THSCC Forums

GPS Course Map:


Total Distance: 0.91miles (1.47km)

Stats from my best run (86.8s):

Top Speed: 53.6mph
Average Speed: 37.8mph

Max lateral g's: 1.1577g's turning left, 1.1522g's turning right

Max longitudinal g's: 0.507g's accelerating, 0.659 braking

A quick glance at the data reveals that my car is very balanced left-to-right but doesn't accelerate or stop worth a darn. Nothing earth-shattering there, that's for sure!

Transitionally, the car is definitely capable of generating high-g loadings but not so much in a steady-state. That is typical of any car but it is interesting to see where the limits are and what the differences may be.

There are a few interesting things to point out in the data but I won't get a chance to write anything until late this evening or tomorrow. Stay tuned for a "quicky" analysis of the optional slalom near the end of the main runway and any other interesting tidbits I can find.

Jim

I also had my MaxQData running on Sunday. I have all 5 of my runs (1 run was a rerun and probably my best front section ) and 3 of Chris Brown's. My unit is way more portable than Jim's DL1. I want to put it in some other cars at the next event.

This is my first time using it but I am also gonna try and have some data this evening.

I may need your help Jim

_________________
02 Focus SVT
STF 9

"Stay tuned for a "quicky" analysis of the optional slalom near the end of the main runway "

Very much interested in what you have to say on this. I chose a left entry at first and had to slow down significantly to hit it. Actually missed it my first run and hit the first cone. Second attempt made me realize that runs 3 and 4 should be right entry. Tried right on those two runs and it felt very awkward changing the gameplan. Entry felt OK, exit felt horrible and overall I realized that I'm not adept at switching my game plan. Runs 3 and 4 were faster but that element was my nemesis.

_________________
Beauty is in the eye of the beer holder.

What's not portable about the DL1 (unless you decide to hard mount it)?
Maybe what we need to do is have a tech session get together for all those with data recorders to share techniques of data analysis????

_________________
SPIN or WIN!
there's no glory for going slow.

Jim told me that the DL1 "brain" needed to be mounted pretty close to horizontal and "securely" to get accurate readings.

Plus you have the antenna to deal with too.

_________________
02 Focus SVT
STF 9

That is only if you want to make any sense out of the accelerometer data. It will collect the GPS data similar to the MaxQGPS in any orientation.



It is magnetic so it really isn't that hard to mount. Unless you're driving a 'Vette... But it is another factor to deal with running the wire so that it doesn't distract or interfere with the driver.

The bottom line is that unless you don't care about the accelerometer data, you do have to find a way to mount it level and fairly securely. At the RallyX, I simply taped it to Carl's dash with painter's masking tape and it did very well. It did have a slight lean in the longitudinal axis but it was still easy to interpret the acceleration and braking data if you knew what the initial offset was.

As always, it depends on what you are after.

Jim

The mag mount on the vette is no problem, I use a postage stamp sized piece of velcroon my roof and its held for two days at VIR with top speeds of 135. Right now comparisons of entry and exit speeds is all I've done with it. however the eyeopener was the fact that my fastest run was not the run where I achieved the fastest time only the highest average speed matters.

_________________
2004 C5(415whp,390ft/lbs),
1997C5,1997Trans Am, 1986 C4,
1990 Miata, 1976 MGB,1997 Protege, 1989 MR2

That's similar to our RacePak G2X. It has to be flat, stationary and we also have the antenna to deal with. In the Miata, I have to run a power tap off the battery (my lighter isn't working anymore) and we just tape the crap out of it to the trunk floor. Then the antenna is run out the trunk and put on the body work. Not too bad except for the tape thing.

The funny thing is, even though it has been in my car several times, I still haven't played with any of the data. It always ends up back at Adam's place!

_________________
Todd Breakey
STS 42 - 1992 Sunburst Miata
Dammit!
"You souldn't play leap frog with a porcupine. You might get hurt." - Eliza

Mo data:

on the best run I have recorded

Max G: 1.19 on the last right coming out of the P

Chris recorded a Max Lat G of :1.15 G in the same spot.

