"Underwear?" Jarno Trulli has had to make many sacrifices to reach the pinnacle of motorsport, but stripping down to his underpants must rank among the more bizarre ones.

Finding the comfiest driving position in your Corolla or Avensis is easy because the seats and steering are designed to adjust for a wide range of body shapes and sizes. A Formula 1 car has to be packaged to suit each individual drivers at the design stage - but the techniques used to achieve these disparate aims are remarkably similar, even down to using the same CATIA software.

Wrapping the TF105 around Trulli (and Ralf Schumacher) begins with a careful set of measurements supervised by Panasonic Toyota Racing partner Dassault Systèmes. Millimetres count here, which is why Trulli undergoes the first few passes in his smalls.

"The shape of the cockpit is defined by the rules," says John Litjens, project leader in Panasonic Toyota Racing's chassis design office. "What we have to do is fit the driver into the space we're allowed. We like the driver to sit as low as possible, to aid the weight distribution, but he also needs to be high enough to see out of the cockpit."

They also have to consider the impact of the technical regulations. The driver's feet, for instance, have to be behind the front axle line.

"For safety reasons the FIA have imposed precise measurements on the dimensions of the monococque [the central 'tub' of the car, which incorporates the crash structure]," says Francois Barrovecchio from Dassault Systèmes. "Being able to fix the position of the driver without having to build physical mock-ups saves a lot of time. Using the CATIA software enables the team to cut down on the design and manufacturing time. That's not only important for reacting to changes in the regulations, but also developments within the racing season - this year there are 19 races, some only one week apart. If the team discovers a design problem, they need to be able to create new parts quickly."

There are 103 different measurements - width of the nose, head, hands, feet, circumference of the head, and so on - which are fed into the computer to create a 'mannequin': what you might call a 'virtual Trulli'. This can be positioned in a virtual cockpit.

"Once our software has created the mannequin we try to move it into exactly the same posture as the driver will have in the cockpit," says Eric Coutu, an ergonomist with Dassault Systèmes. "That's where we use the scanner to 'map' the real driver's posture. The aim is to get the best visibility, the comfort for the back and reach to the controls.

"We can do it in two hours, but the timing depends on the measurements we take. And we like to do this three times, too avoid errors. We also do it with and without clothing to find out what impact the thickness of the clothing has on cockpit comfort. We'll even measure the soles of his shoes."

Jarno is relieved to be able to don his suit, shoes and a helmet for the next stage of measuring up, for this isn't the warmest corner of the factory. He poses for a series of 'posture' readings with the scanner, which looks rather like an x-ray device. Then he replicates the pose in a full-size dummy cockpit complete with seat and a cockpit surround, discussing the minutiae of the seat position with Litjens and race engineer Ossi Oikarinen.

"We can decide to simulate an entire population," says Coutu. "So we can say, 'OK, this is the smallest person we can get, and this is the tallest person we can get'. We'd use those mannequins for a wide design - for a typical road car, where people of all shapes and sizes must be able to sit comfortably, to have a good view and to reach all the controls.

"What we're doing here is to narrow our 'population' - to focus on two particular drivers, Jarno Trulli and Ralf Schumacher, make specific measurements and create detailed mannequins of them."

Since his environment for the new car is shaped with such care, one wonders how much Trulli had to compromise when he first arrived Panasonic Toyota Racing, shortly before the 2004 Japanese Grand Prix.

"When Jarno joined us it went quite smoothly," says Litjens. "He came here for a seat fitting and went testing straight away. But for sure there are some compromises; Jarno wanted his head to be further up in the TF104B and that wasn't possible. We incorporated these lessons into the TF105, so it was useful for him to have started so early.

"The software can also simulate the driver's viewpoint from within the cockpit, showing lines of sight to front and rear. This helps the design team arrive at optimal mounting points for mirrors. Since Toyota produces its F1 engines and chassis under one roof at the factory in Cologne, the synergy that has enabled the engine and chassis departments to work in a more closely integrated way can also help to work out what the driver will see in his mirrors (note, for instance, the way the exhaust 'chimneys' have changed size and shape).

"The complete car is on our database," says Barrovecchio. "We're able to measure the weight of each component and calculate the effect it has on the centre of gravity. We also simulate the effects of varying fuel loads.

"A digital part is easier to change. You can see how those changes will affect the rest of the car. Each driver weighs around 73kg, so his position affects the centre of gravity of the entire vehicle - with the mannequin we can test the effect of lowering it even by a centimetre."

Another benefit of doing so much detailed work in software is that it enables the team to streamline its operations and cut costs - especially important in the current climate, in which the sport's governing body (the FIA) has introduced new rules with a view to reducing the expense of F1. Computerised design cuts down on line drawings and model making, and can improve quality control. The aim is for all the parts to arrive in the workship ready to be slotted together - no filing down components to make them fit. The team has learned from Toyota's expertise in the science of road car manufacture to improve its processes - for instance, the Toyota Production System (TPS), which strives to drive down costs and weight while maintaining durability and increasing speed of manufacture. It was Toyota that pioneered 'just in time' manufacturing techniques, syncopating the arrival of parts so that there is no wasteful surplus or costly stockpiling

Nevertheless, there is still no substitute for the final stage, that of getting out onto the road for real. It's at this point where you encounter the unexpected, no matter how hard you've worked to make sure everything fits.

"At the design stage you can get the driver environment 90-95 percent right," says Litjens. "When they're driving, and the g-forces are acting on them, sometimes there are effects on the muscles that can't be foreseen by a computer."

- source: Toyota -