Choosing Indycar’s 2012 Chassis Design

Auto racing is about more than getting cars to go as fast as possible. Premier groups like the Indy Racing League (IRL) also want to keep drivers safe, fans engaged, and technology relevant to real-world consumer applications. They also want more teams competing.

To that end, IRL’s IndyCar chassis is getting a refresh. Officials are hoping to choose a chassis and engine platform for the 2012 season by June 1 of this year.

Early this year, IRL President Brian Barnhart outlined what the organization is looking for in a new car, and designers were quick to respond. Five firms have entered the competition for the 2012 chassis, including current chassis constructor Dallara, Parma, Italy, and LeMans and ChampCar designer Lola, Huntingdon, Cambridgeshire, U.K. Swift Engineering, San Clemente, Calif., a seasoned design firm, notably of the current Formula Nippon design, is also developing an entry.

The field’s two relative newcomers are BAT Engineering, Indianapolis, led by principals with experience at Lola and other race-car constructors such as Reynard and March, and DeltaWing Racing Cars, Indianapolis, featuring the technical head of Target Chip Ganassi Racing which took the IndyCar championship in 2008 and 2009.

Car criteria
IRL clearly set out its expectations for the new car in February. The new chassis must meet current safety standards, but winning designs need to propose additional ways to prevent crashes and make them less dangerous for drivers, crew, and spectators.

“It is often said about the 3S of racing — safety, strength, and speed — that you need safety first,” says Andrea Toso of Dallara. “If you are fine with safety, then you move to logistical and engineering strength, including reliability, economics, support, and distribution. If you are fine with strength, then you go to speed or performance. And anytime you have an issue in the safety or strength department, you have to address it right away, even by conceding on speed.”

IRL’s second priority is keeping IndyCar races interesting. Specifically, they want cars to be less sensitive to turbulence generated by competing vehicles or have cars leave cleaner air in their wakes.

The car has to be able to hit a lap speed of 235 mph with less engine power than the current 630 hp. It will have to generate less drag to do so, while at the same time creating enough stable downforce to permit safe cornering in traffic.

Third, the league wants these changes, and racing in general, to be affordable for teams. Officials are hoping the new car will cost 40 to 50% less than the current model. IRL predicts costs savings will come mainly from reducing the inventory teams need to compete on both oval and road or street courses.

According to Toso, this means a car with all the options, including oval and road course suspension, aero, and differential packages; sensors, electronics, and data acquisition; and fuel hardware, should cost less than $400,000. A fully loaded car currently costs around $700,000.

Also on the economic front, IRL has specified that the new chassis must be built in the U.S., preferably in Indiana. And most entrants have pledged to base manufacturing around the Brickyard in Speedway, Ind., near Indianapolis.

According to Bernard, a U.S.-built car would let the league “take advantage of more-competitive pricing and the existing American supplier network for parts,” as well as protecting teams from currency fluctuations.

The fifth requirement is for a lighter chassis that will have aerodynamic effects similar to the current model. A lighter car would need less power to meet target speeds and have better fuel efficiency.

Team’s strategies for building lighter cars would also play into the sixth requirement: IRL wants the new chassis to be relevant to the consumer auto industry.

Seventh on the list is an updated aesthetic. Specifically, IRL wants more space for sponsor logos. They also want it to be easier for fans to identify cars and drivers they are rooting for.

The final requirement is one of the vaguest: The car should be “green.” “The IRL prides itself on its role in the greening of racing and wants to maintain its position as a leader in environmentally friendly initiatives with this chassis,” states the league’s press release establishing car criteria.

Prospects for some items that have long been on the wish list of some fans and commentators, like a multichassis or multiengine series, are slim.

“Intense competition and battles with other race-car manufacturers is a fantastic spectacle and a rich environment for our engineers,” says Lola head of special projects Peter McCool. “However, it is not conducive to keeping cost down, which has been a key criteria. But a return to multichassis grids may well be an option in stronger economic times.”

