Wayne.B wrote:

Take a look at flow patterns through props some time. You're
assuming that all the flow past the rudder (when on the suction
side) is parallel to the keel (center) line, as it *basically* is
on the discharge side.

The intake side of the prop, however, has a cone-shaped intake
pattern, with the prop at the apex. If the rudder is at an angle
to the centerline, flow will take the path of least resistance,
and to the extent that there is impact pressure on the rudder side
with the highest aspect ratio, this will just cause
disproportionate flow around the other side, increasing impact
pressure on that side, until an equilibrium is reached. Once past
the rudder, the flow resumes its 'along the centerline' flow, so
there is no net deflection, and all 'thrust' is parallel to the
centerline.

Keith Hughes

If flow deflection takes place (rudder at angle to flow), a force is
exerted. Old news to everyone, Nobel prize not likely.

okay, yo-yo. which WAY is the rudder deflected if it is pushed to port?

please explain your reasoning.

the water pressure on either side of a rudder is the same for water drawn
over
the rudder.
====================

Only if the rudder is parallel to the direction of flow. At an angle
to the flow, water is deflected, momentum is changed, force is
created. It's not very much force in reverse, not enough to be useful
for maneuvering, but a force nevertheless.

wtf are you talking about? it's awfully early in the day to be so incoherant
from alcohol.

Intuitively, most people sense that water "pulled" over a rudder will cause
a
rudder to change direction of a boat in much the same way as water "pushed"
over a rudder does. However, intuition misses some things along the way.
[...]
end) to port. However, the water drawn over the rudder's port side hits
that
side and is deflected towards port. Then the rudder would push the boat
(after end) to starboard. And equal and opposite reaction. Net, net, the
boat
does not turn. The pressure on each side of the rudder is equal. Nada.


Jox, since you're such an "expert" on Feynman inverse sprinkler problem
and how to misapply it to any situation, maybe you can answer a question
about it. While it's true that the sprinkler won't turn when water is
being sucked in, it's not true that no net force is generated by sucking
the water in. In fact, there is a net force generated. It's just not
in a direction that will turn the sprinkler.

In relation to your discussion about about equal and opposite, net net,
no net force, etc., how do you reconcile that with the fact that it's
not true for the inverse sprinkler problem?

Steve

nice, Keith.

Wayne.B wrote:

Take a look at flow patterns through props some time. You're
assuming that all the flow past the rudder (when on the suction
side) is parallel to the keel (center) line, as it *basically* is
on the discharge side.

The intake side of the prop, however, has a cone-shaped intake
pattern, with the prop at the apex. If the rudder is at an angle
to the centerline, flow will take the path of least resistance,
and to the extent that there is impact pressure on the rudder side
with the highest aspect ratio, this will just cause
disproportionate flow around the other side, increasing impact
pressure on that side, until an equilibrium is reached. Once past
the rudder, the flow resumes its 'along the centerline' flow, so
there is no net deflection, and all 'thrust' is parallel to the
centerline.

Keith Hughes

If flow deflection takes place (rudder at angle to flow), a force is
exerted. Old news to everyone, Nobel prize not likely.

On Mon, 29 Mar 2004 08:59:59 -0700, Keith Hughes
wrote:
this will just cause
disproportionate flow around the other side, increasing impact
pressure on that side, until an equilibrium is reached. Once past
the rudder, the flow resumes its 'along the centerline' flow, so
there is no net deflection, and all 'thrust' is parallel to the
centerline.

======================================

Point taken and understood. I was assuming a starting condition with
the rudder parallel to an established flow, and then turned at an
angle causing a deflection and small side force. Given the general
weakness of the flow and somewhat unfocused direction, it's quite
believable that an equilibrium could be reached. Until that happens
I'm still convinced that a small amount of deflection and force would
be produced, similar to what the good professor at MIT observed with
his fan.

similar to what the good professor at MIT observed with
his fan.

what the "good professor at MIT observed" was that starting with an an empty
tube there was a tiny movement until the tube filled.

wayne, you may have noticed in your travels that water surrounds a boat in the
water, so there is no waiting for the tube to fill.

you are trying to salavage an untenable position.

On 29 Mar 2004 17:33:21 GMT, (JAXAshby) wrote:

wtf are you talking about? it's awfully early in the day to be so incoherant
from alcohol.

