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IndyCar
INDYCAR: Inside The 2012 Car’s Design & Development Issues
SPEED's Marshall Pruett delves into the issues facing the new Dallara DW12 and what the IndyCar Series and its partners are doing to solve those problems ASAP.
Cutting weight off the back of the Dallara DW12 has been focus of all those involved with the production of the car and its drivetrain components. (Photo courtesy of Dallara)
Power, weight, downforce, drag, grip and balance. Those are the six keys that dictate the lives of race car drivers, designers and engineers.
As the IZOD IndyCar Series has found with its new Dallara-built 2012 chassis, miss the one key by a small margin in any one of those six performance categories and the overall package will suffer. Miss the key in two or more areas, and like a six-string guitar with multiple strings out of tune, no one will want to play the instrument until it’s fixed.
With INDYCAR acknowledging a few areas that require immediate attention (weight/weight distribution, balance and drag), and others pointing to the need for a major re-think on the levels of power, downforce and grip needed next season, it’s clear a lot of tuning and tweaks will take place between now and March 28th, the first race on the 2012 calendar.
Understanding The Design
The general design philosophy for the Dallara DW12 centers on achieving a level of performance that would surpass the previous Dallara IR07 package through two main factors: a significant weight reduction coupled with an even greater drop in aerodynamic drag.
The DW12 was conceived to be lighter on its feet and more slippery through the air, to be nimble on road and street courses as well as on ovals, and, thanks to its weight and drag savings, could do all of this while using a smaller, more efficient engine.
But, as recent tests have shown, a discrepancy between the expected lesser weight/lower drag figures in Dallara’s digital world and what the DW12 has delivered at Indianapolis and on a variety of road courses has been a cause for concern for all of the parties involved.
General Concerns
For IndyCar teams, the new-car price tag came with the promise of greater performance, but so far, the DW12s have been between 10-15 mph slower at the Speedway, and just a few tenths faster on road courses.
For the series, which expected Dallara to achieve its performance targets from the outset, the need to rush fixes into place after INDYCAR concluded its official program has led to non-stop work at the INDYCAR offices and at Dallara’s base in Italy.
For those who’ve driven the DW12, general praise has been offered on its low- to medium-speed handling traits on road courses, but in almost every other performance category, the positives, as of late November, have been sparse.
And, to make matters worse, as each problem area is changed going forward, it affects the others, creating a rather cyclical challenge for INDYCAR, Dallara and its key vendors involved with the DW12 to stay on top of. It’s lengthy process that all involved are familiar with, but the time and effort required to tune every aspect of the DW12 should not be underestimated.
That being said, the DW12’s problems are solvable with time and money, but who will pay for the fixes—Dallara, its vendors, the series or the owners buying the cars--remains unclear.
Some cars hit the track for the first time, offer few problems and tick all of the performance boxes in a short amount of time, while others need a second, third and possibly a fourth round of revisions to hit those targets. As INDYCAR and its new-car partners embark on those multiple rounds with the DW12--listed in the order of importance below—and with the clock winding down, they can ill-afford to make more mistakes.
Weight & Weight Distribution
The biggest problem the DW12 is facing involves an excess of weight, and specifically, where that weight is found within the chassis.
Originally expected to weigh 1380 pounds (185 pounds less than the 1565-pound 2011-spec Dallara), the DW12 has only shed in the region of 100 pounds, coming in at approximately 85 pounds over its target. That 100-pound weight savings is still beneficial in terms of general performance, but won’t help to achieve the low weight/less drag performance gains that were expected.
According to Will Phillips, INDYCAR’s Vice President of Technology, the origins of the DW12’s unexpected rearward weight bias can be attributed to a number of vendor-supplied items being delivered well above their specified weights, rather than Dallara intentionally shifting weight to the back of the car.
