F1 cars

More opera than soap

Formula One has never been short on controversy, with reports down the years of spying, lying and sex scandals prompting some observers to compare it to the best soap operas and a new episode is being played out as this issue of E&T goes to press.

Formula one is on the brink of disaster as the FIA (Fédération Internationale de l'Automobile - the governing body for world motorsport) is trying to impose a €45m cap on spending for 2010. However, the F1 teams are fed up with being dictated to and are showing their disdain by refusing to sign up to the new agreement, which had a deadline of 29 May.

One team, Williams, did sign the agreement, and was immediately expelled from FOTA (Formula One Teams' Association). Ferrari are threatening to withdraw from F1 altogether over the budget cap issue and where would that leave the F1 spectacle, you have to ask?

FOTA has issued a counter proposal that will see budget capping phased in. As E&T went to press, the FIA announced that it had extended the deadline to the close of business on 19 June. This is to allow for further discussions and for the five remaining FOTA teams to lift the conditions of their entries.

Only time will tell whether the F1 roadshow will be seen in its current form next year or whether it will be missing some of its most famous names. It's all going to be about brinkmanship, and we will have to wait to see who will blink first.

Getting back to the current season, the teams are constantly searching for technology to give them a competitive edge within - and sometimes outside - the rules and regulations. It's easy to see why this is arguably the world's greatest spectator sport.

But all is not well in F1. With engine specs frozen until 2013, the imposition of a standardised engine-management system from McLaren and Microsoft, and tyres from a single supplier, Bridgstone until 2010, the cars have become very evenly matched, with the gap between the fastest and slowest often as little as 1.5 seconds. Overtaking has become, at best, difficult, and winning a race from pole position common, making many races rather dull. So, for 2009, the FIA has revised the technical regulations to encourage more overtaking and more open races.

Yet controversy is never far away, and this year's big one has been over the rear diffuser, which helps to improve the cars' aerodynamics, and a new take on its design by the Brawn, Toyota and Williams teams. Although their diffusers were cleared by the FIA in January, the other teams cried foul as the new designs were unveiled and Brawn's results showed the advantage they were given.

Getting the right design

The FIA has since decided that the diffusers are legal and by the sixth race of the season, at Monaco on 24 May, the two Brawn drivers, Jenson Button and Rubens Barrichello, were heading the field on 51 points and 35 respectively, with Red Bull's Sebastian Vettel third on 23 points and Jarno Trulli of Toyota on 14.5.

The other teams have been scrambling to come up with their own designs, but after the opening race in Australia - with a memorable Button and Barrichello one-two - Renault's Fernando Alonso was just one driver branding the Brawn cars "nearly unreachable". Brawn's subsequent five wins out of six so far are proving him right.

The diffuser, though, is only one aspect of an F1 car's aerodynamic control, and because there are so few areas left under the rules for mechanical improvements it is this area that now holds sway in the teams' efforts to shave even hundredths of a second off their lap times.

Designers, naturally, want their cars to cut through the air as efficiently as possible, but they also want to create downforce using the car's front and rear wings and underbody to maximise grip on the track and speeds around corners. But creating downforce necessarily entails disturbing the airflow over the car, which creates drag, and this means having to strike compromises in a car's aerodynamic characteristics.

These compromises vary according to each team's approach, as well as the nature of each race track - high downforce set-ups are used for twisting circuits like Monaco, and low ones for the faster flowing tracks like Monza. Yet, even though there are so many variants and permutations among the teams, there are some common design threads. 

Front wing dynamics

Clearly, the front wing is key to a car's aerodynamics as it hits the air first and governs how the air will flow over the car. Typically, it generates about one-third of the total downforce, and is fitted with endplates to direct air over the front wheels to reduce drag.

