Switching Horses by Paul Haney Switching horses in midstream is a phrase used to describe a risky action, and that seemed to be the case when Patrick Racing decided to abandon their new Swift 010.c chassis in favor of year-old...
Switching Horses by Paul Haney
Switching horses in midstream is a phrase used to describe a risky action, and that seemed to be the case when Patrick Racing decided to abandon their new Swift 010.c chassis in favor of year-old Reynards just before the first race of the season.
At CART spring training, the early buzz was how could the '99 Reynard keep up with the new Swift when so few changes were made from the '98 car. But after the first track session Patrick Carpentier, in an Ilmor/Mercedes-Benz-powered Reynard, led the time sheet. Meanwhile, Adrian Fernandez had the quickest Swift in 12th spot, 0.7 seconds slower than Carpentier.
Swift fortunes failed to improve during spring training, and Patrick Racing jumped ship shortly thereafter. One of the reasons cited was a problem with the Swift's aerodynamic center of pressure, or C.P. The guys at Patrick said the C.P. was too far toward the rear of the car, unloading the front tires and causing a chronic understeer -- a push that prevented Fernandez and P.J. Jones from turning competitive laps. This photo of Fernandez's Swift was taken during spring training at Homestead the first week of February. The unpainted carbon fiber tab on the outer edges of the front wing is an attempt to get more downforce at the front and solve that understeer problem. But why is this such a big deal? Why isn't Newman/Haas dumping their Swifts?
A Champ Car has a front and a rear wing mounted upside down compared to an airplane. Each wing accelerates the air under it generating a pressure drop that results in downforce. Another wing under the car also produces a lower pressure and downforce. The result of all the pressures at all points under all of the wings and bodywork determines the C.P.
Downforce increases the grip of the tires, without adding weight to the car, resulting in faster cornering. The trick is to balance the downforce, so the front and rear tires share the work evenly. When the driver has to turn the steering wheel too far to get the car to turn, the car is pushing or understeering. The opposite is oversteer, when the rear end wants to slide out. The middle ground of these extremes is a balanced car with more grip.
The Reynard chassis works well when the bottom of the car scrapes the ground. The team members paint the skid plates black and look under the car every time it comes into the pit during practice sessions. They adjust the ride height at the front and rear so the bottom is just scraping, not hitting hard. Before the car goes back on track, the team sprays more black paint on the bottom to tell if the adjustment made a difference. The Swift underwing is designed to produce maximum downforce with some ground clearance, and that is more difficult to achieve. You can't see scrape marks if the bottom isn't touching the ground.
Newman/Haas engineers Peter Gibbons and Brian Lisles were intimately involved in the development of the Swift chassis from the very start of the design project, so the racecar evolved to work well with their drivers and their setups. Michael Andretti is known as a very adaptable driver, and Gibbons, his engineer, can explore setup combinations that would be considered radical for other teams.
On the other hand, Patrick Racing began working with the Swift only a few months ago and is still learning the car. But there are other reasons why Patrick is having more problems than Newman/Haas.
At spring training, when the Patrick engineers wanted more front downforce, they couldn't just crank up the front wing because it wasn't designed to operate at higher angles of attack. The front wing on a modern racecar is extremely critical because its wake influences the aerodynamics of all parts of the car downstream. It's a package: Change one thing, and that changes everything else. The bottom line is the Reynard is a good piece. Swift is working hard to adapt and will have a new front wing and other aero bits in time for the race at Motegi. Patrick Racing still has to decide which cars to use.
Andretti, his Newman/Haas teammate Christian Fittipaldi and Richie Hearn of Della Penna Motorsports will all drive Swifts. Their performance will be the report card for Swift.
Source: CART Online