As most open-wheel engineers will attest, a half-percent rearward shift in weight bias will generate a significant handling change—especially on an oval. The DW12, according to multiple sources, was delivered with a staggering four-percent shift in rear weight bias, and with most, if not all of that weight falling on or behind the rear axle.
“Dallara did not go out to put [the weight distribution figures] where it is now,” said Phillips, who inherited the 2012 project eight months after Dallara was awarded the contract by INDYCAR. “They were expecting it to be closer to where it was [specified]. Now, obviously, as you go from the wheel centerline back towards the back of the chassis, any weight saving change that we now make will be most helpful. So if we can pull weight out of the gearbox, if we can pull weight out of the diff, there’ll be much more benefit than the same amount of weight coming off the engine, for example.”
But not everyone in the paddock believes the companies involved with providing the gearbox and its internals should take the blame for the DW12’s handling dilemma.
“I think the CFD model [Dallara’s] done is a bit too rudimentary, and it has bitten them in the end,” said one prominent IndyCar engineer with extensive CFD experience, who, along with another current IndyCar race engineer, voiced the same concern.
“They’ve out-smarted themselves. Look at the aerodynamics on the Formula One car they delivered for HRT. That thing was barely suitable for that series, and if you look at the [DW12], they’ve also come up woefully short. You can’t dabble in these things. I’ll just put it this way: every rudimentary Indy car CFD model I’ve seen has said the rear of the car needs more weight bias than it actually requires. When you see that data returned, it should be a prompt to spend more time on [improving] your model, not to go off and start making a car based off that weight distribution figure. I’ll bet you [taking] a shortcut on the model has set this entire chain of problems in motion.”
While he’s clearly more focused on finding solutions than finger-pointing at this stage of the DW12’s development, some of Phillips’ statements to SPEED.com’s Robin Miller on the topic only seem to support the engineers’ “bad data” theory.
Whether it’s CFD data leading Dallara to believe the car should be faster in a straight line, or possibly its CFD-derived simulation data saying the rear-heavy DW12 will handle better, so far, the car’s virtual information cannot be trusted.
“So the car isn’t going as fast as we wanted or expected and we’re trying to identify why the theoretical world doesn’t match real world at the race track,” he said. “At very high speeds, we have disparity in the data.”
The next steps, as Phillips will chronicle, involve solving the mistakes in the DW12’s data and reducing its mass in strategic locations.
Weight Distribution: Ovals
When pushing the car hard at Indy, drivers noted the DW12 exhibited dangerous handling traits on corner entry and exit. With the rear-heavy car wanting to spin once they began to turn, drivers found the DW12, like a pendulum now swinging back in the opposite direction, wanted to plant the nose into the wall as they left each turn.
The handling dynamic, experienced by Indy 500 winners Dan Wheldon, Dario Franchitti and IndyCar veteran Tony Kanaan, had nothing to do with a lack bravery or experience. Calls for the DW12 to be harder to drive notwithstanding, its test pilots found that to safely negotiate Indy’s four corners, lifting off the throttle and doing serious amounts of coasting was the only real solution to keep the Dallara in one piece. With the oval equivalent of a dragster on its hands, immediate action was required by the series and the car’s manufacturers.
Quantified numerically, the 2011 Dallara-Honda Indy 500 package had a delicately balanced but safe weight distribution of approximately 45 percent at the front and 55 percent at the rear. With the DW12’s numbers closer to 41/59, carving weight from the back of the car was the first option taken to get the figures closer to 45/55.
Weight Distribution: Gearbox
“We’re working with Xtrac, and they've done a good job of moving away from the prototype ‘boxes over to where the cars are running now,” said Phillips, as he began to detail an ongoing effort by Dallara’s gearbox vendor to reduce weight with each new unit during the DW12’s intensive testing program.
“And, indeed, that's ahead of where the cars were that Dan [Wheldon] was driving. We had the heaviest ‘box to start with and the three prototype boxes for the engine manufacturers; they've had small amounts of weight removed but the production boxes got another 3 or 4 kg (6.6 to 8.8 pounds) off of them.”
