Chinese GP: Renault technical preview

China: Tech File

The Shanghai International Circuit is one of the most impressive facilities on the Grand Prix calendar. Like most of the circuits designed by Hermann Tilke, it features a wide variety of corners, both fast and slow, as well as a long straight followed by a tight hairpin which provides an ideal overtaking opportunity. Technically the circuit is a challenge for the drivers and engineers, not least the never-ending first corner which almost takes the cars through a full circle.

Aerodynamics
As with many modern circuits, Shanghai includes a mixture of high-speed corners and long straights which means the level of aerodynamic downforce has to be judged very carefully to protect position on the straights, without compromising grip in the corners. Turns 7 and 8 make up two of the high-speed corners and lead into the tricky double lefthander of turns 9 and 10.

Fernando explains: "Turns 7 and 8 are a fun part of the lap and you can really feel the performance of the cars here as we take these corners in 6th gear and there is plenty of grip. On the exit of turn 8 you're straight into turn 9 where you have to be very precise as it's a corner where you can find a lot of time. We take it in third gear and accelerate hard on the exit so that turn 10 is taken flat. Get it right and it's a really rewarding section of the lap."

Suspension
In mechanical terms, it will be important to find the correct compromise that gives the driver confidence in the car's handling over the full race distance. Shanghai features a lot of braking from high speed, some fast corners and plenty of acceleration phases. Combined with a number of changes of direction at both high and low-speed, it means we generally run a stiffer, more reactive set-up at the front of the car -- and then make the springing softer at the rear, for optimum traction and braking stability. In particular, we concentrate on making the car stable under heavy braking and on partial throttle openings, as the drivers often have to turn and brake/accelerate simultaneously, for example in turns 1 and 2 or turn 8.

Tyres
In general terms, Shanghai is a tough circuit for the tyres. Not only are the front tyres heavily loaded by corners such as turn 1 (left front), 7 (right front) and 8 (left front), but the numerous slow corners mean the rear tyres are worked hard under acceleration. Turn 1 in particular is a very challenging corner and demanding on the tyres because it tightens up as it progresses, as Fernando explains:

"You have to brake very deep into the corner, keeping the car on the limit and gradually lose enough speed to make it around and hit the apex. You need quite a neutral balance in the car as any oversteer will make it difficult through this first part of the lap and cost you time."

Turn 13 also deserves a special mention where the front left tyre is heavily loaded through this 2700x00b0 corner, all the while accelerating and putting high lateral and longitudinal loads through the rear tyres.

In terms of compounds, Bridgestone will bring the medium and super-soft tyres to this event as was the case for the opening race of the season in Melbourne.

Engine Performance
Shanghai is not a particularly severe test for the engine with only 55% of the lap spent at full throttle. However, with a long back straight, good peak power is important as the approach to turn 14 offers the best overtaking opportunity of the lap. This will be a good opportunity to see the potential of the KERS-equipped cars, as Nelson explains:

"Turn 14 is easily the best place to overtake on the lap. We come off turn 13 which is a long right hander that can be taken flat-out and then hit the longest straight on the circuit where we reach well over 300 km/h. It can be difficult to follow a car closely through 13, but KERS should make it easier to get closer and pick up the slipstream. Braking for 14 is always tricky and you have to be careful not to outbrake yourself which can ruin you lap time and cost you a position."

-credit: renault