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more aerodynamic = more rocks hitting windshield

Discussion in 'Gen 2 Prius Main Forum' started by starla30, Apr 26, 2004.

  1. starla30

    starla30 New Member

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    A rock recently flew up and hit my windshield putting a lovely spider-web type crack a little over a half inch wide on the lower middle. :cry: A friend at work did some sleuthing and discovered that the more aerodynamic a car gets, the more prone it is to rocks flying up and hitting the windshield. This would explain a lot as my stepmother has been complaining that Toyota seems to be getting more prone to this than it used to. She's a longtime Toyota customer. Of course now we know it's not Toyota but the trend of cars getting more aerodynamic. I thought I should warn you guys seeing as the Prius excels in this area.
     
  2. jasond

    jasond New Member

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    Just fyi, the windshield is an important structural piece of the car. If the crack goes all the way through the glass, you should get it fixed or replaced if possible. Cracks all the way through the glass seem to spread over time anyway, so you'd need to replace it sooner or later -- better to do it sooner.
     
  3. paulisme

    paulisme New Member

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    Man, that sucks.

    By the way, has anyone noticed that the Prius' windshield is almost completely flat? I just thought it was kinda strange compared to other cars I've driven.
     
  4. randalla

    randalla Member

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    A number of insurance companies will have your windshield repaired or replaced (including mine: Geico) at no charge to the customer!
     
  5. efusco

    efusco Moderator Emeritus
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    So the rocks sense an aerodynamic car coming, and as it approaches they fly up and hit them in the windshield?! :wink:

    Ok, seriously, I know what you're trying to say, but I think this makes no sense at all. I'd like to see the results of your friend's 'sleuthing'--particularly if it's an honestly good reference.

    What DOES make sense on the surface is that 1)More aerodynamic cars have smaller percentage of the vehicle hitting the oncoming wind. 2)Thereby reducing the functional surface area, 3)thereby having a LOWER chance of being hit by said random flying rocks.

    Lighter objects that would stay in the airstream would be LESS likely to hit the car (i.e. bugs), but I don't think the converse is likely to be true--that heavier objects are more likely to strike. I think you're having a little bad luck and if you were driving any other car at that exact time in that exact place and that exact rock flew up in the exact same way it would have had the exact same result--a cracked windshield in the other car.

    Again, I'm not completely closed minded to this and if someone can show me scientificly/mathematically how this could be true (more aerodynamic more likely to take rock hits) then I'll conceed. Until then I think your friend's sleuthing is hooy.
     
  6. jasond

    jasond New Member

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    Just speculation...

    Perhaps they get hit by rocks less often, but are more prone to cracking when hit? Due to the steep angle or something like that?
     
  7. starla30

    starla30 New Member

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    I think the theory is that the hood is smaller and smoother and thus little protection from rocks. In a huge square car there's a lot more metal between the road and the windshield. In the Prius, well that's obviously not the case. ;)

    I misremembered where I got this information from. It was actually a different friend at work who told me his mother experienced 2 such rock incidents with her newish car and it was the glass autoshop who explained about rocks and aerodynamic cars.
     
  8. mikepaul

    mikepaul Senior Member

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    I'd say the non-aerodynamic car 'breaking' through the atmosphere creates it's own protective pressure cushion/barrier, where large objects are deflected more.

    Aerodynamic cars are less or un-protected, since the cushion is almost non-existent as it slides through the air.

    Or maybe not...
     
  9. xlarimer

    xlarimer New Member

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    I think surface area is just surface area.

    If an aerodymanic car gets hit more than a non aerodynamic car, I'd be amazed. Maybe it has to do with bigger surface area windscreens get hit more than smaller area surface area?

    What would be a good test? VW New Bettle vs Audi TT?
     
  10. oxnardprof

    oxnardprof Member

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    I agree with efusco. I don't understand why the aerodynamic windshield of any type is MORE prone to cracks or being hit by stones. If the stone is small enough to be carried by the airstreams, then the aerodynamic windshield would be less likely to be struck, since small stones would be carried along with the air.