Beyond paring weight from the aluminum gearbox housing, a change in philosophy on the gearbox internals has also made in an effort to aid the DW12’s oval handling issues.
“For the speedways, we were, for reason of economics, just going to put a blocker inside the road course differential and thus save componentry,” Phillips explained. “But because of the concern over the weight distribution for the ovals we're now looking at opening up an option of a lightweight spool, which could be fitted for the ovals. And that would give us another 3 kg (6.6 pounds) or so of weight savings, again, right in the [area of the car] where we’d like to do it.”
Getting all of the four-percent rear weight bias tipped back to where it belongs will be a challenge, as Phillips shares, due to the cost constraints that are involved. If the DW12 was a cost-is-no-object F1 car, the weight 45/55 balance would have already been corrected.
“If the gearbox weight is 7 or 8 kg or 10 kg (15.4 to 22 pounds) heavier than expected, and that's right on the rear axle centerline, that has an enormous change for the change to the weight distribution. We’re now also looking at what else can we do. Magnesium bellhousings perhaps? But at the end of the day, [with] the cost reduction that was required by Dallara to make – they've got to be very careful. In order to put the weight distribution forward a little more than where it is now, if we go and throw a ton of money for every car we’re going to defeat one of the main objects of the whole 2012 philosophy which was reduce costs. So we've got to go about it in a proactive cost way.
“But it's difficult. It's quite easy to move a couple of a percent—two percent; it's not so easy to move four. So I don't think we have to have the same weight distribution exactly as we had before. But obviously working with a four-percent different weight distribution is more of a challenge for the engineers than it is in having a two-percent different weight distribution. It significantly changes the car’s setup and its reactions.”
Compared the already lightened aluminum gearbox case, replacing it with magnesium units, and also making the Dallara bellhousings from the same material would offer a further savings of just over 3 kgs (6.6 pounds). From a production standpoint, each engine manufacturer uses a custom bellhousing that was made by Dallara to fit its powerplant and turbo system, which would necessitate three separate magnesium units to be made.
With Phillips’ points in mind, the costs involved in going to magnesium would likely cause an uproar by team owners, making it a worst-case option.
As the IZOD IndyCar Series has found with its new Dallara-built 2012 chassis, miss the one key by a small margin in any one of those six performance categories and the overall package will suffer. Miss the key in two or more areas, and like a six-string guitar with multiple strings out of tune, no one will want to play the instrument until it’s fixed.
With INDYCAR acknowledging a few areas that require immediate attention (weight/weight distribution, balance and drag), and others pointing to the need for a major re-think on the levels of power, downforce and grip needed next season, it’s clear a lot of tuning and tweaks will take place between now and March 28th, the first race on the 2012 calendar.
Understanding The Design
The general design philosophy for the Dallara DW12 centers on achieving a level of performance that would surpass the previous Dallara IR07 package through two main factors: a significant weight reduction coupled with an even greater drop in aerodynamic drag.
The DW12 was conceived to be lighter on its feet and more slippery through the air, to be nimble on road and street courses as well as on ovals, and, thanks to its weight and drag savings, could do all of this while using a smaller, more efficient engine.
But, as recent tests have shown, a discrepancy between the expected lesser weight/lower drag figures in Dallara’s digital world and what the DW12 has delivered at Indianapolis and on a variety of road courses has been a cause for concern for all of the parties involved.
General Concerns
For IndyCar teams, the new-car price tag came with the promise of greater performance, but so far, the DW12s have been between 10-15 mph slower at the Speedway, and just a few tenths faster on road courses.
For the series, which expected Dallara to achieve its performance targets from the outset, the need to rush fixes into place after INDYCAR concluded its official program has led to non-stop work at the INDYCAR offices and at Dallara’s base in Italy.
