Transcription
In 2019, race engineers recorded something that shouldn't exist. They'd been analyzing onboard audio from a rival car. Pretty standard practice in racing, trying to figure out what the competition was doing. But that car was creating two frequencies, not what you'd expect from a single motor. And even weirder, one of them was backwards. When the car slowed down, the frequency sped up. When the car accelerated, it slowed down. That's not how motors work. Unless someone had figured out something very clever. And as it turns out, they had. Very clever and very fast.
Now, I couldn't find out much about this genius invention online. So, I went to find the people involved and found that 2 years earlier, one of the team had found a massive loophole in the rules. "To find that special idea that you think nobody else has seen, um, that reads between the lines, that sits slightly in that area where it's, it's legal, uh, but it's not obvious, and you, you think that nobody else is going to have seen this. Actually, you fret that everybody else will have seen this."
Dr. Chris Vag, the lead engineer on this project, and I sat down with him and others involved to understand one of the craziest ways to get around rules that I've ever seen in racing. Inspired by a piece of technology invented in 6,000 BC. And from the very first race weekend, it was obvious they'd found something special. "It started to become quite clear that we were going to dominate qualifying, um, throughout. And it also started to become clear that the race pace was going to be a dominating factor as well."
This is the story of a small team of brilliant engineers who thought outside the box to produce a race car so radically different the other teams wanted to get it banned. >> "Well, I tell you, the Nissan of the Straight is on a different planet. Don't know what it is, but it's really strange." >>
It's 2017, and somewhere in a development center, Chris Vag had been given a simple brief: find performance. But he wasn't looking for a tenth of a second. He was going bigger. >> "The starting point was, what would it take to get a second per lap of performance, or even better, to be able to lap every other car on the circuit and be the only people on the final lap of the race." >>
A second per lap. In motorsport terms, that's not an improvement. That's a different car. So Chris went back to first principles. What are the actual limits? One is energy and the other one's power. So both are limited by the regulations. You've got a maximum amount of energy that you can deploy in the race, and you've got a maximum amount of power that you can deploy at any point in time. And to be able to get around them, or to be able to exceed them even temporarily, would be a massive advantage.
So here's the problem. You can't take more energy from the battery. That's capped. And you can't deploy more power. That's capped as well. Which led Chris to a question that sounded impossible. >> "So, how could we take out more power, deliver more power out the wheels without it coming from the battery?" >>
When I first heard this, I didn't understand. He wanted more power that doesn't come from the power source. How is this not a violation of physics? But Chris wasn't trying to create energy from nothing. He was asking, "What if I stored it somewhere else?" >> "I explored a whole range of different options for that. So thinking about how else can we store energy on the car and how else could we deliver that to the wheels, and looked through all of the different types of energy storage that exist physically. So we thought about, for example, kinetic energy storage, potential energy storage, chemical energy storage, nuclear energy storage. And then quite quickly, we worked out some of these aren't really feasible options. So we tried to narrow it down to a few options that might be feasible in a racing car." >>
Potential energy, storing energy by raising a mass. That would mean lifting something heavy inside the car. Not practical. And chemical energy storage. Well, that is what a battery is. And because of the rules, you can't just add more. Nuclear, well, no, that's not going to be possible. So, that left kinetic energy, storing energy in motion. But here's the problem. In a race car, you can't just throw something across the cockpit and catch it later. You need motion that stays in one place. And the answer is rotation. Spin something up, keep it spinning, and you've got a reservoir of energy that you can tap into whenever you want. And that's called a flywheel.
And flywheels aren't new. Potters were using them in 6,000 BC. Da Vinci used them for lathes, and James Watt used them for steam engines. Today, flywheels are everywhere. Power grids use them to keep electricity stable. Underground train stations use them to recover braking energy, and hospitals use them for backup power. The physics is ancient, but the question was, can you put one in a Formula E car?
Now, here's where it gets clever. Using a flywheel in Formula E was technically illegal. The regulations were clear about energy storage, but there was a loophole. So, the Formula E rules at the time said that you were allowed to have no more than two motors. So, you're allowed to have two motors. And the question was really, is there any interest in having two motors? Is there any potential tangible benefit? Most teams didn't actually bother with two motors. They'd settled for a single efficient unit. But the rule was still there. And Chris realized that a motor is a spinning mass. If you spin it fast enough, it stores kinetic energy just like a flywheel. So the second motor wouldn't just be a motor.