As a general rule of thumb, Chris broke more often and stronger than I did. That's a factor of not "knowing" a CSP Miata needs little braking. Im still trying to keep my foot off the middle pedal myself. Except for the Chicago box, I broke way too hard for that all day (and subsequently recorded our max braking Long G at .94).

Chris also seems to attack the second cone in a slalom and I seem to try and get behind the first cone. Its cool that you can actually see that.

_________________
02 Focus SVT
STF 9

I don’t have time to do much tonight but since the “input density” issue came up in the course discussion thread, let’s look at that first. The following is a graph of lateral acceleration versus time for my last (and best) run of the day. Anything below the 0-axis represents turning left while anything above it represents turning right.

Lateral Acceleration -vs- Time for 4th run:


Each peak or valley essentially represents a change of direction which should be fairly equivalent to Roger Johnson’s definition of a steering input. I counted the number of peaks and valleys and got 46. It seems that Walter’s memory is pretty good and is certainly in the same ballpark as other accounts.

OK, so we had 46 inputs in 0.91 miles which is roughly 38 in 3/4 mile. According to RJ, a good course will have 25 to 35 inputs per 3/4 mile and anything over 45 is probably way too much. We were definitely pushing the upper envelope of his “comfort” range and it looks like his metric is fairly accurate. I think it illustrates the notion that if a couple of the elements were stretched out a hair, the entire course would have been perceived as being a lot less busy. It might have been as simple as a cone being picked up from a couple of the slaloms (with the rest adjusted accordingly) but given that the designers were working around the surface of the moon, that may not have been entirely possible.

More to come…

Jim

i suck, i know...i probably won't get the hang of the go kart until the third event or so.

_________________
05 MCS

very interesting, guys, keep it coming.

the later accel graph is especially interesting in what i presume to be the onion ring. Looks like some FWD rotation techniques were being employed

Race technology, maker of the DL1 recommends using funtack as an attachment method for temporary installs. I used it this morning to test with and it held quite firmly.

_________________
SPIN or WIN!
there's no glory for going slow.

That's very interesting. I wonder how your GPS-based acceleration data correlates with the DL-1's accelerometer-based data? We should test that at Greenville to get an idea for future comparisons.

Assuming they are close, we were hitting similar max-g's despite the tire difference. From a quick glance of the data, it seems to support the notion that the street tires are capable of generating great initial grip and then fall off rapidly. In other words, they are very good through a slalom but get murdered in a sweeper. I'm certainly not saying they can match R's in a slalom but simply that the gap is much closer than in steady state maneuvers.

The steady state gap in grip shows up nicely in the highest speed Ryan, Gwen and I saw on course. The GPS speeds are definitely accurate enough to compare across products and I was the slowest at 53.6mph. We all saw our maximum speed after the sweeper coming on the the taxiway and while it is a pretty big leap to assume that we all entered the sweeper at a similar speed, I can probably make the case they were very close. Either way, I'll go out on a limb and say that my 1900lb CRX will out-accelerate Gwen's Mini and yet she was still a full mph faster than me heading into the slalom on the taxiway. It would be interesting to know if Gwen was flat-out around the sweeper. I had to lift a little in the middle to get some rotation otherwise I would have ended up in the weeds.

Speaking of rotation, if you look at the lateral acceleration graph again closely, there seems to be something else going on as well with respect to generating high g's. Dan hinted at it in his post and we'll see if we can make any sense out of the data very soon.

Jim

Just went through the data again. at the third lane change just before the sweeper I had 37mph entry speed, then accelerated to 43mph out of the lane change held 43mph till the car rotated. Then accelerated to 54.41mph through the double cone slalom then braked at 1.146508G's for the single cone slalom. obviously the highest top speed does not mean you will be the fastest. I obviously sucked on quite a few other elements.

_________________
2004 C5(415whp,390ft/lbs),
1997C5,1997Trans Am, 1986 C4,
1990 Miata, 1976 MGB,1997 Protege, 1989 MR2