Rod Dynamics ?

daytripper typed:
On Tue, 7 Nov 2006 07:47:36 -0500, "Robert11"
wrote:

Hello:

Was reading a book on ballistics the other day, and the author was
describing conditions
where a rifle barrel would drop a small amount as a shell was fired.

He used an example that if one held a fly rod rod truly horiz., and
gave the handle a very quick
upward (I think he means backwards; toward ones head) pure rotation,
the tip momentarily goes Downward.

Have my rods away for the season, so can't try it.

Can't visualize this happening.

Does it ?
Why does it, if so ?

B.


I can't see how any downward force vectors at the rod tip increase in
this scenario, so while he's correct that the rod tip will point
below horizontal, it doesn't "drop", it simply lags behind the rest
of the rod movement, establishing an arc...

I s'pose the same thing could happen with rifles, to some (hopefully
vanishingly small) degree...

Are we discussing a slow rifle or medium-fast?
--
TL,
Tim
---------------------------
http://css.sbcma.com/timj/

On Tue, 7 Nov 2006 22:34:04 -0500, "Tim J."
wrote:


daytripper typed:
On Tue, 7 Nov 2006 07:47:36 -0500, "Robert11"
wrote:

Hello:

Was reading a book on ballistics the other day, and the author was
describing conditions
where a rifle barrel would drop a small amount as a shell was fired.

He used an example that if one held a fly rod rod truly horiz., and
gave the handle a very quick
upward (I think he means backwards; toward ones head) pure rotation,
the tip momentarily goes Downward.

Have my rods away for the season, so can't try it.

Can't visualize this happening.

Does it ?
Why does it, if so ?

B.


I can't see how any downward force vectors at the rod tip increase in
this scenario, so while he's correct that the rod tip will point
below horizontal, it doesn't "drop", it simply lags behind the rest
of the rod movement, establishing an arc...

I s'pose the same thing could happen with rifles, to some (hopefully
vanishingly small) degree...

Are we discussing a slow rifle or medium-fast?

A cane rifle, of course...

/daytripper (ya gots to pay attention, son ;-)

daytripper typed:
On Tue, 7 Nov 2006 22:34:04 -0500, "Tim J."
wrote:


daytripper typed:
On Tue, 7 Nov 2006 07:47:36 -0500, "Robert11"
wrote:

Hello:

Was reading a book on ballistics the other day, and the author was
describing conditions
where a rifle barrel would drop a small amount as a shell was
fired.

He used an example that if one held a fly rod rod truly horiz., and
gave the handle a very quick
upward (I think he means backwards; toward ones head) pure
rotation, the tip momentarily goes Downward.

Have my rods away for the season, so can't try it.

Can't visualize this happening.

Does it ?
Why does it, if so ?

B.


I can't see how any downward force vectors at the rod tip increase
in this scenario, so while he's correct that the rod tip will point
below horizontal, it doesn't "drop", it simply lags behind the rest
of the rod movement, establishing an arc...

I s'pose the same thing could happen with rifles, to some (hopefully
vanishingly small) degree...

Are we discussing a slow rifle or medium-fast?

A cane rifle, of course...

Ahhhh, the kind with silk bullets. . . my favorite!

/daytripper (ya gots to pay attention, son ;-)

Hel-LO! This is usenet - you don't have to pay attention to answer posts
as if you're an expert. Not that I've seen, anyway, and I've had some
damn fine teachers.
--
TL,
Tim
---------------------------
http://css.sbcma.com/timj/

Robert He used an example that if one held a fly rod rod truly
Robert horiz., and gave the handle a very quick upward (I think he
Robert means backwards; toward ones head) pure rotation, the tip
Robert momentarily goes Downward.

Robert Does it ?

According to Don Phillips' "The Technology of Fly Rods" (page 87), yes
it does. He says that he demonstrates this by having someone hold a
piece of paper rear of the stroke direction and then initiating a cast
with a rapid pulse (it does not have to be up, sideways will do as
well). If you are interested in this, I think it is relatively easy to
make a convincing experiment to confirm this.

Phillips also says that this phenomenon has practical importance: if
you initiate a cast too quickly, it will cause slack.

Robert Why does it, if so ?

I have some guesses, but since I am not a physicist I will pass and
leave this issue to be resolved by someone more educated.

--
Jarmo Hurri

Commercial email countermeasures included in header email
address. Remove all garbage from header email address when replying,
or just use .

On Wed, 08 Nov 2006 20:59:00 +0200, Jarmo Hurri
wrote:


Robert He used an example that if one held a fly rod rod truly
Robert horiz., and gave the handle a very quick upward (I think he
Robert means backwards; toward ones head) pure rotation, the tip
Robert momentarily goes Downward.

Robert Does it ?

According to Don Phillips' "The Technology of Fly Rods" (page 87), yes
it does. He says that he demonstrates this by having someone hold a
piece of paper rear of the stroke direction and then initiating a cast
with a rapid pulse (it does not have to be up, sideways will do as
well). If you are interested in this, I think it is relatively easy to
make a convincing experiment to confirm this.

