Rod Dynamics ?

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.

My knowledge of the actual numbers behind physics is very limited, so
I'll offer up my simple minded version of Newton's Third Law. Could it
be that every action has an equal and opposite reaction?

...but I'm a designer not a physician er, physisonian, or was that a
physisoligist. Oh hell I don't now what I'm talking about.

-Ethan


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.

"Robert11" wrote in message
...
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 ?

Yes

Why does it, if so ?

You might be able to see it more clearly with a full-flex rod as in the case
of bamboo.
While holding the rod in the horizontal position, the start of the arm
motion upward begins the stored energy in the rod and translates it
throughout the length. Since the fly rod has a continuous taper with the
thicker part at the butt and thinning as it progresses towards the tip, the
upswing motion caused the tip to bend momentarily and ever so slightly
downward before it begins to move and follow the rod stroke path.

Not quite sure how the author relates this to rifle ballistics as you
described.
fwiw,
-tom.

Tom Nakashima wrote:
"Robert11" wrote in message
...
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 ?

Yes

Why does it, if so ?

You might be able to see it more clearly with a full-flex rod as in the case
of bamboo.
While holding the rod in the horizontal position, the start of the arm
motion upward begins the stored energy in the rod and translates it
throughout the length. Since the fly rod has a continuous taper with the
thicker part at the butt and thinning as it progresses towards the tip, the
upswing motion caused the tip to bend momentarily and ever so slightly
downward before it begins to move and follow the rod stroke path.

That explains nothing.

Wolfgang
who suspects that the downward motion is an illusion......but wouldn't
be much surprised if it is in fact real. in either case, recent
developments in the roffian math club suggest rather strongly that a
comprehensible answer will forever remain but a dream.

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.

The moment of inertia of the tip (and every other point on the rod) coupled with
the flexibly of the rod would cause the rod to flex when it was rotated, but it
wouldn't cause the tip to go down - that would violate the conservation of
angular momentum AFAIK.
--
Charlie...
http://www.chocphoto.com

On Nov 7, 6:47 am, "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.

It *moves*, yes, and if that movement is downward, then it drops. When
a rifle, or any other firearm, is fired, the barrel vibrates. The
manner in which it does varies with a number of inputs -- length, heat
of combustion, thickness of barrel, bedding, etc. If its bedding or
stocking is such that it kicks in a certain direction, than it can be
drilled near the muzzle to use escaping gasses to overcome this
tendency.-

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 ?

It does, for reasons that Tom outlined. An outdoor writer mentioned
this in a magazine article LOOOOOOOONG ago (I think it was Trueblood in
F&S). He was fishing for short-strike bluegills, using a vintage
bamboo (read "noodle") rod. At the strike, the tip DROPPED when he
pulled up. So he had to overcome natural reflex and, as he stated it,
"...swat at them like swatting flies with the rod tip" to tighten the
line for the strike.

cheers

oz

MajorOz wrote:
On Nov 7, 6:47 am, "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.

It *moves*, yes, and if that movement is downward, then it drops. When
a rifle, or any other firearm, is fired, the barrel vibrates. The
manner in which it does varies with a number of inputs -- length, heat
of combustion, thickness of barrel, bedding, etc. If its bedding or
stocking is such that it kicks in a certain direction, than it can be
drilled near the muzzle to use escaping gasses to overcome this
tendency.-

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 ?

It does, for reasons that Tom outlined. An outdoor writer mentioned
this in a magazine article LOOOOOOOONG ago (I think it was Trueblood in
F&S). He was fishing for short-strike bluegills, using a vintage
bamboo (read "noodle") rod. At the strike, the tip DROPPED when he
pulled up. So he had to overcome natural reflex and, as he stated it,
"...swat at them like swatting flies with the rod tip" to tighten the
line for the strike.

Horse****.

Wolfgang

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.