Braking and turning in - Trail Braking

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Juzh
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Joined: 06 Oct 2012, 08:45

Re: Braking and turning in - Trail Braking

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@Ciro Pabón

What's with the additude? You think just because you write "period" at the end of post it makes you automaticaly correct and everyone else wrong? Not to mention nearly everything you posted is full of rubbish. We're talking F1 here, not some 5th local racing league you seem to marshal at.

This pole lap is a good example of trail braking at it's max. RB6 was clearly inferior to the ferrari at that particular weekend and still vettel managed to pull it of with an incredibe lap when it mattered. Unlike weeber.

[youtube]http://www.youtube.com/watch?v=ucZG95PjYDI[/youtube]

Also, check silverstone pole, more of the same. Had he not trail braked, he'd probably be at least 0,5s slower.

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raymondu999
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Joined: 04 Feb 2010, 07:31

Re: Braking and turning in - Trail Braking

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So rather than bickering over "surely" statements, I went and tried to look out for racing onboard footage that had the telemetry dials.

Hamilton still does:
[youtube]http://www.youtube.com/watch?v=tD_Qfv-vxtM[/youtube]

Vettel still does:
[youtube]http://www.youtube.com/watch?v=jCQlZJvixVk[/youtube]

Button still does:
[youtube]http://www.youtube.com/watch?v=G9Bn78E7YhE[/youtube]

Alonso still does:
[youtube]http://www.youtube.com/watch?v=EOaZkBQvVF8[/youtube]

Raikkonen still does:
[youtube]http://www.youtube.com/watch?v=UYXw--068xU[/youtube]

Webber still does:
[youtube]http://www.youtube.com/watch?v=iL_xTt5zhvk[/youtube]

Alonso, Raikkonen and Webber seem to coast more at the apex than the others, but they still trail the braking up to the apex. Ciro mate, I love your posts, but sadly I'm going to have to go against you on this issue mate.
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Mchamilton
Mchamilton
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Joined: 26 Feb 2011, 17:16

Re: Braking and turning in - Trail Braking

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In my opinion, trying to think about it logically. Not trail braking would be an inferior way of driving.
The more time you spend coasting before the apex the more time you'd spend at your minimum speed, and I'd
Presume, the earlier your initial braking point would be. And coasting I'd of thought would allow you less
control of the car than trail braking, so long as your brake bias is rearward enough then you can get your car
to rotate into the apex just as well if not better. Correct me if I'm wrong

Greg Locock
Greg Locock
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Joined: 30 Jun 2012, 00:48

Re: Braking and turning in - Trail Braking

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I haven't waded through all 10 pages, but if you look at a v-g-g plot (or even g-g) it is very apparent when someone is trail braking, and it is intuitively obvious (what the engineer says when he hasn't done the maths to confirm it) that restricting your acceleration vectors to the x and y axes is going to be slower round the circuit than if you kept on the periphery of the friction circle at all times.

One way of thinking about is that trail braking is way of 'using up' spare grip in the friction circle if you can't hit max latacc straight away (which you can't) on entry to the corner.

Another way of thinking about is that nobody recommends staying off the throttle out of the corner, so why would you recommend staying off the brakes into a corner?

bhall
bhall
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Joined: 28 Feb 2006, 21:26

Re: Braking and turning in - Trail Braking

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I wonder if Ciro's concerns were less about trail braking, for some reason, and more about braking too late and locking up the rear wheels so that they slide to hasten (or attempt to hasten) the yaw rate of the car through a turn.
Last edited by bhall on 12 Mar 2013, 01:43, edited 2 times in total.

Greg Locock
Greg Locock
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Joined: 30 Jun 2012, 00:48

Re: Braking and turning in - Trail Braking

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Ciro raises a good point in amongst the venting and innaccuracies- what is it about trail braking that makes it so hard to do well consistently, compared with putting the power on out of a corner which every 18 year old learner driver understands and attempts intuitively?

Jersey Tom
Jersey Tom
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Location: Huntersville, NC

Re: Braking and turning in - Trail Braking

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Greg Locock wrote:Ciro raises a good point in amongst the venting and innaccuracies- what is it about trail braking that makes it so hard to do well consistently, compared with putting the power on out of a corner which every 18 year old learner driver understands and attempts intuitively?
Easier to go in one direction than the other.. to be near the limit of traction and gradually feed in throttle as you sense the yaw attitude of the car and how much it can handle.. than to just intuitively know exactly how deep you can brake and then feather off into cornering.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

Greg Locock
Greg Locock
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Re: Braking and turning in - Trail Braking

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So, why can't 'we' feather brakes like we feather throttle? FWD or RWD most people seem to be able to accelerate out of the corner OK, but without ABS or ESC then it requires training and experience to trail brake. Why is the one not the mirror image of the other? That's what I don't understand.

Here's my guess.

A throttle is a fairly weak control, flat to the floor and in most cases you'll manage half a g or less. The time constant is quite long, first the throttle opens, then the carburettion recovers, finally you get some crankshaft power, then it winds its way down the driveline and 160ms later it hits the road.

Whereas brakes are set up so that within an inch on pedal travel you get 1g, and the time constant is faster.

