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V.R. Metaphysical Aesthetics


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#76 John Woods

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Posted Mar 19 2018 - 06:07 PM

View PostJonnyA, on Mar 18 2018 - 10:25 AM, said:

Still don't like his line into Hugenholtz though!

In Grand Prix Legends its a good line if you are passing under braking but otherwise its hard to get up the hill that follows.

Actually take it and Tarzan more like arena supercross riders than like Taruffi suggests...staying outside a little longer and getting a better run up the hill, more like the line he suggests for banked ovals.

Probably because real track back then was cambered differently and/or crowned and GPL version is not?
Or maybe he's got it right?

In attached, Taruffi recommended line, (close enough), is in red and my idea of very late clipping point, in green, to get most time accelerating up hill and most speed before Jan de Wijker. (Now looking at the drawing all finished and posted up think my line typically makes a wider arc, more on the outside at entry and exit).

With no traffic, the goal is one entry and one exit, all one safe motion with minimum loss of speed, minimum time in constant radius, and maximum time for exit?



:D

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Edited by John Woods, Mar 20 2018 - 03:25 PM.


#77 Pete Gaimari

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Posted Mar 20 2018 - 03:29 PM

Yeah, John. Blind turns are hard enough, but when we're going that fast there's no room for error. Turn in late or early and we're in trouble.

#78 JonnyA

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Posted Mar 20 2018 - 03:56 PM

I find it difficult to get all the way across to the RHS of the track after Gerlach, but I do my best because I find it gives me room to brake nice and deep into Hugenholtz which makes it easier to rotate the car. For Tarzan and Hugenholtz, over time my line has got deeper with a much later apex - all focussed on getting onto the throttle ASAP. If I used Taruffi's line into Hugenholtz I think I'd end up parked on the apex at about 0 mph!

But as you say, GPL Zandvoort and real Zandvoort may be rather different beasts.

#79 Saiph

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Posted Mar 20 2018 - 07:58 PM

Most of the driving advice I've seen in the past says that it's always the exit of a series of bends which should take priority, as good exit speed leads to better speed on the following straight. So to get the best line and speed up the hill towards Hunserug, you need a good exit from Hugenholtz. To get a good exit from Hugenholtz, you need a good entry, with a late apex to get on the power early. To get a good entry into Hugenholtz, you need to get over to the right after Gerlacht. That means that you may have to go through Gerlacht a bit slower to give you time to get the car over to the right-hand side. The time you lose compromising your speed and line through Gerlacht should be more than made up for by the better exit and better speed between Hugenholtz and Hunserug. At least that's how the theory goes. :D I always try to drive according to that ideal, but sometimes it's not easy!

#80 John Woods

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Posted Mar 25 2018 - 09:16 PM

It would  be interesting to see some of the driving lines GPLRA reveals the WR challengers have made from Tarzan to Jan de Wilker.

My preference seems to be exiting Tarzan on the inside and staying to the right up to the crest at the bend to the left, almost in a straight line from entry before the crest to entry to Gerlacht, crossing over to the left side to clip the bend at the crest, so after the crest the car is on the outside for entry to Gerlacht.

If a driver rather goes to the outside exiting Tarzan and does not cross over to the right before the crest, after the crest they will likely be on the inside approaching Gerlacht, forcing them to slow before climbing the little rise that precedes the short straight down to Hugenholtz.

In contrast, landing on the left side of the track after cresting at the bend places the car ready to take the maximum arc thru Gerlacht, possibly with less incline to overcome, and the option at exit of choosing any entry point to Hugenholtz.

Once there, Taruffi's suggested line offers the opportunity to apply constant radius around the extreme track camber close on the inside thru the turn...which actually seems a good enough line that takes less time in the turn even tho the car slows to 45 or so MPH.

The problem is the hill that follows. So far glimpsing a few times at the speedo up near its crest reveals a rough guess that taking Taruffi's line is about 5-10mph slower at that point than my erratic late wide apex guess of the fastest average exit speed thru the turn.

Which line is faster overall? I have no idea.

Lately been running consistent 1:27s in the 67LotusF1 with 14-lap fuel load down to a few 1:25s when the car lightens up, (just saying so you know, for me its all about style not being fast...because I'm not, plus daydreaming a lot).

Edit: Well, hm...now uncertain exactly where Gerlach is and how to spell it. Going by the GPL Program Menu track map comments above might be confusing, or the track map is, (which I figure its not).



:D

Edited by John Woods, Mar 26 2018 - 01:39 PM.


#81 John Woods

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Posted May 12 2018 - 09:51 AM

Being too easily distracted its been awhile now since touring Zandy. It is certainly possible to very quickly get thru Hugenholtz by inducing a constant radius line similar to the line Taruffi diagrams.

So quick for me its really too quick and easy to take it way too far around.

In the meantime, yet again, here is another incomplete fantasy about what Taruffi et al describe regarding how to place all four tires in slip, sustaining maximum lateral load on the line of least resistance, and therefore taking the quickest route thru a turn.

Questions and guesses...

hm grumble edit: already see need to make changes for sake of clarity, (not content, yet), so current drawing is here as placeholder.



