Starts (why Mark Webber is losing out)

[Lycoming]

I was referring to the rev drop that occurs when he dumps the clutch, if thats what you were wondering.

[Richard]

Its a combination of clutch pressure setting determined by the engineers from telemetry, the driver's fingers, and his right foot. One is predetermined, and two are manual inputs by the diver. The clutch setting is constant, the other two vary over time.

Any error in how those three factors are combined over the duration of the launch will cause the car to bog down or wheel spin.

Strad - if you've looked at the footage, are you saying the revs are lower before the lights go out, or after?

[HampusA]

The purpose of this thread is to get an exact description of the start and to undertstand how much influence the driver has on the start.

How can Mark Webber be that bad?

I for one thought that most parameters were established by the engineers, the driver only has to rev up and when the time comes, put in the first gear. Voilá!

Can somebody who knows(not "I think so") or has the time to find out the drivers start procedure step by step(starting with warming up the tyres on the out lap). Maybe we can find a video of a start with the speed, rev, brake and gear display. We can continue discussing the different parameters(drivetrain, tyres an so on...) from an engineering point of view.

Maybe we'll get to the bottom of why Mark Webber is starting so much worse than Sebastian Vettel allthough they are in similiar cars...

Without traction control it´s not easy sending 700+ horses down to the ground
Especially in a car with so little torque.

Basically the driver during the weekend will do starts and feel how the clutch bites and checking how slippery the racetrack is etc.

Even if you have a certain idea on how to set the car up it´s still very much a gamble since you have 24 other guys also doing starts with probably slightly different settings and obviously different cars.

As far as Webber and starts... I think he just has to little revs.
Many times the car has bogged down and i have never seen him loose places in the start due to excessive wheelspin.

To get the perfect start you must first have some luck that your settings you chose is actually the best settings and choosing rpm limit on where you will dump the clutch etc.

What the engineers say can only go so far. In the end it´s up to the driver because he´s the only one actually knowing the grip levels.

[raymondu999]

I remember Martin Brundle saying the system is very sensitive. If you have too little revs you'll bog; and if you have too many revs; you'll get wheelspin

[dren]

I'd think you would want a little spin over bogging. That's from my autoX experience.

[HampusA]

tires generate the maximum grip with some slip so yes, wheelspin is preffered, especially in these cars.
Not to much though. and not to little because then you´ll bog down like Webber has done alot this year.

the clutch i would guess is more like a switch then what we are used to.
It´s all or nothing basically and then it´s up to the driver to modulate wheelspin.

[marekk]

Let's not forget about aero. By blowing directly into diffuser, RB's generate some amount of downforce even on the grid. One more variable to play with, and maybe it's just one to many for Mark.

[HampusA]

Sounds abit ambitious in my opinion.
I doubt exhaust gases create any notable downforce, i thought the exhaust gases was mainly there to create a "bigger" diffuser.
But obviously that involves travelling at high speeds where aero has an effect.

[raymondu999]

I think marekk is talking about some teams already blowing their exhausts at the start so that there's more vertical load on the tear tyres; to add more traction from the startline.

[HampusA]

Yea but are there any numbers we could look at or atleast a theoretical number on how much downforce exhaust gases can produce at around 15-18.000 rpm´s?

[strad]

Without traction control it´s not easy sending 700+ horses down to the ground
Especially in a car with so little torque.

That's why they do those practice starts...So the engineers can select just the right clutch grab point and how to map the engine for the start. Yes he has control of his right foot, but the computer controls how much power and the clutch bite point that is preset..

[raymondu999]

Yes but the right foot plays a very major part in it, as I understand it. Which is what I've been saying is very sensitive, in terms of how many revs you have, vs the optimum number. More, you'll get wheelspin. Less, you'll bog down

[strad]

It is not like this anymore.
The computer and the engineer handle all he talks about at the end of this short video I edited. All Mark has to do is hold a preset rev number.
http://www.stradsplace.com/VIDEOS/Brundle_the-Start.mpg

[marekk]

Yea but are there any numbers we could look at or atleast a theoretical number on how much downforce exhaust gases can produce at around 15-18.000 rpm´s?

I did some time ago in other thread quick and dirty calculations with foilsim III and it was about 30-40 kgf from exhaust alone. Taking additional jet pump effect into account not insignificant numbers. Tricky part - if you got to much wheelspin, you go off the throttle and loose this additional downforce - very sensitive negative control loop.

The same for Renault, which produces their downforce by blowing leading edge of the floor, but they usually go off the line pretty good, so it's up to Mark IMO.

[HampusA]

It is not like this anymore.
The computer and the engineer handle all he talks about at the end of this short video I edited. All Mark has to do is hold a preset rev number.
http://www.stradsplace.com/VIDEOS/Brundle_the-Start.mpg

You still have to modulate the wheelspin. Which is a crucial part in getting off the line.

It´s not just hop in, get a number from the engineer and viola, super starts everytime.
The egnineer can "guess" at best because usually people do practice starts out of pits and they are done a few hours before the actual race.
Temps and whatnot can change pretty dramatically over the course of a few hours.
Aswell as the different grip levels of tarmac then add the factor of "off-line-dirt" for half the grid etc.