Mercedes' head of engines, Andy Cowell comments on the new drivetrain regulations and in particular how the Brixworth departments adapted to that as an engine manufacturer and supplier to three teams.Andy, what was the thinking behind the new Power Unit regulations?
"The initial discussions between the FIA and the engine manufacturers were focused on delivering a more efficient internal combustion engine and more potent Hybrid systems. Both sides were keen to move the sport in this direction. With a normally aspirated engine, the power potential is controlled by the flow of air into the engine via the capacity and the rpm it can be run at. However, the automotive industry is focused not on air consumption but on fuel consumption - and the CO2 emissions this generates. The sport has therefore turned the rules on their head with a formula where the performance is restricted by two fuel mechanisms: a maximum fuel flow rate of 100 kg/hr and a maximum race fuel allowance of 100 kg. The fundamental challenge is to convert as much of the chemical energy in the fuel, into mechanical energy, as efficiently as possible at the prescribed flow rate. Conversion efficiency is now the key."What technologies have been used to achieve that step in efficiency?
"To achieve the step change in efficiency required in order to maintain performance levels, we have developed technologies that break new ground not just in racing but also in the wider automotive world. When the regulations were written, it was decided to fix aspects such as the engine configuration, bore size and crankshaft centre line height, to stop the engineers spending time on areas that we are familiar with but where there's no efficiency gain to be had. So instead you focus on areas such as the waste energy in the exhaust flow from the Internal Combustion Engine (ICE), where you can put in a turbine to recover some of that energy, use it to drive the compressor and improve the efficiency of the ICE. Likewise, any excess energy can be put into the battery via an electric motor for use to minimise turbo lag and therefore make the car faster. Equally, we recover kinetic energy under braking, through another electric motor connected to the battery. And having that motor coupled with the ICE allows us to maximise shaft power during acceleration. We have achieved an efficiency gain of over 30% - in other words, we are producing over 30% more power for every unit of fuel consumed compared with last year's V8 engine."How big a change is this in absolute terms?
"I don't think we have ever had such a large change that was mandated in the regulations. The move from the V10 to V8 was compulsory but we were still dealing with a naturally aspirated engine, even with the restrictions that were put in place. KERS in 2009 was not compulsory but rather a performance opportunity to be taken if you could make it work. This change is of an altogether different order of magnitude."The new Power Unit has been developed hand-in-hand with, and for, the new F1 W05 race car. What have been the advantages of conducting this project as a full works team?
"We can go all the way back to the discussions around these regulations, before they were finalised, evaluating their impact. Those conversations happened with our colleagues in Brackley. From the first simulation exercise, we have worked on delivering the fastest possible race car within the regulations to score the most championship points. Everything has been done as one group of engineers. Having that relationship right from the start is a huge benefit because your level of understanding, reasoning and discussion builds from the same point. We haven't lost time with one system team catching up with another, which makes the development journey more efficient. It also keeps the spirit and ethos constant so that, when it comes to hurdles, we have good balance in our decision-making process around what can be compromised and what must not be. It has resulted in a highly integrated assembly with good common understanding of what makes a fast and reliable race car. That spirit of teamwork has also extended to our Research and Development colleagues in Stuttgart, who have made an invaluable contribution to the project in specific areas, such as the turbocharger. It has been a true team effort to develop the best possible technology that Mercedes-Benz can deliver."How pleased are you with the final result and the level of vehicle integration that has been achieved?
"The integration of the Power Unit has been an interesting journey over the past few years. We have gone from initial schemes where you look at the PU in scale compared with the aero surfaces of a racing car and think: "How is that going to be done?" That's where we started the journey and, by working together, you can make those trade-offs in a completely open way. It's been one group of engineers all working to make this Silver Arrow as fast as possible."One of the major changes comes in the form of a significantly more powerful Hybrid Energy Recovery System (ERS). What learnings were taken from KERS into the new system?
"Our learning during the KERS project was the bedrock for building ERS. But we are talking about a big step not just in absolute power but probably more significantly in terms of duty cycle, in other words the percentage of the time around a lap that it is operation. You could in theory combine two of last year's KERS motors on a single shaft to achieve the maximum power of 120 kW. But instead of using the motor for just short of seven seconds per lap as we did last year, now it's on for over 30 seconds of every lap. And there is also a much greater reliability requirement, because there are only five of these motors per driver per championship. So it's more power, a harder duty cycle and significantly greater reliability demands. What's more, it's no longer something that's 'nice to have' - given the power and the duty cycle, the car will be seconds slower without the MGU-K working, so you need it to do laps. Stitching all of that together with an absolute deadline is a big challenge, probably to an order of ten times more challenging. And that's just one of the six parts of the Power Unit we are producing."The 2014 rules contain both a maximum race fuel allowance and a maximum fuel rate. In a formula where fuel is now the controlling performance parameter, how important has the contribution of PETRONAS been to delivering the new Power Unit?
"PETRONAS have been a really significant partner with huge input into the project. They have been pivotal to the fuel engineering and combustion engineering. The characteristics of the Primax fuel and the way it performs during combustion are key to an efficient and therefore powerful and reliable ICE. The regulations on what can be done with the fuel are pretty tight and they essentially define a regulation window. With a high-revving normally aspirated engine, you end up in one corner of that window; I'd say we are now in a completely opposite corner. The PETRONAS Syntium lubricant also plays a crucial role, with regards to low friction and achieving good life, especially in the new areas of the Power Unit, such as the turbocharger, that require quite different lubricants. It has been invaluable having PETRONAS as a partner right from the start of the project."Reliability is being widely talked about as the biggest obstacle to success for this season. What is the scale of the challenge?
"Change typically risks reliability. If it's the introduction of something totally new like turbochargers, with electric machines connected to them revving to over 100,000 rpm, that is doubly challenging - and therefore a bigger risk to reliability. There are dozens of topics - some technology, some all about detail - that could potentially compromise reliability. And that's the same thing that we have always had in motorsport. There will be hard choices to be made against serious opponents who will push us right to the edge - and there may be mistakes. But we are still talking about getting to the end of a race, faster than anybody else, using the least amount of fuel, on a knife-edge of reliability. That's motor racing; and that's what makes it such a passionate and exciting sport to work in."