On the Subject of Fuel Tanks

October 5, 2009

Renault F1 cars in 2005 & 2006 had a reputation for excellent starts

Renault F1 cars in 2005 & 2006 had a reputation for excellent starts

Although much of the media interest in F1 is currently on the drivers’ market, I would like to consider an even more exciting topic, fuel tanks. Most of the 2010 F1 car designs should be reasonably well advanced by this time. One of the biggest changes for 2010 is that there will be no-refueling during a race and so the cars will be required to carry enough fuel to complete a two hour race. This has major implications for one of the main parameters that F1 designers get excited about – Centre of Gravity or CoG. The theoretically ideal CoG is one which is as low as possible, and located centrally in the car equidistant between the wheels along the axle, and also equidistant between the front and rear wheels. This gives the car the best possible handling characteristics.

Of course a fuel tank which is twice as large presents an interesting problem to try and keep the CoG as optimal as possible. The other important twist is that moving the CoG can potentially offer a competitive advantage in certain situations. The Renault F1 cars that Fernando Alonso used to world champion winning effect in 2005 and 2006 had a reputation for being incredibly fast off the starting line – was this due to some electronic gizmo or Fernando’s fantastic clutch control? No it was mainly due to the fact that the car was designed with the CoG further towards the rear wheels thereby giving greater mechanical grip in a situation where aerodynamics were ineffective – the start of the race. Every F1 car is an exercise in compromise and therefore some cars perform better in certain conditions than others (you only need to look at the performance of the Force India cars on low downforce circuits like Spa and Monza to see this). Renault created a car that had more traction at the start of the race, but this meant that the front of the car would carry less weight and so would understeer more, a characteristic that Fernando was quite happy in dealing with. So the designers will make compromises, but compromises that will hopefully give them the edge over the competition across all the circuits and conditions they will encounter.

Another point about fuel tanks is that they will start the race with the CoG in one position and as the fuel load reduces this will change by the end of the race. The interesting question is do you want the best performance at the start or the end? These different questions will create different solutions and cars will perform at their maximum at different points. Of course there is one other factor in here – engines. The FIA has suggested that the engine manufacturers may wish to equalize their engines at the end of the year – why on earth would Mercedes wish to reduce the power advantage they currently have? One answer is fuel economy, if your engine uses less fuel than your competitors then you can design a car with a smaller fuel tank and so have a better CoG. So next year the race may be more about fuel economy than maximum performance – who says F1 doesn’t move with the times?

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