:D

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Edited by John Woods, May 12 2018 - 12:15 PM.


#82 Remco Hitman

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Posted May 18 2018 - 03:39 PM

Here's the simple explanation: Four wheel drift is the summum of the adage "Throttle comes on, steering comes off".
This is the best advice in car control: the more throttle you use, the less steering input you should give.
Put differently, less steering input allows for more throttle.

If you can negotiate a stretch of non-straight while maintaining little to no lock, you will be as fast as you can be on that particular stretch, basically because it allows for more throttle.
Combine this with the fact that tyres sure love a bit of slip angle and you're golden.

#83 John Woods

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Posted May 21 2018 - 03:21 PM

Throttle on, steering off.
Great adage.
Thanks Remco.

Just as true whether drifting or not.

Way back when someone else also much wiser than me on a long gone forum noted there are only three modes to worry about: acceleration, coasting, and braking.

For years that was pretty much all I knew for sure.

Nice when things are that simple.
Its like, well okay, at least we got this far.

All the rest is detail, where it never seems so easy and everything seems counter-intuitive and complex.

BTW, seems to be no history and little or no definition of the term "lock" as it applies to driver technique, when it seems to become a verb and have a different meaning than "full lock" and "lock-to-lock."

Try searching for "steering lock."
:P

Has the term lock been used since stage coach days?
"Driver Plan B: To avoid going off cliff, apply some lock and whip the horse to full run."
Is its lineage nautical?
"Lock her down and rig all sails tight. We'll outrun this puppy and beat them all to Tortuga!"

Sorry for having too much fun.

What is locked up? Is something locked up?

To negotiate a constant radius turn, (refer to diagram at post #70), steering is held almost straight, pretty steady, and sort of firm.
Its only constant radius btw on a flat surface like an airport circuit or Skid Fun.
On any surface the car takes the line of least resistance.

The biggest lockup is that steering and throttle hold the suspension out away from static CoG hopefully with sustained intent somewhere near maximum lateral load.

Seems appropriate to describe its use as in "to place a car into lock," or "applying a little lock," and that it means to countersteer in response to coast induced oversteer, or just oversteer?

So the three phases of drift thru a turn could then be 1) entry into lock, 2) in lock, 3) exit out of lock?

Please don't forget...its questions and guesses.

PS to JonnyA, yes it is amazing reading Taruffi confirms experience with Grand Prix Legends.
Now have a lot more confidence blathering on about things I thought were new to me that without understanding it I knew all along because of GPL.
:D

Edited by John Woods, May 22 2018 - 08:25 AM.


#84 Remco Hitman

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Posted May 22 2018 - 11:30 AM

Maybe it's just me but to me "lock" means any amount of steering input greater than zero. To which you will surely reply "Is zero steering input any input at all?" :lol:

"Full lock" means maximum allowed steering input so some lock isn't quite as much.




View PostRemco Hitman, on May 22 2018 - 11:29 AM, said:

"Is zero steering input any input at all?"

It is, by the way.

Edited by Remco Hitman, May 22 2018 - 11:31 AM.


#85 fajanko

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Posted May 23 2018 - 04:32 AM

"Lock her down and rig all sails tight. We'll outrun this puppy and beat them all to Tortuga!"

:lol1:

#86 John Woods

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Posted May 24 2018 - 04:20 PM

Hey JP, hope all things are well.



Zero input is input?

Think I understand.
Zero input is when you let go of the wheel?


Isn't applying lock more specifically counter-steering, with the intent to put the front at a specific angle of slip?

So it could be zero steering input or, maybe theoretically, even with the direction of the turn as long as its balancing against the rear that is itself going toward being in slip?

Just my humble guess you first have to know what the rear will be doing before tossing it against some patch of track camber and expect to match its motion with a quick spot on flick of the steering wheel, all at the proper instant.

Amazing when you get it right.
Curious it seems sometimes the Ai up ahead syncs in and advances in unison?



:D

Edited by John Woods, May 31 2018 - 05:51 PM.


#87 John Woods

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Posted Jul 05 2018 - 06:33 PM

Another bucket list must read checked off...thanks Grand Prix Legends.

Finally after many years of dumb procrastination, forgetfulness, and occasional wishing about it, now have a re-print paperback copy of Denis Jenkinson's c1958 classic, The Racing Driver, The Theory and Practice of Fast Driving.

First time thru it is kind of a slow sloggy read with too long paragraphs of uncertain direction all bundled into a rambling jumble of way too much detail, side stories, and occassional apparent inabilities to stay on point or get to one.

Then later, maybe days later, something clicks and that chapter has to be read all over again, now that it is starting to make some sense why he went on so long about some peculiar aspect of sidecar riding that is of particular interest to the professional F1 driver.

Then on and on and on about slip angles after summing it all up with the simple declaration that science and engineering confirm the optimum slip angle for a racing car is designed to occur when 15deg of steering lock is applied.

Have to wonder if that's still the case.
(Thinking probably not).

There's a graph to prove less is not enough and more is too much. It was also noted, if the driver is not getting out there to 15degs of lock at the tire patch that they are not going fast enough. Apparently the optimum speed is just past way too fast to get thru the turn otherwise. Better get it right.

