As the first round of testing for the 2009 Formula 1 season concludes there remains many questions about the development and viability for Kinetic Energy Recovery System (KERS) to make its debut in Melbourne. I though it would be interesting to take a more practical look at KERS and discuss some of the ways the teams are applying this technology to date.
Formula 1 teams have chosen two methods of developing KERS technology into Formula 1 cars, the first is to convert braking energy into electricity, store the electricity in a capacitor or battery and release the energy into the drive-train via an electric motor. The alternate method (Williams is known to be developing this) is to use braking energy to spin a second flywheel, then have the spinning flywheel release the energy to the drive-train through a CVT (Constant Variable Transmission). There is a third method for utilizing KERS, one we are all familiar with from our childhood, that is to use a torsion spring to store energy and release through a clutch system back into the drive-train. This is the method used to power our wind-up toys.
One of the main issue with KERS seems to be weight. This is presenting two challenges, the first is where the weight is located and the second is the total weight of the vehicle vs. additional available energy. The 2009 FIA regulations stipulate that KERS must collect energy from the rear wheels only, it is also necessary to locate the power source in the rear of the car as that is where the engine and transmission systems are located. This presents a problem of weight balance, race cars typically want 45% of the static weight on the front wheels and 55% on the rear. This may change from track-to-track and is adjusted by moving the ballast in the chassis to achieve optimum balance. A Formula 1 car uses an average of 70 kg of ballast (Almost 10% of the cars dry weight), KERS is weighing in at close to 35 kg or half of the available ballast and this weight is located behind the driver. This is presenting a problem for handling as the cars are running rear heavy at the moment. Ferrari is rumoured to be working on locating the batteries in the nose of the car. This solution, although creative, presents the problem of running high voltage wiring through the cockpit.
The second challenge is total weight. KERS equipped cars will weight more than non-KERS equipped cars. Power to weight ratio is a major contributor to performance (Formula 1 cars have a power-to-weight ratio of less than 1.5 lb/hp this compared to NASCAR in the 4.5 area and a Le Mans Prototype at about 3 lb/hp.) The lower the power-to-weight ratio, the more additional weight will affect performance as the additional weight becomes a greater percentage of the whole. Toyota engineers have hinted that KERS equipped cars will gain .2-.3 seconds per lap at most. Many circuits may not yield positive results. That forecasted gain is not sufficient to facilitate over-taking.
This is only round one however, and development will continue. As I mentioned in my previous post, Formula 1 engineers have exceedingly large brains. They are a resourceful group and, given time and money, will solve the problems they are faced with. The positive news is that most of the teams are sub-contracting much of the development work to third parties. This means that the technology will not be locked in the computer banks of the teams alone.
It does seem to indicate that my dream for more passing in Formula 1 may not materialize in 2009. Don’t despair just yet, the FIA regulations limit the additional power from KERS in 2009 to 400 kJ (80 hp for 6.67 seconds per lap), by 2011 this will be increased to 800kJ and for 2013 1600 kJ and also be allowed to work on the front and rear wheels. Perhaps this is the best solution in the long run, after all, the only successful way to eat an elephant is one bite at a time.