Flat Spot On by Jonathan Ingram If It Looks Wrong... There was a time in the not-too-distant past when a sports car that looked right generally went right. These days, an interesting batch of new prototypes indicate that if they look a bit ...
Flat Spot On
by Jonathan Ingram
If It Looks Wrong...
There was a time in the not-too-distant past when a sports car that looked right generally went right. These days, an interesting batch of new prototypes indicate that if they look a bit awkward, then perhaps they'll run better.
Compared with their predecessors, the LMP1 prototypes that contested the Sebring 12 Hour did not have the classic lines of the old standard bearers like the Porsche 956/962 or the Audi R8.
The new Acura ARX-02a and the Audi R15 look more extraordinary when they're running than when standing still. But given the record distance covered in the battle for the victory between Audi and Peugeot and the Acura's winning pole lap, the new cars are decidedly more efficient, appearances to the contrary.
Blame it on any mathematical genius of your choice. The use of Computational Fluid Dynamics, a computer modeling program derived from wind tunnel testing, has changed the racing world we live in forever. Although CFD has been around for quite a while, it now provides enough reliable data that designers are willing to bet on radical new approaches because they can predict a positive outcome.
Add to these new ways of predicting airflow over, under and through a car with advances in material technology and presto! Designers start bending body parts into weird places, hence the exposed ribs of the Audi R15 or a huge extended splitter hanging from an elevated nose as found on the Acura ARX-02a.
This all began God knows where for sports cars. I'd venture to look most carefully at the Toyota GT-One of the late 1990's as the first to radically exploit the air with a front end design that was not only clever but unique in appearance. The GT-One raced only at Le Mans, where despite some stunning speeds it never had the right strategy or luck to win over-all.
The first awkward-looking success has to be the Panoz LMP1 Roadster S, the front-engined leviathan which won five races in head-to-head match-ups with Audi's all-conquering R8.
Because an engine in the front meant no driver footboxes were required for crush-proof safety, the Panoz had some unique options for routing air to produce front downforce as well as the unique weight distribution. Where the Panoz suffered was in getting traction with the rear tires off the corners.
Getting that rear traction initially was the key for the Audi R8. In an air-restricted engine equivalency formula like the one used by the Le Mans rule makers, getting to the top speed quicker off the corners and into the long straights was the key task. If you spent more time at top speed on the straights, then you were way ahead of the game. Audi was the first to introduce paddle shifting with this in mind -- and hedged its driveline bet by being prepared to change the gearbox in mid-race.
These days, due to the intense competition spawned by Audi, a car design must exploit every phase of the game moreso than ever..
Generally, you can get all the downforce you might want at the rear, but if you can't balance it with the front then you'll never get the car right. The new Acura uses the same large tires and wheels on the front and rear -- a four-square approach in the old parlance -- to gain a larger contact patch for braking and cornering. With the high nose and flat deck between the front fenders, it generates the downforce necessary to get those contact patches to work effectively.
The inherent risk of this design "was huge," said Nick Wirth, who designed the car in conjunction with Honda Performance Development. "Race cars are such complicated animals. Any engineers who think they understand how they work are kidding themselves." (This goes double for journalists, of course!)
The challenge was building the rest of the car once the large front wheels and tires were chosen. The question marks were numerous. "Would we be able to compensate for the drag?" said Wirth. "Could we develop all the other technology around it? We had to get more weight on the front of the nose without using ballast."
Once the downforce was generated at the front, HPD's challenge was building a 4.0-liter engine that could power a car with not only the drag but extra downforce at the front.
How much front downforce does the Acura have? Scott Dixon, one of the fittest drivers in the sport, has been forced to strengthen his neck to handle the g-loads in the corners. "I asked for some padding to support my head like they use in Indy Cars," said Dixon after winning the pole from the new Audi by 0.082 seconds. "I believe they call it a pussy pillow." (The reigning Indy 500 champ was turned down by his co-drivers.)
The Audi R15's hoover-like front end and exposed ribs inside the sidepods are testament to a similar concern with getting downforce on the front end for efficient tire use and then getting the air through the car to avoid an excessive drag penalty. The late-race lap times from Allan McNish gave the Audi a debut victory, courtesy of not changing tires on the last stop despite their heavy workout in the hands of the flying Scot. So it seems the trade-off between cornering grip and straight line speed has been well exploited.
All this came straight from Audi's German Touring Car Championship entries, said Martin Muhlmeier, the technical director at Audi Sport. Seriously. The development skills for the prototype came from the Touring Car coupes.
"It was a concept we learned with the GTCC car," he said. "It was the same concept. We learned new methods with the wind tunnel and CFD. In the wind tunnel you can see what's going on. With CFD, you can generate technical information to understand the effects."
The Peugeot 908, with its pumpkin seed cockpit, appears to suffer from too much emphasis on low drag at top speed and not enough grip in the corners. But it's difficult to assess if the Peugeot approach is valid, because fragility and pit strategy have played to Audi's favor in victories at Sebring, Le Mans and Atlanta.
Life used to be more practical and intuitive. In 1997, Don Panoz told designer Adrian Reynard to put the engine in the front of his Esperante GTR-1, "because that's where the engine is in the cars we sell." Two years later, the project led to the creation of the redoubtable Panoz Roadster S.
When the inaugural Audi sports car appeared at Sebring in 1999, the R8R looked traditional but a bit lumpy due to standard fender arches and its carbon black paint scheme. The drivers all complained about ill-handling on the bumpy Sebring circuit and Audi's podium finishers all showed off blistered hands from the sequential shift lever. Worst of all, the heat from a front-mounted radiator poured into the cockpit.
Dr. Wolfgang Ulrich, the chief administrator of Audi's racing program, decided to check out the heat problem for himself. He got in the cockpit of the R8R after one of the Sebring practice sessions and drove the car back to the team compound in the paddock.
"By time I got out," recalled Ulrich, "I had decided we must change the concept." Hence, the birth of the R8 the following year, the winner of 63 races in 77 starts, including five Le Mans victories.
Jonathan Ingram can be reached at jonathan@jingrambooks..com.