Bzzzt!!! Wrong answer jox. Try again. It's clear you don't understand
the sprinkler problem. While you're cogitating on why you're wrong in
applying feynman's sprinkler problem to this arena, here's another,
simpler question for you:

Say you have a wind tunnel with a rudder mounted at the test point.
First case is a blower at one end forcing air though the tunnel and past
the rudder at 1mph. You turn the rudder at a 45 degree angle to the
airflow. Is there a lateral force generated by the rudder?

Second case is a blower at the other end of the tunnel but now it's
sucking air through the tunnel past the rudder at 1mph. You turn the
rudder at a 45 degree angle to the airflow. Is there a lateral force
generated by the rudder?


Intuitively, most people sense that water "pulled" over a rudder will cause
a
rudder to change direction of a boat in much the same way as water "pushed"
over a rudder does. However, intuition misses some things along the way.
[...]
end) to port. However, the water drawn over the rudder's port side hits
that
side and is deflected towards port. Then the rudder would push the boat
(after end) to starboard. And equal and opposite reaction. Net, net, the
boat
does not turn. The pressure on each side of the rudder is equal. Nada.


Jox, since you're such an "expert" on Feynman inverse sprinkler problem
and how to misapply it to any situation, maybe you can answer a question
about it. While it's true that the sprinkler won't turn when water is
being sucked in, it's not true that no net force is generated by sucking
the water in. In fact, there is a net force generated. It's just not
in a direction that will turn the sprinkler.

In relation to your discussion about about equal and opposite, net net,
no net force, etc., how do you reconcile that with the fact that it's
not true for the inverse sprinkler problem?

Steve

schlackoff, you are using a constrained airflow? know what that means? know
how it is different from unconstrained.

get some sleep, schlackoff, and you will feel better by tomorrow afternoonn.

wtf are you talking about? it's awfully early in the day to be so
incoherant
from alcohol.

Bzzzt!!! Wrong answer jox. Try again. It's clear you don't understand
the sprinkler problem. While you're cogitating on why you're wrong in
applying feynman's sprinkler problem to this arena, here's another,
simpler question for you:

Say you have a wind tunnel with a rudder mounted at the test point.
First case is a blower at one end forcing air though the tunnel and past
the rudder at 1mph. You turn the rudder at a 45 degree angle to the
airflow. Is there a lateral force generated by the rudder?

Second case is a blower at the other end of the tunnel but now it's
sucking air through the tunnel past the rudder at 1mph. You turn the
rudder at a 45 degree angle to the airflow. Is there a lateral force
generated by the rudder?


Intuitively, most people sense that water "pulled" over a rudder will
cause
a
rudder to change direction of a boat in much the same way as water
"pushed"
over a rudder does. However, intuition misses some things along the way.
[...]
end) to port. However, the water drawn over the rudder's port side hits
that
side and is deflected towards port. Then the rudder would push the boat
(after end) to starboard. And equal and opposite reaction. Net, net, the
boat
does not turn. The pressure on each side of the rudder is equal. Nada.


Jox, since you're such an "expert" on Feynman inverse sprinkler problem
and how to misapply it to any situation, maybe you can answer a question
about it. While it's true that the sprinkler won't turn when water is
being sucked in, it's not true that no net force is generated by sucking
the water in. In fact, there is a net force generated. It's just not
in a direction that will turn the sprinkler.

In relation to your discussion about about equal and opposite, net net,
no net force, etc., how do you reconcile that with the fact that it's
not true for the inverse sprinkler problem?

Steve

On 29 Mar 2004 23:27:42 GMT, (JAXAshby) wrote:

schlackoff, you are using a constrained airflow? know what that means? know
how it is different from unconstrained.

Interesting that you think it makes a difference. Ok, try it again but
this time with a theoretical infinitely sized wind tunnel, or a physical
one large enough that the difference between constrained flow and
unconstrained flow is negligable, like a 1 mile diameter wind tunnel and
a 1" rudder. In one case the air in an infinite wind tunnel is being
pushed at 1mph past the rudder and in the other case it's being drawn
past the rudder at 1mph. In both cases, air is flowing past the rudder
at 1mph and the rudder is at a 45 degree angle. Does the rudder
generate a lateral force in both cases?

Steve

wtf are you talking about?