But there was a catch. The two motors have to be connected together at all times. So you can never disconnect one from the other because the obvious thing to do might be to try and use the second motor as a clutched flywheel. So you could accelerate it up to a crazy high speed and then disconnect a clutch so you can store it there. Uh, but it was clear that that was, um, not allowed. So the question became, how do you spin up a second motor, store energy in it while it's still physically connected to the drivetrain?
The answer was an epicyclic gearbox. It's a bit like the opposite of a differential. So with a differential, you've got one input and two output shafts, and the sum of the outputs has to equal the input. And with the epicyclic, it was the opposite of that. So you've got two inputs and one output. And so the speed of the output shaft is kind of the average of the speed of the two input shafts. >> In a normal setup, if two motors are connected, they'd have to spin at the same speed. But with an epicyclic, you can vary them independently. Speed one up or slow the other down, and the output to the wheels stays smooth. And this means that the two motors are connected at all times. And it's completely legal. >>
But storing and deploying energy wasn't the only advantage of the epicyclic gearbox. There was a third benefit, one that's arguably just as important. Electric motors, just like combustion engines, have a sweet spot. There's an ideal combination of speed and torque where the motor is at its most efficient. Stray too far from that window and you're wasting energy as heat. Now, most Formula E teams ran a single motor with a single fixed gear ratio. And that ratio was always a compromise. You'd pick something that kept the motor reasonably efficient across most of the lap, but it was never perfect. And some teams tried two-speed gearboxes to keep the motor closer to its sweet spot. But gearboxes add weight and mechanical losses. So eventually, everyone settled on one gear.
But the twin motor epicyclic system acted like a continuously variable transmission, or CVT. Because the two motors could spin at different speeds, the teams could vary the effective gear ratio infinitely, keeping both motors operating close to their peak efficiency window at all times. It was genius. So in any given moment, the system had three things it could do. One, hold the second motor still, and the car behaves like a normal single motor Formula car with a fixed ratio. Two, spin the second motor up under braking, storing kinetic energy in the flywheel. Or three, slow the second motor down on corner exit, feeding that energy back into the wheels for extra power. And any combination of speeds in between was possible. It wasn't just three modes, it was a spectrum.
So, how did this actually work on track? Well, in Formula E, when a driver brakes, the electric motor works in reverse, turning the car's momentum back into electricity that feeds the battery. The regulations at the time capped regenerative braking at 250 kW. Once you've used all that braking capability from the motor, the car has to use the mechanical brakes, and that energy is wasted. It just turns into heat. So this was Chris's idea. We could get around the regen braking limit, and instead of being capped at the 250 kW in regen braking, we could actually brake as hard as we liked and recover all of that energy.
When the car braked and the main motor hit its 250 kW limit, the excess energy went into the second motor, spinning it up and storing the energy for later. And then on corner exit, >> "our double motor solution would be able to deploy 200 kW from the battery, and then on top of that could deliver the kinetic energy that was stored in the second motor. So you could deploy more energy, or deploy at a higher power level, as well as harvesting energy at a higher power level. So there was an advantage both in braking and in acceleration." >>
Every other team was throwing away energy as heat, but Nissan was storing it and using it twice. On paper, it was brilliant, but building it, well, that was another problem entirely. So, Chris ran the numbers. And for a flywheel motor to store enough energy to make a difference, while being small enough to fit in a Formula car and light enough not to kill the handling, it would need to spin at 100,000 RPM. "We were looking for something that's kind of no larger in diameter than a dinner plate, but also, uh, no heavier than kind of 10 kilos, give or take, and that was rotating at a design speed just over 100,000 RPM." >> "And at that speed, things can start to go wrong." >> "There's all kinds of problems with spinning something super fast. Uh, the biggest one is probably the centrifugal force. So, it's trying to tear itself apart at those kinds of speeds." >>
The whole rotor had to be wrapped in carbon fiber just in case it ripped itself to pieces. But that wasn't the only problem. The velocity around the circumference of the rotor was so fast, it was going to generate incredibly high aerodynamic losses. So it was actually faster than the speed of sound. And in order to get around that, we ended up having to use a vacuum pump. The outer edge of the motor was moving faster than the speed of sound. And just the air rubbing over the surface was creating so much friction it would burn itself out. So the team then put it inside a vacuum. No air, no friction.
