DDC - Heel &Toes

[Number Six]

Blatman,

 

"Whilst I am not qualified enough to debate at any length with Peter the various merits of his science,"

 

Unless you are Mr. Carman [Michael?], Q.C. (Deceased) - setting up one's adversary, this is no way to start an argument. You are just as qualified as any other person on this forum!

 

Science changes. Or rather it's validity does. Four Centuries ago the Earth was flat. Two Centuries ago we bled people to cure them. Last five/ten years Stack introduced datalogging. The world stopped spinning. Old Peter's version of science is just that, a version, and will be disproved in years to come. Actually, if Peter was more up to snuff with how Einsteinian Theory (sic) has been proved to be a lod of old cobblers, he might lay off slightly with the "science is God" mantra.

No one is impressed by pre A-level formulae spouted to try to convince us all that Peter knows what he's talking about.

 

"Science is not a matter of labcoats. Science is the art of knowing. Cartesian principles regarding the accumulation of knowledge do not exclude that unstructured experimentation can yield a result (your artistic driver). In order for the greatest knowledge to be extracted from the experiment the observations need to be placed within the context of what is already known and a model of the behaviour needs to be formed. Only then can the potential of that knowledge be unleashed on a repeatable basis, winning races."

 

Models are formed in the mind. The best drivers form these models intuitively. They just "know". Telemetry, logging, metrics, ultimately mean nothing. In the heat of battle who stops with a pyrometer? Who puts his foot down and takes a chance and who backs off? The intuitive driver or the statistician? And who, with cars spinning all over the place, might LFB to get out of a situation that the mathematician had given up on?

 

Obfuscation Peter.

 

 

 

Andy

[Number Six]

One more thing Peter.

 

Apologies to Dave J. once again for the lack of oxygen.

 

"Are all the folks going to believe you on the basis of your say so? That isn't even the beginnings of a level playing field that you are setting up here. If LFB works there is a reason. If you can explain the reason or if you can knock holes in my argument (yes, I bothered to phrase an entire structured argument) then maybe we will get somewhere and then I will be happy to back down and I will learn something along with everyone else. The reason I am still typing is because you are mucking around with other peoples' knowledge and you aren't stepping up to the mark."

 

Now, Peter, you in your usual (I'll be careful here) "way", have tried to convince us all that LFB as an technique was (and I'm being kind once again) "academic" in an RWD car such as a 7. The master (who knows nothing about LFBraking or Pentii or any lateral thinking concepts about LFBraking...) speaks!

 

To me, "academic" means worthless, not worthy of consideration to an [Academic (sic)] such as yourself, superfluous, in the context in which it was quoted.

 

If LFBraking is Academic... (and in a good driver's repertoire it should be a part of the puzzle) ... yes, even in an RWD configuration... I said in a previous thread that I wouldn't give away any of my secrets, and I'm damned if I will now. Peter, take your R500 wannabe and go practice on an airfield around some cones. See if you can disconnect your RHB from your LHB and come up with some answers... (B as in Brain, LH, RH OK?). Meanwhile, as for other folks on this thread agreeing with your original (and I'me being careful here) flawed assertion...

 

And I quote:

 

"left foot braking can only be used with RWD to promote understeer in a trail-braking situation."

 

End quote...

 

You say Peter that...:-

 

And I quote...

 

""Many" have not begged to differ."

 

End quote...

 

Oh yes they have...

 

Peter = Understeer (left foot braking can only be used with RWD to promote understeer in a trail-braking situation)

 

So what we have is...:-

 

Andy = I'm not telling.

 

Peter = Understeer (left foot braking can only be used with RWD to promote understeer in a trail-braking situation)

 

Graham Perry = Understeer (yes to reduce understeer at high speed, BUT, you must keep the throttle hard down)

 

Marius = Still figuring things out

 

Peter = More blather

 

Marius = no comment

 

Andy = Incredulous!

