2006 US GP Technical Review

Indianapolis brought the Formula One season quite fittingly into its second half. We have now seen every type of circuit, from slow to fast, and in Indy's case a mix of extreme slow and fast.

In the previous races at the brickyard, with the V10 engines, the cars ran quite a lot of downforce - such was the power from the engines that the gains the cars could make on the slow infield section were not offset by the slower top speed on the main straight.

This year, the lower powered V8 cars needed a compromise in downforce to make up for their lack of power. As a result, the cars ran much lighter levels of downforce, making the track very conveniently similar to the Montreal race a week before. Most teams ran similar solutions, with flatter rear wing elements and slimmed front wings.

Tyres for Indy

After the debacle of last year's United States Grand Prix, both tyre suppliers brought a selection of compounds and constructions to safely meet the circuit's needs. Indeed, it was the Bridgestone and Michelin's differing approaches to tyres that shaped the teams' competitiveness, and for Indy the balance shifted towards Bridgestone.

This particularly affected Renault and Ferrari. Whereas in Canada the expected competitiveness of the Ferrari chassis was compromised by the tyres, for the American race, the Bridgestone suited the car and conditions perfectly. Renault, in the mean time, suffered a lack of balance and grip all weekend, leaving Fernando Alonso uncharacteristically struggling.

The reverse in competitiveness between Ferrari and Renault was potentially down to several reasons - not least of all, Ferrari's top speed advantage and their enviable record at the US track. But taking into account the events at this race a year ago, the tyres were clearly a major factor.

Last year, the Michelin tyres were failing around the shoulders leading to complete failure on Ralf Schumacher's car. The problem afflicted all the Michelin runners whose tyres presented the early signs of just such a failure. No clear reason was ever found to the cause of the failures, but the revised track surface, with diamond cuts machined all over it to improve grip, are widely believed to be the key reason.

This year, no changes were made to the circuit or its surface, and this allowed Michelin to prepare for the track. Although any repeat of the failures wouldn't bear thinking about on either safety or commercial grounds, Michelin were clear that safety of their tyres was paramount, but were equally adamant that the tyre's performance wouldn't suffer.

Nick Fry of Honda was clear that safety was the first concern. "I think it is completely natural that Michelin should be conservative, and in their position you wouldn't be anything other than that. It was expected, and that is what happened."

Fry further admitted that Michelin's approach did contribute the Bridgestone's runners appearing more competitive. "The Bridgestone runners did better today, compared with their normal performance, than the Michelin runners, and that resulted in clearly the Ferrari and Toyota looking rather better and Renault and McLaren looking worse."

In their preparation for the race, Michelin prepared six types of tyres, and their weekend was problem free. On Friday, one type of Michelin tyre displayed premature delamination problems, albeit not of the type seen last year. This harder tyre was dropped from their selection and their other tyres ran with out any problems.

The unusual approach Michelin had to take for this weekend was a one-off, however. With a return to a more conventional weekend at the next race, and on Renault's home turf at Magny Cours, the situation is expected to return to the status quo.

"In Magny Cours, I would expect that to be reversed," Fry added. "I think there is a good chance, given that it is Michelin's home ground, that we could be seeing the opposite [of Indy]. At least we hope so."

Restricted V10 engines

As Indianapolis has the longest flat-out section in F1, it was the common belief that the V10 engines fitted into the Toro Rosso cars would have an advantage in the US GP. The Cosworth V10 engines are restricted in two ways: a restrictor plate, and a rev limit. Some teams feared this would not be restrictive enough, leaving the cars with more power than the immature V8 engines. Also, intuitively these two limits should only strangle the engine's peak power but still allow a strong power delivery.

These fears have been proven as wide of the mark. Cosworth also produce the V8 engine in the Williams car and Cosworth's Alex Hitzinger has confirmed to autosport.com that the V8 has more peak power than the V10. When prompted about the power delivery, he said the V10 also lags behind the V8.

Apparently the restrictor plate design also affects the power curve, producing losses throughout the rev range. Overall, Hitzinger confirmed that the v10 is inferior to the V8 in all respects and that the FIA have the dyno information to back this up.

So while the common belief pre-Indianapolis was the V10 had an advantage, it does in fact have a handicap - or, more correctly, several.

Firstly, and most importantly, the engine is based on the spec used in 2005 and was remapped to work with the restrictions. But, since then, the engine has not been developed and there are no plans for any upgrades to the unit this year. So while other teams are progressing with their engines, increasing the revs available in the race and improving power outputs every two races (with each scheduled engine change), Toro Rosso have stood still, which is effectively going backwards in F1.

So the Cosworth V10 does not produce more peak power than the V8 and also struggles to produce its mid-range power as well as the V8. But, there are other issues related to how the engine is rev-limited.

As the restriction is a hard limit (16,750rpm), the team do not have the over-rev ability of the unrestricted engines. This hits Toro Rosso in two ways: firstly, the drivers don't have the "push to pass" options of other drivers - often drivers are allowed to run extra revs in the race to overtake at the expense of engine life. Having to use the full rev limit to produce power, the V10 doesn't have this extra four or five rpm to play with.

Secondly, this hard rev-limit restricts the ability of the car to slipstream behind other cars. When a car slipstreams another car, the lack of wind resistance allows the car to reach a higher top speed even if the engine doesn't have the power to reach that speed on power alone. To allow this, the teams gear the car slightly higher than optimum to have a small amount of extra speed, allowing the engine to over-rev before hitting the rev limiter.

