Bridgestone on getting to grips with Hockenheim 16 Jul 2008
This weekend Formula One racing will visit the German race circuit of Hockenheim for the tenth round of the FIA Formula One World Championship, and although this circuit has hosted 30 Grands Prix, this will be the first time that Bridgestone Motorsports current range of dry grooved Formula One tyres will be used at the track.
The current Hockenheim circuit is 4.57 kilometres long and features 17 corners. It can be described as a stop-start track in the respect that fast sections are followed by slow corners. The first two sectors are quicker than the final sector, the stadium complex, which is a succession of lower speed turns.
Hockenheim is a track that is quite harsh on tyres because there are many different types of corner, explains Hirohide Hamashima, Bridgestone Motorsports Director of Motorsport Tyre Development. Particularly notable is the Turn Five Parabolika curve which is a very long, high-speed left hander. Because of the length of this corner, and the high speeds through it, there are a lot of lateral forces going through the tyres which generates a lot of heat.
As well as the high-speed Turn Five, there are also two straights where Formula One cars top 300 km/h and other places on a lap where speeds approach this.
Most of a lap of Hockenheim is taken at high speeds in a Formula One car, but there are notable slow corners, explains Hamashima. Turn Six, which is the slowest corner, comes immediately after the fastest corner, meaning that our tyres will be subject to many different stresses during the course of a lap.
For instance, the heavy braking into Turn Six generates a lot of heat, especially as teams run with low levels of downforce, and this comes at a time when the tyres are already very hot from the lateral forces from Turn Five, so the tyres have constant severe forces acting on them.
These forces do not lessen. Even on the exit from Turn Six, because of the low downforce set-ups, traction from mechanical grip is called upon and the tyres continue to suffer.
This is just one part of the track, and over an entire lap Bridgestones tyres have to prove their worth. But its not only the circuit layout which makes the tyres work hard.
Previously, we have seen the German Grand Prix at Hockenheim be one of the hottest races of the year, explains Hamashima. We bring the hardest compounds in our dry tyre range and although there could be problems with overheating due to the high ambient and track temperatures and high stresses placed on the tyres by the circuit, blistering should not be a big problem.
Recent weather in Hockenheim has been far from that requiring sun lotion, with rain being a feature of the recent test there. Our current tyres have a wide temperature working range, so even if it is cooler there should be no problems, says Hamashima, especially as so much heat is generated in the tyres themselves due to the circuit layout.
And, of course, our wet and extreme wet tyres deliver good performance in difficult conditions, just as we saw during the recent British Grand Prix.
Like many longstanding circuits on the Formula One calendar, Hockenheim is a track which has undergone considerable change in its circuit layout over the years.
The German Grand Prix was first held at Hockenheim in 1970, after Formula One drivers decided to boycott the previous venue, the old Nurburgring, on safety grounds. After improvements were made to the Nurburgring, Hockenheim would not see its next Grand Prix until 1977 after Formula One racing finally left the fearsome 14-kilometre Nurburgring Nordschleife.
Hockenheim then held every German Grand Prix from 1977 to 2006. The 6.8 kilometre circuit became synonymous with slip-streaming epics on its long straights heading into the forests. The circuit went through a major change in its make-up before the 2002 German Grand Prix, when its famous long straights were culled from the layout.
The previous layout of Hockenheim was very distinct, with three long straights over the course of a lap, explains Hamashima. This meant that the track was seen as being a power circuit where a teams engine and engine power were tested to the maximum. However the long straights also presented some interesting areas for consideration for our tyres as they meant that tyre pressure was particularly critical, especially if pressure were too low.
Low tyre pressures allied to long straights driven at high speeds mean the tyres generate heat at a time when they would normally be cooled down on a lap. In fact, running at high speeds with low pressures could result in what is referred to as standing waves when there are very high temperatures in the shoulders of the tyres. The long straights put a lot of stresses through the tyres construction, and low pressures would increase the forces through the tyre, requiring extra vigilance from teams about tyre pressure, explains Hamashima.
These straights were broken by chicanes meaning heavy braking, and yet more heat going through the tyres. When we have heavy braking and low levels of downforce, the tyre is absorbing most of the energy and getting hot as a result, says Hamashima. This is different from heavy braking when there are high levels of downforce where the aerodynamics of the car greatly assists with the slowing.
Although it is not the same circuit it once was, Hockenheim will present its own problems to be overcome when the Grand Prix visits.
Of course, it is interesting every time we visit a track that is new to us, or a track like Hockenheim that we didnt race on last season. Last year we raced at the Nurburgring, and the weather we faced made for an exciting event, says Hamashima. By not always visiting the same venues every year we do have an additional challenge for our engineers and the teams and drivers, so from this respect we benefit.