 

Pierre = no comment

 

Alex = no comment

 

gee_fin = Oversteer (helps to promote oversteer)

 

Graham Perry = Understeer (I find that by holding the throttle down and LFB'ing I don't spin and nor do I end up on the grass on the exit to the corner. Instead what happens is that the nose jinks slightly towards the apex and often solves the problem.)

 

Rory = no comment

 

Elie = nothing on RWD but knows damn well the possibilities

 

Matt = Motoring journalist = Oversteer (LFB? Only mid-corner on my favourite roundabout to provoke lunatic oversteer)

 

Paul Ranson = Yet another technique Peter...! (By definition if you can DDC properly then you can also clutchless downshift. This allows you to LFB (not necessarily against power) which will safe significant amounts of time, perhaps going into the Molehill at Curborough)

 

Peter C = echo teeth.gif - gotta laugh...

 

Paul Ranson = yet another technique young Peter (I think some F1 drivers do brake against power, I suppose it's possible this is for handling reasons, I can't convince myself one way or the other about over/understeer. One thing it does give you is instant go when you get back off the brakes, maybe it can take a significant time to get the throttle open, the air flowing and the power back up.)

 

Mark Hall = and another thechnique Peter. Sorry if this is overwhelming for you... (The warmed brakes allowed Mika to brake "for real" a bit later than Brundle, who used an almost traditional 2 footed approach to braking.)

 

David W. = last one... yet another technique that "The World's Greatest Scientist" has overlooked (Left foot braking under power in a kart is an effective and sensitive way of balancing the kart round long corners right on the limit. I haven't tried it in a 7, but it should work too I would have thought.)

 

Keep doing track days Peter, you're less danger on the road to the rest of us.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Andy

[excess baggage]

Peter,

Having read all this VERY technical stuff that you spout I think that some of us newcomers that are thinking of competing this year will think again! Do we really need to know about friction circles to be able to enjoy ourselves? If someone brakes with their left foot why are you the one to tell them that they are wrong?

[Peter Carmichael]

I won't be able to hold mass attention in attempting a structured reply to Andy's points.

 

I have a rhetorical question to ask generally:

 

What would happen in the situations which are being described as left foot braking if one or other of the inputs (brake of throttle) were not being applied?

 

e.g. Matt's "Only mid-corner on my favourite roundabout to provoke lunatic oversteer"

If you didn't have the throttle down and you hit the brakes, would you or would you not get lunatic oversteer?

 

eb: no you don't *need to know* anything about friction circles. But many who compete reach a point where they start to seek advantage and do so by reading books or by getting training. The transfer of knowledge needs models which attempt to illustrate the continuity. If the models are wrong or they are misapplied then they will support misinformation. This is why I have asked for a critical response which picks apart my model or structures observations in an alternate model.

 

I will have a try at suggesting an alternate (shorter) model:

 

Suppose you are braking and then apply the throttle (the sequence of events is unimportant). The power of engine will work against the braking being applied at the rear, effectively giving you less rear braking. The braking at the front is unaffected. Therefore LFB is a technique for adjusting brake bias towards the front of the car. More brake bias at the front of the car promotes understeer.

[Peter Carmichael]

I like Blatman's contribution:

 

The science then determines which change to make next, and by how much. The science, by it's very definition is objective, but surely driving feel is subjective.

---

 

I also am aware that the science can also suggest changes to make. When such a change is introduced to the car, the driver will be asked to adapt his style to test out the possible advantage. The validity of the change will not just be decided by the feel for the driver, but also the result on the stopwatch/tyre wear/fuel consumption. If the feel is no good then it may prevent the advantage from being realised in which case there is no point in making the change.

 

The best drivers are those who are not necessarily wedded entirely to one particular style. This is where Schumacher is the engineer's favourite driver because he can adapt like a robot given a new program.

[spiderman]

I've been reading these comments with interest, avoiding becoming invovled but this may (or may not) help...