Phillips also says that this phenomenon has practical importance: if
you initiate a cast too quickly, it will cause slack.

Robert Why does it, if so ?

I have some guesses, but since I am not a physicist I will pass and
leave this issue to be resolved by someone more educated.

Ok, I just happened to have a 9' 3wt Winston standing up behind my desk, and
next to my glass collection it's the slowest rod I own (even my 2 weights are
faster). I put it together, stood at one end of my office with the rod held
reasonably horizontally, with the tip lined up with a detail feature on a
closet door. Once the rod was steady I gave it a quick wrist-flip to rotate
the rod, while observing the tip.

Whoa! The tip dropped close to a foot before heading upward!
Yikes! How totally non-intuitive, I couldn't have been more wrong.

/daytripper (head-scratching time...)

daytripper wrote:
Yikes! How totally non-intuitive, I couldn't have been more wrong.

Kinda like the ol' helium balloon in a car thing. Weird; but despite
the known physics, you still have to see it to believe it.

Joe F.

What a strange thread. I don't really understand how a fly rod could be
analogous to a rifle barrel, in any sense (except action/re-action). The
comments on the rod forming an arc with the tip following (but not dropping)
makes sense. And...anyone who looks at the physics involved in firing a
bullet i.e. explosion/action/reaction...the force from the explosion pushes
backwards...BUT...the design of the rifle, the way it is held, whether or
not the barrel is ported, are things that are all contributing factors. All
things considered, the shooter and the design of rifles generally tend to
absorb the shock going backwards and also direct it in an upward arc. The
only way I can imagine a rifle barrel dropping is by putting it in some kind
of vise that directs more downward than upward pressure, but that's not how
rifles are held by a shooter nor is it the way rifles are designed (which is
why ports are designed to force gases to exit from the top portion of the
barrel rather that the bottom). I guess, technically, if the barrel was
designed to push backwards with no design to cause it to arc in any
direction...and the barrel was supported in a way that provided no push in
any direction other than directly against the force, the barrel would only
be minimally influenced by gravity and would tend to move in a direction
that is almost totally opposite the force. But, gravity will cause both
bullet and barrel (in a vacuum and with no other considerations) to arc due
to gravity. Depending on the location of the chamber and length of the
barrel, the chamber end would tend to be leading initially, with the barrel
following. With gravity, part of the arc would be with the barrel moving
down initially...but that's not anything that I could see happening in "real
life". My head is starting to hurt...

Obviously, I'm not a Physicist. But....I don't believe the author of the
book is any more of a Physicist either.

I also can't believe I took so much time thinking about this thread LOL

Barry


"Wolfgang" wrote in message
ups.com...

wrote:
On Tue, 07 Nov 2006 10:35:15 -0500, daytripper
wrote:

On Tue, 7 Nov 2006 07:47:36 -0500, "Robert11" wrote:

Hello:

Was reading a book on ballistics the other day, and the author was
describing conditions
where a rifle barrel would drop a small amount as a shell was fired.

He used an example that if one held a fly rod rod truly horiz., and
gave the
handle a very quick
upward (I think he means backwards; toward ones head) pure rotation,
the tip
momentarily goes Downward.

Have my rods away for the season, so can't try it.

Can't visualize this happening.

Does it ?
Why does it, if so ?

B.


I can't see how any downward force vectors at the rod tip increase in
this
scenario, so while he's correct that the rod tip will point below
horizontal,
it doesn't "drop", it simply lags behind the rest of the rod movement,
establishing an arc...

I s'pose the same thing could happen with rifles, to some (hopefully
vanishingly small) degree...

/daytripper

I'd offer that it would be a bit difficult to hold the average fly rod
"truly horizontal"

Well, you'd never know, would you? So, it's close enough.

...unless one just had a lesson or two and the fly rod
in question was the all-new and improved O' Cedar Fishsweeper XLT1000,
for which the instructor was the sole local distributor...

Zzzzzzzzzzzzzzzzzz

OTOH, I'd offer that any rifle barrel that couldn't be held "truly
horizontal" might make a better fly rod than rifle barrel...

Shows what you know. A rifle barrel can't be held truly
horizontal.......EVERYBODY knows that!

And finally, I'd observe that someone who suggests the physics/mechanics
involved in a rifle barrel at the moment of a round's discharge are
generally the same as someone lifting a fly rod would likely not know
much about either...

If anybody ever suggests that, remind us to ask you to remind
us......o.k.? Meanwhile.....amuse us. Tell us what you know about
either.

but on the plus side, they'd be readily recognized
as an expert by some on ROFF...

And thus, YOU must be a recognized expert on SOMETHING!........right?
Hold your breath.

As for the OP's reference to conditions that would cause a rifle barrel
to drop, I'd be interested in learning what those conditions are and
why the author thought that the alleged downward motion of the flyrod
tip was analagous.

Wolfgang

....my initial reaction was as several others i.e. it didn't make sense that
the rod tip would go down. But, what I wasn't considering is that the rod
is stiffer at the butt and not as flexible. When an arc is formed by
pressure, the mid-point of the arc will be that point where the pressure up
and down is equalized...by flexibility and by weight. If that's true, then
the "mid-point" of the arc is more toward the butt of the rod. Which means
that the arc on the front half of the rod is a longer arc and has more rod
length involved. It makes sense to my one functioning brain cell anyway.

