2007 Australian GP Technical Review

When the season opens we get the first chance to see the cars more clearly, unobstructed by the screens and covers used in testing. And this year, with rule changes having little visual effect on the car, the main differences are all in the details.

The single tyre supply has already affected the car design and is now throwing up new options for race strategies on soft tyres, while equally, no season could start without a protest about the aerodynamics of one team or another.

GENERAL TRENDS

Tyre strategy

As result of the new tyre regulations the teams had more than just the new Bridgestone's tyres to contend with this weekend - the requirement for each car to run both the hard and soft option tyres in the race meant the teams had a new variable in their strategy.

Clearly each team wanted to run the soft tyre in qualifying due to its greater grip over one lap, but then each team had to decide when to run the softer tyre in the race.

For most drivers this was a two-stop race, thus creating three stints. The softer tyre will degrade more rapidly over a longer stint and also its longevity would suffer if it was abused early in a stint on heavy fuel, so it is an important decision.

For the majority of the two stopping cars, the choice was to run the soft tyre for the last stint of the race. Two teams - Ferrari and BMW - decided to run the soft tyre for the first stint on one of their cars, surprising many teams. But the two scenarios were for different reasons.

For BMW the decision to put Nick Heidfeld on soft tyres was to create a faster opening stint and, in hindsight, this seems a sensible idea as the first stint for the top-ten qualifiers tends to be shorter because the cars are fuelled a little lighter after qualifying. Additionally, the softer tyre allows a faster start off the line, and while both BMWs were quick off the line the benefit of the tyre was clear in comparison to the neighbouring McLarens.

Ferrari chose to give Massa a soft set for his opening stint, and in this case the reasoning was to allow him to make up places in the early part of the race when he had the most backmarkers to contend with. Running heavy fuel, however, he had to be careful with the tyres and some of the advantage was lost.

Following BMWs strategic success it will be interesting if other teams opt for a fast starting shorter opening stint in Malaysia.

Flexing floors

There was controversy following the race that some teams were flexible floors, with suspicion focusing on the method used by Ferrari and BMW Sauber to attach their splitter section to the front of their cars' floors.

Both teams use a sprung device to allow the floor to move upwards should the exposed splitter hit a kerb or obstruction. The suggestion is that this could also be used to allow the floor to move downwards under aerodynamic load to alter the car's aerodynamics. If the splitter were to move, this would disrupt airflow under the floor and lead to the diffuser stalling, and this would have two effects.

Firstly, the downforce the diffuser produced would drop dramatically and any resulting drag it produces would also be cut. Last year we saw teams were employing flexible rear wings to increase straight line speed through stalling the wing and cutting drag. However, the diffuser produces very little drag so any stalling would have a minimal effect on top speed.

One positive effect of reducing downforce at the rear at speed would be to improve the cars aerodynamic balance. The car's centre of pressure is the point about which the downforce is equal front to rear; this is like the centre of gravity is for mass. The two are linked and teams tend to run the centre of pressure a small amount behind the centre of gravity and as the car increases speed the centre of pressure moves backwards as the diffuser's efficiency increases.

Thus, an imbalance of downforce and weight distribution is created and makes the car less balanced. By bleeding some rear downforce at speed, the balance is maintained. Teams already achieve this by more conventional methods, but the possibility of a more easily tunable system from the front floor would be realistic.

The FIA rig applies a load from underneath to test the splitter (yellow) © Scarborough (Click image to enlarge)

To prevent teams making the floor flex, a test dating back to 2000 is still enforced. The FIA scrutineering rig has the facility to test the upwards deflection of the front section of the floor and when the cars are on the rig they are bolted down and a hydraulic ram pushes up on the floor to measure the deflection.

Of course, this test only measures for upwards deflection and, as with rear wings, any deflection that might occur above the FIA test loading is acceptable. Thus it is possible that the floor might be tuned to deflect at higher loadings or indeed droop rather than lift.

But considering the immense weight of the splitter, which is now made from solid Tungsten alloy, it is unlikely the part could be made to be supported in normal use and only deflect at speed. The components weight could see it move from its own inertia from any vertical movement of the car over normal bumps and braking, and this would make the cars handling unpredictable.

Brake ducts

With no aerodynamic rule changes to speak of, the teams are looking for ever smaller gains from the car's bodywork. This and the freeing up on bodywork around the wheel last year has lead to a proliferation of devices fitted around the brake ducts.

Any bodywork around the brake duct area no longer needs to solely be used for brake cooling, so new fins and flicks can be added to improve the passage of air from the front wing endplates around the wheel. And because the front wing and endplate has been higher since 2005, the relationship between the endplate and inner face of the wheel has gained importance.

For some time Renault and McLaren have added fin-like cooling ducts low down on the inner face wheel. Ferrari then sported more blatant winglets above and below the wishbones in 2006, and similar solutions were employed by BMW and Toyota later last year.

This year most teams have extra fins and fillers around the bottom of the front brake ducts. McLaren have an upwards curved vane at the bottom of their brake duct, while BMW have a bulge and fin arrangement similar to that used on rear brake ducts.

McLarens brake duct sports a curved vane to lead flow around the inner face of the wheel © Scarborough (Click image to enlarge)

At the rear of the cars, bulky complex bake ducts have been exploited for some time. Again, last year teams started to add fins and flicks to augment the duct in managing the flow around the wheel and, just as crucially, over the diffuser.