 

Suppose you are braking and then apply the throttle (the sequence of events is unimportant). The power of engine will work against the braking being applied at the rear, effectively giving you less rear braking. The braking at the front is unaffected. Therefore LFB is a technique for adjusting brake bias towards the front of the car. More brake bias at the front of the car promotes understeer.

 

Now I'm assuming that this is all happening during cornering and the car is very close to, or on, it's lateral grip limit. Let's say (for ease of explaination) that the slip angles are the same front and rear at the mid point in the corner. Throttle is, and remains wide open and the left foot then applies the brakes. I agree that the braking force at the front is unaffected whereas at the rear they are working against the power. If the tryes are already at the limit of their lateral grip the tyres can not work any harder an therefore the slip angle increases more at the front than the rear.

 

However if the car is not at that lateral grip limit before the brakes are applied something different could happen. With more tyre grip to play with the front tyres now bite harder than the rears (up to the point when the rubber starts to slide). This effect explains Graham Perry's comment about the nose tucking in and would therefore promote oversteer in this situation and not understeer. It is to my mind very similar to lift-off oversteer. The weight balance shifts to the front transfering more grip there and whilst reducing the amount at the rear, although in this situation grip to rear is not reduced - it's increased, but not by the same as the fronts.

 

Now that's assumming the slip angles front and rear are the same, they may not be...

 

So I'm agreeing with Peter, but can see that there are situations where an opposing effect may be experienced. It's easy to see where the confusion can occur.

 

Now maybe this is all nonsense, I've not studied it, but that's the way my mind sees the physics behind what I experience from behind the wheel. If you don't get understeer through LFB, you're not using the friction circle to the full extent or to put it another way, you're either not going fast enough or the car is not properly set up for the corner (so that the slip angles are not equalised).

 

Or in another words, I agree with everyone (sort of). Er, and I never use LFB in my Seven and don't know any racers who do...

 

Edited by - spiderman on 21 Jan 2001 09:45:21

[Blatman]

Number 6, thanks for the confidence inspiring support.

Peter

I actually thought that science was aiding Schumacher to set the car up to his liking, not to what the scientists say is the "best" setup, but rather the best set up for the driver. It is Schumachers ability to feel (that word again) whether the changes are right or wrong for him, not for the scientists, who, apparently, can't be wrong because driving is a science not an art form. In any event the science of a situation will force a driver to make compromises to his "normal" style, in order that he can win the race, but I don't think that science determines the responses that the driver makes, he just knows, because he can feel. As a last thought (from me anyway!) science can only really be useful on the grid. As soon as things heat up, wear down, pick up or go off, there is a degree of variability. As far as I am aware science cannot (yet) predict absolutely the degree of change during a race, so the driver must be adaptable to the changing feel of the car, potentially rendering all the science and measurements "out of date" (for want of a better phrase), as soon as something unpredictable happens.

Sorry Peter, if this frustrates your attempts at teaching us the many benefits of deep understanding of physics and engineering mechanics that you posses, but then again I don't need to understand the physics to know that I am about to understeer, oversteer, or lock up or whatever. I can just feel it, and I'm sure you can tooblush.gif

[Number Six]

What got me annoyed was Peters comment about my heroes:-

 

"quote:

--------------------------------------------------------------------------------

 

Jim Clark and Stirling Moss did not have data logs.

 

Driving is not a science, it is an art.

 

--------------------------------------------------------------------------------

 

Bollocks.

 

end quote:"

 

What Peter fails to appreciate is that Clark and Moss did not just drive one make of car. They were free agents and drove all types of cars from week to week and season to season. Something that rarely happens these days at the highest levels.

 

That is why I say the best drivers are intuitive and in Clark and Moss you have supreme examples.

 

Quote:-

 

"This is where Schumacher is the engineer's favourite driver because he can adapt like a robot given a new program."

 

End Quote:

 

This proves my point completely. Yes, he can adapt to ***one*** iteration of the ***same*** car. As can all Grand Prix drivers to varying degrees.

