In the first of a two-part series looking at trends in technology in 2011, John Beamer talks tyres and the controversial Drag Reduction System.
As pre-season testing indicated, the characteristics of the Pirelli rubber are very different to the old Bridgestones. It’s worth going through a bit of history to understand how we got here.
Ten years ago pit stop strategy was an essential element of Grand Prix racing. The tyres would wear out quickly and teams had to work out whether the speed advantage of a series of short sprints outweighed the cost of spending more time trundling down the pitlane. The problem was that Ferrari and Michael Schumacher were imperious and the spectacle was dull.
To try to spice things up in 2005 the FIA banned tyre changes. The thesis was to bring tyre management into play and make the sport more exciting.
The tyre companies (Bridgestone and Michelin) at the time poured research in to developing more durable compounds that wouldn’t degrade so much over a 300km race.
The racing was better but this was because the Michelin-shod teams had better rubber and were able to close the gap to Ferrari who stuck with Bridgestone.
Then came the ill-fated 2005 US Grand Prix where the high lateral loads caused by the banked Indy speedway dangerously weakened the sidewalls of the Michelins.
We all know what happened next – the Michelin teams weren’t allowed to race turning the Grand Prix into a farce. That saw the sport scarp the ‘no tyre change’ rule and move to a single supplier for tyres (Bridgestone) for 2007.
The 2007 control tyre was based on the compound developed in 2005 and the tyres were very durable – degrading a maximum of a 0.05s per lap. Fuel stops still gave a strategic angle to race day.
It wasn’t until 2010 and the refuelling ban that the F1-watching public started to cotton on to how important tyres were in deciding the outcome of a Grand Prix.
Sebastian Vettel demonstrated how durable the super-softs were last year in Monza when he ran them for practically the entire race distance.
A few races earlier, the combination of compound choice, rain and asphalt characteristics turned the Canadian Grand Prix into an overtaking bonanza as the tyres lasted a handful of laps.
These events dovetailed with Bridgestone’s decision to exit the spot and when Pirelli was selected as F1’s sole tyre supplier it was give the mandate to make rubber that would degrade faster.
In the Bridgestone days the biggest problems the teams had was graining. This is when the first layer of rubber is torn by the asphalt temporarily resulting in reduced grip. Once the graining phase was over the tyres would work as normal.
Simply put, the Pirellis don’t grain. The tyres just degrade – the rubber is more consistent throughout the tyre and it wears away (hence the marbles which appear off the racing line).
Driving style has a limited effect on degradation. Witness Lewis Hamilton having to claw back places in Turkey following a poor start – his tyres were done a couple of laps before the others.
Drivers have to work out when to push and when to hold back but the point is that two drivers going the same speed will have a very similar degradation pattern whereas with the Bridgestones there was more scope for managing the tyres.
The other point of note is the extent to which the Pirellis amplify the difference between team mates, particularly in qualifying.
Vettel, Hamilton, Alonso and Rosberg have consistently outpaced Webber, Button, Massa and Schumacher respectively – and typically by a greater margin than last year:
- Sebastian Vettel 2011 form guide
- Lewis Hamilton 2011 form guide
- Fernando Alonso 2011 form guide
- Nico Rosberg 2011 form guide
DRS and rear wings
The Drag Reduction System is probably the most radical rule change to F1 since shaped under floors were outlawed.
As everyone who reads this site knows the flap may open by a distance of 50mm reducing its angle of attack. Drag squares with speed and the open flap allows cars to find roughly 10-15 kph on the straight.
As we saw in Turkey the effect DRS has in the race can be substantial. However, perhaps the bigger and much less discussed consequence is that Red Bull’s qualifying dominance is largely down to its ability to use DRS where others can’t.
At the recent Spanish Grand Prix, coming out of the last corner the RB7 had its wing open entering the last corner where as the McLaren, its closest challenger, waited until the car was past the corner apex. It confirms how much raw downforce the Red Bull has.
On an average track in qualifying trim the RB7 has a second a lap advantage over the MP4-26. That’s huge. On Sunday when DRS use is restricted the gap contracts to a less jaw-dropped 0.2s (and McLaren believe they are quicker over a race distance), which goes to show how unrestricted use of the DRS exaggerates the performance gap.
In addition the design of the DRS system and rear wing can also effect performance. The Mercedes has the most aggressive DRS design.
The chord length of its rear wing flap is short and in the early races when the DRS deactivated it took too long for airflow to reattach to the underside of the flap. This meant that downforce couldn’t be recovered quickly enough and was one reason why Schumacher and Rosberg struggled during qualifying in the early races.
Ferrari’s banned rear wing
There wasn’t a lot of innovation in rear wing design until Ferrari appeared in Spain with a raised lip on the trailing edge of the rear wing (pictured) that resembled a gurney flap – and caused the rear wing to exceed a maximum height threshold.
Closer inspection revealed that the trailing edge is part of the extended wing separators as specified by article 3.10.3 of the technical regulations.
The article mandates two central supports between 2-5mm thick and a maximum distance of 30mm from the wing surface that fully enclose both the main plane and flap of the wing. Ferrari joined the two separators together and then split them at the trailing edge of the flap so they then shadow the rest of flap along its length, 30mm from the trailing edge.
The benefits were obvious with the device acting a gurney flap, which is an efficient way to add downforce to the car. However, before free practice 3 the FIA deemed that Ferrari’s innovation contravened the regulations and it was banned.
At the start of the 2011 campaign there were fears that the writing of the DRS regulations would introduce new loopholes that canny teams would exploit to produce the 2011 equivalent of the f-duct. So far it hasn’t happened – at least not to the naked eye.
The only parameters that designers can tweak are chord length and profile thickness. A shorter flap (i.e., small chord length) will shed drag more quickly when open but will produce less downforce when closed.
The second part of this article tomorrow will look at exhaust-blown diffusers, flexible bodywork, and the planned changes for 2013.
This is a guest article by John Beamer. If you want to write a guest article for F1 Fanatic you can find all the information you need here.
- Why F1 cars keep getting heavier
- Why do F1 cars keep running out of fuel?
- New restrictions won’t put teams off passive DRS
- McLaren MP4-28 and MP4-27 compared
- F1′s new V6 engines for 2014 in numbers
- Why Hamilton and Mercedes could surprise in 2013
- Late front wing development on 2012′s fastest car
- Why covered cockpits and wheels may be F1′s future
- Top teams remain close as McLaren peg back Red Bull
- Red Bull boost diffuser performance with twin tunnels
Images © Renault/LAT, Bridgestone/Ercole Colombo, Red Bull/Getty Images, Daimler