Tuesday, May 19, 2015

Has Indy hit on solution for flying cars?

(by John Oreovicz espn.go.com 5-17-15)

This was supposed to be the year that aero kits brought speed and style back to the Indianapolis Motor Speedway.

Instead, unproven aerodynamic components have made safety the watchword in a week when three cars got upside down and airborne during testing at IMS.

Ed Carpenter's crash in a Sunday morning practice session was the third in the past five days in which a Chevrolet-bodied Indy car snapped out of control and took to the air, a disturbing pattern that cannot be viewed as coincidental.

Carpenter's situation prompted IndyCar Series officials to delay qualifying by more than five hours. They also implemented changes to both Chevrolet and Honda cars, reducing engine power for qualifying and requiring Chevrolet teams to remove several aerodynamic components that they believe may have contributed to the three crashes and subsequent flights.

An additional hourlong practice session and qualifications went off without incident. But heading into Sunday's Indianapolis 500 serious questions remain unanswered about the stability of the latest generation of Indy cars in general, and cars running the Chevrolet aero package in particular.

"It's definitely a concern and we don't know enough about it," Indy car legend Mario Andretti said. "We haven't seen whether a Honda car would pick up speed when going backward and I hope we never see that.

"The cars today have such huge square inches of floor area, and unfortunately they are susceptible to flying," Andretti added. "I've said that from the beginning and I'm one of the ones who had experience. That's one of the issues that may need to be addressed, narrowing the sidepods. I think it may have to be done."

Andretti retired from full-time driving in 1994, but famously went for a flight in a Dallara Indy car while making a test run for his son's team in 2003. On that occasion, Andretti's car took off like an airplane after hitting a piece of debris on the track from a crash that had just occurred in front of him.

The three accidents involving Chevrolet cars this week appeared relatively innocuous by Indianapolis crash standards until the cars spun around backward and launched into the air after hitting the wall.

In the only Honda wreck of the week, Pippa Mann's machine remained planted to the ground despite hitting two different walls.

The similarity between all three Chevrolet accidents has focused attention on the company's aero kit, specifically an unusually small rear wing that features no traditional end plates or fences.

Honda's rear wing appears much more substantial, with rectangular end plates and additional winglets for additional downforce and stability.

Arron Melvin, the chief designer of the Chevrolet aero kit, said that the tapered "Coke bottle" aspect of the Chevy's side pods helps the chassis create sufficient levels of downforce that reduces the need for a highly effective rear wing.

"We emphasize downforce in areas that aren't the rear wing," Melvin said Monday night at the public launch of Chevrolet's superspeedway aero components. "We need a very slender wing and therefore endplates are not particularly powerful or efficient anymore.

"On a higher downforce configuration, the endplates add more aerodynamic power and value, and we didn't need them," he continued. "The main plane looks very small because we can make a very efficient wing for oval events. It actually has just as much [aerodynamic] strength as the old wing and most of the time it's just providing a small amount of trim. It also has the nice side effect of lighter weight, which is a big factor for these cars."

The question is whether Chevrolet went too far in its quest for efficient downforce. Is the lack of rear-wing endplates contributing to the way the cars are suddenly snapping loose without warning, and to the seeming propensity for them to fly?

Carpenter says it's far too early to rush to judgment.

"There's a lot to understand and I don't think it's fair to say that this is an aero-kit issue," Carpenter said. "We have multiple variables going on this year. We have new tires, there's a new underwing [floor] with a huge hole in it, and aero kits.

"It's all just speculation at this point and we really need to learn what's causing this."

Still, it's a question that we probably wouldn't be asking right now if the IndyCar Series had been more adequately prepared for the introduction of the speedway version of the aero kits.

In an effort to maintain secrecy about their designs, Chevrolet and Honda did little on-track testing, by traditional standards, trusting their designs to wind-tunnel studies and computational fluid dynamics.

Teams did not receive the new wings and other parts until April 27, and for most drivers, a May 3 test at Indianapolis was their first experience with the new package.

Nobody ran more than 95 laps that day. And nobody crashed.

But the issue at Indianapolis really isn't the fact that cars are crashing. That's a natural and normal part of racing.

What isn't normal is the way the Chevy cars are taking flight. And until a crashed Honda car gets upside down, it's going to take time and real world testing to determine whether IndyCar is dealing with a Chevrolet aero problem or a problem endemic to the current iteration of cars in general.

That's why IndyCar mandated the changes it did Sunday morning, to try to make the cars as stable as possible for the short term while it buys the time it needs to research a more permanent solution.

With an oval race coming up June 6 at Texas Motor Speedway, arguably the most dangerous oval the series races on, the pressure is on IndyCar to get to the root of this problem quickly.

"Since the first incident that we had with the No. 3 car [Helio Castroneves' crash on Wednesday], we're working with both manufacturers and trying as fast as we can," IndyCar competition president Derrick Walker said. "They're running supercomputers day into night to try and compare what we have been doing in the past and what we're doing now and see if there are any big red flags that say we're going the wrong way here.

"Crashes are very hard to simulate," Walker added. "They have such good computing power nowadays. They can simulate a car in yaw or 180 degrees going the opposite way, and that, quite frankly, is the best way to get there as quick as we can."

Because it was a safety issue, Honda took the high road and didn't complain that changes were required for its cars when the problems that occurred this week all involved Chevrolet cars.

However, there's a strong feeling that Honda was disadvantaged by the changes. Honda's top qualifier was Justin Wilson in sixth place, 1.5 mph slower than Scott Dixon's 226.760-mph pole speed.
But the drivers supported IndyCar's efforts to make things as safe as possible for them under the circumstances.

"It was a pretty hard decision, but I think they did the right thing," second-place qualifier Will Power said. "The problem was the fact that when you crash, the car flies, but I think that this is the first year we've ever had with this car that you could trim enough to make it quite hard to drive and people were making mistakes and crashing.

"I think it has kind of identified a problem with this car and until they get that fixed, I'm not sure what they can do. It's a pretty tough problem. But I don't think it's just Chevy, either. I think it's just the fact that the floor is built for a road course, and we're running it on an oval and it's quite steep. That's maybe one problem. But I'm not an engineer; I don't know."

Two days of on-track activity remain between now and race day: A full day of practice on Monday and Friday's hourlong Carburetion Day shakedown.

One thing is for certain. Whether it's a Chevy problem or, as Andretti suggested, a more basic issue associated with the wide, flat underbody of the current generation of cars, the IndyCar Series truly does have a problem. How IndyCar reacts moving forward is of utmost importance to the safety of its drivers and spectators and the integrity of the sport.

"Safety is obviously a big part of the sport and oval racing is one of the most dangerous forms, so it's always in the back of your mind," Dixon said after claiming the pole at 226.760 mph, a reduction of 4.309 mph from Carpenter's 2014 Indy pole speed. "All the crashes have been in very different scenarios and different situations.

"We don't want to see cars get in the air, but there are very few tools in the box for us to make changes to the cars," he added. "IndyCar used what they had and with the speeds down, I think safety is going to get better."

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http://espn.go.com/racing/indycar/story/_/id/12904775/indycar-facing-major-problem-third-car-flies

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