2008 Brazilian GP Tech Review

The final grand prix of the season was one of the most exciting of the year, but from a technical point of view it was probably the least.

Being both the last race and one in a series of fly away races, most teams did not appear with any significant updates to their car. Development has long since moved onto 2009 and McLaren were the only exception with a package developed specifically for the final race.

Interlagos runs anti-clockwise and is formed of three distinct sectors, the first and last being largely flat out blasts down long straights, with a slow and twisty section in the middle. This gives the teams a choice of aero strategies: either a loInterlagos is still no Monza, so even the lower downforce setting is a medium level and uses a heavily-twisted rear wing to reduce the induced drag and aid top speed.

The Brazilian track is also notorious for its bumps, although this problem is negated by the lack of fast turns, which might otherwise demand a stiff suspension.

For the teams this year, the biggest issue was the weather - intermittent rain, often falling torrentially for a short period. As a result, the straights tend to have standing water and a risk of aquaplaning, while the traction zones for the slow middle sector and the opening Senna Esses become treacherous. Fortunately, the short bursts of rain and warm weather allow the track to dry rapidly, bringing the adaptable Bridgestone intermediate tyres into their own - working well both on a wet track and in the nearly dry conditions that prevail a few laps later.

McLaren

Oddly for McLaren, their development this season has been overt. Many a visual upgrade has underlined the effort put into this year's title chase and nowhere has this been more apparent than at Brazil.

Despite the major rules changes for next year requiring design resources, the team had a major upgrade to the car developed and tested before this final race. Although the team appear to have performed well at the previous two races, the stricter demands of Interlagos on aerodynamic efficiency, especially on the lower end of the aero scale, meant McLaren felt they needed a wing set specifically for this race.

The Brazil package was based around a new rear wing, T-wings and modifications to the Pod wings. The package set out to increase straight-line speed without great cost to downforce. It certainly appears to have boosted the car's top end speed, often at the top of the speed traps, but the car also suffered in the slow middle sector, suggesting that some downforce was lost.

To reduce drag without losing too much downforce is a rear wing function. The new rear wing was still quite deep in its middle section, but the outer tips were sharply inclined to reduce the load at the endplate, which in turn reduced reduces drag. In achieving this shape, McLaren also merged the rear wing flap into the endplate to a greater degree than the Japan\China rear wings.

This merged flap and endplate bleed high pressure air above the wing to the outer face of the endplate to neutralise the pressure difference at the wing tip. This reduces the vortex often seen spiralling from the rear wing in humid conditions, which actually creates drag and slows the car on the straights.

Allied to the rear wing, the new T-wings mounted behind the sidepod chimneys were introduced. These were smaller winglet element affairs, unlike the steeper two-piece winglets used previously. Again, these reduce the car's downforce and drag.

While the car had at least six new aerodynamic parts, the only other visible change was some reinforcement made to the pod wings. Since these vanes were lengthened for the Singapore Race, they have been seen to move around - blown by the turbulence off the front wheel as the car runs along the straights. As Brazil is be bumpy and fast, the team chose to make the joint between the fin and the sidepod stronger. This was evidenced by the small rectangular section of carbon fibre bonded to the lower edge of the fin.

To move weight forwards, Red Bull fitted ballast in pockets on the front wing endplates © Scarborough (Click to enlarge)

Red Bull

Along similar lines to other teams and most recently Renault, Red Bull Racing moved more weight forwards by adding ballast to their front wing endplates.

The biggest issue for teams in placing ballast at the front of the car is finding places to safely mount it. Red Bull already have ballast inside their front wing, this can only be altered at the factory. At races earlier this year the wings had to be sent back to the factory overnight to have their weights altered. By using the thickest portion of the front wing endplate, the ballast can be removed easily to tune the car's set up.

In Brazil, the fin on the front wing endplate was mounted to a detachable section, revealing the ballast pocket moulded into the endplate. Inside this pocket, blocks can be added to move weight as far forwards as possible to make the front tyres work better.

Williams

A small alteration to the Williams for the final race was a tweak to the front wing profile. Still suffering from increasing downforce loss leading to understeer in long turns, the car needs to be less sensitive to front wheel steer. Just as with Renault's recent front wing, Williams made the outer section higher, reducing the angle of attack.

This loses downforce which needs to be made up in other portions of the front wing, but the load created at the wing tip is less sensitive to the front wheel angle. This makes the handling more predictable, especially in long turns when the wheels are at an angle to the airflow for a longer period.

The rear wing moving over bumps misled some people into reporting that the Renault's wing was illegally flexing © XPB (Click to enlarge)

Renault

Reports of Renault's recent return to form due to running flexible wings were circulating at Interlagos. This is largely due to an onboard clip of the car from a rear facing camera, showing the entire rear wing assembly moving vertically. While it's clear the rear wing moved, it did so as the car hit a kerb and sent a shock up through the rear suspension. The rear wing assembly flexed, but not in a way likely to improve performance.

The rules are clear that any degree of flexibility is not allowed for the bodywork (including the wings). However, it is inevitable that parts will need to move to prevent them being too heavy or susceptible to damage from bumps on the track.

The aim of the rule is to prevent the wing's elements sinking to a different geometry at high speed to reduce drag, then springing back at lower speeds. The video clips did not suggest that this flex in the wing was in any way beneficial.