Holding car design until the last possible moment is an essential part of modern F1. (LAT photo)
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• Personnel from the Lotus Renault Grand Prix team will be blogging for RACER.com throughout the Formula 1 season. This time, we hear from team technical director James Allison (LEFT).
We've made a step forward with this car, really just continuing the step change we made with last year's. It's got us two podiums in the first two races and although we are not yet challenging for victories on merit, we have a direction that we are following and it seems a fruitful one.
With the regulations changing going into this season, it was very important that we found what, for us, was the best concept – and that process went very late into the day before we finalized it. In fact, we had already started on a more conventional car when we took the decision to go with this one – and that gave us an even bigger fight than normal to get it ready in time for testing and the start of the season. That fight just gets more extreme and intense every year.
Prior to 2009 the regulations were more stable – changes were incremental, and your rate of aero development was much lower than now. Since '09 not only have the regulations changed more frequently but our tools – particularly CFD, but also in our case our wind tunnel – have become much more powerful. Which is great – but it means that if you blink those tools have added you more performance. So the best strategy by far is to start the season with as much of that performance on as possible and then develop, not to start slow and then forlornly try to catch up.
So internally there is great pressure to respond to this performance you're finding and to wait, wait, wait and wait some more before you commit. Not just to the frilly bits around the edge, but to the core of the car: the tub, the layout of the engine and gearbox, the things that set the baseline level of your car because they are difficult to engineer your way out of them once you've selected them – because it's just getting faster and faster as each week goes by. You are trying as many different fundamental layouts as possible, then try to push those layouts as late in the day as you dare. Which means that by the time you say, ‘OK, let's go,' you are horribly behind on trying to make it all happen in time. That's how it was with this car – even more than in previous years.
It wouldn't be quite so bad if only you in isolation had adopted this approach, but of course everyone else has too. By November-January you not only will have clogged all your internal stuff but all the external suppliers are absolutely maxed out. It becomes the most desperate struggle and you are asking ever more of your people, to keep coming in on evenings and weekends to get through what is just a blizzard of parts.
The central philosophy of the R31 is the forward-blowing exhausts. Because of last year, everyone would be considering blown exhausts and how to retain their benefit with the single diffuser regulations. You want to get the energy of the exhausts to work the floor but the rules are now fairly restrictive and there are not that many places you can introduce that flow and have it benefit, because the floor is no longer allowed to have holes in it. So you have to operate around the periphery of the floor. I'm sure everyone will have studied the periphery and that quite a few of them will have considered the forward layout. We considered it very early on but it took us until late August/early September to find a layout that we believed we could make work.
As that was going on we had a parallel program and were a long way into the design of a more conventional layout. In fact, that was the basket the majority of our eggs were in. But into late August, suddenly we had this configuration that was suggesting itself as better. That's very late. Your aero guys are telling you the numbers of the concept and they are good, so you get your design guys together and ask them, ‘Could this be done?' and they are a highly experienced bunch of people with a can-do attitude and they say yes. So all I have to do is press the button, but I get huge confidence in pressing that button by the caliber of people in the team and my faith in them that when they tell me something is achievable, I believe them.
I pressed the button in early September – which was about a month late, but it was also about a month more complicated, so we had to try to recover a couple of months. The main impact of the layout is on the cooling system of the car because you have to lift it up to create room for the exhaust. It also impacts upon the bodywork at the back of the car because you no longer have to stick pipes out there, so new aero opportunities become available there. It changes the materials you have to make things out of because there is hot stuff at places there didn't used to be. We had to do a side-impact structure that was different to anything we'd done in the past.
I'm pleased with the way it's turned out. Throughout testing and in the first three races we have not had a single exhaust-related reliability issue and, aerodynamically, it is giving us what our tools were telling us it would. How much downforce you get from it is a function of how hard it blows and the steepness of that slope is the key: You want a lot more downforce as the blowing increases, and the way in which it moves the car's aero balance backward and forward is another key parameter. These are all exactly as we'd hoped they'd be.
Running the car is straightforward enough – the design just works. It's a tribute to the people at Enstone, England, who did it and to the power of CFD. You couldn't have conceived of doing a project like this just two years ago. The hope now is that we can build upon those early podiums and develop the car to the front.