Barry

"Jarmo Hurri" wrote in message
...

Robert He used an example that if one held a fly rod rod truly
Robert horiz., and gave the handle a very quick upward (I think he
Robert means backwards; toward ones head) pure rotation, the tip
Robert momentarily goes Downward.

Robert Does it ?

According to Don Phillips' "The Technology of Fly Rods" (page 87), yes
it does. He says that he demonstrates this by having someone hold a
piece of paper rear of the stroke direction and then initiating a cast
with a rapid pulse (it does not have to be up, sideways will do as
well). If you are interested in this, I think it is relatively easy to
make a convincing experiment to confirm this.

Phillips also says that this phenomenon has practical importance: if
you initiate a cast too quickly, it will cause slack.

Robert Why does it, if so ?

I have some guesses, but since I am not a physicist I will pass and
leave this issue to be resolved by someone more educated.

--
Jarmo Hurri

Commercial email countermeasures included in header email
address. Remove all garbage from header email address when replying,
or just use .

"hiouchibear" wrote in message
nk.net...
What a strange thread. I don't really understand how a fly rod could be
analogous to a rifle barrel, in any sense (except action/re-action). The
comments on the rod forming an arc with the tip following (but not
dropping) makes sense. And...anyone who looks at the physics involved in
firing a bullet i.e. explosion/action/reaction...the force from the
explosion pushes backwards...BUT...the design of the rifle, the way it is
held, whether or not the barrel is ported, are things that are all
contributing factors. All things considered, the shooter and the design
of rifles generally tend to absorb the shock going backwards and also
direct it in an upward arc. The only way I can imagine a rifle barrel
dropping is by putting it in some kind of vise that directs more downward
than upward pressure, but that's not how rifles are held by a shooter nor
is it the way rifles are designed (which is why ports are designed to
force gases to exit from the top portion of the barrel rather that the
bottom). I guess, technically, if the barrel was designed to push
backwards with no design to cause it to arc in any direction...and the
barrel was supported in a way that provided no push in any direction other
than directly against the force, the barrel would only be minimally
influenced by gravity and would tend to move in a direction that is almost
totally opposite the force. But, gravity will cause both bullet and
barrel (in a vacuum and with no other considerations) to arc due to
gravity. Depending on the location of the chamber and length of the
barrel, the chamber end would tend to be leading initially, with the
barrel following. With gravity, part of the arc would be with the barrel
moving down initially...but that's not anything that I could see happening
in "real life". My head is starting to hurt...

Obviously, I'm not a Physicist. But....I don't believe the author of the
book is any more of a Physicist either.

I also can't believe I took so much time thinking about this thread LOL

Barry



Not commenting on comparison to fly rods and can not connect the two. But
modern rifles do not have an explosion in the firing chamber. That went out
with black powder. Modern powders are considered propellents and have a
longer burn time. Different powders, different burn rates. As to barrel
movement. Guns normally tend to climb at the barrel as the lever arm is
upward. The M-16 is designed to not climb or drop as the barrel is in line
with the back of the stock. Why it has a carry handle. The sight plane is
along the top of the handle.

"Calif Bill" wrote in message
ink.net...

Not commenting on comparison to fly rods and can not connect the two. But
modern rifles do not have an explosion in the firing chamber. That went
out with black powder. Modern powders are considered propellents and have
a longer burn time. Different powders, different burn rates.

The distinction between propellants and explosives is doubtless a useful one
in trades where people routinely use one or the other to make loud noises,
and my reading confirms your classification of modern gunpowders among the
former, as well as burn time being the deciding factor. However, I suspect
that the distinction is rather arbitrary. The burn rate of high explosives
makes them dangerous even when burned in small quantities in open air, while
doing so with the slowest of propellants is relatively safe. THAT
distinction is lost at whatever point is agreed upon as the dividing line
between propellants and explosives. And, anyway, "relatively safe" is, if
you will pardon the usage, a loaded term.

The point of all this is that, "modern rifles do not have an explosion in
the firing chamber" is dangerously misleading. Steam, air and carbon
dioxide are not explosives; they are not even combustible. Nor, except in
some specialized applications is any of them even a "propellant." And yet
any of them (as well as a host of other more or less inert substances) can
and DO cause explosions when confined under pressure. When all is said and
done, it doesn't have to be an "explosive," as the term is used among
pyrotechnicians, to explode. What takes place in the chamber of a gun
(whether the motive force is supplied by burning powder or compressed air or
carbon dioxide) IS an explosion.

As to barrel movement. Guns normally tend to climb at the barrel as the
lever arm is upward. The M-16 is designed to not climb or drop as the
barrel is in line with the back of the stock. Why it has a carry handle.
The sight plane is along the top of the handle.

The muzzle of an M-16 doesn't rise as radically as that of many others, but
it DOES rise. Been there......got it on film.

Wolfgang