The launch of the Formula E Spark-Renault spec car at last week’s Frankfurt motor show was billed as a window into the future of motorsport. Be that as it may, the future looked pretty conventional to our eyes – and not far different from the globe-trotting prototype.
Cliff Rassweiler, racing driver and specialist in honing electric vehicles for the track at ProEV, comments: “The 30kWh limit announced on the Formula E official website matches the power pack that was in prototype (29.5kWh), so it means the organisers are planning a pack around the same size. I don’t expect max power and charge to change.”
The shell that was unwrapped at the motor show did not include the powertrain and energy source. These are expected to be installed ready for shakedown later this year, while regulations are expected to be firmed up this month at the FIA’s World Motor Sport Council.
“The organisers may be redefining or completing these specifications as they work on the latest draft of the regulations,” says Rassweiler. “If the series is to open up to other chassis after a season or two, setting a limit on kWh delivered from the battery has advantages over just setting a maximum battery pack weight.”
The skinny steel suspension components have raised a few eyebrows too, although Rassweiler says that isn’t necessarily an issue: “Suspensions are not supposed to be robust. In crashes, they are designed to absorb energy and crumple. The arms look pretty standard, incredibly slim one way, incredible stiff in another direction.”
Flexibility in car settings for the new sport and new tracks is important too. “Formula 1 suspensions are very specialised and I would guess their operating window is well understood and narrowly defined. Any extra adjustability is just extra weight,” Rassweiler explains. “However, Formula E is a work in progress. Who know what ride height, spring rate or dampener setting will be right? At this stage, it’s best to put lots of adjustability into the design.”
According to reports, the car is also set up to have a very tight turning circle to best suit the city circuits, and the battery pack is positioned in the chassis in much the same place that a fuel tank would be on a petrol-engined version.
Apart from the side winglets, the only immediately obvious external differentiators between racing cars in other Formulae and the Spark-Renault are the 18 inch wheels shod in low profile Michelins.
“Formula 1 tyre design is set by regulations, not optimised for performance,” explains Rassweiler. “There are a many potential gains to be unlocked from lower profile tires. Rubber deforms (which helps it grip the pavement) then rebounds. All that flexing wastes energy. We see this as greater rolling resistance. In electric racing, low profile (less rubber to flex), high pressure (less flexing) tyres will give greater range.”
Current E will be chatting to Bluebird later in the week to get a different perspective on building an electric car to race in Formula E. We expect much more radical thinking to emerge as the series gains traction and constructors come on board.