Track day data acquisition

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RX8R3Rod
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Track day data acquisition

Post by RX8R3Rod » Mon Oct 08, 2012 4:09 pm

I’m not sure if this is the best place for this, so mods please move as you think fit.

Steve Lewis introduced me to Qstarz at Snetterton, and I ordered one just before I left for Africa. Having got back for a short while, I thought I’d try it out in preparation for a couple of track days where I can try out the new Dunlop Direzza track tyres. Woo-hoo!

The Qstarz data logger is a small device you attach to the dashboard with tape, Velcro or blu-tak, and records GPS data and G-force at a rate of 10 cycles per second, for up to 400,000 data points. If you assumed an average lap of ‘a track’ took 2 minutes (=120 seconds = 1200 data points) that would be a capacity of > 300 laps, if my maths is correct? So plenty of capacity, it would seem.

The data is then downloaded onto a PC via USB (or possibly Bluetooth, though haven’t tried that) into the Qstarz software, where you can view and / or compare individual laps, where you can see:

1. The track, and your track position every 1/10th of a second around the track, so you can really see which lines are quicker / slower than others. In the screen shot below, the 'dot' on the track represents the car and the length of the lines represent g-forces (which are also shown on the g-force diagram (2))
2. G Force, so you can see where a change in line might stress the car more or less, where you are braking relative to a corner, and what that does to the suspension
3. Speed v distance

You can also ‘play back’ a lap (or up to 3 comparison laps simultaneously) with pause and rewind controls so that you can really dig in to what you are doing when.

If you spend another $40, you can apparently overlay this on time-coded video. I haven’t tried this yet, but hope to in the next few days.

Some examples are shown below, in the sequence of the bullet points above.

This is from taking my partners MX-5 out onto a road (at road-legal speed) with roundabouts at each end and, as it turned out, a fair bit of traffic. But I think you get the idea.

So, a nice, simple way of helping one to gather some facts about what’s happening on track to learn from and to (hopefully) improve.

And as you can't see any time data whilst you are driving, it apparently doesn't seem to contravene the 'no timing' rules on lots of track days.

Apologies if this is old news to everyone else, by the way.
Attachments
qstarztrack.JPG
qstarztrack.JPG (46.67 KiB) Viewed 879 times
qstarzgforce.JPG
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Qstarzspeedvdist.JPG
Qstarzspeedvdist.JPG (49.53 KiB) Viewed 879 times
Aluminium R3 Nov 2010
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NicKD
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Re: Track day data acquisition

Post by NicKD » Mon Nov 05, 2012 6:33 pm

I think you can get the GPS device to talk directly to Race Chrono via blue tooth on your mobile. It does not even have to be a very up to date smart phone for this to all work. Many, many circuits are already preloaded or down loadable for the Race Chrono website and even if you are doing this is a field, the setting up of your own circuit is pretty easy.
Depending on the accusition rate for the latest phones you can probably get a very reasonable read out even working on the phones base settings without as high Hz input.

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Re: Track day data acquisition

Post by RX8R3Rod » Wed Nov 28, 2012 8:16 am

I tried this Nick, but they didn't seem to do software for iPhone. Doh!

Still, here is a slightly more useful display from the Qstarz QRacing software taken from Bedford Autodrome.

In the comparison of two of my laps you can see the yellow line represents a slightly slower entry and tighter line at the hairpin, and earlier but smoother braking at the chicane equates to around an extra 10mph at the end of the straight. :D Funky stuff, IMHO, and potentially really useful for helping gain insights into what works better and what doesn't work so well.

For ~£100, it seems like pretty good value.
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Aluminium R3 Nov 2010
Cusco Zero 2 coilovers & ECON, Racing Brake BBK, 20"/18" OZ Ultraleggera, Dunlop Sport Maxx GT 245/30/20/Direzza 245/40/18, Pettit exhaust, Pettit front and RB rear ARB's, Full Paintshield and Rustmaster, M'Z Custom nose and rear skirts, new engine & clutch @ 44,500 miles, and then ...
190 Winning Blue 05-08, R3 Aurora Blue 08-10 ... fabulous friends

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Re: Track day data acquisition

Post by NicKD » Wed Nov 28, 2012 12:10 pm

Excellent.

Is that this corner?
http://maps.google.co.uk/?ll=52.229929, ... 4&t=h&z=17
If so I am curious at the profile of your data map.

If it is that corner, it is a classic "late apex" corner. Many people turn in far too early, as shown in your wide trace meaning they can't apply power till much further on.

You have two very good examples there of how small things make such a difference.
The first, the hairpin, , if you turn in too early, you go wide and have to stay off the power to avoid running off the track on the outside. While entry speed is greater exit speed is slower and that that equates to slower all down the following straight. There have been some very good examples in the last two F1 races.

The second is the chicane, where turning in that bit earlier has given you a much flatter line through the chicane making he bends less aggressive and so speed can be carried through rather than having to slow. It looks like you achieved this however by having a little holiday off the throttle while you picked your braking point, your next goal would be to work on your braking points so you can keep on the gas all the way up to the point you need to brake, but while still getting the right turn in point.

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Re: Track day data acquisition

Post by RX8R3Rod » Wed Nov 28, 2012 3:01 pm

Not sure. I don't think it is (though could easily be wrong, maps not being a strong point). Although the day was at some point advertised as being on the GT circuit, we ended up on a subset of it, if that helps?

I'd have to say it surprised me that such seemingly small things can make such big differences in terms of attainable speed, and things like the Qstarz seem really helpful in pointing it out in black and white.

You're dead right about the throttle holiday. #-o One day, maybe ....
Aluminium R3 Nov 2010
Cusco Zero 2 coilovers & ECON, Racing Brake BBK, 20"/18" OZ Ultraleggera, Dunlop Sport Maxx GT 245/30/20/Direzza 245/40/18, Pettit exhaust, Pettit front and RB rear ARB's, Full Paintshield and Rustmaster, M'Z Custom nose and rear skirts, new engine & clutch @ 44,500 miles, and then ...
190 Winning Blue 05-08, R3 Aurora Blue 08-10 ... fabulous friends

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