hydroplaning

[Lawrence C Leung]

Works about right fo me.

LL - NY

On Tue, 30 Jan 2001 19:35:25 -0500 Patrick Austin <paanta at yahoo.com>
writes:
>>
>>How can that be if the weight of the car or the tire pressure hasn't
>changed.  A wider tire only changes the shape of the contact patch, 
>not its
>total area.
>
>Well, think of it this way:
>If it takes more power to remove the water than it does to support 
>the
>weight of the car on that cushion of water, then the car will 
>hydroplane.  
>
>Say you've got a contact patch, moving through the water at a 
>constant
>velocity, V.   The total water moved per unit time is proportional to 
>V
>times the width of the contact patch times the depth of the water.  
>The
>length of the contact patch doesn't matter here, because once the 
>water is
>gone, it doesn't take any power to keep it out of the "hole" left by 
>the
>tire.  Anyway, the contact patch doesn't change size, but it DOES 
>become
>more narrow when you go to a skinny tire.  So, it takes less power to 
>move
>all that water aside...so the car has to move faster to float on the 
>water.
> It's like a boat planing.
>
>Correct me if I'm wrong.  I just came up with that right now, so it 
>may be
>entirely bullshit..I'm a manufacturing engineer, not a mechanical
>engineer...I've never taken a fluids course.  However, I _think_ it 
>makes
>sense. :)
>
>  
>						**************
>						Patrick Austin
>						paanta at bu.edu
>						(617)782-9115
>						**************
>
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