Saturday, March 24, 2007

Movable floors

The first Grand Prix of the season took place in Melbourne last week, and, as winter testing suggested, the three fastest teams were Ferrari, McLaren, and BMW-Sauber. Intriguingly, it's been revealed that two of those teams, Ferrari and BMW, are using movable floors. Both of these teams mount the front section of the floor, the so-called 'chin-stay' beneath the raised nose, with a sprung device. It's thought that Ferrari and BMW are using this to reduce the drag of the car in a straightline, and possibly to balance the car in higher-speed corners.

The underbody of a Formula 1 car, and the upswept 'diffuser' at the rear, both generate downforce, but also generate drag as a by-product. Downforce is only required for cornering, so if one can induce an aerodynamic device to 'stall' at straightline speeds, or simply to perform less work, say by reducing the airflow it receives, or by impairing its angle of incidence, then drag is also reduced, and straightline speed is enhanced.

BMW-Sauber, in particular, seem to have made a significant leap forward, and given their aerodynamic resources, perhaps this is of no surprise. They currently have both the most sophisticated wind-tunnel in Formula 1, and the most-powerful supercomputer on which to perform computational fluid dynamics research and development. Built by DALCO, the Albert 2 supercomputer is reputed to be the most powerful industrial-use supercomputer in Europe.

"In Formula 1 we use computers for almost everything," said the team's head of aerodynamics Willem Toet. "The whole world is changing over to mathematical simulation. F1 is no exception and we use it in every area we can think of. I don't expect we can ever give up wind tunnel testing but then unlike some other teams we don't expect we'd need to build another windtunnel. We do additional testing using mathematical simulations. This is one of the very best windtunnels on the planet. We are able to use a full scale car, we can move the model up and down, pitch it, roll it yaw it, move the wheels, simulate crosswinds but there is still a huge amount we cannot do. We cannot simulate true cornering, sliding dynamically the angle of the air is different at different points on the car. We cannot simulate true distortion of tyres in a corner. With computational fluid dynamics we can do these things."

Last season, BMW-Sauber developed flexible rear wings, which developed reduced drag at high speed. The rear wing of a Formula 1 car consists of the main plane, and at least one additional flap above it, separated by a so-called 'slot gap', and both mounted between the rear wing endplates. Ferrari developed flexible rear wings which closed the slot gap at high speed, thereby causing the wing to stall, and to generate reduced drag by this means. BMW-Sauber, in contrast, developed a rear wing in which the trailing edge of the main plane deformed downwards at high speed, opening up the slot gap, and reducing the work-load of the wing more progressively. A sprung device was incorporated into the rear-wing endplates to control the deformation. When this wing was introduced, the performace of the BMW-Saubers took a sudden leap, and they were swiftly prevailed upon to discard the design. (Autosport 14/21 December 2006, p82-83).

This year, however, it appears that the spring-mounted chin-stay is very much within the regulations, and both BMW and Ferrari are likely to reap the rewards of developing this device before the other teams.

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