Kinetic Energy Recovery Systems have been around; they experienced a year's hiatus, and now they're back—this time likely for good. As defined in the terminology of the Federation Internationale de l'Automobile, a KERS is "designed to recover kinetic energy from the car during braking, store that energy and make it available to propel the car." FIA's goal in all this has been twofold: Increase the opportunities for F1 overtaking through driver-selective enhancement of propulsion. And bring environmental relevance to the sport by virtue of this hybrid technology.
KERS entered Formula 1 regulations for the 2009 season (see "Regen Coming to Formula 1," Tech Tidbits, September 2007). The power expended is limited to 60 kW (about 80 hp). Energy released in any one lap may not exceed 400 kJ. The power must remain under the complete control of the driver, with limitations implying he has less than 7 seconds of enhanced performance per lap. Note as well, this stored energy must come solely through braking; unlike road-going hybrids, the engine can make no contribution. Nor can any energy be added during a pitstop. Then, as it is now, a team's adoption of KERS remains optional.
The 2009 Season
Initially, proposals for KERS energy storage ranged from purely mechanical flywheels to flywheel electrics to ultracapacitors to batteries. In fact, though, only -Sauber, Ferrari, -Mercedes and Renault actually competed with KERS in 2009, and all chose battery storage.
Early development stages were not without incident. In the summer of 2008, Red Bull-Renault had a battery fire scare that evacuated its Milton Keynes, England, works. Less than a week later, a BMW-Sauber mechanic was zapped by a KERS-equipped car during Jerez testing.
Come 2009, Red Bull-Renault chose to run without KERS. BMW-Sauber had it on Nick Heidfeld's car, but only to mid-season. Because of KERS weight and packaging, the car of teammate Robert Kubica—a taller and heavier driver—did without it from the onset.
Lewis Hamilton's McLaren- gave KERS its first victory at the 2009 Hungaroring. The next race, at Valencia, Spain, found McLarens gridded 1-2. Then, a week later, Kimi Räikönnen's KERS-equipped Ferrari won at Spa. Indeed, this win was seen as directly attributable to KERS-enhanced performance.
Through the technical artistry and Formula 1 pen of Giorgio Piola, we've come to know a little about these systems. (See "Tech Tidbits" elsewhere in this issue for a review of his fine book.) The McLaren-Mercedes KERS had a lithium-ion battery pack weighing 32.4 lb.—and costing €70,000 (about $96,000)! What's more, it's rumored that the pack was renewed more than once each race weekend. Its associated electronics control unit weighed 10.8 lb. The system's 11.9-lb. electric motor, sourced from Zytek, was mated to the front of the 2.4-liter V-8's crankshaft.
The monocoque located its lithium battery pack low in a hollowed-out portion that necessitated raising the gasoline tank several inches. Other components were located nearby to reduce the length of connecting cables. Ferrari and Renault got their lithium-ion battery packs from French supplier Saft at a relative bargain €30,000 (about $41,000) each. By the way, to put these F1 expenditures in perspective, the cost of a battery pack has been estimated at $11,000–$15,000. On the other hand, the Leaf's is expected to last 10 years or more.
So by midseason 2009, KERS had gotten off to a more than credible start. Yet —probably knowing as much as anyone about hybrids and brake regeneration—eschewed the concept. Ditto, the championship-winning Brawn-Mercedes as well as Red Bull-Renault, which together took 14 of that season's 17 races.
As Laurence Pomeroy noted years ago in The Grand Prix Car, "A law of automobile design is that the first concept of a superior principle is always defeated by the perfect example of established practice."
A 2010 Hiatus, Followed By...
KERS remained on the F1 books. However, lagging worldwide finances proved more compelling and the Formula One Teams Association (FOTA) came up with a gentleman's agreement to do without the technology for 2010. Then, by midseason, FOTA changed its collective mind considering KERS for 2011 and beyond.
