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Model S saves another life

Discussion in 'Model S' started by tgbrad, Apr 8, 2016.

  1. tgbrad

    tgbrad Member

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  2. SCW-Greg

    SCW-Greg Active Member

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    Tragic.
    Besides all the inherent safety built in to the Model S structure, you're talking about one car's mass of 5400lbs vs the Cobalt at barely over 2,000. Things don't stop equally with direct impacts like this.
     
  3. Peteybabes

    Peteybabes Member

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    This is great news for the safety of Tesla. My mom woke me up this morning with "Whoa - score one for Tesla"

    I know this is devastating, but Tesla is basically a huge crumple zone because of the awesome aluminum structure.
     
  4. ggr

    ggr Roadster R80 537, SigS P85 29

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    "... treated at the scene..." is pretty impressive, given that the combined speed was probably in triple digits.
     
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  5. caps04

    caps04 Member

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    I read somewhere that in a head-on collision, the speeds are not added to calculate the impact. So it's not 70+70 = hitting a wall at 140 MPH. In fact if your car is slightly heavier than the oncoming car as in this case and both are going at the same speed, it might be even slower than hitting a wall at 70 MPH because the "wall" would move/buckle a bit.
     
  6. Sir Guacamolaf

    Sir Guacamolaf The good kind of fat

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    "Grabor was pronounced dead at the scene. Patel was treated at the scene for his injuries."

    ... seriously, if you can afford to drive a Model S, why wouldn't you. Assuming you keep your car for 8-10 years, what are your odds of being in an accident in 8-10 years? And in this case, the Model S driver was not at fault. No matter how careful you are, there are plenty of other idiots on the road.
     
  7. InsaneDriver

    InsaneDriver Member

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    Sad story at the end of the day. There have been a lot of wrong way accidents in South Florida over the last 12 months but no one walked away.

    The pictures looked like the Tesla driver was able to open his door and walk out vs being cut out. Simply amazing in an accident of that magnitude.
     
  8. sorka

    sorka Active Member

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    Sorry, but the 2008 Cobalt curb weight is 3216 lbs which is still crazy light for a sedan, but let's get our facts straight please.
     
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  9. sorka

    sorka Active Member

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    If both cars weigh the same, and bot are traveling 70 MPH, then it is exactly like hitting the same car 140 mph with the other car sitting at 0. If the brick wall doesn't move but the car you hit does, then hitting the brick wall will be worse. But some brick walls are thin and you'll go right through them which would be better.
     
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  10. sorka

    sorka Active Member

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    Treated at the scene means the Tesla driver didn't even go to the hospital while the other driver was killed. What a massive difference in safety.
     
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  11. supratachophobia

    supratachophobia Active Member

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    Just thought I'd include a link to the type of freeway interchange at work.

    Imgur: The most awesome images on the Internet

    I'm told it's a "diamond interchange". Right before you go over the bridge, you change directions and move to the other side of the road. Then when you get to the other side, it reverses back. Having driven that exact road, it is *possible* for a driver to not obey the two dozen signs and end up making a hard turn to get on the freeway in the wrong direction.
     
  12. pmadflyer

    pmadflyer Member

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    Not quite, if two similar vehicles collide head on, they will both absorb energy in such a way that it is like a single car impacting a non -deforming object at 70. In theory, the Model S crumple zone helps the other vehicle also. In practice, the other vehicle is so poorly build (compared) that it will be destroyed anyways.
     
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  13. supratachophobia

    supratachophobia Active Member

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    Looking at the other car, the S basically drove through the other car. Unfortunately, the skateboard design of the battery pack appears to have acted like a knife.
     
  14. McRat

    McRat Active Member

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    No, it's not like hitting a wall at 140mph, but it's like hitting a car at 140mph. Avoid hitting immovable objects at all costs, those crashes are really nasty.

    Think about this way. 2 cars. One moving 140 mph and one parked. Does the parked act like a 0 mph collision? Or does the 140mph car act like 70 mph? Do other ratios, 100/40 80/60 10/130, etc, does it change things?

