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This concerns a Smart Passion Cabriolet that was involved in a wreck. The car was purchased in August and was involved in an accident on November 2008.


According to the driver, she was struck directly behind her driver's door after someone ran a red light at an intersection.

Her Smart went airborne, flying into the air, flipping over and rolling down (some witnesses claim 5 times) the street and after traveling some 40 foot, landed right side up on all four tires like a cat.


She was wearing a seat belt and spent 3 days in the hospital, badly bruised, but fortunately not having any broken bones.

She believes very strongly that the cars safety cell saved her from certain death.


The car actually looks pretty good under the circumstances but, was eventually totaled by her insurance company.

She's wondering why her airbags didn't deployed, possibly minimizing her injuries?

Perhaps someone with airbag expertise, past experience or a similar encounter could explain if this is normal or not?

Thanks
 

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if the airbags didnt goo off it's because they didnt need to!

the front airbags arent going to go off in a side impact.... well only if you own a hummer or something mate of cheap chinese plasticine!!

the car looks in very good shape considering the accident you describe.
 

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Good question... glad to hear she's relatively ok. My best guess, without claim to expertise, is that the air bags are programmed to deploy only when a certain amount of force is detected coming from directions which would benefit from the airbag. Since they use explosives to inflate, there's a certain amount of risk and they only inflate if they're really needed. That said, there is a known issue reported on the forums with seat air bags having a bad wire or loose connection, triggering a SRS warning light. My thought is if it were a bad wire, you'd see the warning light as part of the self diagnostics. I would be curious to know what exactly triggers those side air bags if not a side collision and flip. Maybe the impact wasn't hard enough (30MPH?) to trigger. Front air bags should only deploy in a frontal crash, if I'm correct.

Naturally, anyone with real expertise is welcome to supplement my thoughts based on internet and couch research.
 

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Maybe the impact wasn't hard enough (30MPH?) to trigger.
Naturally, anyone with real expertise is welcome to supplement my thoughts based on internet and couch research.
Sent the car airborne, and rolling at 30MPH? I have a hard time with that. Anyway, I thought air bags deployed at lower speeds than 30 MPH. I have been wrong before.
I'm eager for someone else to pitch in.
 

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Airbags deploy based off of a principle of deceleration.

Essentially - multiple stages of sensors have to be triggered by a rapid enough deceleration to deploy the bags. The sensors have a relatively narrow field of observation in which directions they will trigger.

In this case - the forces would have been more of a spinning force - and by the time it rolled, they would not have been in a direction where the bags would have helped. This may have been on the verge of deploying the driver's side airbag - but the forces would have had to have been closer to the front of the car.

She should be glad... you want no part of an airbag going off if you don't need it... besides the pain/noise/smell, they destroy the interior panels behind which they are mounted.
 

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The car does look in good shape considering the description of what happened to it.

It's good to hear that the owner although hospitalized was not seriously injured.


James.
 

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Airbags deploy based off of a principle of deceleration.
Acceleration and deceleration is the same thing, its just a matter of the frame of reference.

Side airbags do deploy in side impacts as shown by the crash test videos. As the driver did not suffer serious injuries, it would be safe to assume that the deployment of the airbags was not warranted. In any case, airbags do not protect from rollovers because they inflate and deflate almost instantaneously.

Given that a smart is 20.3 feet in diameter, rolling 5 times within 40 feet would be a pretty impressive feat :rolleyes: (I think the witness might have been mistaken)


She should be glad... you want no part of an airbag going off if you don't need it... besides the pain/noise/smell, they destroy the interior panels behind which they are mounted.


I think damage to the interior panels is a minor consideration in this case.
 

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page 109

....side trigger sensors in the left and right inner sills near the B pillars for detecting a side impact...

jetfuel
 

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Acceleration and deceleration is the same thing
They are. Change in speed, relative. You could call deceleration negative acceleration. Still, the same.
In any case, airbags do not protect from rollovers because they inflate and deflate almost instantaneously.
Good point!
Given that a smart is 20.3 feet in diameter
Huh??? Wow, I knew it was bigger inside than outside, but that's ridiculous, LOL I'm guessing you meant circumference. I won't do the math.
I think damage to the interior panels is a minor consideration in this case.
No doubt!
 

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...the question still remains...Why no side air bags?
...let the lawyering begin...
...going back to the tech manual...
jetfuel
 

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Glad to hear she is OK - and THANK YOU for sharing the story/pictures with us.

I have a feeling the insurance people are going to see if the airbags really needed to deploy or if they were designed to deploy in an accident like that meaning taking a hit from that angle.
 

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...the question still remains...Why no side air bags?
...let the lawyering begin...
...going back to the tech manual...
jetfuel
There really is no question... the forces on the car at the point of impact would have been centrifugal and would most likely not have tripped the threshold of deployment. A lawyer isn't going to be able to do a damn thing in this situation - the car did what it needed to do and is operating as designed.

One cannot look at a car and say whether or not the bags should have deployed. If the bags had deployed, it would have recorded post-deployment information in the DERM that could be examined - but even then, it's not going to tell you anything except what events triggered the system and if any errors occurred in the deployment process.

I would be curious to know if the belt pretensioners fired in the above accident, however.
 

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Impact was on drivers side and if no passenger, passenger seat airbags are deactivated. So no reason for drivers side bag to deploy.. just my 2-cents
 

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Acceleration and deceleration is the same thing, its just a matter of the frame of reference.
Correct... and in this instance, it made more sense to use deceleration instead of using negative acceleration.

I think damage to the interior panels is a minor consideration in this case.
Agreed, I was speaking in general, however. On more than one occasion, I have seen a car totalled because of the collateral damage caused by the (potentially unneeded) deployment of airbags.
 

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MD...don't know if I can agree with you...
...sensor should have deployed the side air bag...
...while looking at the side view picture of the OP I see something that's hanging right in front of the rear wheel that looks like if it is suspended by two wires...hummm
comparing the two car damage it seem like they are similar.
It will take some time and the data to really understand what went on...

jeyfuel
 
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