It appears IRL will stick with its single-engine format and its current engine supplier, Honda. But what kind of powerplant they will provide remains unclear. Discussions last year leaned toward switching from a four-camshaft, normally aspirated V8 to a turbocharged, four or six-cylinder engine with dual overhead cams. So the 2012 car might sport a fuel-efficient, turbocharged, four-cylinder engine.

DeltaWing Racing Cars
DeltaWing is taking a radical approach on many fronts. In addition to being supported by key IRL teams rather than an established chassis builder, DeltaWing has pledged an open-source design process. Anyone can access the car’s specs and CAD drawings, and anyone can submit original design ideas.

The concept has produced a radical design, including a 160-lb, 2.0-liter, 300-hp, four-cylinder, turbocharged engine, that is projected to weigh 1,030 lb with a driver and cost around $600,000. The engine and transmission are nonstressed members of the chassis, so the car can accommodate different powertrains. DeltaWing is pushing for IRL to restrict fuel-delivery rate to the engines and leave other engine specs up to teams.

The smaller powerplant and mass are made possible in part by bodywork that nearly encloses both sets of wheels. Distance between front wheels is 24 in. while in back it is 70 in. Cutting the drag of open wheels, narrowing the track, and beefing up the front fairing, let DeltaWing cut the drag coefficient 60% to 0.24. Replacing the rear wing with a vertical fin keeps the car stable in turns but doesn’t add drag on straightaways. And the absence of front and rear wings makes the car less sensitive to “dirty” air when following closely and leaves a cleaner wake.

Simulation and full-size wind-tunnel testing confirm that 80% of the aerodynamic downforce acts on the rear of the car, which also supports 72.5% of the mass. This aero and mass balance give better traction to the 12.5-in.-wide rear tires during acceleration without adding weight. Stability is also enhanced by a six-speed, driver-controlled differential with full torque vectoring and active stagger that eliminates the need for different diameters on the inner and outer tires on oval tracks.

Bodywork in front of the front wheels and behind the engine absorbs crash energy to further protect the driver. Tegris polypropylene composite from Milliken & Co., Spartanburg, S.C., will add impact and intrusion resistance without adding weight to DeltaWing’s prototype. Compared to glass and carbon-fiber composites, Tegris resists two to five times the impact energy, has comparable stiffness, and is easier to manufacture and recycle.

BAT Engineering
Former Lola chief designer and Reynard North America president Bruce Ashmore, former March chief designer and engineer Alan Mertens, and longtime open-wheel racing engineer Tim Wardrop made a safe cockpit the top priority of their clean-sheet design. They consulted with IRL safety and technical directors Jeff Horton and Les Mactaggart and Indianapolis surgeon Dr. Terry Trammell.

A stiffer suspension, stronger suspension mounts, and less fragile body work promote fast, close racing with less chance of having race-ending contact with other cars. More-crushable structure, bodywork that extends to the outer edges of the tires, and a stressed engine that helps hold the car together in a crash will protect racers and spectators.

Although some of these stiffening and crashworthiness improvements add weight, Ashmore says the new car’s weight will be “very similar” to that of the current model. Enhanced efficiency comes from smoother, more-aerodynamic contours. The current chassis has a lot of angular bodywork specifically designed to reduce downforce and slow the overpowered cars down.

Although the engine will ultimately be IRL’s decision, Ashmore would like to see a V6 twin turbo. Such a car would be slightly cheaper to build and have fewer parts that could break during long races. League organizers could bleed off turbo-induction pressure so cars could run a safe 500 hp on ovals and get the 750 hp they need to perform on road courses. Twin turbos have better cooling performance than a centrally located single unit.

“Turbos are relevant technology for modern vehicles,” Ashmore says. “In a truck or SUV that is mostly driven on flat roads with a single occupant, a V6 gives enough power; you don’t need a V8. When you are towing a boat and transporting six people, a turbo could nearly double your horsepower.”

BAT Engineering proposes to build its chassis within a 30-mile radius of the Indianapolis Motor Speedway. The company says it is already forming partnerships with local firms and organizations to prepare for the production of a 2012 chassis that will cost about half what the current model does.

Dallara
Dallara designed the current, 2003-vintage IndyCar. The Italian firm says any of its three proposed 2012 chassis would be built near Speedway, Ind., and cost 55% less than the current design. The cars weigh 1,390 lb without a driver or fuel. This compares to 1,530 lb for the current design.

