Indy 2000: Safety sets the pace

Just as the calendar rolled over this year for a fresh start, the Indy Racing League (IRL) has turned a page by updating vehicle design specs to freshen racing competition as well as improve both driver and spectator safety.

During the last two seasons, two accidents, one on the CART (Championship Auto Racing Teams) and another on the Indy circuit, saw wheels and suspension parts from track impacts fly into the stands, killing and injuring fans. While measures were taken at the time to prevent such a reoccurrence, this year a general car redesign scheduled for IRL allowed the car builders to directly integrate safety improvements into basic chassis configurations.

Skeleton and muscle. To help control costs, Indy teams buy chassis from one of three certified builders, Dallara Automobili da Competizione (Parma, Italy), G Force Precision Engineering (West Sussex, England), and Riley & Scott (Indianapolis). Likewise, engines are either the Oldsmobile Aurora V8 or the Nissan Infinity Indy V8, and are based on technology found in the engines in the Olds Aurora and the Infinity Q45 performance sedans.

This year, regulations reduced powerplant displacement from about 4 to 3.5 liters, with power dropping from roughly 700 to 650 hp to cut speed for greater safety. Such a change was easy to achieve by shortening the piston stroke, which also decreases piston speed-increasing reliability. Teams were able to reduce stroke by retrofitting a new engine crank, cams, pistons, and connecting rods-saving money over completely new engines. For racing leeway, the IRL-supplied electronic rev limiter now cuts in with a controlled misfire at 10,700 rpm rather than 10,000 rpm.

Also new this year, the engines are mated to the IRL's new Xtrac (Finchampstead, England) gearbox (for details, go to www.designnews.com ). This cassette-style 6-speed sequential unit replaces the older H-pattern transmission that the drivers had to "walk up" through to shift gears. Now a driver just tips a lever rearward, for upshifts, and forward, to downshift. A clutch pedal is still used to disengage the transmission during shifting. Next season will see clutchless shifting in the IRL.

The race teams receive the chassis and integrate the engine and transmission, which become load-bearing parts of the monocoque structure. In addition to the transmission, the rear wings are also IRL specified parts to control aerodynamics.

In highlighting the changes in Indy cars (which will essentially hold for three racing seasons), engineers Eric Bretzman and Brad Truax of Kelley Racing in Indianapolis note their new car's aerodynamics achieve less drag but similar track-holding downforce (even with less horsepower) as the cars used for the previous three years. They are also quick to emphasize the improved safety and driver survivability the IRL has mandated and the builders achieved in the racers. Their Kelley team runs two cars, both Dallara chassis powered by Olds, one sponsored by Delphi Automotive Systems and the other by GM Buypower/OnStar.

Safety first. Starting at the rear of the car, new protection features include:

A crushable, energy absorbing structure for the new Xtrac sequential gearbox, making it a safety element. The company used Unigraphics Solutions V.14 extensively in its design. At the rear of the gearbox is the additional impact attenuator made of aluminum honeycomb in a stell shell.

An extra roll hoop on the Dallara chassis behind the driver. This is in addition to the IRL hoop in the airbox (engine intake) above and behind the driver.

Sidepods that contain cooling air ducts are now an inch taller, providing more composite and honeycomb structure around the driver to absorb impacts. The pods also extend four inches farther forward, cutting the gap between them and the front wheels to prevent locking wheels with other racers.

More volume for the driver's legs inside the car nose, which again results in more structure to absorb impact energy. Suspension mounts are now integral with the body and do not project into the protective tub surrounding the driver, lowering risk of injury.

An integrated suspension and wheel energy management system consisting of cables made of wound Zylon. These multiple restraints attach at points on the chassis and suspension to contain the wheels and suspension components during a collision and are a direct result of the spectator casualties. The cables, whose breaking strength is 10,000 lbs, are located under carbon composite covers on select suspension arms.

Cockpit improvements, starting with a 19-inch wide opening to allow removing a driver without twisting his shoulders. Into this opening is inserted a quickly removable, U-shaped foam headrest that also provides side support for the driver's head. And drivers are also wearing a foam neck collar to reduce injury risk.