In the past the front wing's central section has been sculpted to direct air under the car, but for 2009 the FIA has specified a straight central section that actually produces some lift. The wings are also lower - 75mm off the ground instead of 150mm - and wider, now spanning the width of the car, forcing designers to use endplates to push air around the outside of the front tyres. And drivers can now adjust their wings up to twice per lap and by no more than six degrees, the first time in more than 40 years that moveable aerodynamic devices have been allowed.

Although the wing's central section has to be straight, designers have plenty of scope to innovate in the outer sections. McLaren, for example, is using a four-element wing on its MP4-24 to maximise downforce. The flaps integrate with an endplate that is designed to direct airflow around the wheel and seal the underside of the wing. The wing also has a series of slatted 'fences' on the inner side of each endplate to prevent the airflow being overly disturbed by the air pushed off the front of the tyre.

Brawn's front wing, meanwhile, does away with traditional endplates. It has a fence protruding from the footplate but it isn't connected to any flaps. For Monaco Ferrari have modified theirs similarly.

Nose cone air force

Introduced by Tyrell in 1990, the nose cone is designed to force air under the car to help create downforce. A higher nose forces more air under the car and makes the rear diffuser behave more consistently; a lower nose impedes airflow but can create a Venturi effect between the wheels to add downforce.

The shape of the nose cone is now more significant as designers search for ways to claw back the downforce lost under the 2009 rules. So the teams all have their own shapes, sizes and positions. For example, this year Toyota's is raised quite high while Brawn's is described as a bulbous droop, and Ferrari have chosen a very long and high central section to boost the volume of air passing underneath.

But most teams are keeping them smaller than the maximum allowed to give themselves the option of adding strakes - fin-like ridges - to the nose to control airflow over the section of the car towards the rear wing. And some are choosing a fat nose to house the batteries for their kinetic energy recovery systems (KERS).

Downforce from the rear wing

Like the front wing, this produces about one-third of the total downforce. These vary the most from track to track as they create the most drag, so their angle of attack is tailored to the configuration of each track. This year they are narrower and taller than before, putting them level with the engine cover.

Only two elements in the wing are allowed, and the depth of the upper section has been raised by 10 per cent to allow for more powerful aerofoils. But the endplates can now be larger, which allows for better management of wingtip vortices to help reduce drag.

Raising the height of the wing means it runs in less turbulent air, so it's more efficient and allows more downforce to be created for a given angle of attack. It also decouples the wing from the diffuser, the aim being to raise up the low-pressure zone created by the wing and reduce upwash vortices from the rear of the car.

Again, though, there is scope for designers here - Ferrari and McLaren, for example, are using rear wings with slots in the middle of the main plane.

Diffuser decks

This does the opposite of the front and rear wings by sucking, rather than pushing, the air upwards. Mounted under the rear wing, its volume rises outwards to create a low-pressure zone to suck the air away from under the car.

Its design is critical because the faster the air can be drawn from under the car, the greater the downforce. F1 rules prohibit shaping of the car's underbody, or undertray, to create downforce, so the diffuser plays a key part here, and its typical contribution is about a quarter of the total.

Rule changes for 2009 have made diffusers smaller and narrower, reducing their net volume. Although the outer sections are slightly more powerful, overall the 2009 diffusers produce only about half the downforce than before.

The controversy over the Brawn, Williams and Toyota diffusers stemmed from their interpretation of the rules. Some teams followed a literal interpretation and made all the channels in their diffusers the same height and length, but Brawn and the others use a vertical or horizontal hole to feed the top side. The Brawn and Williams designs are 'double deck' while Toyota's is a 'triple deck'.

The other teams tried, unsuccessfully, to get them banned, so they've been rushing to modify their designs. By the Monaco race, for example, Red Bull had a Brawn-inspired twin diffuser.

Despite the priority given to aerodynamics in F1 these days, designers and engineers still have plenty of scope to search for competitive edge on the mechanical side.

Kkinetic energy recovery systems

One of the most hotly-debated changes for the 2009 season has been the introduction of kinetic energy recovery systems (KERS), which store energy whic would otherwise be lost as heat during braking. The two main ways of achieving this in a road-going car are mechanically, using a flywheel, and chemically, using batteries.

