German GP: Renault technical preview

Tech File: Nurburgring

The Nurburgring has a reputation for being a 'complete' circuit in the sense that it includes a wide variety of corners. There are high-speed sections, medium-speed chicanes, and some very slow corners with high traction demands. The R29 will have to meet all of these challenges this weekend. Overtaking is difficult but possible into the first corner and the chicane at turns 13 and 14. However, the weather is a constant concern and no matter what the season, rain and cool conditions are an ever-present threat in the Eifel mountains.

Aerodynamics

The Nurburgring demands some of the highest downforce levels of the season, not only for the numerous high and medium-speed corners, but also to maintain good stability under heavy braking for the first corner and the slow chicane of turns 13 and 14.

Fernando explains: "The left-right chicane of turns 13 and 14 is probably the best overtaking opportunity as it's one of the biggest braking zones of the lap. If you are following another car closely, you can pick up a good slipstream on the approach and make a lunge down the inside. We take it at about 100 km/h in second gear and you need to be aggressive with the curbs to straight-line the chicane as much as possible and carry speed through the corner."

Chassis balance

Corners such as turns 5/6, 8/9 and 10/11 in particular demand a neutral handling balance to avoid compromising the optimum line through the second corner in the sequence, and the engineers will often work through the weekend to dial out understeer in the medium-speed corners.

A quick, responsive change of direction is required in both the slow-speed section at the start of the lap, and through the quicker corners. Mechanical grip is particularly important through turns 1 to 4, but cannot be achieved at the expense of aerodynamic performance around the rest of the lap.

Fernando explains: "The run through turns 1 to 4 is not very exciting for the drivers, but we spend a lot of time in them and that means that any mistake is likely to be very costly, especially in qualifying. We need to be precise with our braking and keep the car under control all the time as too much understeer, oversteer or a missed apex will put you out of shape for the following corners. The car balance is never perfect at such low speeds either, so we are always fighting understeer in the very slow corners, and a nervous rear end when we accelerate away."

Tyres

Tyre performance will, as always, be a critical performance parameter for all teams this weekend with Bridgestone providing the super-soft and medium compounds from its 2009 range. Ambient conditions will play a role in determining which compound is the preferred tyre for the race as we often experience cool temperatures at the Nurburgring.

Brakes

Wear on the brakes is not a major concern. None of the braking zones are particularly severe and there is no reason to think that wear levels on the discs and pads should be abnormally high as a result.

Engine

The Nurburgring is not a circuit that presents the engines with any extreme challenges, and its overall impact is further reduced by the fact that the circuit is situated at altitude, some 500m above sea level. This has the effect of reducing engine power by approximately 5%, while also reducing loads on certain engine components such as the pistons.

The engine is at full throttle for just over 64% of the lap -- a value slightly above the season average of approximately 62%. The longest single period at full throttle barely exceeds ten seconds, so the main challenge for the engine team is ensuring strong performance from low revs so the engine launches well out of the slow corners, particularly turn 7 which leads onto the uphill drag to turn 10.

Nelson explains: "We approach turn 7 downhill in seventh gear at almost 300km/h before braking and downshifting to third for the hairpin. It's really important to stay online and hit the apex through this corner so that you can apply the throttle early on the exit to carry as much speed on the long drag back up the hill towards the high-speed chicane of turns 8 and 9."

The circuit includes a number of elevation changes, but none are sudden enough to cause the engine systems any concern. The only note of caution is finding the best line through some of the bumpier corners, and particularly the chicane, to avoid spending too much time on the rev limiter, which is potentially damaging for the engine.

-credit: renault