Two things that are interesting in his analysis of a racing driver's skill, (entirely unlike mere mortals), is first, compelling a car at will to demonstrate an oversteer or understeer attitude regardless of its predisposed inclination, and unlike the rest of humanity, do it with incredibly focused nonchalance within a few fractions of a second at the precise micro-second the move must begin and end, and second, doing it at somewhere over 180mph where there is zero tolerance for error.

Also clearly no doubt in Jenkinson's view any use of steering input, even zero lock, can be "applying lock."

Paying attention to use of the term lock has narrowed the search for a reasonable practical definition to "the use of steering input to direct the car away from the line of minimal resistance," to a line of greater resistance and greater grip.

Note the line of minimal resistance is where the car would go if the driver released the steering wheel and let the car roll. It is the same as the line of least resistance, as others use the term, and the fastest way thru a turn if that line is available from entry thru exit. If not available at the speed that must be maintained, it is time to try a little lock.

"Lock" is a verb. It means "to hold in position." So where the steering wheel is relative to zero at 12 o'clock, or any number of degrees either way, is secondary to the art of applying lock to set the car on a certain line.

In the context of suspension dynamics, is it more appropriate to think of the steering wheel as a lever, that pivots off the rack, to keep the suspension steady out near the break-away limit of no more marginal returns?

How do we reverse engineer 15deg of tire patch lock into Grand Prix Legends setups?

BTW, Denis rode professionally on winning sidecars and rode with Stirling Moss to win Mille Miglia. Many of the side stories used as examples, (like a book within a book), are about his many years of very special direct experience with racing and race drivers.

Then it finally hit, on a sidecar the rider is the active suspension.
On the Mille Miglia, the rider is as much a part of the car as its driver.
Stirling could not have made a better choice, and together they proved it.

This post could have been much longer if all the scope of this book had been covered.

Forgot to note the two turns DJ mentions as being especially suited to serious applications of lock are Abbey and Woodcote, (nice they are on the same circuit), and also the last turn before the front straight at Rouen.


Read this book, then read it again and again and again...

Maybe it won't help you be faster.
It will help you become a better driver and better understand firsthand what it was all about back then.


:D

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Edited by John Woods, Jul 12 2018 - 09:13 AM.


#88 Remco Hitman

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Posted Jul 16 2018 - 12:16 PM

Slip angle is not measured by steering wheel input. Slip angle is the angle of the roll center of the tyre compared to the direction it travels at.
Grip builds up as the slip angle increases (but not linear) until a certain point after which it falls away again (though not a steeply as some sims will have you think). It is generally believed the optimum slip angle in GPL is somewhat high, allowing for quite aggressive sideways driving without taking it beyond the optimum. This is aided by the lack of tyre (temp) degradation.
Front tyres push the car around the corner at a greater angle than required to keep the car following the radius, thus developing some slip angle and increasing grip. The rear tyres follow suit. The momentum of the car pulls the car outward, creating a friction in the rears which acts as a slip angle.
In a controlled slide, the slip angle of the rears is increased as the body of the car is set at an angle to the direction of travel. The increased slip angle yields some extra grip which can be used to put more power on the road.

#89 gliebzeit

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Posted Jul 16 2018 - 03:28 PM

:thumbup:

#90 John Woods

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Posted Jul 18 2018 - 09:52 AM

Hi Remco, appreciate your insights and another perspective that helps understanding.
Howdy Greg, thanks for checking in.


There is an essential to the era driving technique that has been described in very specific detail by Taruffi and Jenkinson. It is the technique of quickly making a single-motion counter-steering input to lock the front in exact and simultaneous correspondence to coast-induced slip on the rear.

Ferrari's description of his surprise, shock, and fear while first riding with Nuvolari at racing speeds through a series of turns includes a similar although almost frantic analysis of this technique.

Jenkinson in 1958 points out the optimum slip angle is 15degs and notes F1 drivers from Fangio to Moss (his reference) consistently caught the rear by tossing the front tires out near 10-14 degrees of slip.

By 1975, Niki Lauda noted in The Art and Science of Grand Prix Driving that then current tire technology had reduced the optimum slip angle to a range of 8 to 10 degrees.

The wider the tire patch, btw, the less slip angle at maximum grip.

It follows that the tires, while enjoying the approach to optimum slip, are doing so in coincidence with a symmetrical rotation of the car around its CoG.

Seems the setup idea then, especially if interested in exploiting this technique, should be to help the car rotate to optimum slip and no more.

Related to this is knowing when to put the car in coast and at the same time, (all within 4/5sec), how far on period-correct hard tires to turn the steering wheel in response, so the car "sets" itself and the driver then has only to comfortably accelerate with confidence on the resulting, hopefully the preferred, line of travel.

Rather than, otherwise, fighting with throttle and steering to keep the car close to some minimum line of maximum grip, even if that is another talent that separates the best race drivers from the rest of us.

The key is a dynamic setup that compliments the technique and yields a car eager to slide upto into and outof optimum slip.


We can dream.
:D

Edited by John Woods, Jul 18 2018 - 01:09 PM.





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