However the energy is stored in a KERS system, all F1 teams have gone for an electrical link between the car's drivetrain and its KERS system. A motor is connected to the driveshaft at the front of the engine and cabling then carries the energy to and from the KERS, although here there is a lot of difference between each team's design.

FIA rules specify that cars can collect and store energy at a rate of 60kW during braking, up to 400kJ of which can be fed back into the drivetrain each lap, giving an extra 10 per cent or so of overall power. This energy is used as a boost and controlled by the driver, usually when he wants to overtake another car or is coming out of a corner. By its nature, it's an eco-friendly technology with applications already feeding into mainstream hybrid vehicles, although for F1 the headline aspect is its ability to boost performance.

Flywheels have many advantages over the battery systems - they charge up and release their energy quicker, for example, and have a longer working life - and the FIA is known to favour them. But, apart from Williams, which is using a system with a flywheel and integrated motor, the teams have opted for the battery approach because of the short lifecycles in F1 and because they're lighter than a flywheel system.

Several teams, including Ferrari and Scuderia Toro Rosso, are using a system from Magneti Marelli, which uses an electric motor/alternator to convert the kinetic energy to electrical and vice versa. The units weigh about 4kg, about a tenth of the Williams flywheel system.

Actual energy storage is decided by the teams, and it appears that most are using lithium-ion batteries. KERS is only an option at the moment, so while Ferrari, for example, used it in Bahrain and Barcelona, Renault is still evaluating it on a race-by-race basis - saying that, like the other teams, it probably wouldn't use it at all at Monaco - and BMW has dropped it altogether.

Suspension inerter

In what is now a tyre-controlled sport, attention has switched to improving suspension, to make better use of the tyres, and the inerter is one of the key technologies in this respect to emerge from F1 in the past year or so.

Standard suspension systems are based around springs and shock absorbers, or dampers, and are tuned for handling, comfort and grip. But no matter how the system is tuned, there is always a compromise. In F1, where comfort is less important, the suspension needs to be set to give sensitive handling, which requires a harder suspension, but it also has to offer good mechanical grip, for which it needs to be softer. Having to compromise between the two means there is always some oscillation as the load on the tyres varies, which lowers the car's grip and therefore slows it down.

The inerter, however, adds a third component to the spring-damper system. Superficially, it looks like a conventional shock absorber, with one end attached to the car body and the other to the wheel assembly. As the car moves up and down along a track, a plunger slides in and out of the inerter's main body. This causes a flywheel inside it to rotate in proportion to the relative displacement between the attachment points.

The flywheel, therefore, stores rotational energy as it spins. In combination with the springs and dampers, the inerter reduces the effect of the oscillations and so helps the car keep a better grip on the road.

Invented at Cambridge University, the inerter was raced covertly for the first time by McLaren, which had an exclusive deal with the university to exploit the technology, at the 2005 Spanish Grand Prix, which McLaren driver Kimi Raikkonen won. It is said to give cars an advantage of about 0.2 seconds per lap - quite sizeable in F1 terms these days - and the technology has now been licensed through the university's commercialisation arm, Cambridge Enterprise, to US company Penske Racing Shocks, as well as others that cannot be named because of confidentiality agreements.

Cambridge Enterprise does say, though, that it has shown, at least in theory, that the inerter also provides benefits for motorbikes and that it is exploring applications in larger transport vehicles.

In F1, meanwhile, the inerter is now regarded as something of an open secret, and insiders believe most teams have started using them - exactly who, of course, no-one will say, although Ferrari are believed to be one of the first and comments by Renault's director of engineering, Pat Symonds, last autumn suggest they have adopted them as well.

And so the race for World Championship glory continues - this time next year, however, it could be a whole new batch of technologies, and teams, grabbing race fans' attention.

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