Why curve driving line when straight line is shortest

[Eager Learner]

Watching some F1 races, even when the section of track is a long straight, why do all the drivers drive a curve line? Isn't it more distance to cover and cost more time?

Most of the time they deviate the line very slightly only like the blue line in the image below. Why not straight line like the red line?



Is it because by approaching the next turn at a slight they are able to complete some lateral load transfer even before turn in point and so at turn in the response is more instant?

Watching the Indy 500, the drivers do this a lot more down the front straight. It is done to much higher degree so there must be a different reason. Is it the gradient of the track at Indianapolis? Or aerodynamic reason?

[richard_leeds]

Could you highlight a particular circuit where you have seen this?

[beelsebob]

The only time I've noticed this significantly is at Monaco coming down to Mirabeaux, and that's because there's a huge dip in the track there that would badly unsettle the car.

[MrBlacky]

Well, i think the time loss is negligible..

[astracrazy]

i think i know what your trying to highlight and this is why i think it is. (when you say moving over i guess your meaning about 2 feet or so)

When they come out of the corner they will tend to touch the outside kerb. Then they pull back onto the track and the obvious thing to do is not go along the side of the track because of debris. Then approaching the corner they move slightly over to open the corner up.

Is this what your asking about?

edit: if you drew a corner at the top of your image, you might see what I'm saying

[Diesel]

The do this after the final turn at Indy because running close to the wall actually adds drag and slows you down.

Also, sometimes they might make use of curb/runoff on the outside of the corner entry to take a wider entry for better exit speed.

Generally though, I would imagine the drive doesn't want to run the entire straight running right on the white line, but when he gets to the corner, he uses all of the track for the best line through the corner.

[Pierce89]

It's also because when you come off a corner, you're often not pointed perfectly straight but a little bit inwards, especially if it's a corner that engenders oversteer.

[n smikle]

Bumps and dips in the track.

[snorri788]

Sometimes bumps and dips like towards Mirabeaux. In wet races drivers may also want to avoid puddles or mud at the edge of the track that has been brought onto the track from someone going off.

[rifrafs2kees]

I have always wondered about this. One track that comes to mind where I see this often is Malaysia. I agree with Blacky that the time loss quite small but still.......

[Diesel]

Both straights in Malaysia have a racing line that cuts diagonally across the track...

[Giblet]

I would also think since you are breaking, you want maximum ground effect, and that is not where your front wing endplare is almost on the grass.

[snorri788]

I suppose that if everyone does it, then there is no real time loss.

[Eager Learner]

I have seen it in Brazil, Abu Dhabi, Malaysia , and other tracks. Abu Dhabi example here. See from 34 second mark down the very long straight, he only moves over to the turn in point on the right quite late. http://www.youtube.com/watch?v=HbDeXMNtmvU

I can only think of two possible reasons

a) running down a long straight with wheel very close to the edge leaves no margin of error. Steering error or braking error close to track edge can have major consequence

b) arriving at turn in point with slight level of lateral acceleration means response is slightly sharper when the remaining steering input is made

c) staying away from the wall on the right for aero drag reasons? ( as diesel above said)

?

[Belatti]

All reasons given here are true, but for ALL those reasons at the SAME time. Sometimes are the dips, others the wall induced drag, others the influence of borders in ground effects.