What different?

[Andrew Longman]

I believe six IRL cars, both Dallara and GForce have gotten airborn this season. I don't believe any did last year (or if they did it was a lot fewer).

Something must be different with the design of both these cars when compared to the Dallara and GForce models of last year.

Sure airboxes and wing angles and bottoms racing on ovals and all that may contribute to the cars getting up in the air as soon as they get a little out of shape, but UNLESS ONE OR SEVERAL OF THESE THINGS CHANGED FROM LAST YEAR IT DOESN'T EXPLAIN WHY WE HAVE THE PROBLEM THIS YEAR AND NOT DURING THE LIFTIME OF THE PREVIOUS MODELS.

So, I'm sure things did change arounnd these things, and I'm sure other things changed too. But what is the precise difference that could be cause the launches?

[Treeface]

Toyota, Honda and their big dollar teams trying to figure a way around the mandated high downforce.

:(

[RaceGrrl]

This article on grandprix.com discusses the OW race car "launch" problem.

Interesting read (http://www.grandprix.com/ns/ns12081.html)

[mapguy]

Originally posted by RaceGrrl
This article on grandprix.com discusses the OW race car "launch" problem.

Interesting read (http://www.grandprix.com/ns/ns12081.html)

Good article. Thanks Grrl.

[FRANKY]

Originally posted by Andrew Longman
I believe six IRL cars, both Dallara and GForce have gotten airborn this season.


This was the first GForce. But in my book I don't see that it matters. They are both built to fit certain specs.

[Andrew Longman]

Originally posted by FRANKY
This was the first GForce. But in my book I don't see that it matters. They are both built to fit certain specs.

Then what's different about the specs?

Some difference I think you CAN rule out sound like:

Front wing design and/or angle: Wheldon went over with one wing folded under the car and I think the other on gone.

More HP from new engines/higher speed: Wheldon went over going while slowing down and doing maybe 100. More to the point Renna went over at 218 which is pretty slow by OW standards.

Running on ovals: This did not change

Big wings: They've been big for years. I don't think they are any bigger this year.

Air getting under the rear of the car: Air got under the car last year. Several of the airborn events started with the car going forward

Running a lot of downforce causing the front to point up: Did that last year too. Anyone know if the noses are any higher this year?

Anything to do with the sidepods: This seems possible but unlikely because while the sidepods of both cars are different from last year they are also very different from each other. It seem unlikely that two different designs share the same fault.

General front/back downforce imbalance: If the center of pressure is too far back, clearly you risk a blowover. And trimming the car out does seem to have that effect. It seems such an obvious design fault that I have trouble believing two companies would make the same mistake

I have a few ideas:

The noses of both the GForce and Dallara are very skinny and skinnier than last year's car. That would displace less air going around the nose of the car and allow more air towards the sidepod and undertray. That's probably the design intent, but it would also direct more air under the car should it get a little out of shape.

Here another one: The skinnier nose creates less downforce itself, relying more on the front wing for front downforce. If the nose goes up much the air pressure moves to the underside of the front wing from the top. With less downforce from the nose to counterbalance this, the "tipping point" comes too easily.

[rabbit]

Originally posted by RaceGrrl
Interesting read (http://www.grandprix.com/ns/ns12081.html)

The current IRL regulations dictate that the cars have flat-bottoms but generate downforce with aerodynamic wings and sidepods. If air gets under the cars at high speed they can take off, despite weighing 700kgs. I thought IRL cars used ground effects. :confused:

[Racewriter]

The wings are, in fact, bigger this year. I'd have to look up the percentage. There was also a reduction in undertray venturi area, which has the net effect that more of the downforce is generated by the wings as opposed to underbody effects. They likely did this so that mandated wing angles would more effectively limit top speed.

Now, as we know, IRL teams have been running the cars with a nose-up, tail down attitude, to get the big rear wing out of the air. Here's where it's hard to know what happened, because we don't know how Renna's car was set up yesterday morning.

But the bottom line is that you have a race car that is very aero-dependent, that gets extremely unstable when that aero is disturbed - as Mario proved, it can run over a fairly small piece of debris and take flight. If Renna clipped the turn three apex too early, the transition from the grass back to pavement could have been that disturbance. The car takes flight, and disaster.

[Napoleon]

Originally posted by Racewriter
But the bottom line is that you have a race car that is very aero-dependent, that gets extremely unstable when that aero is disturbed - as Mario proved, it can run over a fairly small piece of debris and take flight.

I still consider the Mario thing a "fluke" in that the debris appeared to be foam which would have suddenly cut of all down force created by the undertray and IMO may have actually caused the opposite of downforce. I suspect if it was a Champ car there may have been a pretty good chance at something similar happening.

But the other flips. . . that may be a differant story.

[FTG]

Originally posted by Racewriter
Now, as we know, IRL teams have been running the cars with a nose-up, tail down attitude, to get the big rear wing out of the air.

In order to get them to go faster (reduce drag), you need to make them more unstable.