ColorChange

The driver can not significantly influence the capability of a car. The quasi-static capability of a car is defined by its g-g-V curve. You can usually ignore the V for non-down force cars (although it does significantly affect the accel and decel capability at high speeds), for simplicity sake, we will ignore the V component. The driver cannot change the capability of the car significantly (he can move his head (aero in F1, scrunch down lowering the cg slightly, diet, etc., but these effects are quite minor). It is the job of the race car engineer to maximize the capability of the car through design, tuning, and set-up. Tires, as always, are absolute kings here.

OK, what can the driver do? The better driver can extract more of the g-g capability of the vehicle on the better line than the other driver. For example, let’s say we hit a 100 ft skid pad with our street shod car and can pull 0.95 lat g’s max. But when a pro driver hops in, he can pull 1.10. How is this possible? If the car is poorly set-up (understeer), and the first driver did not correct for it, he would be driving the car at HIS limits (not the cars), where the front tires broke loose first at 0.95 g’s. The pro driver hops in, feels the push, and uses the throttle to kick the rear end out and maintain closer to the optimum slip angle for the front and rear tires and wa la … 1.10 g’s. He has NOT changed the capability of the car. He has extracted more of the capability of the car, and that is one part of his job, the other part is selecting the optimal line (we are disregarding racing scenarios in these examples where traffic management, mechanical issues, etc. often come into play).

Hope this helps.

macnewma

CC-

What exactly are you trying to explain or answer here? Did I miss something?

Are you defining the term "Maximum lateral G's" that you have used in prior threads?

Max

38D

That's all fine and dandy, but unless you have a pro drive your car, you don't have the "real" baseline to compare against. If I go out with my DL-90 and pull 1.4g down the carousel at Watkins Glen, unless I have someone else's data (while driving my car), the 1.4g is meaningless. Now, if I can see an upward trend in the lateral Gs (and a corresponding decrease in lap times), that good -- but I still don't know if I've just improved from horrid to mostly horrid. My suggestion, go to some of the tracks where there are big club races (like at Watkins Glen), compare your laps times to those guys...you'll figure out where you stand pretty quickly.

ColorChange

Max, sorry, on SundayDriver's thread on g importance, there appeared to be some confusion on this point.

Pesky, yes you do have a baseline for most corners based on skid pad work first. Secondly, drive and exceed the limits on purpose for those corners that are non-normal (camber, elevation changes, etc.) and then you will know fairly well those corners as well.

But, your point of having a pro thrash you car being extremely valuable is dead on and I agree wholeheartedly (and have said so repeatedly).

Larry Herman

Boy, you just don't know how wrong you are. Driver input at and around the transition point has a major influence on the limit of the vehicle. Once you learn how to drive, if you ever do, you may just figure this out. No real flames intended, it's just the way it is and all of your theories and data acquistion crap can't change that.

Premier Motorsp

Larry,

CC said 'capability'. By this he means the car CAN do something whether the driver asks it to or not.

Your point is correct as well, as the example CC gave in Post #1 shows.

However I would like to point out that maybe the g-g curve capability is not so cut-and-dried. In reality the driver does play a huge role in this. If he overheats the tires on one lap, the g capability is smaller on the next lap.

I also have a theory that a balanced chassis makes a larger friction circle than the math would indicate. Maybe it just feels that way to the driver.

Chris Cervelli
Premier Motorsports

ColorChange

Chris, I agree with you. The balanced chassis maximizes the chance for the driver to get all four wheels closest to their optimum slip angles (and therefore max g's, same thing). My understanding is most drivers prefer a neutral car.

Larry, You are wrong about my being wrong. We are agreeing as Chris pointed out. A particular drivers g-g max is likely to be quite different from another’s, just like the example you list and I listed. The point is the car could do much better than that. The poor drivers were not able to extract it, but that did not change the cars capability. The poor drivers did not achieve their goal, maximize g's on the appropriate line. This is not the same as maximizing their personal g’s on an whatever line.

Larry Herman

Ok, here's something for your data banks. Forget the steady state cornering of the skid pad, it really is not a true indicator of a car's handling potential. Here's an example of a typical mid-speed corner (60-75 mph).

You are entering a corner trailing off the brakes and turning in at the limit of the front tires. That limit is higher than steady state because you are weighting the front through braking, increasing the grip at the front. Now in an instant, the rear develops slip angle, but because they are relatively unloaded (as compared to the fronts) they start to slide because you are above their limit. You transition hard to the gas, and the rears load and hookup, generating grip above that of their steady state capability. The fronts will experience less slip angle due to the rotational effect that has been imparted to the car, and you will be cornering above the G force that you can acheive on the skid pad. As the corner continues, the rotational effect diminishes, the weight transfer to the rear diminishes, and the car returns to a more "normal" level of grip.

That point in the corner is above the car's limits (steady state wise) and what gives the truely gifted the ability to fly into corners and "make the car grip", and then fly away from even the best of us.

38D

This is where the crux of my issue is:

As others have stated, the dynamics on the track can greatly impact the lateral Gs generated. In addition, the track itself and the weather play huge roles. If it's 50 degrees and humid when you do your skidpad work, and 90 and sunny, you're skidpad is gonna mean squat. Also, nearly every turn on the track is different: some are banked, some are off camber, some have new pavement, some have concrete patches, etc, etc, etc. At best, the skidpad number is directional. If you did a skidpad run before every single track run, then maybe it would help some (at least would eliminate the weather as a factor).

Look, I do use my DL-90 as a learning tool, and yes it can help me better understand if I am improving and where I am improving (mostly using segment times). But, there's just no way for any DAS to tell you how close/far you are from the real limit (well maybe if you have the simulators like F1 teams, then you could come closer...but even they need real world tests). And if you think you're anywhere near the limit after a few track days, you're just kidding yourself.

ColorChange

Larry, how about you retract or apologize for you incorrect and overly aggressive statement "Boy, you just don't know how wrong you are. " first.

ColorChange

I do not have enough track experience to respond from first hand knowledge (data) and I can't site any direct text references so I will have to leave it as a difference of opinion for now unless you can present data that supports your opinion.

38D

I'm planning on having my DL-90 going for Lime Rock this weekend, so hopefully I'll have some data to post.

Larry Herman

I'm sorry if that offends you...but it is true. And from your video, and your many incorrect statements that lots of experienced drivers have tried to correct, I stand by my statement. You patently ignore some of the best advice around, and you seem to want to cram your theories down everyone's throats. But if I offend you, I won't comment on what you have to say anymore.

P.S. I was going to end with "When you can drive faster than me, let me know" but felt that it would be too over the top. What do you think?

ColorChange

OK Larry, I will exhibit patience and try once more.

No this statement is 100% wrong. Driver input controls how much of the g capability he can extract from the car, not the amount the car is capable of. If he put in a bigger engine, he would be changing the capability of the car. If he put better tires on, he would be changing the capability of the car. Turning a wheel or stepping on a pedal does nothing to the capability of the car. Is this clear?

A driver who drives the car in such a way as to reduce the g capabilities of the car IS NOT changing the capability of the car. He is changing the g capability HE can extract from it. The car's performance remains intact; he simply lacks the skill to access it. He may be on the limit for HIS driving ability and line choice. This may not be the limit of the car or the ideal line.

Larry Herman

Ok, in the spirit of your patience, no, I don't get it, and I guess that I never will. If a car is capable of .95 Gs on a skidpad, and I can get that car to pull 1 G in a corner, what is the true capability of that car? Or are you saying that our hypothetical car here would never corner better than .95 Gs?