 

Finally, I said I wouldn't divulge any secrets, but what the hell. I'm going to regret this but in the spirit of 7 ownership...smile.gif

 

Hint - ever hear of a brake bias valve? Tilton make a particularly good one and it is hugely popular in the USA. You can instantaneously switch from the cockpit from full front bias, to even stevens, to full rear bias. Much better than the Wilwood often fitted to Caterhams, which is a turn-screw affair, and does not give the instantaneous adjustment of the Tilton.

 

Depending on how you set the car up (different pads are possible, front to rear) the effect can be as dramatic as using a full electronic line-lock. In sprints the effect can be similar to inducing a handbrake turn depending on how hard you LFB dab, or heel and toe.

 

Think about it... think laterally, you can even cadence LFB with or without power on either full front bias or full rear bias to achieve different effects.

 

I rest my briefcase!teeth.gif

 

Andy

[Peter Carmichael]

I know I use more words than are perhaps necessary but I wish you would read the ones I write.

 

If, when the brake bias is set fully to the rear the fronts are still doing something, by applying the throttle at the same time as the brakes you are modulating that bias towards the front. If the fronts are not doing anything, then there is precious little point in operating the throttle and brake at the same time.

 

Are we not in vigorous agreement, for how could it be otherwise when we observe the same events?

 

I am saying that the oversteer you are getting in any situation is less than you would get if the throttle was not applied at the same time. I call this a tendency to understeer.

 

I have marked out the limits of the term left foot braking by considering control inputs that cannot be achieved when transferring the right foot off the throttle in order to operate the brakes.

 

Quote:-

 

"This is where Schumacher is the engineer's favourite driver because he can adapt like a robot given a new program."

 

End Quote:

 

This proves my point completely.

---

 

It only proves that you can quote out of context.

[Number Six]

Well Peter it was you that likened old Schumi to a robot and I Jim Clark and Moss to artists. I stand by that.

 

As for LFBraking you initially seemed very stuck in your ways about what it could do for an RWD car like a 7.

 

I merely pulled you up on how you were interpreting the many folks on this thread who outlined all manner of effects which you apparently glossed over in a very blinkered fashion because what was described to you did not fit your "model".

 

Ergo, your LFBraking "model" for a 7 must be wrong.

 

Try a Tilton and see how you get on.

 

Andy

[spiderman]

Ah, so now you're saying that oversteer can be described as 'a tendency to understeeer.' So a pot of black paint that has had a drop of white added is no longer black, it has a tendency to be white.

I know what understeer is and I know what oversteer is and I know what reduced oversteer is, but I've never heard oversteer described as understeer before. No wonder we are confused.

It's not that you use 'more words than are perhaps necessary', but perhaps you are using the wrong ones or not explaining the ones you are. Had you wriiten:

I am saying that the oversteer you are getting in any situation is less than you would get if the throttle was not applied at the same time. I call this a tendency to understeer.

at the start of all this, I'd have been with you all the way.

I am now in full agreement with you. Hurrah!

[gee_fin]

 

Yikes, you leave the forum for a couple of days, return and this thread's four pages long!

 

With regards to "gee_fin - promotes oversteer".

 

My reason for stating this is that if you turn into a corner trailing ONLY the brake the back will step out (just think of the friction circle - if you turn in and use the full width of the circle with lateral grip, then add in the braking load, bingo, outside of the circle and into slip territory), however, I think Peter C was talking about trailing the throttle as well (LFB, RFT), this would balance out the weight transfer and if done correctly promote the understeer depending on the level of throttle/brake applied.

 

Just needed to clear that up :)

 

Graeme.

 

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[tgracing]

I'm getting withdrawal syptoms during the close season. I'm DDC/HT'ing in the Diesel 4x4. Good job I've got big feet.

 

I find that if I don't DDC/HT braking into a serious bend then drivetrain snatch (that most embarrassing personal problem) is a serious problem/useful technique. On some bends where you want to dive around (Molehill at Curborough) it can be very usefult to chuck the back end round and a good snatch of the drivetrain can be useful. Whilst most of the time on a circuit I want the back end to behave and DDC/HT as best I can.

