Turkeys treacherous turn eight
Bridgestone heads to Turkey and the Istanbul Park Circuit for the seventh round of the 2010 Formula One season where teams, drivers and Bridgestone will encounter the hardest corner of the season, the notorious Turn Eight.
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“This corner is one we know very well, and one which has caused us many challenges over the years,” says Director of Bridgestone Motorsport Tyre Development, Hirohide Hamashima.
“In fact, it is one of the corners from which we have learnt the most for our tyre development, because of its challenge.”
Nestled neatly between turns seven and nine, Turn Eight is a multiple apex left hander which takes around eight seconds for a Formula One car to complete, with the forces acting on the car building all the time.
“The corner starts with a downhill entry, although most of the corner is actually quite flat compared with most of the Istanbul Park circuit,” explains Hamashima.
“The crucial aspect is that the corner is quite high speed, but it is very long, so the G Forces acting on the car are very high. Last year the peak lateral forces were over 4G, but for this year with the heavier cars with their aerodynamic evolution, we estimate that the peak lateral force will be over 5G.
“The corner turns left, meaning that the greatest force is acting on the front right tyre. Our calculations show that the right front tyre will experience average loads of 800kg on this corner, with a peak load of around 1100kg.
“These loads are so high because of the aerodynamic downforce acting on the car with the car’s weight combined with the lateral cornering force. Because of these high loads, we monitor this tyre very closely. For the driver behind the steering wheel, Turn Eight is one of the highlights of the season.
“The radius of the track is not constant as there are three or four apexes, however drivers attempt to drive the corner in a continuous radius as it is the fastest way around. This means that the force is always building all the way round the corner.
“As a driver is working on the edge of adhesion, he is always small corrections, so the corner is never taken in exactly the same manner. There is also an element of bumpiness to the track here, which makes the corner all the more of a challenge.”
The Istanbul Park Circuit is a track which does not get a lot of use during the course of the year as its race calendar is not as full as some other permanent race facilities on the F1 calendar.
“When we visit Istanbul the track surface starts the weekend quite dirty meaning that grip levels are not as high on the Friday as they become by race day. This means that the stress going through the tyres is not the same due to the different reaction between the circuit surface and the track when there is less rubber on the surface.
“Once there is rubber laid on the track surface the tyres generate more grip, meaning that the cornering loads are higher and the stress through the tyres is greater.”
2007 was the year when Turn Eight proved to be the most problematic for Bridgestone. “This was our first year as sole tyre supplier to all of the teams in Formula One, with the challenge of bringing two compounds to each race circuit from a range of four compounds,” says Hamashima.
“This was a big change from the previous situation of competition where we would have special compounds for each race circuit, and this season was a big learning curve for ourselves and the teams.”
Whilst there were generally no problems, season rookie sensation Lewis Hamilton experienced a tyre break-up near the end of the race.
“Lewis suffered from a particular phenomenon called chunking,” explains Hamashima.
“This is when the outside edge of the tread was subjected to the very high lateral forces, causing the rubber to break up and then separate from the belt.
“The actual belt on Lewis’s front right tyre then became damaged, leading to the problem that everyone saw with the tyre breaking up.” Improvements were made to the tyre construction and compound for the following season.
“For 2008 we revised the construction of the tyre and the set-up limits for settings like camber. These measures proved successful and we did not see the issue of chunking reappear. In terms of strategy that year we did see Lewis Hamilton opt for a three stop strategy as the fastest approach, and he achieved a good result through this.”
Last season saw the reintroduction of slick racing tyres to Formula One, and Turn Eight presented no issues.
“A slick racing tyre is inherently stronger than the grooved tyres we used previously. This is because there is a bigger tread surface area so the tyre tread area does not move around as much as it does with a grooved tyre.
“A good illustration of this was that we saw Lewis use a one stop strategy for his race in Istanbul last year.”
As well as a being on the Formula One calendar, Turkey is a popular holiday destination, and with the high temperatures experienced there, it is easy to see why.
“We have often experienced some of the hottest temperature of the year in Istanbul,” explains Hamashima.
“In 2007 the race took place late in August at the track temperature reached 49C. Last season the track was even hotter, reaching 52C, with the race at the beginning of June.
“The circuit layout itself produces high temperatures in the tyres, before you even consider the track temperature, so thermal degradation will always be a factor to consider at this track.”
For 2010 there are new rules meaning that there is no refuelling, meaning that Turn Eight will be tackled by very heavy cars on the early laps.
“Tyre strategy will be interesting in Istanbul this season, especially as it will be a severe test of the latest narrower front tyre,” says Hamashima.
“However, we have seen this season that teams and drivers have very quickly understood the best approaches for our current tyres so we do not expect any issues, however we always remain vigilant.”