By year's end, FIA had promulgated several changes in F1 regulations that encouraged KERS adoption. Minimum weight, driver included, has crept upward from 605 kg (1334 lb.) in 2009 to last season's 620 kg (1367 lb.) to 2011's 640 kg (1411 lb.). Generally, cars—with their drivers—are figured at less than the minimum, thus allowing ballast to be fixed for optimal handling from circuit to circuit. It's thought that 640 kg includes the added KERS weight; note that McLaren's 2009 hardware sans connectors totaled 55.1 lb. (25 kg). Also, however, there's a new regulation of chassis reinforcement that further complicates the 640-kg minimum and team targets of optimal ballast positioning.
A regulation beneficial to KERS tuning for 2011 only is a fixed weight distribution of essentially 46/54. This is characterized as "the weight applied on the front and rear wheels must not be less than 291 kg and 342 kg, respectively, at all times during the qualifying practice session." Yes, this totals less than the minimum 640 kg; we can assume the missing 7 kg lurks in that "applied to the front and rear wheels." And, actually, this regulation has nothing to do with KERS per se. It's a leveling of the playing field with regard to Pirelli being the new tire supplier.
KERS + Rear Wings = €€€
It's clear that KERS 2011's new (and required) driver-adjustable rear wing put real development pressures on teams, especially the smaller ones. Where to spend your meager tens of millions? This is also complicated by limits on testing and wind tunnel time. Also, if you were planning aero by computational fluid dynamics, there's a limit on teraflops (i.e., on how much computer power can be employed).
It's said FOTA initially set a €5 million cap on the cost of KERS development, along with a €1 million charge to any other team buying into a system. However, even before FIA's official regulations came out last December, it was reported that Mercedes had upped the price of its 2011 KERS, said to be 4 kg lighter, to €6 million. Small teams registered dismay. Others developing their own systems questioned this inflated figure.
A couple of thoughts on this: KERS developers selling their hardware to others profit from the sharing of data in more testing time. Also, as refueling is prohibited—and cars are starting races with as much as 60 gal. of fuel—there's the tantalizing idea of teams using KERS for enhancement of fuel economy as well as power.
Whatever the strategies, KERS and wings are certainly going to keep the lads busy, both in the pits and paddock (where, by the way, another new regulation prohibits all-nighters) as well as in the cockpit.
Figure on a combined KERS/wing trim giving periodic doses of an additional 160 horses. On the other hand, early testing has demonstrated how ill-tuned KERS can play havoc with braking.
Who's Running What—For 2011 and Beyond?
KERS for this season are likely to be similar to the battery systems run in 2009, only lighter and more optimally packaged. They're not the only feasible options, though.
Flybrid, for instance, has its CVT-based mechanical flywheel. At one point of negotiations, the company offered to provide this system as a mandatory fitment for the entire F1 field. FIA (and no doubt FOTA) passed on the offer.
Williams Hybrid Power, an offshoot of the Williams F1 team, has its "hybrid" flywheel electric system. Its efficacy has already been proven in the Porsche 911 GT3 R Hybrid, which would have won the 2010 Nürburgring 24-hour race but for a problem with its traditional powerplant (see R&T, August 2010). Conceptually, this is the same system fitted to the Porsche 918 RSR.
At a recent SAE symposium, Ian Foley, managing director of Williams Hybrid, told me that it's evident that the current 60-kW cap favors battery storage. However, some teams (Ferrari, in particular) have urged a doubling of this limit, something that's likely to occur with 2013's 1.6-liter engine regulation—if not before. Foley senses that a 120-kW output could favor other KERS technology including the Williams Hybrid approach.
The application, though, is too bulky (its flywheel essentially occupies the passenger seat) and heavy (total weight is 170 kg). On the other hand, the 911 GT3 R Hybrid had a pair of 60-kW motors.
For 2011, it's reported that Williams is developing its own conventional battery-based KERS.
I'm writing this before the (belated) start of the season, but can predict that sufficiently well-heeled teams will generally share their engine-supplier's KERS, all of them battery-supported. The chart to the left identifies who's running what. Last, it has already been announced that the back of the pack, Virgin, HRT and likely Team , will be without this power enhancement. "Merely filling out the field," said one specialist.
On the other hand, don't forget Laurence Pomeroy.