Coalition casualties for september

Peter Skelton wrote:

:On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
:
:Sure it will, but it's from the lubrication of the water reducing
:the friction between the wheels and the rail, not hydroplaning.
:
:There is a difference between lubrication and hydroplaning?
:Aren't they different aspects of the same thing?

Actually, this is true. Hydroplaning is actually a lubrication
phenomenon. We don't generally consider it 'hydroplaning' when it is
a braking phenomenon, though.

At least I don't think we do. :-)


--
"It's always different. It's always complex. But at some point,
somebody has to draw the line. And that somebody is always me....
I am the law."
-- Buffy, The Vampire Slayer

Fred J. McCall wrote:

Peter Skelton wrote:

:On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
:
:Sure it will, but it's from the lubrication of the water reducing
:the friction between the wheels and the rail, not hydroplaning.
:
:There is a difference between lubrication and hydroplaning?
:Aren't they different aspects of the same thing?

Actually, this is true. Hydroplaning is actually a lubrication
phenomenon. We don't generally consider it 'hydroplaning' when it is
a braking phenomenon, though.

At least I don't think we do. :-)

I don't either...you need speed to get the conditions that
constitute hydroplaning. You aren't required to be above any
particular speed to cause 'sliding' with a lubricant like grease
so I don't think that it's the same thing at all.
--

-Gord.

In article , "GordBeaman" says...

Sure it will, but it's from the lubrication of the water reducing
the friction between the wheels and the rail, not hydroplaning.

Well, as long as you don't have the wrong kind of leaves.....

Cheers,
dba

"Gord Beaman" ) wrote:

:Fred J. McCall wrote:
:
:Peter Skelton wrote:
:
::On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
: ::
::Sure it will, but it's from the lubrication of the water reducing
::the friction between the wheels and the rail, not hydroplaning.
::
::There is a difference between lubrication and hydroplaning?
::Aren't they different aspects of the same thing?
:
:Actually, this is true. Hydroplaning is actually a lubrication
:phenomenon. We don't generally consider it 'hydroplaning' when it is
:a braking phenomenon, though.
:
:At least I don't think we do. :-)
:
:I don't either...you need speed to get the conditions that
:constitute hydroplaning. You aren't required to be above any
articular speed to cause 'sliding' with a lubricant like grease
:so I don't think that it's the same thing at all.

Although actually it is probably easier to 'grease-o-plane' than it is
to hydroplane, given the viscosity of the stuff. As I understand it
(which is at a pretty basic level - apparently this is an immensely
complex subject when you start looking at the mechanisms) we refer to
hydroplaning (non-boat type) when a vehicle which has freely rolling
contact with another surface is going sufficiently fast that it
essentially 'traps' a thin layer of water (or whatever) between the
surface of its wheels/tires and the surface it is rolling across by
essentially exceeding the speed with which the lubricant can flow out
from under the wheels. Poorly stated, but what it amounts to is that
the lubricant doesn't have the chance to flow out from under the
wheels/tires before the vehicle has moved on to the next bit of
surface.

I used to think this was a surface tension sort of effect when I was
young, but apparently it is not. For tired vehicles, other than sheer
speed the biggest determinant is inflation pressure of the tires.
Lower inflation pressures for the same weight vehicle allow a larger
surface area of the tire to come in contact with the surface being
traveled across. This means the lubricant fluid (water, in the case
we normally think of) must essentially flow out from under a larger
surface area for the tire to make contact with the pavement. This is
why tread patterns CAN help, if they provide channels for the water to
flow out from under the road contact surfaces. Large decreases in
vehicle weight can also make this much worse, as they lower the
pressure forcing the lubricant out from between the tire and the
roadway.

The preceding is why commercial airline pilots are taught that
hydroplaning is a function of aircraft speed, tire inflation pressure,
and gross vehicle weight (because the difference between loaded weight
and unloaded weight can be an appreciable percentage of the weight of
the vehicle).

[So now everyone can tell me how I'm wrong. :-)]

On Sat, 25 Oct 2003 02:12:12 GMT, "Gord Beaman"
) wrote:

Peter Skelton wrote:

On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
) wrote:

"Duke of URL" macbenahATkdsiDOTnet wrote:

"charles krin" wrote in message
m
On Fri, 03 Oct 2003 17:56:05 GMT, "Gord Beaman"
) wrote:
"Brian Sharrock" wrote:

Now, go and check your tire pressures before the next rain shower.

