These race cars are fast, stealthy, cool—and electric
It’s Saturday in Brooklyn, and I’m sitting in the grandstands, 30 paces from the track, as a bevy of race cars shoot by. I almost have to be warned that they’re coming, because together they give off only a faint, high-pitched whine.
You know it beforehand, but still it comes as a surprise: Formula E, the all-electric equivalent to the famed Formula 1 circuit race, is conspicuously sedate.
At 80 decibels super close up, it’s definitely louder than the 70 decibels of a passenger car at highway speeds, but it’s way, way quieter than the brain-curdling 130 dB you’d get from a Formula 1. The motor is quieter than the braking, unless the motor is running in reverse as a regenerative brake, to recharge the battery. And the cars are totally stealthy as they roll into the pit, halfway through the hourlong race. The drivers have to swap cars because, after about half an hour, each car’s battery is tapped out.
The eerie silence lets me speak easily to my corporate hosts, the electrical experts from TE Connectivity who handle the wiring for the MS Amlin Andretti Formula E team. And so I pepper them with my stupid, newbie questions:
- What’s the dry ice for? Answer: To pre-cool the batteries.
- When does the driver switch from his first race car to his second one? Answer: It may well happen after the midpoint in the 43-lap race; that way, the driver can run down the charge in the second car’s battery that much more aggressively.
- Why is a “safety car” holding back all the race cars? Answer: By slowing things to a crawl, the safety car gives crews time to haul away a broken-down race car.
This is the third season of Formula E, and its first appearance in Brooklyn, near the famous bridge and within sight of Lady Liberty. In the early days, the race cars were standard, right down to the ground, but now the authorities are opening the machines up a little. Each team is now allowed to design its motor, power management system, and sensors, though the chassis itself remains standardized. So does the all-important lithium-ion battery pack, together with its safety features and cooling elements, all courtesy of Williams, the official supplier.
In another couple of years—by Season 5—most of the rest of the car will be opened up to the engineering talents of the various teams. Battery technology is expected to be far enough along to dispense with the two-cars-per-driver model. Even the aerodynamics will be fair game. And that means that the big-money racing behemoths, like Audi, BMW, and perhaps others will be able to make their deep pockets count.
A couple of days before the race, I spoke with Judith Henzel, a mechanical engineer seconded by TE to the Andretti team. She couldn’t tell me much about the motor—hush, hush, and all that. Plus, it’s only partly the work of the TE people. But she did say TE had salted the vehicle with special race-spec connectors, terminals, tubing and sensors, the better to diagnose problems both during races and in testing.
“You can see how the forces are, which forces have influence on the driver and car and chassis and suspension and so on,” she said. “This accelerator under the seat goes up to 50 g forces.”
But isn’t that enough to turn a driver into a mancake? “Well, it’s also for testing,” she says. “We have it in a development car, testing in the UK.”
Henzel concedes that Formula E cars aren’t yet the equals of their internal-combustion cousins. With those babies, you go flat out at every opportunity, braking viciously hard only to squirt out of a turn in zero-to-60 times that leave even Tesla’s Ludicrous Mode in the dust.
“Oh, the maximum speed of Formula 1 is 225 kilometers per hour [140 mph], and the [fossil fueled] Formula 1 go way higher,” she says—up to 233 kph. And the tracks are also way shorter, and you have a lot of heavy curves. And, sure, with electric propulsion you have all the power right from the start, but still, these cars aren’t made for maximum acceleration. The goal is how far can you go with one battery if you do really good energy management.”
Everything revolves around energy management. It’s a little like the early days of aviation, when virtuoso pilots like Lindbergh would nurse a plane along at just the right engine speed and with just the right mix of air and fuel, in order to stretch a tank of gasoline.
So, what’s the best strategy? Do you run the first car in a relatively laid-back fashion to conserve battery, then run the second car fast to finish strong? How hot can you let the batteries and motor get, given the ambient heat—29 degrees Celsius (84 ºF) on race day? Do you run regenerative brakes, or do you resort to less energy-efficient mechanical braking to avoid overheating the electronics?
All those decisions are still being made by human beings, though the ancillary race of Formula E robotic cars may finally set an expiration date on that.
The Andretti team’s two drivers, Robin Frijns and António Félix da Costa, raced at the same time, and each used two cars—that’s a total of four cars to turn around in the pit. Frijns finished in 9th place on Saturday and Felix da Costa finished 12th.
First place went to Sam Bird of DS Virgin Racing, who was heartily congratulated by Virgin Airlines CEO Richard Branson. It probably wasn’t just luck, either, because Bird did it again on Sunday, when the drivers all took their cars out for another quiet run around the track.
Article by Philip E. Ross, Read more on http://feedproxy.google.com/~r/IeeeSpectrumFullText/~3/uXTV0mA9ERQ/formula-e-in-brooklyn