So, why don't race engineers set their cars up with the same 'lazy' brake response as you get throttle response?

timbo
timbo
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Re: Braking and turning in - Trail Braking

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Greg Locock wrote:So, why don't race engineers set their cars up with the same 'lazy' brake response as you get throttle response?
Cause it's slower.
Every (true, yeah, and probably a Scotsman) racer would love engine with that much power and response.

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raymondu999
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Joined: 04 Feb 2010, 07:31

Re: Braking and turning in - Trail Braking

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If I may venture a guess as to Ciro's worry...

I think Ciro's concern is that trail braking is generally performed at the very limit of traction, and because you're braking so deep and on the power right after the apex, there's no margin of error.

Hammering the tyres with such compound loading in two directions consistently is also probably not ideal for tyre preservation.
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timbo
timbo
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Re: Braking and turning in - Trail Braking

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raymondu999 wrote:If I may venture a guess as to Ciro's worry...

I think Ciro's concern is that trail braking is generally performed at the very limit of traction, and because you're braking so deep and on the power right after the apex, there's no margin of error.
That is true. And the brakes are opposite to throttle in that respect -- if you're too early on the throttle and sense a back stepping out, or you running out of track on exit, you can back off the throttle and correct that. If you're braking at the limit of traction and delay braking to last possible bit (which is what you do when trail braking) you cannot back off on brakes because you will run wide. If back end steps out on braking (which may happen when you trail brake) you also either spin, or you release a brakes and run wide.
It becomes critical on tracks with heavy braking and tight corners -- like Monza. I remember Alonso or Button said something like "if you brake 2 meters later you gain 0.1 sec, and if you brake 5 meters later you loose 0.5 sec".

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Ciro Pabón
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Joined: 11 May 2005, 00:31

Re: Braking and turning in - Trail Braking

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Juzh wrote:@Ciro Pabón

What's with the additude? You think just because you write "period" at the end of post it makes you automaticaly correct and everyone else wrong? Not to mention nearly everything you posted is full of rubbish. We're talking F1 here, not some 5th local racing league you seem to marshal at.
I disagree completely. It's not a 5th rate league, it's more like a 6th rate league. The oldest guy is 10 years old (and I'm not making this up).

On the other hand, kids down here agree with your opinion: they think I "seem" to marshal (and that's when I'm not running away from older "Youtube racers").

Of course everybody knows that when you write "period" at the end of a sentence you're automatically right and everybody else is wrong. I wonder why this simple trick is not as extended as it could.

You could call it "trail perioding".

Finally, my deepest condolences for reading everything I've written here. There is a reason why I don't post anymore and it's for contributing to the well being of humankind (I'm assuming you're human).

When I fall in temptation I'm quickly reminded of why it's not a good idea.

Anyway, what the heck. I already started to post, so there you go.

About the Youtube "demos", trail braking should not be confused with settling the rear end tapping at the brakes while you accelerate. That's why the only guy in the grid that trail brakes is Kobayashi and there is a reason why he doesn't have a car this year.

On the lessons about trail braking and why it is a good idea, well, yes, I'm pointing it's hard as hell, wastes rubber and it will ruin your whole weekend if you got it wrong once. Of course, team mechanics do not mind to work for 72 hours straight for you to send their work to the rubbish bin in one elegant move.

It's like running with scissors. I only have one question about it: "why?"

That's why people that knows better do not use trail braking unless:

a. You race bikes
b. You race in the dirt
c. You're in a spec series
d. You're in dire need of a car length and you don't mind if you ruin the weekend

Those who claim it's a better technique because it's subtle, evidently have never, ever in their life stomped on a brake in a braking zone. Only those who have driven a car with drum brakes in the rain understand the sensation: the darn thing doesn't stop.

Dear padawans, braking while racing, in real life, it's like kicking a rock with your bare toes. Scary as hell and as subtle as Chuck Norris cutting a tomato with his hands. On top of that, that's something you're doing at 200 kph plus and on machinery you could never repay if you mess up. So, the happy comments about it are... well, not that subtle
Ciro

Jersey Tom
Jersey Tom
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Joined: 29 May 2006, 20:49
Location: Huntersville, NC

Re: Braking and turning in - Trail Braking

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Ciro Pabón wrote:About the Youtube "demos", trail braking should not be confused with settling the rear end tapping at the brakes while you accelerate. That's why the only guy in the grid that trail brakes is Kobayashi and there is a reason why he doesn't have a car this year.
Completely untrue. More evidence, beyond what the DAQ I posted earlier:
Image

Pretty clear trail braking from the throttle & brake overlay there at the bottom. Plain as day, best example being into T1 - very aggressive (vertical) initial brake slope, followed by a gradual trail off, then back to throttle.
Grip is a four letter word. All opinions are my own and not those of current or previous employers.

timbo
timbo
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Joined: 22 Oct 2007, 10:14

Re: Braking and turning in - Trail Braking

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Jersey Tom wrote:Pretty clear trail braking from the throttle & brake overlay there at the bottom. Plain as day, best example being into T1 - very aggressive (vertical) initial brake slope, followed by a gradual trail off, then back to throttle.
Better yet, there's steering trace in there, and combined braking and steering application can be seen.

thisisatest
thisisatest
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Joined: 17 Oct 2010, 00:59

Re: Braking and turning in - Trail Braking

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...and everyone has seen Hamilton lock up the inside front wheel around corner entry. It wouldn't be happening without trail braking. (His aggressiveness and the car's setup lead to the lockup)