Drafting?

[superstring]

So there's something I don't understand about the current aerodynamic situation in F1 when it comes to passing. On the one hand, the cars aren't supposed to be able to follow each other closely because the wash from the car ahead messes up the following car's aero. But on the other, cars seem to be able to pick up a tow in all this turbulent air and that facilitates passing. In my mind these 2 things seem contradictory. Anyone have an explanation?

[mike]

in a straight line over say 5th gear the car is not traction limited that means the downforce is in excess and hence the turbulent air is beneficial, since at high speeds most drag comes from pressure drag, however in the corners cars are always on the limit of traction so when you have turbulent air, the car in the back cant follow the car behind properly.
the end result is that cars cant follow out of the corners and the tow they get in the straight pass the traction limit zone is not enough to get them in a position to over take.

the only way to fix this is to increase the N of drag per N of downforce, or reducing the anti-lift coefficient

[747heavy]

I will not claim that I know the perfect answer, but may can point out one part of the problem.

If your straight is long enough, you can still draft, get a tow and use the extra speed to pass the car in front, if you can do so before you need to brake or turn in for the next corner.

The "problem" is that most straights on the current tracks are simply not long enough to do so. Spa, Monza and Sepang, probably a bit Canada are the exceptions.

The main problem in this context is, that the car behind cannot follow close enough in the corner, that leads onto the straigh, because of the lose in front downforce.
This will cause the car behind to understeer, and if done for a couple of laps, ruin the tires.
If you can´t follow close enough, it´s more difficult to make a overtake manouver on the following straight stick. That all the cars have a common rev limit now, does not help either.
Having said this, it´s also down to the driver, some drivers are simply better then others. So there is a technical part to it, but it is also used as an "generic" excuse. IMHO.
As a modern F1 car generates a lot of his downforce (front downforce) by the front wing, this is a problem. A wing is much more sensible to turbulent air, the a tunnel or diffusor which relys more on the mass flow. (e.g. sports cars, LMP)

[DaveKillens]

The lead car creates a lot of turbulence behind it, as well as a low pressure area. An aero-dependant car requires a smooth airflow to make all the aero tidbits work. So basically, there is a lot of downforce lost when following a car.

But the air behind the lead car is low pressure, so the following car can enter this zone and pull up on the car leading.

[raymondu999]

Yep. So to summarise, you lose downforce. But then again, you lose drag too

[Just_a_fan]

One problem what was mentioned by Brundle (BBC commentator) on Sunday was that the following car often runs out of revs before it can make use of the tow. This was mentioned as Vettel was trying to pass a mid field car. He was making good use of the tow but couldn't get by because he ran in to the rev limiter before he could pass.

Of course, if the following car could be closer coming out of the preceding corner then this problem would be reduced somewhat.

[Caito]

That's why it's written all over the books that you should be below limit RPM at the end of the straight in case you are passing someone during the race.

For some reason, RedBull though(calculated) that what was be lost, didn't compensated what could be won.

[strad]

a tailwind perhaps?

[747heavy]

Keep in mind that the rain tires have a larger outside diameter then the dry und intermediate tires., and that Spa has on straight going uphill quite a bit, and the other on going downhill/being flat.
It´s difficult to gear perfect under this conditions.
It is not umcommon togear shorter and let the car travel at the limiter or max rpm for a while, you still can win in overall lap time, due to better accleration and traveling longer at top speed, epecially when you hace an rpm limit.
If you gear for a possible overtake move at the end of the second straight, before the Bus Stop chicane, you will lose time on the uphill section.
Remember, that this year you can´t change gear ratios between Qualy and race, so you have to find a compromise and make your pick. In the past, you would choose your gear ratio for the race depending from your starting position. (e.g. the guy on pole does not have many cars to slipstream/draft with, but if you qualify > P10, and want to have a overtake advantage, it would make sense to gear a bit taller)

[marcush.]

uphill a bit ...747h ...you used healthy scooters for your trip around the track ,I guess ...the elevation change in total from the compression to les combes is 50m ,the distance is 1000m so thats 5% average ...
the backstretch is only slightly uphill according to the circuit map, downhill
section is to Rivage (Bruxelles )down to Poohon
,Fagnes and Stavelot(paul frere) as the lowest point ..
http://www.spa-francorchamps.be/en/pdf/ ... ap-pro.pdf

[747heavy]

Yeap you are right Marcus,
the back straight before bus/stop and S/F is slightly uphill
From memory it looked rather flat, but it has been a while (~12years)
since my last visit to Spa.

[marcush.]

when I first walked up the hill i was totally speechless ,I have to admit..but you are right the backstretch through Blanchimont you would not relise that this was going uphill but 100m in elevation change is something to take in .

[strad]

I understand but I thought they had their own form of push to pass in the form of a different engine map that allowed a few extra revs. Wouldn't your explanation not allow for that,,or perhaps he didn't use it.
They do cut it so close that it's said that a tail wind (or a shift in the wind to a head wind ) can play hell with their figuring of the final drive gear ratio.