Yep that's right...we used to use "nine times the sq root of the
tire pressure" for the onset of hydroplaning, which is about
right...you ever think about where a steel wheel rolling on a
flat steel surface will hydroplane?...

follow ups trimmed...
I doubt that the rail road rolling stock has much problem with
hydroplaning...

It actually is a serious consideration when the rails are underwater,
as happens frequently out here in the Plains when we get heavy rain.
Engineers have to be aware that it's going to take longer than usual
to come to a stop.


Sure it will, but it's from the lubrication of the water reducing
the friction between the wheels and the rail, not hydroplaning.

There is a difference between lubrication and hydroplaning?
Aren't they different aspects of the same thing?

Peter Skelton

I see that quite a number answered this so I'll just give my gut
reaction to your suggestion Peter. I feel that it isn't
hydroplaning because speed isn't required to start the process.
The wheel will 'slide' on the rail just as easily no matter how
slowly it's being moved, therefore it's not the 'pressure' of the
wedge of fluid 'lifting the wheel' but the molecules of the
lubricant that's filling the dips and valleys between the two
surfaces that's reducing the friction.

That is not correct. Speed is a factor.

Peter Skelton

On Fri, 24 Oct 2003 12:08:54 -0500, "Duke of URL"
macbenahATkdsiDOTnet wrote:

"charles krin" wrote in message

On Fri, 03 Oct 2003 17:56:05 GMT, "Gord Beaman"
) wrote:
"Brian Sharrock" wrote:

Now, go and check your tire pressures before the next rain shower.

Yep that's right...we used to use "nine times the sq root of the
tire pressure" for the onset of hydroplaning, which is about
right...you ever think about where a steel wheel rolling on a
flat steel surface will hydroplane?...

follow ups trimmed...
I doubt that the rail road rolling stock has much problem with
hydroplaning...

It actually is a serious consideration when the rails are underwater,
as happens frequently out here in the Plains when we get heavy rain.
Engineers have to be aware that it's going to take longer than usual
to come to a stop.


I agree, but I doubt that this is a result of traditional
hydroplaning...but rather as a lesser level of 'lubrication' between
the rail and wheel...

ck
--
The Ten Commandments display was removed from the Alabama Supreme Court
building, But here was a good reason for the move.*

You can't post "Thou Shalt Not Steal" in a building full of lawyers and
politicians without creating a hostile work environment.

Edna H. on alt.books.m-lackey, 20030930

Peter Skelton wrote:

On Sat, 25 Oct 2003 02:12:12 GMT, "Gord Beaman"
) wrote:

Peter Skelton wrote:

On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
) wrote:

"Duke of URL" macbenahATkdsiDOTnet wrote:

"charles krin" wrote in message
om
On Fri, 03 Oct 2003 17:56:05 GMT, "Gord Beaman"
) wrote:
"Brian Sharrock" wrote:

Now, go and check your tire pressures before the next rain shower.

Yep that's right...we used to use "nine times the sq root of the
tire pressure" for the onset of hydroplaning, which is about
right...you ever think about where a steel wheel rolling on a
flat steel surface will hydroplane?...

follow ups trimmed...
I doubt that the rail road rolling stock has much problem with
hydroplaning...

It actually is a serious consideration when the rails are underwater,
as happens frequently out here in the Plains when we get heavy rain.
Engineers have to be aware that it's going to take longer than usual
to come to a stop.


Sure it will, but it's from the lubrication of the water reducing
the friction between the wheels and the rail, not hydroplaning.

There is a difference between lubrication and hydroplaning?
Aren't they different aspects of the same thing?

Peter Skelton

I see that quite a number answered this so I'll just give my gut
reaction to your suggestion Peter. I feel that it isn't
hydroplaning because speed isn't required to start the process.
The wheel will 'slide' on the rail just as easily no matter how
slowly it's being moved, therefore it's not the 'pressure' of the
wedge of fluid 'lifting the wheel' but the molecules of the
lubricant that's filling the dips and valleys between the two
surfaces that's reducing the friction.

That is not correct. Speed is a factor.

Peter Skelton

Speed is a factor in what?...hydroplaning?, of course it is, in
the case of a wheel losing traction because of the action of a
lubricant?, no it isn't.
--

-Gord.

