tires would be at the limit of grip all the way through the turn, and the G loading would not drop off until right at trackout.

Note how Van maintains G loading all the way through turn 5 (with a slight hiccup). I'll bet that his car feels pretty neutral in this corner.

Seth, you could very well be correct, and maybe it would have been more accurate to say that I saw an understeering condition in many of the corners.

Matt Romanowski

Does anyone have data from the toe that shoes something different in regards to under/oversteer?

Van

Very insightful, Larry!

Larry Herman

Thanks, I try.

dmwhite

Out of curiosity, I looked at the WGI data from last year in our ST cars and found the same "trailing off" in the lat g's in those same corners. It directly corresponds to the steering angle going back to zero (opening the wheel) and throttle position increasing past apex. We definitely don't set the cars up to push.

I would think the nature of T5 compared to the turns in the boot would lead to less "trail off" in the lat g trace since you maintain your steering (and throttle) input for so much longer in T5.

ProCoach

Yep, and the key factors in calculating lateral g's are Radius (steering angle) and Velocity (speed).

The Boot is not an area where people gain a lot of speed through the corner even as the radius opens at the end. Especially as the hill gets steeper closing in on the apex. Naturally, the lat g trace would fall off even in a proper handling car.

Turn 5, OTOH, is able to generate a steadier lat g trace due to increasing speed ALONG with increased radius, even though the steering angle isn't relaxed.

Increased compression and the multiplying effect of the banking as you accelerate through Turn 5 (leveling only as you cross at the end to the track out curb) serve to accentuate that sustained lat g trace.

Also, the climbing compression in the Toe causes a spike in lat g's as the car compresses, then the bumps and the hill sap that loading. It's possible the lat g could be better maintained if the hill didn't slow the car's acceleration so much.

Stuff is never as simple as it seems...

ProCoach

The coolest and best coordination of lat g's (and steering input) that indicate and illustrate handling balance (under/oversteer) is Bob Knox's scatter plot shown in his new book.

Capable only of being illustrated by interpretation software that allows math channel construction, this plot can show and identify prevailing chassis balance balance very nicely. Jorge Segers also has a nice worksheet in MoTeC for that.

The way to do it in TM is simple. Use video or install a logged TM channel to observe the steering input angle, turn down the "Filter" and then zoom in to look at lat g's.

I have seen corrections in Race-Keeper's software that made me go back and look at the video to confirm. Yes, you can see it in the lat g trace.