Bzzzt!!! Wrong answer jox. Try again. It's clear you don't understand
the sprinkler problem. While you're cogitating on why you're wrong in
applying feynman's sprinkler problem to this arena, here's another,
simpler question for you:

Say you have a wind tunnel with a rudder mounted at the test point.
First case is a blower at one end forcing air though the tunnel and past
the rudder at 1mph. You turn the rudder at a 45 degree angle to the
airflow. Is there a lateral force generated by the rudder?

Second case is a blower at the other end of the tunnel but now it's
sucking air through the tunnel past the rudder at 1mph. You turn the
rudder at a 45 degree angle to the airflow. Is there a lateral force
generated by the rudder?


Intuitively, most people sense that water "pulled" over a rudder will
cause
a
rudder to change direction of a boat in much the same way as water
"pushed"
over a rudder does. However, intuition misses some things along the way.
[...]
end) to port. However, the water drawn over the rudder's port side hits
that
side and is deflected towards port. Then the rudder would push the boat
(after end) to starboard. And equal and opposite reaction. Net, net, the
boat
does not turn. The pressure on each side of the rudder is equal. Nada.


Jox, since you're such an "expert" on Feynman inverse sprinkler problem
and how to misapply it to any situation, maybe you can answer a question
about it. While it's true that the sprinkler won't turn when water is
being sucked in, it's not true that no net force is generated by sucking
the water in. In fact, there is a net force generated. It's just not
in a direction that will turn the sprinkler.

In relation to your discussion about about equal and opposite, net net,
no net force, etc., how do you reconcile that with the fact that it's
not true for the inverse sprinkler problem?

Steve

steve, consider just where the air on the "supply side" of the fan blades come
from and consider how that differs from the air on the "demand side". the
demand side is more or less a stream that expands. the supply side is more
like a hemi-sphere of air (actually, air from the demand side passes back to
the supply side as each blade of the fan passes, i.e. tip vortices).

Consider, also, that *if* fluid drawn over a rudder by a prop have any effect
on the rudder, mariners would all know which direction the stern moved with
which rudder position. Even the guys who insist pulled water affects a rudder
don't have a clew which way the boat turns. indeed, the "good professor" was
reduced to claiming that friction in the rudder bearin made the difference.

schlackoff, you are using a constrained airflow? know what that means?
know
how it is different from unconstrained.

Interesting that you think it makes a difference. Ok, try it again but
this time with a theoretical infinitely sized wind tunnel, or a physical
one large enough that the difference between constrained flow and
unconstrained flow is negligable, like a 1 mile diameter wind tunnel and
a 1" rudder. In one case the air in an infinite wind tunnel is being
pushed at 1mph past the rudder and in the other case it's being drawn
past the rudder at 1mph. In both cases, air is flowing past the rudder
at 1mph and the rudder is at a 45 degree angle. Does the rudder
generate a lateral force in both cases?

Steve

wtf are you talking about?

Bzzzt!!! Wrong answer jox. Try again. It's clear you don't understand
the sprinkler problem. While you're cogitating on why you're wrong in
applying feynman's sprinkler problem to this arena, here's another,
simpler question for you:

Say you have a wind tunnel with a rudder mounted at the test point.
First case is a blower at one end forcing air though the tunnel and past
the rudder at 1mph. You turn the rudder at a 45 degree angle to the
airflow. Is there a lateral force generated by the rudder?

Second case is a blower at the other end of the tunnel but now it's
sucking air through the tunnel past the rudder at 1mph. You turn the
rudder at a 45 degree angle to the airflow. Is there a lateral force
generated by the rudder?


Intuitively, most people sense that water "pulled" over a rudder will
cause
a
rudder to change direction of a boat in much the same way as water
"pushed"
over a rudder does. However, intuition misses some things along the
way.
[...]
end) to port. However, the water drawn over the rudder's port side hits
that
side and is deflected towards port. Then the rudder would push the
boat
(after end) to starboard. And equal and opposite reaction. Net, net,
the
boat
does not turn. The pressure on each side of the rudder is equal. Nada.


Jox, since you're such an "expert" on Feynman inverse sprinkler problem
and how to misapply it to any situation, maybe you can answer a question
about it. While it's true that the sprinkler won't turn when water is
being sucked in, it's not true that no net force is generated by sucking
the water in. In fact, there is a net force generated. It's just not
in a direction that will turn the sprinkler.

In relation to your discussion about about equal and opposite, net net,
no net force, etc., how do you reconcile that with the fact that it's
not true for the inverse sprinkler problem?

Steve