This year Ferrari have taken a new route with vertical turning vanes added above and below the duct. These appear to turn the flow around the wheel, possibly to keep the untidy wake of the rear wheel away from the more sensitive diffuser.

Lastly, the wheel fairings added to fill in the opening of the rear wheel outer face were run again by Ferrari and Toyota and also by Renault. Ferrari have developed their solution by extending the wheel nut towards the small opening in the fairing, making it easier to change the wheel in pit stops.

In the race, Ferrari's final stints were run with a fairing that had an array of open slots cut into the face. This is a strange development, as the slots would degrade the aerodynamic benefit of the fairing while making wheel changes no easier.

It is, however, possible that the different fairing may alter the cooling of the rear brakes, allowing the team to tune the cooling requirement based on the telemetry from the car in previous stints. This could be an area other teams will protest as making changes to the car in the race is forbidden.

TEAM BY TEAM

It's tight at the top, and each of the leading teams have been working hard in the build-up to the new season. Detail design has been put to the test and while all teams are developing their cars as fast as they can, last year's key contenders provided many of the talking points when they lined up alongside each other in Melbourne.

McLaren

McLaren have merged the pod wing and chimney, to improve flow to the rear wing © Scarborough (Click image to enlarge)

Melbourne saw a return to form for McLaren and their car was both reliable and fast and, up close, the McLaren is a highly detailed and complex car.

One visible complexity is the unique arrangement of the sidepod fins, which are usually used to separate the dirty wake from the front wheels and prevent it from upsetting the flow along the car to the rear wing. McLaren's solution joins the pod wings to the chimneys, with the forward extension of the chimney meeting the lower rear edge of the pod wing.

This sees the flow towards the top of the pod wing pass inside both, and lower down the flow is routed outside the chimney. How this set up works is confusing, but possibly the split flow off the pod wing is aimed to improve the efficiency of both the sidepod winglet and the rear wing rather ran just the rear wing.

The McLaren, like the Williams, has a long strake on the engine cover to meet the minimum cross section. The rules create the so called 'toblerone' cross section of the spine of the cover, and making this thinner improves flow to the rear wing.

Renault

New aero parts and set-up were tried in the final pre-season tests. These changes were subtle and affected the front and rear wings. Even at the launch Renault were concerned they didn't have enough downforce towards the front and it appears testing the new tyres backed this fear up. The new changes were aimed at improving downforce.

One more visible change was to the sidepod winglet, which now uses a slotted aerofoil. Last year this was only used for the high downforce tracks and it has been run with a complex slotted endplate to improve its efficiency. To reduce drag created at the wing tip, slots have been added to the endplate which extend around to cut into the wing itself.

Ferrari

As expected, the team was more on top of the tyre situation than their rivals and, equally, the Ferrari is rivaled only by McLaren in its aerodynamic complexity. In addition to the complex vanes on the brake ducts and wheel fairings, the team also sported new details on the middle of the car.

Ferrari use a fin (yellow) on the side of the car to meet the minimum width rules and a new fin arrangement on the bargeboards (Yellow) © Scarborough (Click image to enlarge)

One curious detail is a triangular fin fitted to the hip area of the monocoque. Being mounted at such a vertical angle, its purpose might not solely be aerodynamic.

The monocoque must meet certain cross sectional dimensions near the dash bulkhead and this fin might be akin to those used along the length of the nose before 2000, which were used to meet the minimum widths in the rules of the time. Renault adopts a bulge in a similar position to Ferrari's fin, which would allow the car to be a little slimmer ahead of the sidepod inlets.

Also, the bargeboards have developed from last year. Previously, they used large flicks on the trailing edge of the board but this year's car uses an aerofoil cross section at floor level, which also employs a small endplate to seal the underside. On the front of the car two small serrated gurney flaps were added to the front wing. These crate slightly less drag than normal solid gurney flaps.

Honda

Struggling with pace, the team ran without the complex sidepod winglets seen on the launch car. This is at odds with the belief that the car is struggling for downforce and, like last year, it appears that Honda is having to simplify their original aero concepts to end up with a more simple starting point from which to understand and develop the car.

BMW Sauber

The increasing aerodynamic complexity of the BMW appears to directly relate to how well the car is performing on track and, now eclipsing Renault for pace, the car appeared in Melbourne with all manner of extra parts around the front end.

Three arrays of fins (yellow) control the flow from the front wing to the back of the BMW © Scarborough (Click image to enlarge)

In addition to the new brake duct bulge and fin, the nose has a wide fin between the wishbones. This manages the flow off the front and is joined by yet another fin on the forward bargeboard. BMW's keel layout is similar in concept to Ferrari in that the lower wishbone mounts under the chassis, although BMW prefer to leave theirs truncated while Ferrari have blended theirs into the floor of the tub.

While the car's aerodynamics and tyre strategy is working, the mechanical side is still letting the team down. Kubica's race retirement, with the seamless gearbox stuck in fifth gear, is a continuation of transmission problems seen in testing.

Now, to help get to the bottom of this problem, chief designer Jorg Zander has been assigned from the Hinwil factory to the power train department in Munich. Zander has a long background in mechanical design having come from Toyota and Honda's F1 programmes.