Brake expectations

It’s often hard to argue with the notion that F1 has become little more than a dull procession of millionaire- propelled advertising hoardings whizzing round a track at high speed.

This is why, in what will certainly rank as one of his more sensible decisions, Max Mosley — boss of the sport’s ruling body the FIA — last year announced a raft of measures aimed at turning the sport into a proving ground for new hybrid technology, while simultaneously boosting its environmental reputation and reinjecting a bit of excitement into racing.

The main focus of this technical push is the development of kinetic energy recovery systems (KERS). Expected to make their first appearance on some of the vehicles racing in the 2009 season, these devices will store the energy that is otherwise wasted when a vehicle brakes and use it to boost acceleration coming out of corners and overtaking.

Intriguingly, in contrast to the freeze on engine design and other areas of F1 development, the FIA has decreed that teams are free to use any system they like providing that no more than 400 kilojoules/lap is recovered, and energy is only captured or released at a maximum rate of 60kW. F1 chiefs last week announced they are to discuss raising the cars’ 605kg weight limit to accommodate the new devices.

With numerous mechanical and electrical systems now enthusiastically vying for a spot on next season’s starting grid, Mosley’s effort to stimulate new automotive developments has apparently worked. And one of the most promising candidates is a fully mechanical, flywheel-based system jointly developed by a trio of UK automotive specialists — Torotrak, Xtrac and Flybrid Systems.

The 25kg system, which has already been licensed to two unspecified teams, is made up of a flywheel, a control system and an ancillary transmission, or variator, that provides a continuously variable connection between the flywheel and the vehicle driveline.

The device, which on an F1 car would be positioned directly above the trans-axle behind the driver, stores energy when the vehicle is slowing down by spinning the flywheel up to speed. This energy is then released when the vehicle speeds up again by slowing the flywheel down. The energy is received from the driveline, and released back into it through the variator.

Adrian Moore, technical director of Xtrac, explained how the variator — based on technology licensed from Torotrak — achieves the complex feat of matching the flywheel speed to the vehicle speed.

‘The flywheel has a speed range of 30,000-60,000rpm and the vehicle goes relatively slowly in terms of rpm and has a speed range of 62-124mph (100-200kph),’ he said. ‘You’ve got to match those speeds with some sort of gearbox and the logical way to do that is with a continuously variable transmission (CVT). You need a speed range of about 6:1 and by happy coincidence a Torotrak toroidal CVT is about 6:1.’