2007 US GP Technical Review

Coming as a back-to-back race from Canada, Indianapolis presents a very similar set of demands for the engineers as Montreal. Thus, the lack of testing time and comparable set-up demands meant that few developments were on the cars for this race.

Indianapolis's layout is split between the slow infield section from turn one to turn 11. From there, the race track passes out onto the oval and its main straight for a 28s flat-out blast.

While the infield section demands downforce and mechanical grip, the lap time is dominated by the long run around the oval. This means that the car's set-up is favoured towards lower drag for speed along the straight. This compromise in the set-up makes the cars tricky to manage around the slower corners.

Additionally, the demands of the long high-speed run means the tyre choice will have to be harder, rather than the softer, grippier compound the infield section would otherwise demand.

For this race Bridgestone provided the soft and medium compounds from their range. Despite this, the softer tyre proved difficult to manage on the hot and fast track.

Most drivers were scheduled for their new engine. All four Honda-powered cars, as well as a Renault and Red Bull, had to carry the same engine that was run in Canada. This is a slight disadvantage, as the other new engines will not see such a punishment at the next round in France.

McLaren drilled twelve cooling holes through the brake pads (yellow) to cool the calliper © Scarborough (Click to enlarge)

McLaren

To aid brake cooling, McLaren adopted the rare practice of drilling their brake pads. The pads are supplied as a pair, with the brake disc from their choice of supplier.

The supplier does allow the teams to drill holes through the pads to reduce the heat passed back to the callipers' pistons. Toyota have also run drilled pads in the past.

The pads are fed with cooling air from the smaller parts of the brake ducts, which wrap around the calliper to feed air to the pistons and pads.

McLaren revised their rear wing and support prior to Canada. Despite the wing supports being moved forwards, McLaren chose to retain two small stumps from the original supports to aid airflow through the rear wing. Additionally, as a drag reduction measure the small flap McLaren add to the rear light pod was removed for the two American circuits.

Various features in America for Super Aguri included a new rear wing, cooling louvers and diffuser walls © Scarborough (Click to enlarge)

Super Aguri

Following on from the success in Canada, Super Aguri improved their car with the adoption of the Renault-like rear wing previously tried by Honda.

As already described for the Honda in Canada, the rear wing has the flap integrated into the endplate to reduce drag created at the wing tip.

Also Aguri ran extra louvers under the chimney to cool the engine on its long, flat-out run from turn eleven to turn 1. While the Super Aguri follows many of the Honda designs, the diffuser has been one area where the independent team have gone their own direction.

To cool the engine oil during the 28 second run around the straight, Renault added these vents (yellow) © Scarborough (Click to enlarge)

The upper walls of the tall central diffuser tunnel have been cut back, creating a distinctive step leading back up to the beam wing. This change may cost the team some downforce, but may also end up making the diffuser less sensitive to attitude changes.

Renault

As with many teams, Renault expanded their cooling outlets for Indianapolis by moulding louvers into the chimney panels, rather than opening up the chimney.

As Toyota continue to run their bi-plane element, their lower wing is among the smallest for Indy © Scarborough (Click to enlarge)

Toyota

Toyota ran one of the flattest front wings of all the teams, but decided to retain the upper bi-plane element.

The flap on the wing had very little angle of attack and a very slim chord, which was reduced to just a narrow strip in the middle.