A 570-hp in-line four-cylinder turbocharged engine could take the car up to 225 mph on laps at the Brickyard, or the cars could sport a turbo V6. Either engine would be a stressed member which lightens the cars by eliminating the frame.

Bodywork slightly wider than the tire tracks keeps wheels from interlocking. The cars are also shaped so that aerodynamics keep them on the ground in a rear-end collision or a crash into the wall. Updated aero packages make the cars less sensitive to the wakes of nearby racers.

Design decision-makers
Decision day is June 1, and hitting that deadline is a must, as IRL President Brian Barnhart estimates IRL will need 18 to 20 months to build, test, and begin making chassis for the start of the 2012 season.

The final decision will be made by IRL CEO Randy Bernard, who took over from Tony George March 1. Bernard will have help from an advisory committee, dubbed ICONIC for its goal of finding an innovative, competitive, open-wheel, new, industry-relevant, and cost-effective design.

The committee is chaired by retired Air Force Gen. William R. Looney III, and IRL team owners elected Gil de Ferran, co-owner of Luczo Dragon Racing/de Ferran Motorsports, Indianapolis, to represent them.

Bernard named Barnhart, former IRL vice president of competition Tony Cotman, and promoter and Texas Motor Speedway president Eddie Gossage to the committee.

Technical experts include Rick Long, a high-performance engine developer, Tony Purnell, a former technical consultant to FIA, the European motorsport organization, and Neil Ressler, former chairman of Jaguar Racing in Formula One and former vice president and chief technical officer of research and vehicle technology at Ford.

Swift Engineering
California-based Swift Engineering focused its aerodynamics study on the wings, seeking to reduce downforce and the turbulence they create. Designers at Swift have come up with two different chassis designs, although the company only intends to build a single winning model. The sharp-nosed “23” model has fully exposed wheels, a sculpted front wing, and a substantial back wing with endplates. Bodywork on the “32” includes front and side pods that protect both sets of wheels and rear-wing end plates that are continuations of the rear bodywork.

Both models dispense with cowlings covering parts of the engine. “We saw an opportunity to showcase the engine and other ‘jewelry’ while preserving efficiency with a much smaller fairing,” said Casper Van der Schoot, Swift’s director of motorsports. The change has little aerodynamic impact, but cuts down on sponsorship space.

A tilted rear underwing borrowed from the company’s Formula Nippon racer is said to sweep up the car’s wake, leaving cleaner air behind it that should promote closer racing and passing. Swift also intends to place LED lights on the roll hoop, side pods, and upper bodywork to signal spectators the car’s position, fuel level, and throttle and brake positions throughout the race.

Although producing the cars in Swift’s California facilities meets IRL’s US-manufacturing requirement, it may knock down the firm’s feel-good points for not locating in Indiana.

Lola
Designers at British firm Lola, known for their LeMans Prototype (LMP) 1 and 2 chassis and ChampCars, have come up with two visually different cars to add variety to the grid and accommodate two engine manufacturers, if IRL chooses to go that way. The company plans to wind-tunnel test both 1,380-lb configurations in the wind tunnel across the entire ride height range to ensure parity.

One body style might have a slight edge on oval courses while the other is better for road races, so Lola engineers are designing a series of sized and configured aero blockers for the underbodies of the cars. The blockers would detract slightly from the cars’ aerodynamic efficiency and keep the two body styles on a level playing field.

A large central underbody panel boosts downforce and let designers shrink front and rear wings that can leave turbulence in a car’s wake. Rear-wing endplates also minimize vortex rings that form over the back of the car at race speeds and inhibit passing. The front and lower rear wings also serve as bumpers to limit wheel-to-wheel contact if cars collide.

The bones of Lola’s designs will work for both IndyCar races and IndyLights development series with slight changes to the upper body work, a concept Lola engineers say makes both series safer for drivers and keeps teams’ costs down. “The crossover will encourage new teams to enter both IRL and Indy Lights,” says Peter McCool, Lola head of special projects.