But that created another problem. Unlike a sealed flywheel in a power station, this motor had to stay connected to the drivetrain, which meant that the spinning shaft had to pass through a vacuum seal. "We also had to maintain a vacuum around a moving shaft that's rotating at 100,000 RPM. So, it's a doubly challenging condition to try and satisfy because you have to try and maintain the vacuum, but you also have to allow a rotating shaft through the seal."
And because the system used an epicyclic gearbox, there were gears spinning at those speeds, too. And gears need oil. But at 100,000 RPM, even the lubrication became a problem. >> "You've got the surfaces of the gears which are running over each other, which are rubbing over each other at extremely high speed. And then you've also got the friction with the oil because the gears are moving through oil and churning it up. And that process generates more heat." >>
Somehow the team got through it. They built a working prototype and so they took it testing. But the first test was an eye-opener. >> "Uh, I remember it was Sebastian Buemi doing the first, let's say, real performance check of the car, and he was like, 'Yeah, if it was wet, it would be impossible to drive.' So, um, we knew it was a long way to go before the car could perform well in races." >>
The problem was the power delivery. Imagine what's happening. The driver brakes hard into a corner. The regen kicks in. The excess energy spins up the flywheel motor. Then on corner exit, all of that stored energy gets dumped back into the drivetrain. >> "So the drivers found that a little bit unpredictable, a little bit unsettling because the car would suddenly, um, would suddenly deliver more power, and in some cases, actually they could even break traction again. They'd be coming out of a corner fully committed, and the car would just snap into wheel spin. And that extra power couldn't be modulated by the driver." >>
So when all this power got dumped into the car, it would destabilize it at the exact moment when the driver needed precision. So they had a car that was theoretically faster, but there was almost impossible for the drivers to drive. And that wasn't the biggest problem. Even if the team did solve the drivability issue, there was a deeper question. How do you actually figure out how to use this thing? The system could harvest the extra energy under braking, and it could deploy the extra power on acceleration. It could even spin itself up when standing still to get the ultimate start. But the interactions between all of these benefits were incredibly complex. "The system's actually incredibly difficult to try and operate in an optimal way, and there are quite a few different benefits that you can draw from the system. And it was not obvious to try and work out which benefits would be the most important, or the most important at particular times, or on particular circuits."
So, do you use the extra power at the start of the straight or at the end? Do you harvest from every braking zone, or do you just use the heavy ones? And how do you balance it with your battery usage across an entire race? Every track was different, every corner was different, and the number of possible strategies was essentially infinite. "Basically, a human couldn't calculate all of that information."
So, the team turned to Canopy simulations. >> "Nissan came to us and said, 'We've got this innovative invention in our car, um, and we need some help simulating it. Uh, it's extremely complicated, and, uh, we need optimal control lap time simulation to figure out what's the best deployment to get the best lap time out of this system.'" >>
That's Roland Joet, product manager at Canopy Simulations, specialists in lap time simulation. And the problem Nissan brought to them wasn't simple. It wasn't just when should we store energy and when should we deploy it. It was that plus what speed should each motor run at at every single point on the lap to keep both motors as close to peak efficiency as possible. All while managing the heat the system generates, balancing battery usage, and not making the car completely undrivable. And then do all of that for every circuit on the calendar.