Out in the shop. A visit to the Kelley Racing operation shows how little "room" both engineers and drivers have to do their work. The cars are crafted around the engine and driver, and thus must be structurally efficient-which means going to high strength-to-weight composites for the chassis but with proven metal components for the suspension.

The driver does not climb into an Indy car but puts it on like a mechanized suit of armor-a suit that can clock around 200 mph. Like the space-capsule couches of the early astronauts, each driver has his car "seat" molded out of beaded foam in several sections to the contours of his body. This year, Bretzman and Truax point out, the headrest behind the driver's head and neck must smoothly transition into the seatback contour, thus avoiding an abrupt projecting corner that can cause spinal injury in a rear collision. Also in the cockpit, each driver will be signaled directly by a yellow light whenever the caution flag is out. This will avoid any driver missing the flag signal. Under IRL rules, the caution flag applies to all drivers immediately when signaled, rather than having cars "race to the caution" at the finish line.

At the track. While design engineers at the chassis and engine builders do the heavy R & D to adjust structural characteristics and responses, aerodynamics, and power curves, the racing team engineers must take and fine tune them for the individual drivers, tracks, and racing conditions-a skill that approaches art.

Also entering the equation are the tires, of which Bretzman says, "You have to learn how to use them with pressures and stagger." The latter puts tires of slightly different diameters on the left and right sides-taller tires for oval races on the right side, or outer, wheels, to improve handling. "You want a set of tires to go the length of a fuel run, roughly 70 to 80 miles," he adds, handling well when either fresh or worn, under full and light fuel loads.

This year, Bridgestone/Firestone is the only tire supplier to IRL teams, so there are less potential tire differences for the teams to work with to gain an advantage. Goodyear has withdrawn from both IRL and CART racing and is the exclusive NASCAR tire supplier.

For the car itself, Bretzman adds, the aim is getting the same long-distance performance for the car as for the tires. "You don't want a two- or three-lap wonder that really qualifies well, but rather a stable car over 80 miles." For this, the team engineers adjust the engine control units to map the fuel system performance for various engine conditions. Variables include fuel pressure and pulse rate to give desired fuel flow versus rpm under various loads. He emphasizes that with the lower displacement engines introduced this year, such engine tuning is even more critical to optimize performance. Specific examples Bretzman offers are fine tuning the fuel map for running under caution or finding the best fuel/air ratio at 3/4 throttle.

Team engineers also take such engine information and combine it with car aerodynamic data from the chassis builder, along with the team's suspension set-up, to simulate overall track performance, adds Truax. "We use Pi Sim software from Pi Research (Indianapolis) to see trends with different track maps and compare simulated to actual laps."

How successful the engineers have been in optimizing a car is often quickly apparent from driver input once it's taken out on the track. To this is added the quantified telemetry data for correlation with driver comments and feedback into the simulations. Truax adds, "The drivers and engineers really have to like each other and work well together in order to go back and forth to try different things. If a driver says one thing but telemetry shows another then you may, for instance, ask him baited questions to get to the problem," which can be indicative of different track conditions, running in turns or traffic, or a full fuel load. "Sometimes the driver is right, other times the engineer," he concludes.

Driver individuality also enters into how a car is set up and performs. Truax notes, "Scott Sharp, because of his aggressive driving style will attack a corner differently than [teammate] Mark Dismore. A rookie would need a different set up. You want to have a car set up for the skills of the driver and give him a safe handling ballpark, especially on a track where a driver hasn't competed before. The driver trusts knowing he won't be too close to the edge."

Finally, in preparing for the 2000 season, both Bretzman and Truax say there have been some growing pains getting used to the new chassis. But they also praise the control now possible with the sequential gearbox. They add that the things they, and other teams, discovered racing over three years with the previous cars are now standard. Bretzman says, "We may have lost horsepower but, thanks to chassis and aerodynamic refinements, we are close to the same laptimes."

Now on to the Indy 500. Gentlemen, start your engines!