However, the Toro Rosso cars don't have this flexibility to over-rev, and this limits the gearing options. Should the team use a taller gear to allow over rev, the car might not make full revs when not slipstreaming, slowing the car's top speed on the majority of laps. This may explain why Scott Speed was unable to pass on the long straights, as he had no more revs to pass the other cars.

Williams

As mentioned in the Canadian technical review, Williams have two winglets added on to the nose to improve flow over the rear of the car.

The team have run the small cascade wings attached to the endplates since the start of the year - in testing these have been replaced with even wider versions in a bid to create some more front downforce.

Williams's Sam Michael has been candid in saying the car is lacking, and aerodynamics are a key area that need improving. The new cascades - and also other developments - are due for the next Grand Prix, in France.

Honda

Honda retained their Renault-like rear wing endplates merged into the wing's flap, but for this race the main plane of the rear wing has been revised.

This was not the deeply stepped frontal profile seen in Canada, but instead it more subtly stepped, where the thickness of the profile is much thinner at the outer edges. The thinner cross-section should produce less drag, which would have helped Honda's top speed on the main straight.

Also due for some aerodynamic upgrades in France, Honda have been testing new Williams-like cascades to the front wing endplates, rather than their bi-plane arrangement seen at the higher downforce tracks this year.

Toyota

On Thursday the team presented their car for scrutineering with an extra flap added to their front wing. The extra flap (yellow) is attached to the endplate and sits between the main wing and the winglet.

Clearly designed to add downforce, the device was not needed in the end, and both the flap and winglet were unbolted from the wing and replaced with blanking plates.

A small detail on the sidepods was a new cooling outlet. Toyota use a heavily louvered exhaust fairing, and this was supplemented with narrow louver panel in between the exhaust and chimney.

BMW Sauber

After the promise shown in Canada, BMW had another good weekend in Indy. The revisions in Canada also included a new front suspension geometry, and the car has been making extremely good starts.

With the fuss over flexible wings, and BMW's impressive straight-line speed, BMW designer Willi Rampf made an interesting comment, suggesting that a good rear brake duct can have as much effect on the top speed as a flexible wing.

Backing up Rampf's comment, BMW have a complicated rear duct, which extends as far inboard as the rules allow; and while it has a lower fin - which was added back in Australia - the duct now uses two much wider flaps (yellow) above and below the axle line.

With the freeing up of aerodynamic restrictions, BMW are the first team to really develop this area at the back of the car, beyond the usual bulbous shape adopted by most teams.

Standard ECU and Microsoft

As part of the FIA's cost cutting initiatives, president Max Mosley announced last year that Formula One will move to a single source of Electronic Control Units (ECU) from 2008 onwards. This was seen as a controversial move, as the teams are precious about their technology especially with their electronics, which are probably second only to aerodynamics in performance gain per dollar.

The FIA put out a tender earlier this year for companies to supply a single spec ECU to F1 from 2008 until 2010. This week, the FIA announced that Microsoft MES won the tender process.

Microsoft needs no introduction; as a global brand and as a non-automotive specific company, they would appeal to the FIA in broadening the sport's profile. Microsoft is perhaps best known for its operating systems and related PC software suites. Equally, Microsoft is expanding its remit to include hardware-based solutions like the Xbox game console and embedded systems to be put into mobile phones.

One direction Microsoft has headed into with their embedded systems is in the automotive field for road car dash displays. This new deal with the FIA would be aligned with Microsoft's broadening developments.

One fear may initially be that Microsoft does not have the track record in these sorts of systems. Many thought that suppliers like Marelli or Pi Systems would have been successful with the tender. But the Microsoft MES business is a joint venture with Siemens, who is much more used to the hardware end of business.

Quite how the FIA plans to introduce this single ECU in 2008 and what it will entail is not yet clear.

An ECU in its simplest terms is a computer, with a large number of inputs and outputs. Much like a computer, the ECU consists of the hardware and the software. What makes the ECU really do its work is the commands it processes to control the car's systems. These commands, in the form of software code, are unique to each team even if they are using the same brand of ECU as other teams.

Currently the teams utilise ECUs to control various aspects of the car. The main controller is the one covering the engine's functions - everything from the basics of fuel injection, ignition and driving, to the dash displays.

Some teams also run a second ECU known as the chassis controller. This primarily controls the transmission (gearbox, clutch and differential) and takes in all the data from the sensors on the suspension and transmission on the car's movements.

Both ECUs talk to each other, allowing one controller to invoke commands on the other. Classic interactions of this type are sequencing the engine and gearbox during gear shifts, equally traction control covers functions on both controllers.

As the car's systems are so blurred between engine and chassis, some teams are now running a single ECU covering both functions. For teams with customer engine deals, this unified ECU approach is often not possible, as the engine supplier wants its own ECU for the engine, leaving the team to provide their own chassis controller.

With the FIA's decision to go to a single ECU, it seems it's the engine controller that is to be specified. This will take the form of the hardware and the software that runs over it. Again, it's down to the teams to write the code that actually controls the engine's systems.

However, this ECU is only mandated to be used for race weekends - in testing, it seems the teams are free to run their own ECUs. This will force the teams to develop two systems: one complex system for testing, and the Microsoft one for races. Quite where the cost cutting comes into this arrangement is unclear.

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- The Autosport.com Team

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