KERS in F1, was it worth it?
There are no regulations stating a system must be mounted at point A while being of specific type B with configuration C, unlike engines. We can also see that in 2011 and in 2012 KERS packages have converged in design principle. But we do know that there are no traction control devices allowed. With free regulations, one could easily imagine harvesting KERS energy while under positive acceleration! If the rear wheels were spinning too fast, energy can be taken from the drive train, and put into the KERS system, and hence bring the car back under control. The regulations also prevent
The regulations also present the KERS unit to charge and deliver power at the same time. Opening this possibility would allow the driver to opt for charging KERS straight out of a corner until its capacity is full albeit at the expense of the rear tyres, and then delivering the same power moments later down to the next corner.
We can also see that the energy offered for use in KERS is a mere drop in the ocean compared to what the engine already develops. At 740HP, the car produces an equivalent 552kW or 552kJ in one second, each second! This already is more than the 400kJ that KERS is allowed to deploy, but if we wish to make the sport greener just take note of these numbers.
Assuming a standard lap time of 90 seconds, and 70% at full throttle, the car would deliver a total of over 33.58MJ of energy. As a result KERS only adds a total of 1.2% extra energy to the forward motion of the car during the lap, and one would have to say this is hardly a race winning number, which can be compensated for by driving smoother and cleaner. And if we take an assumed 40% engine efficiency (at best) into account an F1 car will put out a staggering, 83.95MJ of energy per lap. By looking at the numbers the FIA cannot say that there trying to create a greener sport, but instead develop road relevant technologies perhaps. On the track where the car may be braking for as little as 10-20 seconds per lap we can see here that there is ample time for energy recovery, but also very little time to use it.
We can see how little impact KERS has on total power to the car, but this extra 1.2% of energy can only be delivered during a ‘massive’ 7.7% of the total track time. At a track like Monaco this becomes 8.1% track time, while at Spa, this equates to 6.4% track time. Assuming that 3 tenths of a second is in fact realized, then the total time recovery on track is a mere 0.33% improvement on a 90 second lap time. if we were in any other world where sliver’s of a second weren’t so critical we’d instantly dismiss this sort of technology to the recycle bin of our desktops and go with the way that things had always been done and laugh our young graduates out of the office, dismissing this on the pretence that the return does not justify the investment. And yet the simulations are nearly undeniable although only suited to ideal circumstances.
As a brake itself KERS alone by taking 60kW per second of energy from a car at 320km/H, would slow the car down to only 316km/h after the first second neglecting all other factors, (such as aerodynamic drag, and disc braking) but one must consider that high speed where energy is proportional to the square of the speed, the car will have much higher energies. A 700kg car at 320km/H has the equivalent kinetic energy of 2.765MJ. At slower speeds the KERS brake would be far more effective. For example at 160km/h KERS as a brake can reduce a speed down to 104km/h in just 6.67seconds. although a deceleration of 2.23m/s^s is no where near what the carbon brakes are capable of, in the ‘real world’ this might be useful, specially with more braking and the ability to harness more energy out of a standard road car, specially at slower speeds, where nearly all energy can be regained by a KERS device rather than being wasted in heat via the brakes, because of its massive low end torque capabilities.
Unfortunately in F1 as we can see from the numbers which point to us inevitably pulling the plug (as in the 2010 KERS amnesty), and the graphs which say that we should keep this moving forward, we almost need to accept that with such little time to use it there is little point in making it work. Teams spend millions making there aerodynamics more streamlined, the engine more powerful, because they are in play 100% of the event. As we’ve seen, KERS is actively used for about 8% of the time and 8% in braking, although there is more energy to be harnessed, KERS cannot store more than 400kJ of deliverable energy at any point, although it was proposed that last year in 2012 Red Bull we’re possibly using resistor banks to keep KERS recharging and that waste energy, that couldn’t go into storage was dumped as heat in the floor of the car. And this is what it all boils down to. The benefit of actually using the system. My initial analysis of this system 3 years ago prompted me to suggest that a larger energy storage capacity was needed and a more powerful delivery was required in order to make the system more relevant in competition.This article is the fifth in a series where we look at the KERS systems in use from 2009 to 2013. Click to read part 1, part 2, part 3 and part 4. Text by Richard Ronc, Ronc Industries