For those who’ve driven the DW12, general praise has been offered on its low- to medium-speed handling traits on road courses, but in almost every other performance category, the positives, as of late November, have been sparse.
And, to make matters worse, as each problem area is changed going forward, it affects the others, creating a rather cyclical challenge for INDYCAR, Dallara and its key vendors involved with the DW12 to stay on top of. It’s lengthy process that all involved are familiar with, but the time and effort required to tune every aspect of the DW12 should not be underestimated.
That being said, the DW12’s problems are solvable with time and money, but who will pay for the fixes—Dallara, its vendors, the series or the owners buying the cars--remains unclear.
Some cars hit the track for the first time, offer few problems and tick all of the performance boxes in a short amount of time, while others need a second, third and possibly a fourth round of revisions to hit those targets. As INDYCAR and its new-car partners embark on those multiple rounds with the DW12--listed in the order of importance below—and with the clock winding down, they can ill-afford to make more mistakes.
Weight & Weight Distribution
The biggest problem the DW12 is facing involves an excess of weight, and specifically, where that weight is found within the chassis.
Originally expected to weigh 1380 pounds (185 pounds less than the 1565-pound 2011-spec Dallara), the DW12 has only shed in the region of 100 pounds, coming in at approximately 85 pounds over its target. That 100-pound weight savings is still beneficial in terms of general performance, but won’t help to achieve the low weight/less drag performance gains that were expected.
According to Will Phillips, INDYCAR’s Vice President of Technology, the origins of the DW12’s unexpected rearward weight bias can be attributed to a number of vendor-supplied items being delivered well above their specified weights, rather than Dallara intentionally shifting weight to the back of the car.
As most open-wheel engineers will attest, a half-percent rearward shift in weight bias will generate a significant handling change—especially on an oval. The DW12, according to multiple sources, was delivered with a staggering four-percent shift in rear weight bias, and with most, if not all of that weight falling on or behind the rear axle.
“Dallara did not go out to put [the weight distribution figures] where it is now,” said Phillips, who inherited the 2012 project eight months after Dallara was awarded the contract by INDYCAR. “They were expecting it to be closer to where it was [specified]. Now, obviously, as you go from the wheel centerline back towards the back of the chassis, any weight saving change that we now make will be most helpful. So if we can pull weight out of the gearbox, if we can pull weight out of the diff, there’ll be much more benefit than the same amount of weight coming off the engine, for example.”
But not everyone in the paddock believes the companies involved with providing the gearbox and its internals should take the blame for the DW12’s handling dilemma.
“I think the CFD model [Dallara’s] done is a bit too rudimentary, and it has bitten them in the end,” said one prominent IndyCar engineer with extensive CFD experience, who, along with another current IndyCar race engineer, voiced the same concern.
“They’ve out-smarted themselves. Look at the aerodynamics on the Formula One car they delivered for HRT. That thing was barely suitable for that series, and if you look at the [DW12], they’ve also come up woefully short. You can’t dabble in these things. I’ll just put it this way: every rudimentary Indy car CFD model I’ve seen has said the rear of the car needs more weight bias than it actually requires. When you see that data returned, it should be a prompt to spend more time on [improving] your model, not to go off and start making a car based off that weight distribution figure. I’ll bet you [taking] a shortcut on the model has set this entire chain of problems in motion.”
While he’s clearly more focused on finding solutions than finger-pointing at this stage of the DW12’s development, some of Phillips’ statements to SPEED.com’s Robin Miller on the topic only seem to support the engineers’ “bad data” theory.
Whether it’s CFD data leading Dallara to believe the car should be faster in a straight line, or possibly its CFD-derived simulation data saying the rear-heavy DW12 will handle better, so far, the car’s virtual information cannot be trusted.
“So the car isn’t going as fast as we wanted or expected and we’re trying to identify why the theoretical world doesn’t match real world at the race track,” he said. “At very high speeds, we have disparity in the data.”
