On the fast track with McLaren

How do you design a new Formula One racing car in 12 weeks when you have to accommodate a new engine, new build regulations and a different driver? Total reliance on technology was McLaren's answer to this question, with the result that its new MP4/10, unveiled earlier this month, was the first 100 per cent CAD/ CAM-produced racing car.

And computer design does not mean conformity. At the launch, all focus was on the car's controversial design, especially its revolutionary central wing positioned just behind the driver's cockpit. The wing, as well as the car's other aerodynamic changes, is designed to counter the effects of new Formula One regulations intended to reduce speed and improve safety.

The regulations were introduced in November after a season that saw the deaths of Ayerton Senna and Roland Ratzenburger. Cars must have a "stepped" floor raised to 50mm, regulated body shape and engine air intake, and smaller wing sizes. The cars must have strengthened side-impact protection, an enlarged cockpit and a longer chassis. Together with design changes planned from last season's feedback, plus the changes needed with the new Mercedes engine, the car is 90 per cent different from the 1994 model.

Nigel Mansell's arrival on the team has meant further changes. Several components - steering wheel, pedals, seat fittings - have to be designed for certain drivers, plus adjustments have been made to the chassis design - Mansell has a somewhat larger frame than his teammate, Mika Hakkinen. All of these changes have been designed and tested on McLaren's CAD/CAM system - a network of Sun SPARC stations and SPARC servers running Computervision's CADDS 5 software.

McLaren first started using a CAD system in 1987. By 1990 it was 40 per cent reliant, by 1993 90 per cent. "The system evolved as the technology - and our users - became more advanced," explains Kevin Masterson, McLaren CAD/CAM manager.

Every component of the MP4/10 was designed from scratch on the system, using a range of techniques from basic 2D to complex 3D wireframe and solid modelling. A lot of the early testing is done on the system, too: structural analysis, mechanical simulation, suspension geometry testing and aerodynamics. Mr Masterson would like to do more computer-based testing, but the processing requirement is very high.

The addition to the network of Sun's latest model 71 SPARC system has helped, but Mr Masterson thinks it would take a supercomputer to do all the full 3D modelling the team would like. Completed CAD models are used to programme the machine tools that make the car's components. This saves time, and means there is no risk of design data being misinterpreted. McLaren makes most of the components at its Woking plant, but the larger sections are made by other manufacturers, who receive the CAD data via modem.

McLaren will be pushed to produce five MP4/10s before the first Grand Prix of the season in Brazil on 26 March. The CAD/CAM network means they can keep designing up to the end. "We've had machinists making one end of a component while we're still designing the other," says Mr Masterson. But the work doesn't finish with the launch of the new car. The team will now concentrate on shaping the car for optimum aerodynamics. "By mid-season we'll have tweaked the design to regain the lost speed caused by the regulation changes."

By the end of the 1995 season the design of the MP4/10 will be around 70 per cent different from the model unveiled earlier this month. "The design process is continuous," says Mr Masterson. "After a race we decide what needs a redesign. We've changed up to 50 components between races before now. No two race circuits are the same, so we have to find the optimum design for each. This could mean different shape wings, suspension, gearbox ratios, and so on."

The need for constant change is made more urgent when you consider that the rival Formula One teams also use CAD/CAM systems, albeit not as advanced as McLaren's. "I expect the extra wing to appear on other cars before the end of the season - I'm sure some of them are already testing it in their wind tunnels," says Mr Masterson.

To help it beat the competition, McLaren is increasing its use of technology at the racetrack itself. Since 1993 it has been using Sun SPARC stations to run performance monitoring of its cars, using Atlas (Advanced Telemetry Linked Acquisition System) software designed by one of McLaren's sister companies, TAG Electronics.

This season it will be using six SPARC station 10s - three per car; one each for the engine, gearbox/chassis, and more detailed component analysis. The car's computerised control systems transmit status data via wide- band telemetry links. The system receives a near continuous stream of basic data, such as the car's position and engine performance, with more detailed information transmitted in a single burst when the car passes a guaranteed line of sight - at the pits, for example. The Atlas software will soon indicate if there is something wrong.

"We'll know before the driver does if there's a problem," says Dr Dieter Gundel, McLaren's head of systems engineering. "We can then radio the driver or, if there's something that influences his safety, we can get a message to the dashboard display immediately. Checks are built into the software, which will shut down the engine automatically if there's a problem."

For 1995 the Atlas network has been extended to the pit wall crew - the team manager and race engineers who make strategic decisions such as when cars should come into the pits. They will be using Sun's portable Voyager workstations, receiving lap-by-lap summary data via a radio ethernet link. They also get a circuit map showing the location of the cars - crucial if they need to tell the driver to come in. "It's impossible to speak to the driver when the engine's at full throttle. The noise level in the driver's helmet can reach 165 decibels," explains Dr Gundel.

The data gathered during a practice session or race is worked on by a team of five or six engineers. The drivers also give the engineers their impression of the car's performance, adding a crucial factor to the feedback that will influence the design team's next moves.

"We're studying particular sensors in particular parts of the car. The driver is the integrating sensor, letting us know what's happening to all four corners," says Dr Gundel.

So despite all this technology, from the car's conception to the day of the race, a driver's skill and experience is vital, as Dr Gundel reiterates. "A good driver will still make one to two seconds' difference per lap" - and that's often the winning margin.