Fred J. McCall wrote:


The preceding is why commercial airline pilots are taught that
hydroplaning is a function of aircraft speed, tire inflation pressure,
and gross vehicle weight (because the difference between loaded weight
and unloaded weight can be an appreciable percentage of the weight of
the vehicle).

[So now everyone can tell me how I'm wrong. :-)]


Well, I believe you 'are' wrong in only one little area here. The
Canadian Armed Forces taught that the only thing that had a
bearing on hydroplaning speed was the tire pressure when there
was sufficient water depth available.

Aircraft weight has no bearing because weight governs the tire
pressure and size. The magic figure is "Nine times the square
root of the tire pressure". Both the USAF and the RCAF believe
that and that's plenty good enough for me sir.

If you ever convince them both that they're wrong then please
have them send me letters of abject apology.

Hell, I'll even accept a mousey little 'oops'.


--

-Gord.

On Sat, 25 Oct 2003 22:48:27 GMT, "Gord Beaman"
) wrote:

Peter Skelton wrote:

On Sat, 25 Oct 2003 02:12:12 GMT, "Gord Beaman"
) wrote:

Peter Skelton wrote:

On Fri, 24 Oct 2003 19:04:01 GMT, "Gord Beaman"
) wrote:

"Duke of URL" macbenahATkdsiDOTnet wrote:

"charles krin" wrote in message
news:rkaipvsmq6dtiqib9018j1isgelcffr0m3@4ax. com
On Fri, 03 Oct 2003 17:56:05 GMT, "Gord Beaman"
) wrote:
"Brian Sharrock" wrote:

Now, go and check your tire pressures before the next rain shower.

Yep that's right...we used to use "nine times the sq root of the
tire pressure" for the onset of hydroplaning, which is about
right...you ever think about where a steel wheel rolling on a
flat steel surface will hydroplane?...

follow ups trimmed...
I doubt that the rail road rolling stock has much problem with
hydroplaning...

It actually is a serious consideration when the rails are underwater,
as happens frequently out here in the Plains when we get heavy rain.
Engineers have to be aware that it's going to take longer than usual
to come to a stop.


Sure it will, but it's from the lubrication of the water reducing
the friction between the wheels and the rail, not hydroplaning.

There is a difference between lubrication and hydroplaning?
Aren't they different aspects of the same thing?

Peter Skelton

I see that quite a number answered this so I'll just give my gut
reaction to your suggestion Peter. I feel that it isn't
hydroplaning because speed isn't required to start the process.
The wheel will 'slide' on the rail just as easily no matter how
slowly it's being moved, therefore it's not the 'pressure' of the
wedge of fluid 'lifting the wheel' but the molecules of the
lubricant that's filling the dips and valleys between the two
surfaces that's reducing the friction.

That is not correct. Speed is a factor.

Peter Skelton

Speed is a factor in what?...hydroplaning?, of course it is, in
the case of a wheel losing traction because of the action of a
lubricant?, no it isn't.

Speed is a factor in the ease of slippage of a rail car wheel on
a wet track.

Peter Skelton

"Gord Beaman" ) wrote:

:Fred J. McCall wrote:
:
:
:The preceding is why commercial airline pilots are taught that
:hydroplaning is a function of aircraft speed, tire inflation pressure,
:and gross vehicle weight (because the difference between loaded weight
:and unloaded weight can be an appreciable percentage of the weight of
:the vehicle).
:
:[So now everyone can tell me how I'm wrong. :-)]
:
:Well, I believe you 'are' wrong in only one little area here. The
:Canadian Armed Forces taught that the only thing that had a
:bearing on hydroplaning speed was the tire pressure when there
:was sufficient water depth available.
:
:Aircraft weight has no bearing because weight governs the tire
ressure and size. The magic figure is "Nine times the square
:root of the tire pressure". Both the USAF and the RCAF believe
:that and that's plenty good enough for me sir.

Yes, that probably is good enough for you. It is not, however, the
actual truth, but rather a useful rule of thumb that holds pretty
closely for most circumstances.

The airlines disagree. So do the folks who study this sort of thing,
whose simulation tools tend to go down to all the very small effects.
Even the bias of the tire belting and how the cords are constructed
has an effect.

:If you ever convince them both that they're wrong then please
:have them send me letters of abject apology.
:
:Hell, I'll even accept a mousey little 'oops'.

I'd suggest they need to take it up with commercial airlines, which
disagree with them and include weight in their gross approximation,
since the typical aircraft that they operate can change weight quite
drastically in the normal course of operations.

--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw