Barrichello's Crash

[Valve Bounce]

It could be that Ross pressed the "Rubens distruct" button so that SchM could salvage one point.

Or it might be that BMW has perfected a laser weapon that JPM tested on Rubens. Some of us in Oz might have been watching the James Bond movie before the race, and there was this BMW that took down a helicoptr when 007 pressed a paddle on his stering wheel.

[avsfan733]

My guess, is that something happened with the hydraulics. (much like schumi in the pitstop) which caused some sort of throttle flucuation after he had begun braking. This gave the axle, an acceleration load as well as the deceleration load fighting one another. the failure seems to have happened at the U-joint between the axle and the transmission. which flailed around and kindly removed the suspension mounts. Because the throttles are hydraulic, a loss of pressure would cuase fluctuation, especially as the car tried to downshift during braking. this would also tie in with the problem that schumi had because after the refueling, the mechanic manually closed the fuel flap illustrating a loss of hydraulic pressure. It probably wasn't simply from the engine stalling because the residule pressure surely would be enough to close the flap. A loss of hydraulic presure could also be to blame for the stall itself as it would prevent the clutch from fully disengaging when the car came to a stop

[Valve Bounce]

Well, this is certainly a compehensive and insightful analysis. I didn't know the throttle was hydraulically operated, but if they were, surely a loss in pressure would not cause fluctuation would it? I would have thought a loss of pressure would simply cause lots of stuff in the clutch, gearbox, and engine not to work.
Of course it could simply be caused by a failure of the U-joint, which would cause the shaft to flail and cut the suspension.
Finally, I would rather leave this analysis for Jukebox to confirm or rebutt.

[mortda]

Is it possible looking at the photo of the wheel with the driveshaft still attached that the driveshaft parted company from the transmission drive, allowing that end to flail around destroying the suspention attachments on transmission case end, allowing the whole lot to come adrift

[jetsetter]

It was indeed a frightening moment for Rubens & it will certainly have the Ferrari team worried.

[Speed]

Rubens ahead Michael...

No team orders allowed...

Hmmmmmm... Conspiracy !

[climb]

Well, first of all, congrats to Damon for the good pic!
maybe the problem was relating to left tie-rod failure; after all, it has a one-point attachment to the chassis, whereas wishbones have two, and the failure doesn't appear to be onto the upright... or is my analisys to simplistic?

[JFAUSSAN]

Just glad he made it out in one piece.Also think it's funny things like this almost only happen to Rubens

[Bononi]

Horrible crash. It's scaring to think it can happen at Indy...

[Number Juan]

my simple answer? looks to me not like a suspension failiure - but the transmission blowing a great big hole in the suspension. however, we saw Firman's front suspension doing a similar thing at Brazil...

it was a nasty crash, it's just a good thing theres tyres on those walls!

[pirenzo]

Originally posted by Jordi
Ghislimberti, pirenzo.

That's the one. I didn't mean to be rude by not calling him by his full name, but i couldn't remember it.

[climb]

Just to add another point: normally drivers with understeering problems are advantaged by asphalt outside the track; but in this case gravel would have helped him reduce the impact speed.
Would it be good to (at least partially, in the outer strand) to restore it where eliminated?

[paulzinho]

I'm not a big fan of the tarmac run offs, in accidents like Rubens (ie the more dangerous type) they are blooming useless.

They give the impression of only helping if a driver makes a mistake and runs off the circuit. Surely that isn't right!

[spearce]

What happened to the wheel tethers that are supposed to retain the whhel in the event of a shunt, they didn't even retain it prior to the .....

[Adam43]

Originally posted by spearce
What happened to the wheel tethers that are supposed to retain the whhel in the event of a shunt, they didn't even retain it prior to the .....

The wheel tethers are not designed to retain the wheel. They are designed to absorb and reduce the energy of the wheel in a shunt.

In a slow speed shunt this will mean teh wheel is retained, but in an accident that involves a lot of energy it will break. However the process of breaking the tether reduces the amount of kinetic energy the wheel has when it flys off.

If the tether wasn't there then the wheel would have flown further into the crowdand with greater momentum.

The design breif for the tether was never to keep the wheel on in all accidents. If it was it was unrealistic! It was to reduce the kinetic energy of the wheel in an accident. This is does. Of course when the device was first reported that was not how it was explained.

[Muzza]

Adam,

Would you please explain your last post?

You wrote "The wheel tethers are not designed to retain the wheel. They are designed to absorb and reduce the energy of the wheel in a shunt." I disagree. The tethers used in Formula 1 are similar to a cable, but are made of composite. This setting is quite fragile and has rather limited energy-absortion capability.

Moreover, the tethers are, well, tethers, so they show siginificant resistance to traction, but little to compression.

As the tethers were installed to keep wheels attached to the car - or at least reduce the risk of having a wheel detached - the FIA elected composite cables for the tethers. This two things, objective and material selection, make sense together. They have great strenght to traction. If FIA's intent were to use the tethers to absorb energy, or reduce the non rotational momentum applied to a wheel in case of impact, this would not have been the best choice.

I also did not understand your last paragraph: what did you mean by "Of course when the device was first reported that was not how it was explained"? Earlier this year I witnessed a conversation with Christiano da Matta and the subject of safety in Formula 1 was brought up, and he explained the use of tethers followed the "usual understanding" about these devices.

Or did I get it all wrong? Please let me know your thoughts.

Cheers,


Muzza

[Adam43]

Muzza, an interesting post.

Just a different point of view, I think.

To stop a wheel flying off in an impact and reducing the kinetic energy it has is, to my mind, trying to work against the same force on the tether.

Basically at low speed the energy of the shunt will not be great enough to break the tether. The energy is absorbed by the tether and the wheel stays on the car. Fine.

If the energy is too great and breaks the tether then the tether still does an important job (the same job). It takes a certain energy to break the tether. This energy is then removed from the kientic energy of the wheel flying off.

I suppose what I am saying is I consider the situation where the the wheel stays on the car as the same as the situation where the wheel comes off. When the wheel stays on the car the energy the wheel has been given by the impact is less than the energy to brake the tether. It can be considered as the same as the wheel coming off, but having zero kinetic energy. No harm done.

In a nut shell, whatever energy it takes to stop the wheel being removed (if that is the idea) is removed from wheel if it does come off. It still has done a job.

My main point is that to say the tether failed because the wheel fell off is false. It has still done a very important job.

Anyway, I think I have just said the same thing several times, but I am a bit rushed.

[Muzza]

Hello, Adam,

Thanks for your message, now I understand better what you meant - and we agree.

The statement in your first message "The wheel tethers are not designed to retain the wheel. They are designed to absorb and reduce the energy of the wheel in a shunt" made me believe that you thought that the tethers were conceived as a device that would absorb energy by means of mechanical deformation under compression, what tethers do not do well.

And your sentence "My main point is that to say the tether failed because the wheel fell off is false. It has still done a very important job" is a good reminder for those that still apply an exaggerated dose of intuition when talking about racing and safety.

Cheers,

Muzza

[spearce]

Yes but the wheel still had a hell of a lot of energy left, judging by its speed by the time it reached the tyre wall !!

It is most unusual to see a wheel part company with a car like that without hitting anything, does that mean that the d/shaft broke and did the damage to the rest of the suspension ? A simple w/bone or joint failure would not have resulted in losing the whole shooting match ?

[Ian-S]

rememebr that you can break a carbon wishbone by kicking it at the right angle, they are only as strong as the angle they are hit at, so if the driveshaft did come out and flap around, it would simply tear through the wishbones like a knife through paper because they were being "hit at the wrong angle".

[The Zuschauer]

My thoughts on the accident were that it was caused by a broken rear axle, which flailed around and removed practically every wishbone & the tether as well.

On the replay, you can see when the axle detaches from the wheel, and goes flying into the air. I was more worried about where the axle ended up than where the wheel was going - because it looked like the axle could have easily cleared the safety fence.

The theory about a fluctuating throttle due to hydraulics failure is nothing short of a wild imagination... I'm sure the guy that designed the axle kept in mind that the drivers could left foot brake, and hence be using full throttle and full brakes at the same time, which would put the maximum load on the axle. Or did you design the rear axle yourself?

And in my knowledge, when you're talking cars, there's a big difference between a drive shaft and an axle...

[macca]

While the wishbones are carbon composite and may be shattered by the flailing driveshaft, assuming a u/j failed which looks likely, the diagonal pushrod between the bottom of the rear upright and the bellcrank on top of the gearbox is a steel alloy and it is surprising to see the whole assembly come right off like that - a bearing or upright failure would just have the wheel coming off the hub.

A catastrophic failure in the gearbox which shattered the casing and released the pushrod/bellcrank might account for the total seperation.

[Phoenix1]

I've emailed the circuit to ask about the wheel and to see if anyone was hurt but I hope no news is good news.

[craig1]

Wheel tether or not, I doubt there would be anything that anyone could design that would have kept that wheel attached to the car.
The tether slowed it down during departure and that was the best you could hope for so at least it didn't travel as far as it would have.

[ASCII Man]

At least we wouldn't have a tyre flying off into the crowd like with JJ Lehto and Pedro Lamy in that startline incident at Imola.