And before Nissan even built the car, Canopy simulation showed the concept was worth a massive 8/10ths of a second per lap. In a motorsport context, that's a huge amount, more than DRS on a qualifying lap in Formula 1. But finding that lap time on track meant figuring out exactly where and how to deploy the energy. "From Canopy's side, what we have to do is model the physics. So we have to, you know, model the motor torque, uh, the motor inertia, um, and the gear ratios in the epicyclic gearbox that combines the two motors together. Then we put that into our optimal lap time simulation. And the simulation is just an optimizer. It's just has one aim, which is to minimize lap time." >>
So the software doesn't work like a human strategist making educated guesses. It tests every single possibility. >> "It varies brake, throttle, steer, racing line position, everything a real driver would change to minimize lap time. Um, plus the control of the two electric motors. So once all that physics was into Canopy, then you just press go, and the optimizer figures out all of those driving aspects and what to do with the two motors at each point around the circuit." >>
And that's the thing, it's not optimizing one variable at a time. It's simultaneously choosing the racing line, the braking points, the throttle application, the energy deployment, and the speed of both motors all at once, every fraction of a second, across every corner, on every single circuit. >> "And the real beauty of Canopy is that at every point around the lap, it has perfect visibility of the past and the future. It's basically a racing driver that can predict the future, um, and remember everything that's happened in the past." >>
And given all that data, Canopy found something the engineers didn't expect. Rather than going straight to full electrical power on the corner exit and then adding the flywheel energy on top, the optimal strategy was actually the opposite. Deploy the flywheel energy first. This saved electrical energy for further down the straight, allowing the driver to stay flat out for longer before having to lift. >> "This was a bit of a surprise for us because it's not really clear where we should be spending the extra kinetic energy and, you know, exactly where the benefits come from." >>
That was just on one circuit. But of course, Formula E races all over the world. Each track with different corners, different straights, and different braking zones. >> "We could do tens of thousands of laps with different setups for each lap and then get the quickest lap time for each. Uh, this just isn't physically possible at the circuit. Um, you don't have enough time in the day. You don't have consistent conditions, and it would be prohibitively expensive." >>
So, armed with Canopy strategies and a motor that spun at 100,000 RPM in a vacuum, the team headed into the season. And from the very first race weekend, it was obvious they'd found something. >> "It started to become quite clear that we were going to dominate qualifying, um, throughout." >>
Pole positions, fastest laps. Nissan were the team to beat over a single lap. But then when the lights went out, everything fell apart. "We went through, for instance, four double DNFs in a row. Uh, I think so. That was very, very hard."
The system that made them untouchable in qualifying was destroying them in races. The extra mass hurt their efficiency. The heat generated at 100,000 RPM meant they couldn't run the motor at full power for very long, and the drivability was still horrible. The drivers were fighting the car through the corners. They qualified at the front, but they finished nowhere. Leads were thrown away, mechanical failures, and driver errors forced by an unpredictable car.
But they didn't give up. Race by race, they kept refining. And to solve some of the most complex questions, they turned back to Canopy. "By mid-season, we were starting to really see some performance benefits in the races as well. So we could start from the front of the grid, and we could also be, um, in a good place during the race."
The team was on the rise, and success was close. But then came the heartbreak. Santiago Buemi is leading but locks up into the chicane and throws away a certain victory. Then in Hong Kong, Roland is leading and accidentally hits the wrong button on his steering wheel. Again, another win is gone. But they kept pushing. And at the second to last round of the season in New York, Buemi put the Nissan on pole. And this time, he didn't let it slip. He went flag to flag and took Nissan's first ever Formula E victory.
And what's surprising here is that the car still wasn't running at its full potential. "But we had many things that were in the bag and not introduced yet on the race car that would have increased the performance even even more." >> "So how much was actually left? How much faster could the car actually go?" >> "We were running it probably still only at 3/4 of its maximum performance capability." >>
They were only running at 3/4. They'd won a race. They dominated qualifying, and they were still leaving 25% on the table. So, the following season was going to be something special. But just weeks after the end of the season, the FIA made an announcement, and the twin motor system was banned. >> "We were all very disappointed to learn that the powertrain would be banned from now on, at the end of the season. The amount of work that we all put in was so, so big that we would have loved to keep going with this and to prove that we would be able to be competitive with that car." >> "Unfortunately, I think there was a lot of concern that the powertrain was going to end up dominating the sport and that nobody else would be in with a chance." >>
The other teams had lobbied the FIA, and the math was simple. Nissan weren't going to just dominate one season. They were going to dominate for years. No one else could design and build a system like this in time. So rather than let the sport become a foregone conclusion, the regulators stepped in. And the tragedy is, with more time, with more development, with more Canopy optimization, the car was only getting faster. And we'll never know what it could have become.
But this whole thing is what I love about motorsport engineering. It's not always about the result. It's about a group of brilliant minds pushing into the unknown, finding solutions that no one else has seen. And even when the regulations catch up, that journey matters. "To find that special idea that you think nobody else has seen, um, that reads between the lines, that sits slightly in that area where it's, it's legal, uh, but it's not obvious, and you, you think that nobody else is going to have seen this. When it can deliver the performance that you dreamt it could, is an incredible moment."
Thank you so much to Chris Gum, Roland, and Canopy Simulations for making this video possible. Thank you for watching, and I'll see you next time.