    Everything is relative. Hit a parked car in the grill in at 140, and both drivers get the effect of the speed. Two cars hitting at 70 acts the same. It's really apparent when you see a relatively slow head on impact. Even 25 mph head on destroys both cars.

    Trivia - 90% of fatal crashes are at 45 mph or less! People wonder why crash testing is done at such low speeds. It because higher speeds are seldom survivable.

    http://mpainesyd.com/idisk/Public/carsafety/paine_impact_speeds_jan07.pdf
     
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  15. SCW-Greg

    SCW-Greg Active Member

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    I'm sorry I was off a few pounds 2815-3001 lbs (wiki). Looked to be a convertible so I rounded down. I should have calculated for that.
    Chevrolet Cobalt SS - Wikipedia, the free encyclopedia

    Of course the rest of the world will understand the point.
     
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  16. tezzla

    tezzla Member

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    Mythbusters tackled this recently, the physics says it's like hitting a wall at 70mph (not a combined 140mph).
     
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  17. brucet999

    brucet999 Active Member

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    Combined speed means nothing in a head on impact, only in the closing speed as it affects reaction time.

    If two identical cars impact head-on at 60 mph, neither would push the other backward, so their deceleration would be from 60mph to zero in a fraction of a second, same as it would be in the case of one car hitting a concrete abutment at 60 mph; deceleration from 60 to zero in a fraction of a second.

    In this case, we don't really know the collision force because we don't know the respective speeds of the two cars. An alert Tesla driver may have braked (or automatic collision reduction system may have done so) thus reducing velocity. The impaired Cobalt driver may have been driving at less than 60 mph but at 3/5 the mass of the Tesla and with much less capable crush zone built in, the Cobalt would have decelerated at a greater rate, causing greater injury to its driver.
     
  18. McRat

    McRat Active Member

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    They did that experiment wrong as it applies to car vs car. I don't have audio, but i gleaned what they are talking about from the experiment. Sure, they are right when it comes to hitting a concrete abutment.

    One car is not infinitely heavy though. Both react to the impact. Hitting an immovable object is always WAY worse than hitting something that will move on impact.

    1) They should have set one "car" at BDC then dropped the car at 70 at it. You'd watch the stationary car move, simply because everything is relative. That would be a 70 mph car to car impact, like you hit somebody at a stoplight. Both clay blobs would deform equally.

    2) Then they should have done the head to head experiment with both cars moving towards BDC at 70. Both blobs will be equal.

    3) Last they should have left a stationary BDC car, and hit it with a 140 mph car. Both blobs equal.

    Tests 2 and 3 will show equal damage. Test 1 will be far less damage.
     
  19. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

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    No, speeds are not additive like that. You must calculate the kinetic energy that is required to be dissipated.

    KE = 0.5 * m * v^2

    ==> A 3200 lb car @ 70 MPH hitting a 5400 lb car @ 70 MPH:

    Total kinetic energy to dissipate = [0.5 * 1451.4 kg * 31.29^2 m^2/s^2] + [0.5 * 2449.39 kg * 31.29^2 m^2/s^2]

    = 1.91 MJ


    ==> A 3200 lb car @ 140 MPH hitting a stationary wall:

    Total kinetic energy to dissipate = [0.5 * 1451.49 kg * 62.58^2 m^2/s^2]

    = 2.84 MJ


    In addition, if the stationary wall does not deform, you must dissipate 2.84 MJ of energy using only 3200 lbs of material, whereas in the 2-car collision, you only need to dissipate 1.91 MJ of energy, and have 8600 lbs of material to do it.


    In this case, the Tesla's aluminum construction, crumple zones, and stability of the skateboard platform very efficiently dissipated much of the energy of the collision. The Chevy Cobalt could not at all dissipate this amount of energy, much of which was transferred to its driver. Tragic and unfortunate.
     
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  20. Caligula

    Caligula Member

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    Convertible versions of vehicles typically weigh considerably more than their hard top counterparts due to the need for added frame bracing, etc.
     

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