Before the cars tear on to the track for the first round of testing at this weekend’s Brazilian Grand Prix, they will in effect have absorbed every bump, bounce and undulation of the circuit without having been there recently.
The bumps of Interlagos are notorious and three years ago both Saubers were withdrawn before the race having suffered rear-wing failures attributed to the punishing surface.
Most teams now have the facility to reproduce the characteristics of every circuit in the world by means of a computer programme fed into a machine known as the seven-poster chassis rig. Though tracks such as Imola and Magny-Cours are within transport distance for midseason shakedowns, the cost of flying cars to Brazil, Melbourne or Malaysia for testing purposes is prohibitive.
The £1,5-million rig has thus become a crucial tool in a team’s research and development programme. In a specially configured bay, usually guarded from prying eyes, a formula one chassis sits on hydraulic rams in a pit, one or two metres deep, in the floor. The car’s four wheels sit on these pads, through which a computer programme can reproduce the movement over every undulation. Three more hydraulic rams are attached to the underside of the chassis, two at the back, one at the front, to reproduce roll (the car’s movement from side to side) and pitch (the car’s fore-and-aft movement under braking and acceleration). A dummy in the chassis replicates the weight of the driver.
‘The main requirement is to eliminate every variable from the car development process, to take it away from the driver,†says Gary Anderson, head of race and test team engineering for Jordan-Ford, who were one of the first to invest in the technology five years ago.
‘Therefore, the more tools you’ve got to operate in controlled circumstances, the more you can change small things without other aspects affecting them — like the driver’s input — which is really what it’s all about. The seven-poster rig is a good example of this. The more toys you have to understand the car’s behaviour, the further forward you can go in its development.
”The whole rig is computer-controlled. We gather data at the tracks and it is sent back directly down an ISDN line to our factory at Silverstone. We can match precisely the bumps and other features on the circuit we are dealing with. ‘We can say: ‘Through this section of the circuit we’ve got a problem.’ They have a look at it, change springs and rollbars until they are blue in the face.â€
Mike Gascoyne, the Renault team technical director, says his team often uses data from the seven-poster rig to supplement information gleaned by running the cars on the circuit.
‘This year we have chosen to run three cars in the additional Friday morning test session,†he explained, ”so we are gathering most of our set-up data from that rather than relying on the seven-poster rig as a race tuning tool. We use our rig more as a central element of ongoing research and development. That said, while these rigs are crucial tools, they are nowhere near as important as, say, a wind tunnel in the car’s overall development. It can be quite difficult to get a clear-cut result from them.â€
Martin Shaw, the engineer responsible for Jaguar’s rig, believes there is more potential to be unlocked from the systems.
‘These rigs are important tools and I think they’ll become increasingly so in the optimisation of formula one cars,†he said. ‘Compared with the current level of wind tunnel development, the rigs are at an early stage. But the more restrictions that are placed on real [on-track] testing, the more valuable they’ll become.†—