Why hasn’t overtaking improved in 2009 as planned? And have double diffusers really made that much of a difference? John Beamer looks at the major technical developments this year.
First of all a short apology – these columns were supposed to be a regular feature at F1 Fanatic but I ended up doing some contract work which forbade me from writing. That gig has now finished so I’m back.
Rather than bore you senseless with a technical rundown for each team let me frame some of the issues and innovations in five themes.
Overtaking is only marginally easier than it was
This was supposed to be the year overtaking returned in Formula 1. The first few races delivered but not thanks to the much-vaunted aerodynamic changes. At Melbourne it was largely because of the option tyre losing performance after a few laps, and at Malaysia and China rain mixed up the field.
Recently it is only the KERS cars that have done much overtaking – think of all the races where Vettel got stuck behind, unable to pass (although I suspect Vettel isn’t what we might call a natural born overtaker).
The truth is that the new aero regulations have had limited influence. This is for two reasons.
First, double diffusers allow better aero coupling between the floor and the rear wing. This ‘pumps’ the diffuser resulting in more downforce and a larger wing-diffuser wake. It is this wake which causes a trailing car to lose downforce, particularly in higher speed corners.
Second, teams have found other gaps in the regulations that allow flow conditioning devices – specifically pod wings and bargeboards. Flow conditioners are reasonably sensitive so any disruption to the airflow hampers performance.
However, even without double diffusers its doubtful we’d see much more overtaking. The fundamental issue is that F1 is an aero-dominated formula. At the start of the season the Overtaking Working Group’s objective was to cut downforce by 50%. Unsurprisingly, teams have clawed this back to the 80-85% level. You’d probably need close to a further two-thirds reduction to deliver significantly more overtaking.
- Overtaking: Too much or too little?
- F1’s overtaking problem solved?
- At least the racing is (slightly) better
Double diffusers are a damp squib
At the start of the year much air time was taken up with the benefits of double and triple-decker diffusers. Since Spain, when most teams rolled out a version the brouhaha has quietened somewhat.
Did it make a difference? Not really – McLaren, BMW and Ferrari didn’t immediately shoot to the top of the time sheets. Part of the issue is that an effective diffuser requires integrated design. It’s not as simple as cutting a hole in the floor. Airflow over the car is important to create low pressure above the hole to ensure the device is working properly.
The BGP001 was designed around the double diffuser concept whereas the RBR05 wasn’t – the pullrod suspension lessens the effectiveness of the double diffuser. Simply put, Brawn deploys the diffuser more effectively than almost every other team.
Conversely, the double diffuser is only worth 0.3s per lap. On many tracks KERS is worth at least that – and as we’ve seen with Brawn ‘switching on’ tyres is a critical to race pace. In 2009 it isn’t too difficult to find 0.3s from somewhere.
It’s all about the front wing
Aside from the double diffuser, the majority of aero development has been on the extremities of the front wing – notably the footplate and endplate. Two factors are driving this.
First, the outer part of the front wing has less regulatory constraint than many other parts of the car. Second, the wider front wing means that managing the wheel-wing interaction is more important than it has been in past year.
Last year the endplates were turned in to divert air inside the wheel. To clean up airflow around the tyres teams deployed horizontal vanes to control the air around the tyre.
This year the goalposts have moved somewhat. The central section of the front wing is flat which leaves the outer part to generate downforce. As such the endplates play a critical role both in downforce generation and in reducing drag from the tyre.
Take a look at the BGP001′s endplate, which is intricately designed (especially compared to the boxy BMW Sauber endplate pre-Singapore). The endplate is fulfiling three objectives:
- Diverting air outside the tyres – look at the plan view of a 2009 F1 car and you’ll see the endplates tail outwards
- The vanes set up many micro-vortices between the wing and tyre which keeps higher pressure air away from the wheel (so reducing drag)
- Sealing the underside of the wing by creating a vortex under the footplate (the semi-circular duct is designed to capture and control this vortex).
Endplate and footplate design is the most aerodynamically exciting area of an F1 car – look for an off-season feature on the issue.
Is the tyre war back?
The advent of the control tyre from 2007 was supposed to eliminate rubber as significant racing variable. The move to slicks along with the wider spead between compounds ensured that tyres remained an important talking point for the first half of the season.
On reflection it perhaps isn’t a surpise. It’s been over ten years since F1 donned slicks in anger and unsurprisingly the cars needed a little recalibration.
Slicks have more surface area in contact with the tarmac so are more grippy. This means that front weight distribution was even more important than it has been in previous years. (Incidentally this is one reason why KERS cars struggled at the start of the year – KERS sits back in the chassis and makes forward weight bias harder to achieve.)
The move to slicks was only a minor factor in this performance discrepancy, it was the wider compounds that had a larger effect. In short the target operating temperature between the two compounds didn’t overlap, which meant that drivers could only get one tyre to work properly (be it the prime or option depending on the day). Now that Bridgestone has narrowed the difference in compounds this issue has subsided – the operating windows of the option and prime do overlap which means that teams can make both tyres work.
However the gap between the compounds will be widened once again at Suzuka (where they will use hard and soft) and Interlagos (medium and super soft).
McLaren and Ferrari got it wrong
Before the season began many observers expected McLaren and Ferrari to dominate proceedings. Although both cars are now reasonably competitive neither is the fastest on the grid.
Many pundits speculated that the the intensity of last year’s title battle took the edge off 2009 development efforts. I think that is only part of the reason.
McLaren was caught short by the radical aerodynamics of the Brawn in particular. In January the MP4/24 beat its Australia downforce targets so the guys at Woking relaxed a little. Unfortunately for them no one told Brawn. The impressive rate of development of the new car is a testament to the talent in the team.
I’m a little more worried about Ferrari – it’s not the Schumacher years any more. The aerodynamic talent at the Scuderia isn’t as deep as it was in the days of Rory Byrne. John Iley was extremely capable, has a phenomenal track record but has been fired. Ferrari lacks the systematic approach that McLaren has or the divine inspiration of, say, an Adrian Newey to spur the team onwards.
I’m sure they’ll be OK but that 0.6s from signing Alonso will come in handy…
Tomorrow we’ll take a look at the technical developments from the Singapore Grand Prix.