The ultimate must have trackday gadget:

system · 30 May 2002 12:31

http://www.race-technology.com/WebPage/Products/Logger/DL90Home.html This product has to be a winner, apparently this will be endorsed by some track day companies as no timing information is available at the track. But I am a little sceptical so I think keeping a low profile would still be in order.I have played with the analysis software, which is pretty good but is limited in some areas. Most notably the ability to overlay more than one lap over another on the speed/distance display, but in any case all the processed data is available to export so you can fiddle to your hearts content.There is real time replay and virtual dashboard that can infer from the cars , weight, drag coefficient , rolling resistance etc to derive power delivery at the wheels in a realtime replay + plotsProbably the most useful graph is the traction circle which plots Longitudinal and Lateral g, this is one of the first ways race teams evaluate a drivers performance. I could not find a way to select just a portion of track to plot this for individual corners so extracted the raw data for a Westfield at Donnington going through Redgate. www.mikola.co.uk/Redgate2.htm The graph shows that the driver makes a good exit (which is the easy part) but on the approach takes a while to get off the brakes and wastes some available grip that is to be found by trail braking. The idea is to use all the available grip of the tire when transiting from full braking to full cornering. Tyres can generate both cornering and deceleration at the same time if you look at the capability of a tyre on a graph this is a circle of traction for the tyre. The ideal is to navigate all the way round the edge of the circle (without falling off!!!) in practice I donï¿½t know this can ever be really achieved because of track conditions/camber changes etc but it still gives a good indication and is most meaningfull comparing from one lap to another and looking at the difference in sector times for different cornering techniques.

system · 6 June 2002 15:38

quote:Originally posted by X111GED: looking at the difference in sector times for different cornering techniques.Well the results from Oulton on the 4th Jun look iteresting, if not understandable. Conclusion “Crap Driver” http://www.mikola.co.uk/Oldhall4.gif

IDG · 6 June 2002 15:46

This would appear to indicate you are best when you keep it going for 8.29 seconds!Can you not do this with (the much cheaper) Race Tech g-meter? [Rhetorical, I have one, I’ll check]Ian [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]

system · 6 June 2002 23:14

quote:Originally posted by IDG:This would appear to indicate you are best when you keep it going for 8.29 seconds!Can you not do this with (the much cheaper) Race Tech g-meter? [Rhetorical, I have one, I’ll check]Ian [image]http://www.exiges.com/ubb/NonCGI/images/icons/smile.gif[/image]Ian,8.29Secs I’ll have to check with the Mrs!! [image]http://www.exiges.com/ubb/NonCGI/images/icons/wink.gif[/image]The sector timings do look a bit suspect, 7.3 to 8.3 secs 1 sec difference for one corner!!! I must be horibly inconsistent, but the full set of data shows very similar entry, apex and exit speeds :105.8, 66.89, 73.91 for the 7.34 Sector & 99.4, 64.78, 75.48 for the 8.29 Sector I can’t see any way the difference can be more than the bigest speed diferential of 6% on entry speed which would be about 1/2 sec max and quite probably a lot less, the exit speed is actualy faster just what you need out of old hall!!I have posted the results to race-technology.com for their comment.Unfortunately I did not take up the ï¿½70 option which easyTrack they wanted to charge to carry a video in the car [image]http://www.exiges.com/ubb/NonCGI/images/icons/frown.gif[/image] but that would at least have allowed me check the times for each complete Lap.Even given the questions over the sector timeings the plots still give a good insight into the overall g forces, I think the accelorometer readings are probably more reliable than the GPS derived timings.The other advantage of the DL90 is the software and 90Mins of logging time.

system · 10 June 2002 14:15

I got the following response from Race-technology. I checked the circuit plots to find that the uncorrected postional plot was way off on Lap 4. In conclusion I think that 90% of the time you can rely on the data but sector times in particular can be badly affected.The trick is to find a piece of the circuit where there is good positional repeatability and set the Lap timing to this point. quote:Response from Race-Teccnolgy Support:“hmm… a tricky one for sure!The answer is for whatever reason the GPS data on that section of lap4 andshell corner was of a particularly poor quality and whilst the analysisprogram has done it’s ‘best’ to combine the positional/accelerationinformation into a single track map it is failing to some extent on thatsection. To see the what the raw data looks like, disable the overlay lapsoptions under “run options → analysis options”. The program is correctlyidentifying the position of the track corners and improving the track fromthis raw data, unfortunately the original data is bad enough to causesignificant timing errors, for that particular bit of that lap.Things to bear in mind…1/ Mount the GPS mouse on the car roof.2/ Don’t use tape to hold the GPS mouse it down!3/ avoid high levels of vibration to the mouse.4/ GPS speed data is far more robust to low satellite count than positionis… so trust speeds over point to point timings5/ when GPS data is poor, enable the 'trust accelerometers over GPS option’in the “analysis options” but use carefully, if the GPS is very poor you canend up throwing lot of data away! Best to look at the data without theoverlay laps option first.In this case I doubt very much a wheel speed pickup would have solved theproblem… although it would have helped. A wheel speed pickup will beavailable from us (very cheap… 30ish) as well as other GPS module options(expensive… 1.5k+) over the coming months. I am also working flat out onthe analysis program, and accuracy will improve with improved mathematicalalgorithms.finally a tip (in case you haven’t found it!)… if you do a measurement"change in speed from X to Y” and highlight some cells in that columncorresponding to several laps, you can click graph and you get the sameinformation graphically.I hope you feel that answers the question! Keep an eye on our site foradditional wheel speed pickups and software improvements…

system · 14 June 2002 00:27

Just finished a marathon session of data analysis on the 16Laps I managed at Oulton Park before my clutch expired (hydraulic pipe fractured at the flanged end where it attaches to the salve cylinder). Great service from Paul at Revs 01244 819688 in Queensferry about 20miles from Oulton, got me out of trouble for the run home, and did his best for Miketurn who made it to Warwick with a dead alternator. I would big great to have someone who really understands G plots to confirm my interpretation, I was absolutely amazed at what the data seems to show. Years ago I thought I had lost the habit of using a mini Scandinavian left-right flick into the corners to drive out of understeer , a habit I know I had picked up from watching too much rallying, but not so clever for circuit driving. 10 years on I would have sworn that I had lost this foreverï¿½ï¿½ but the plots show is that I still do this ï¿½ on the brakes going into a right hand turn ï¿½ just before turn in ï¿½ lift - turn left ï¿½ then right. What the plot seems to show is that the more upset the car is at entry ï¿½feels good but slowï¿½ the less of overall traction available is used through the corner www.mikola.co.uk/scand7.gif If my analysis is correct then the this sort data logging is invaluable to really get a handle on how good/bad your driving is, until recently this sort of information was only available to well funded racers. I would love to see a real benchmark from a good / national championship level driver in an Exige.