 

I have bent across the throttle pedal (looks like a blind cobbler's thumb) and use the ball of my foot for braking with a stab of the little toe for throttle.

 

I have used left foot braking when I had a FWD car, but generally (as I haven't been trained by Penti or anyone else) I just ending up throwing myself into the windscreen when I forget it's not the clutch.

 

Davebo

C7 CAR

[Alex Wong1697456877]

Graeme,

 

Good to see you here. Did you go to the last Anglesey weekend? I couldn't make it due to work commitments.

 

Next time I see you in my mirrors, I'll try not to fall off the track!

 

Kind regards,

 

Alex

[Peter Carmichael]

Sorry spiderman. I could have saved a lot of trouble.

 

"We every one of us have our peculiar Den, which refracts and corrupts the Light of Nature, because of the differences of Impressions as they happen in a mind prejudiced or prepossessed."

 

Francis Bacon, Novum Organum Scientarum, Section II, Aphorism V

---

 

[Number Six]

Was Bacon talking about "models"...smile.gif

 

Andy

[spiderman]

For all knowledge and wonder (which is the seed of knowledge) is an impression of pleasure in itself.

 

 

Francis (streaky) Bacon - The Advancement of Learning ( (1605)) bk. 1, ch. 1, sect. 3

---

[Number Six]

Hypotheses non fingo - "I feign no hypotheses"

 

"Are not gross bodies and light convertible into one another; and may not bodies receive much of their activity from the particles of light which enter into their composition? The changing of bodies into light, and light into bodies, is very conformable to the course of Nature, which seems delighted with transmutations."

 

Sir Isaac Newton - "Principia Mathematica"

 

"To explain all nature is too difficult a task for any one man or even for any one age. `Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things."

 

Sir Isaac Netwton - Quoted in G Simmons Calculus Gems (New York 1992).

 

 

 

 

 

 

 

 

Andy

[Peter Carmichael]

spiderman, Andy smile.gif

[Number Six]

Peter, spidermansmile.gif

 

Andy

[spiderman]

Eh?

[Number Six]

Think laterally spiderman... Sir Isaac was telling Einstein 200 or so years before he was born that he'd be wrong...wink.gif

 

Andy

[Rory McLeod]

Yeah, but we are only talking about LFB here not the composition of the Cosmos. Science is the description of the discrete units of the Art that is life and Art is the understanding and application of the discrete units of scientific analysis. Therefore driving as an art is the application of the scientific principles (and vice versa). Is LFB useful in long sweeping bends or not?????smile.gifsmile.gif

[Number Six]

How long's a piece of string Rory?smile.gif How is your car set up, how is the brake balance set up, how fast are you going, how wide is the track, what is the runoff like, are you right on your grip limits...? The way I look at it is that it's just another technique to use or not use as is your wont. I just read a very interesting book by Stephen King on the art of writing. Basically he said that a good writer should, like any good craftsman, carry a full toolbox. In other words he/she should have all tools at his disposal for any given task. You never know when you might need a particular tool, and if you're out on a job and you've left it at home or in your van then you're stuck. So LFB is just another tool. Experiment with it - see if it works for you. Just like DDC and Heel and Toe'ing are other tools, as are handbrake turns in autotests, short-shifting, cadence braking, drifting, draughting etc. etc. You may not need every one for every job but it's nice to have the option...

 

Andy

[gee_fin]

 

Hi Alex,

 

Next time I see you in my mirrors, I'll try not to fall off the track!

 

Well, I was happily pootering along as if Sunday driving (still blowing away the assembled Elises smile.gif) until I got the wake up call from you!

 

I won't be making the next one (Feb 10th), I've had to cancel it too. Next one will be an airfield day though - Anglesey was fun but too frickin' cold and windy!

 

Cheers,

Graeme.

 

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