    I imagine that a equal size (in square feet) windshield that is at right angles to the air would be more likely to be struck.

    Another thing to consider would be the height off the ground. Maybe a windshield close to the ground will more likely be struck, since the stones fly up in the air, and then down. ?More stones would be closer to the ground?

    Anyway, this is fun to think about.

     
  11. starla30

    starla30 New Member

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    Maybe the glass guy was wrong about aerodynamic cars being more prone to rock hits. I have no idea. But it does seem like newer cars get cracks in the windshield more often. The question is why?
     
  12. PriusDreamer

    PriusDreamer Member

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    What does make sense (although I'm not sure that it is the correct answer) is the windshield is extremely large (due to the nature of making the car more aerodynamic), therefore more prone to actually being struck. Hence more cracked windshields.
     
  13. bigbaldcuban

    bigbaldcuban New Member

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    Gremlins. It's those damn Gremlins
     
  14. aarons12

    aarons12 New Member

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    just for clarification, it's not that the insurance company just feels like they should replace your glass... it's that in many states, the comprehensive (also known as 'other than collision') coverage includes the availability of 'full glass coverage'. really it's just a buyback of whatever deductible you carry on damage to the car.

    since glass is either broken or it's not (no such thing as a 'partially broken' windshield or window), it doesn't really pay to apply a deductible, which is designed to avoid the expense of settling smaller claims. the companies find it convenient to negotiate massive deals with the glass companies, with favorable pricing schedules.

    so in the end, to the consumer, it just seems like you call your insurance carrier, or some toll free number they give you, and 'they' replace the windshield. a system that works.
     
  15. m4prius

    m4prius New Member

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    Get the small penny sized spider web crack spot fixed before it starts to crack further... then you will need to get the entire windshield replaced!!! :cussing: ...I believe the Prius uses a special tint and heat reflective glass, right now with limited availbility of parts I would try to get it spot fixed as soon as possible.

    May I suggest that the greater the slope of the windshield (more aerodynamic) the less likely that breaking damage occurs since the force is not normal to the surface. A force hitting normal to the surface will generate the most force (think of a golf club face). I think what your seeing in real life is more trucks on the road without mud guards and they then to throw more stuff at the low profile cars...I bet that big SUVs following our low profile cars see less damage from our cars since a good part of the tire is covered and if we do throw stuff it must fly higher to hit the SUVs windshield. :mrgreen:

    Mike
     
  16. jasond

    jasond New Member

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    When I had my windshield cracked on my old car, I called up the autoglass place, and they did all the paperword with the insurance company. I never even had to call the insurance folks.

    Some glass companies have vans that will come to your home/office, replace the windshield, and then drive off...
     
  17. starla30

    starla30 New Member

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    I've put off the call to the glass place way too long. This happened almost 3 weeks ago. I'll try to straighten it out tomorrow. Thanks for the advice.
     
  18. fred

    fred New Member

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    its funny that this subject comes up. i noticed that when i first got my car that things that would fly over my little benz and other cars ive owned seemed to be attracted to my hood! for instance the first day i took smiley out on the highway a tractor trailer sent a huge piece of cardboard up into the air and smack onto my little hood and winshield. although this is just antedotal i think that the lack of a hood compared to other cars keeps the air around the front from forming a dam and pushing things away like most cars do. anyone else have that feeling.?
     
  19. fred

    fred New Member

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    wow just saw my post. my spelling is awful. i meant to say anecdotal.geeeeshhhh!
     
  20. xlarimer

    xlarimer New Member

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    If the amount of air moving over the front of the hood moves a particle out of the way, it isn't something you should be all that worried about in the first place.

    It is the particles that arc up and coming directly down at you or the direct shot from whatever sent it off (a truck tire.) A wind dam (unless you can get your car to do Mach 1...and then I wanna know what you modded!) won't do too much to save the ding.