hydroplaning
Lawrence C Leung
l.leung at juno.com
Wed Jan 31 19:23:28 EST 2001
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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