17.06.2004 Indianapolis this weekend provides quite an aerodynamic challenge as track boasts the longest straight on the calendar AND cars travel at full throttle for a massive 20 seconds

With just a few days separating the Canadian and US Grands Prix, the Scuderia Ferrari Marlboro mechanics do not have much time to race prepare the F2004s that Michael Schumacher and Rubens Barrichello will use in Indianapolis this weekend.

Apart from getting the cars race-ready, the engineers will be studying data from past races here to establish the best set-up in terms of engine and suspensions settings and the aerodynamic package.

"Indy" provides quite a challenge in this last area: the track boasts the longest straight on the calendar and cars travel at full throttle for a massive 20 seconds.

Ideally, cars need the smallest possible wings to reduce drag down the straight, but then need much bigger wings to cope with the twisty remaining section of the track. As usual it is all a compromise and the best car is one that produces the most downforce (to stick the car to the road) with the least drag (the force slowing it down.)

The F2004's aerodynamic package is the result of hours of experimentation in the wind tunnel at Maranello. In simpl terms, a wind tunnel is a structure that blows air over a car while sensors gather data to check the effect of various car parts on the amount of downforce (the force of air pressing the car onto the track) and drag (how the parts slow the car's passage through the air.)

But as Scuderia Ferrari's Chief Designer Rory Byrne explains, talk of "putting the car in the wind tunnel" is actually a misnomer. "The working section is big enough to take a full scale car, but there would be too much blockage so there are only a limited number of tests you can do on a full scale car," says the South African designer. "Most of our development is done on a 50% scale model."

The wind tunnel, designed by world renowned architect Renzo Piano, is in use almost round the clock. "The whole of the Aerodynamics Department is housed in the wind tunnel building," continues Byrne. "We've got in the region of 50 people working in the aerodynamics department on research. That includes the aerodynamicists that carry out the experiments, those who do the theoretical work as well as those who design parts for the wind tunnel model and technicians who actually assemble the parts. It is quite a self-contained unit."

Although the laws of physics do not change, the flow of air around a modern racing car is extremely complex. "I don't think there is a single person on this earth who understands every aspect of this flow," admits Byrne. "There are so many parts on the car whose shape can be changed that affect the aerodynamics, that the scope for improvement is almost infinite. So you come down to the basic fact that if you use your tools properly, the more aerodynamic development you do, the faster the car will go. I don't see a limit to that in the foreseeable future, assuming the rules remain fundamentally as they are."

So what exactly does get measured in a wind tunnel and how does that affect the performance of the car? "The most important measurement tool we have is a balance, which measures the forces and the moments on the car, created by the flow of air," reveals Byrne. "We measure the downforce, in other words the vertical force, the drag, a longitudinal force and we also measure the side force when we are in cornering condition. In addition to the forces, we also measure pressures on the surface of the car.

"The combination of the force and pressure information will tell us if a component is more aerodynamically efficient: in other words it gives us either more downforce for the same drag or less drag. We select components based on the improvement in efficiency that they produce in the wind tunnel."

Although bodywork and wings are the most obvious example of the aerodynamicists' work, the science goes deeper than that, as air flow goes under and through the car as well as over it. "We need to use the wind tunnel to validate everything," adds Byrne. "There are no parts that go on the car unless they have been tested in the wind tunnel. But out of this testing and the various computational techniques we use come the ideas and the development of the ideas. Occasionally you carry out an experiment and find an unexpected result and that might lead you into a new direction. You have to keep an open mind all the time."

The F1 rules and the amount of time this type of work has been carried out means that the cars have gone down a similar development direction. "The job is all about optimising every single component of the car to work as a package," concludes Byrne. "For example, if you took any component off our car and put it on another team's car, then that car would perform worse than before because the component was not integrated with the rest of their package. I want to emphasise that the most important thing is getting all the components working well together. That doesn't only cover the aerodynamics, but applies to the car as a whole."

This year's US GP will be the fifth staged at Indianapolis, so the Ferrari team knows what to expect from the track. However, there is one significant change this year and is the date: so far the race has always been staged in September, but in June, the teams could experience significantly higher temperatures and that will impact on several aspects of performance, including engine, brakes and tyres. Having won three of the past four events here, Scuderia Ferrari can be confident of another strong showing this weekend.