Korean GP set-up guide: Lewis Hamilton needs to return to form

The Korean Grand Prix is no-one in Formula 1's favourite race, but the track provides a good, all-round challenge for the cars and drivers.

Preparing the car for the Korean International Circuit is a bit of a compromise because the track is split into three distinct - and very different - sections.

The first is all straights and slow corners, in an attempt to promote overtaking. The main straight from Turn Two down to Turn Three is one of the longest in F1, so a car needs good straight-line speed.

The middle sector is a sequence of fast, sweeping corners, where I'm sure Red Bull and Mercedes will dominate in terms of pure speed. The corners are not all on top of each other, but one does lead into the next and the car needs a good aerodynamic balance through that section.

And then the last sector, which is designed to have more of a 'street-circuit' feel, requires good mechanical and front-end grip. So a driver needs to look after tyres in the middle section so they still provide enough grip to give the traction he needs in the final sector.

Getting the best out of the car is not easy because it is such a difficult track. That's why good cars go better there and that's why the races so far have been all about Sebastian Vettel and Red Bull.

He was leading a close inaugural race in 2010 when he suffered an engine failure and Fernando Alonso went on to win in the Ferrari. Vettel has won for the last two seasons.

On current form, on the back of three consecutive wins in Belgium, Italy and Singapore, he will again be the man to beat this weekend.

WAITING FOR A MERCEDES REVIVAL

Mercedes have been through a bit of a lull in recent races. Lewis Hamilton won in Hungary, the last race before the summer break, but they were nowhere in Belgium and Italy.

They looked a bit stronger in Singapore, but again they faded in the race. The car is quick enough; they just seem to have lost themselves in some way.

It's possible that in looking for the best trade-off between qualifying and race pace they have gone wrong somewhere.

It was obvious through the first half of the year that they needed to make the car better in races - it was qualifying very well, but dropping away fast on Sundays.

Now, they seem to have lost the qualifying pace without gaining enough speed back in the race.

There are a lot of experienced people in that team, and they should be able to come up with the ideas to come back and challenge Red Bull. If they can get in front of them on the grid and hold Vettel back on the first lap, the rest of the race could be a very different story.

The radio conversation we heard broadcast between Nico Rosberg and his engineers may have been salient here.

Rosberg felt he needed to back off and conserve his tyres for later in the race; his engineer was telling him to push as hard as possible.

It sounds like there is still in Rosberg's mind a legacy of the early-season problems; I think he was wrong. But only time will tell on that. Certainly, we're seeing more flat-out racing throughout the field than we were in the early part of the season.

What mystifies me about the Hamilton-Rosberg combination is that they are not both there very often. It tends to be one or the other.

The team need to work out what's going on there because they have a car and two drivers who can challenge but they are throwing away that opportunity.

At the same time, Hamilton needs to get his head straight and get up to the front again after a couple of ropey races.

CRUCIAL DEVELOPMENTS AT RED BULL

All the talk at the moment is that Red Bull have made a big step forward with their car, but I do a lot of analysis of the lap times in F1 and according to my calculations they have not moved forwards. They have stood still relatively compared to the rest - but at the front.

I work out each driver's and team's off-set to the absolute fastest time of a weekend and in my latest data-set Red Bull's is the same as it has been all year.

When someone else has dropped back a bit, it's not that Red Bull have done any better, it's just that they have done a very good job every weekend.

I do these numbers as an average for the whole season and for each four-race chunk.

Italy was the fourth race of a four-race block, also including Germany, Hungary and Belgium, and over that period Red Bull were no better or worse than before. They've just kept up that same strong overall consistency.

If Vettel continues his dominance in Korea and beyond that we saw in Singapore then certainly they will step forward statistically, but it would be wrong to adjust the data-gathering period just because one team happens to have dominated in one set of races. There are too many variables that can skew the data in a small sample.

Having said that, there is no question that Red Bull have been extremely impressive in the last three races.

They have made two significant and inter-related changes to their car which are almost certainly at least partly responsible for this - one to the vertical vanes on the floor in front of the rear tyres; and another to the shape of the trailing edge of the diffuser, the upwardly-curved part of the floor at the back of the car.

The vertical vanes on the floor, which direct the exhaust gases towards the critical area between the edge of the floor and the rear wheels, have been modified, with the intention of better directing the gas flow and giving it more energy, thereby increasing its ability to produce more downforce.

Meanwhile, the outboard trailing edge of the diffuser has been shortened and made more curved, the idea being to enable the airflow coming off the diffuser to interact with the low-pressure area behind the rear tyres.

Making the floor shorter in theory reduces the downforce it will create. But if you can get the floor to 'talk to' the low-pressure area behind the tyres, that makes a big difference and increases downforce.

The idea is to turn the airflow coming off the diffuser outwards towards the rear tyres. If that airflow can then connect up with the low-pressure area behind the tyre it will speed up the under-floor airflow dramatically.

So instead of the underbody downforce being created by the diffuser simply expanding the airflow coming through under the car, the low-pressure area behind the rear tyre is also sucking the air through the diffuser and rear part of the car, making it faster and therefore creating more downforce.

Lotus pioneered this solution last season, but as you would expect Red Bull appear to have taken it to another level.

Former Jordan, Stewart and Jaguar technical director Gary Anderson was speaking to Andrew Benson