The next steps, as Phillips will chronicle, involve solving the mistakes in the DW12’s data and reducing its mass in strategic locations.
Weight Distribution: Ovals
When pushing the car hard at Indy, drivers noted the DW12 exhibited dangerous handling traits on corner entry and exit. With the rear-heavy car wanting to spin once they began to turn, drivers found the DW12, like a pendulum now swinging back in the opposite direction, wanted to plant the nose into the wall as they left each turn.
The handling dynamic, experienced by Indy 500 winners Dan Wheldon, Dario Franchitti and IndyCar veteran Tony Kanaan, had nothing to do with a lack bravery or experience. Calls for the DW12 to be harder to drive notwithstanding, its test pilots found that to safely negotiate Indy’s four corners, lifting off the throttle and doing serious amounts of coasting was the only real solution to keep the Dallara in one piece. With the oval equivalent of a dragster on its hands, immediate action was required by the series and the car’s manufacturers.
Quantified numerically, the 2011 Dallara-Honda Indy 500 package had a delicately balanced but safe weight distribution of approximately 45 percent at the front and 55 percent at the rear. With the DW12’s numbers closer to 41/59, carving weight from the back of the car was the first option taken to get the figures closer to 45/55.
Weight Distribution: Gearbox
“We’re working with Xtrac, and they've done a good job of moving away from the prototype ‘boxes over to where the cars are running now,” said Phillips, as he began to detail an ongoing effort by Dallara’s gearbox vendor to reduce weight with each new unit during the DW12’s intensive testing program.
“And, indeed, that's ahead of where the cars were that Dan [Wheldon] was driving. We had the heaviest ‘box to start with and the three prototype boxes for the engine manufacturers; they've had small amounts of weight removed but the production boxes got another 3 or 4 kg (6.6 to 8.8 pounds) off of them.”
Beyond paring weight from the aluminum gearbox housing, a change in philosophy on the gearbox internals has also made in an effort to aid the DW12’s oval handling issues.
“For the speedways, we were, for reason of economics, just going to put a blocker inside the road course differential and thus save componentry,” Phillips explained. “But because of the concern over the weight distribution for the ovals we're now looking at opening up an option of a lightweight spool, which could be fitted for the ovals. And that would give us another 3 kg (6.6 pounds) or so of weight savings, again, right in the [area of the car] where we’d like to do it.”
Getting all of the four-percent rear weight bias tipped back to where it belongs will be a challenge, as Phillips shares, due to the cost constraints that are involved. If the DW12 was a cost-is-no-object F1 car, the weight 45/55 balance would have already been corrected.
“If the gearbox weight is 7 or 8 kg or 10 kg (15.4 to 22 pounds) heavier than expected, and that's right on the rear axle centerline, that has an enormous change for the change to the weight distribution. We’re now also looking at what else can we do. Magnesium bellhousings perhaps? But at the end of the day, [with] the cost reduction that was required by Dallara to make – they've got to be very careful. In order to put the weight distribution forward a little more than where it is now, if we go and throw a ton of money for every car we’re going to defeat one of the main objects of the whole 2012 philosophy which was reduce costs. So we've got to go about it in a proactive cost way.
“But it's difficult. It's quite easy to move a couple of a percent—two percent; it's not so easy to move four. So I don't think we have to have the same weight distribution exactly as we had before. But obviously working with a four-percent different weight distribution is more of a challenge for the engineers than it is in having a two-percent different weight distribution. It significantly changes the car’s setup and its reactions.”
Compared the already lightened aluminum gearbox case, replacing it with magnesium units, and also making the Dallara bellhousings from the same material would offer a further savings of just over 3 kgs (6.6 pounds). From a production standpoint, each engine manufacturer uses a custom bellhousing that was made by Dallara to fit its powerplant and turbo system, which would necessitate three separate magnesium units to be made.
With Phillips’ points in mind, the costs involved in going to magnesium would likely cause an uproar by team owners, making it a worst-case option.
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