Uh... let's see: At the top of each chart, it says, "Heartland", and in a subsequent post, Mark refers to the track as "HPT". My guess is that he's talking about Heartland Park Topeka. Just as a wild guess, I opened a browser window and typed the URL "http://www.hpt.com", and it came up with the website for the track.

I don't think he was jerking you around.

 

Brian P
In my experience, it is often difficult to get the sensors calibrated accurately. The zero point isn't all that critical since it is usually easy to see and correct any offset. The bigger issue is trying to force calibrate the sensors but again, this is usually good enough for our level of analysis.

DJ
Thanks for the "help". I didn't catch what seemed so obvious to you, that was why I asked. HPT lists quite a few different course configurations. I don't know which he ran and his software generates the best map for this analysis because it will match his data the best.

I still don’t know if my input is welcome and don’t want to “bother” anyone.

 

Hi everyone! That MoTeC telemetry is awsome! I can't wait till I can use stuff like that in real life instead of just in racing sims. I'm still a DE newbie, but hey whatever, you gotta learn somehow.

One question to SundayDriver and ColorChange:

When I brake the HARDEST before (or even into) a corner, I always do it in a straight line. Maybe a little bit while turning, but 99% of the HARD braking is in a straight line. Thus, on a telemetry display, this hard braking zone should be an eggshaped blob CENTERED on the graph. (Whereas the Cornering G's - and accelleration G's - might be offset to one side, depending on the track. However the one constant between all tracks is that you always brake in a straight line. Right?

So why is that big blob near the middle of Sunday's chart, off center? Is it faster to brake while turning?

Thanks guys!



PS - SundayDriver - can you superimpose that Motec telemetry to run overtop or sideby side with some on track footage? That would be really cool.

 

Ugh! Opinion of innocent bystander (lurker?) on this and other similar - threads:

CC: I think people would welcome your opinions if stated as such. Example: 'You're callibration might be off.'
What you're doing is stating your opinions as facts: "Your lat g sensor is slightly out of calibration."
This is coming across as arrogant (IMHO)
Also, your constant questions about your input being welcome are annoying, as it comes across as oddly patronizing (IMHO).

Why not state your opinions as such (as Brian, I think? tried to do for you), and work with the others here do analyze the data *jointly*. It seems that you are trying to present a position as fact, then you get lambasted with potential issues that would discount your presumtions. Then you get defensive... The whole thing is more painful than entertaining.

 

Jack:

Thanks, I think your being sincere and I do have a big tendency to "rub people the wrong way". It really is unintenional but if people attack me for sounding like a *****, I really don't get offended because I largely deserve the critcism. I only get really defensive when the perosanlly attack other things, don't admit their errors, ...

Rich:

That was sort of my point. I will go into big detail if Sunday wants to hear.

 

CC: Go into detail. I want to hear it and better my understanding.

 

Yes, as DJ said, it is Heartland. You asked earlier and even though it was on all the charts, I answered in the psot follownig your question. It is the 2.1 config. Go ahead and try to prove all you want but the fact is that such 'proof' is not how you calibrate a sensor. It was zeroed on a lavel platform when the car was set up. It was checked at the track. The only data that should be used to check the calibration is to look at the reading when you are going down a straight that is level. It will be rechecked when the car is on the set-up platform next time, but all indicators is that it is correct. If you want to prove it is out by 0.1g (as if that amount would even matter to us amateurs), then knock yourself out.

As far as whether I want your input, 'Frankly Scarlet...'

 

Thanks Rich. It is a pity that this group seems to only want to focus the discussion on the g-g graph. I find that the be nearly worhtless for any feedback, though it does show a few things. It does demonstrate that 'straights' are rarely straight. While you want to do most of your braking in a straight line, It is not unusual to still have a bit of steering in the car. There are so many places on so many tracks where you have a fast corner that transitions into a slower one - you have no choice but to brake while turning.

Here again, the g-g graph will show this tendencey, but you have no way of relating it to the track and what it is doing. So what you see is a general offset in the center areas of the g-g graph. For the most part, you can not figure out how to go faster from a g-g graph.

MoTeC has some of their own video stuff that will integrate but it is horribly expensive. They are supposedly adding the capability to import your own video into their package later in the year.

 

Mark, can you play back the MoTec telemetry data to have it play start to finish like a video? Is there a screen or a way to tile the windows that displays all the data on the screen at once?

If you can do that, you can overlay it. I had this WICKED .avi file of someone driving the Nurburgring on the top half of the video was a computer game and the bottom was real TV footage from a GT3 at the ring. He timed it perfectly so that game matched the TV footage, then put them both together into an avi file. (and added some wicked music.)

Regarding the G-g graph. I understand what you're saying, there's always a bit of turning involved - otherwise the blob on the g-g would be dot instead of a blob. I agree you can't figure out how to go faster by looking at just it, either. (Although you can check max lateral G at any corner at any given time over the course of the run to see how tyre wear affects cornering limits.. but that's doesn't really help you go faster...)

As to argueing about whether or not it's off center - all you have to do is park the car and see where the dot sits.

 

Rich:

When I brake the HARDEST before (or even into) a corner, I always do it in a straight line. Maybe a little bit while turning, but 99% of the HARD braking is in a straight line. Thus, on a telemetry display, this hard braking zone should be an eggshaped blob CENTERED on the graph. (Whereas the Cornering G's - and accelleration G's - might be offset to one side, depending on the track. However the one constant between all tracks is that you always brake in a straight line. Right?

You are correct. That is why you see on almost all g-g plots the braking centered on the graph. It is difficult for me to see if Sunday’s braking is centered but it doesn’t look like it from the graph. I think g-g plots are better viewed with dots or smoothed lines rather than the unsmoothed lines Sunday showed as it is harder to see what is going on.

I will now explain why I believe (highly confident) that Sunday’s sensor is offset by about +0.1 lat g’s. The dominant straight on the track is part of a drag strip. The drag strip is almost guaranteed to be quite level, and extremely straight. Furthermore, a right hand turn feeds it and a right hand turn ends it, so, knowing it is flat, there is no need to veer the car at all, so stay to the left on track out of the feeding turn, and enter the turn at the end of the straight from the same left side of the track. (While it could be possible that there was an oil spill or something else bizarre on the straight that you want to avoid that could justify a slow veer so that you entered the exiting right hander along the right hand side of the track, I really doubt this was the case.)

As discussed before, his lat – g max appears to be +0.1 g to the right, his center acceleration appears to be +0.1 g to the right, and his max + lat g appears to be +0.1g to the right. While you could try to explain the lat g max offsets, there is no longer any acceptable explanation for the center acceleration offset.

Sunday doesn’t want any input so I will not continue with analyzing his data.

 

Why don't you stop whiing about not wanting input.

At least now you are saying 'highly confident' rather than certain.
If I am wrong, I will admit it. So how do I check the calibration? The car is sitting in it's bay in the garage. It is almost exactly 1" lower on driver's right than left. The track is ~52" (slightly different front and rear so that is what I use). My notebook is sitting here and I can hook it up and read the data. I will bounce the car and get in it. It has not been touched since it came off the track with that data. If I go read the lat g's now is that a valid calibration check?

 

Deleted duplicate...

 

Hear hear, Jack! CC, are you an engineer, or recently graduated engineering student? The voice of conviction with which you speak is not uncommon in the engineering disciplines. I'd add my voice to the others, and suggest that you remember that absolutes are best left where they're derived, in the classroom. When you're in the lab or in the field, the real world does intrude, and insisting on clinging to the notion of absolutes is a good way to limit your career (unless, perhaps you can get a job with Ford ) By all means, continue to discuss these matters and provide your opinions, but try to accept that others may be, shall we say, more correct than you?

As someone who works with a form of data aq on a daily basis, professionally, for the purpose of measuring and calibrating vehicle dynamics, I'd give my professional opinion that an offset of 0.02g lateral is nothing. Anything below 0.1g, in fact, would be quite acceptable.

Regarding Gingerman, while I'm not an expert on it, I have done my time there, and I wouldn't expect that even the back straight, with RH turns preceding and following, would produce minimal Ay (lat accel) values, due to a million stupid little factors that intrude.

I have some data from Grattan, which is another long front straight, I'll have to pull it up and compare...

 

Oh, CC, regarding car setup (l/r bias). Since none of us are racing on symmetric tracks, it would follow that the optimal setup is not necessarily a symmetric chassis setup and weight distribution. In particular, you may recall that one will do best (with respect to lap times) to optimize the car for, first priority, the corners leading onto the straights. While establishing a symmetric setup is a good idea for someone just getting started with a car, or driving, or who doesn't want to try different setups for different tracks, when you're really ready to race, you will need to optimize your setup for the most important corners. This will result in a setup biased to specific turns; the bias may not be as extreme as in circle-track, such as dialing in wedge, but there may be some offset in alignment settings, particularly camber, to help. I do know for a fact that the top dogs at my local track use aymmetric setups.

 

(Insert sound of nail being hit on head)

Absolutely true. Most racers use an asymmetrical setup, for the reasons that you pointed out. Best example - Lime Rock, where you're basically doing a "NASCAR, backwards" car set-up. In formula & sports racers, The LRP set-up is wildly different, and cross-weights are jacked to allow the car to turn right with your foot down. The same is true of the Watkins Glen short course, where I will sometimes run 2 degrees less camber on one side, or in one corner of the car (and...to blow my own horn...I've done this quite successfully, for a long time).

That's an experience thing - learning which parts of the track are "throw away corners", and then figuring out how to optimize the car for the corners that really matter.

CC - remember that we're talking about optimizing lap times here, not making the car easy to drive for students on the HPDE learning curve.

There are few absolutes in racing. Those of you who've raced motorcycles will recognize it when I mention Keith Code's "The Soft Science of Motorcycle Road Racing" (before I started crashing race cars, I fell off lots of race bikes). That nails it perfectly. It's not a hard science, it's a soft science. It's not like chemistry or math, where you can generate a 'proof' of a theory, and have faith in your answer. Race cars don't respond that way, not matter how much we want to think they do. That's why racers test and test and test...because what they think they know and what they actually know are always being proven to be far apart, when they turn a wheel on the track. They have to learn to make compromises in Corner A, if they want to nail Corner B, C & D.

Anyone looking for absolutes here - for "rights" and "wrongs" - is barking at the moon.

The moon ain't listening.