Casting mechanics / Christmas poem (Capt. Jake Jordan)

Walter & Group.........

From Troy Miller (Some of you have seen this from ol Al's messages to his Group). I suggest you print this one out for study and future reference :-

There are basically two types of acceleration that we need to concern ourselves with -- linear and angular.   

Linear acceleration is a change in speed (velocity) in a straight line.  So when we talk about translational movement, we’re talking about how the hand moves along in a straight line in the early phase of the cast, without significantly changing the angle of the rod butt.  If the rod didn’t deflect (load) and you didn’t rotate at all, then the tip speed would be exactly the same as your hand speed.  Of course, neither of these is absolutely true.  We do load the rod, and there will be some negative rotation at the outset of the casting stroke and some positive rotation toward the end of the translational phase.  In fact, we’re in continuous transition throughout the casting stroke.  That’s what makes it all smooth and graceful.  Any surprises to the rod or line, and both will tell you about it… 

Angular acceleration is a change in rotational speed with time.  For instance, if an engine’s crankshaft was spinning at 600 rpm and you gradually increase the fuel delivery, the rpms will increase in response to the additional energy created.  Say you smoothly press down on the throttle and the rpms go up to 700, then 800, then 900 rpm.  This would be considered angular acceleration.  Of course, in flycasting, we don’t even go one full revolution.  We only go something less than 180 degrees on even our most “open” casting strokes.

 So, if we want to think about units, see how this fits: 

LINEAR MEASUREMENTS/MOVEMENTS 

Distance = physical displacement between two points along a straight line between them (examples – inches, feet, miles)

Speed (aka, Velocity) = rate of change of position along that straight line (examples – feet/sec, MPH)

Acceleration = rate of change of speed (if the speed is changing).  (examples – feet/sec/sec, MPH/sec) 

ANGULAR MEASUREMENTS/MOVEMENTS 

Angle = in 2-D (planar geometry), a measurement between two vectors (lines), typically measured at their intersection (degrees, radians)

Angular velocity = rate of change in angle with time (examples – deg/sec, RPM)

Angular acceleration = rate of change in angular velocity with time (examples -- deg/sec/sec, RPM/sec) 

Don’t get confused about vectors.  “Scalar” means how much.  “ Vector” means how much, and in what direction.  So we could say that if I’m driving to Mountain Home to catch the next world record brown, that my average velocity (or speed) might be 62.3 MPH.  But if we wanted to be more specific, then we could assign a compass heading to it and say that I was going 62.3 MPH at a bearing of 19.343 degrees from magnetic north.  Therefore, if someone knew where I started and when, they could take a map and figure out where I would be after any given time interval.  And when I could be expected to arrive, if I specified a final destination.  I’m taking the liberty of neglecting the curvature of the earth, of course… 

Assuredly, we’ve known HOW to cast for a very long time.  We’re just now getting to the point of describing it in accurate physical terms, I think.  That’s how my book starts… 

Let me know if anything needs further explanation.  I’m just on break here in the shop…

 Regards -- TAM

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Troy...

 Well worded and understandable.

One thing I'd emphasize is that there is a period during the casting stroke where there is a blend of linear and angular acceleration (velocity/time) as the translational phase melds into a principally rotational phase.  With some casters, and some casts, this blend exists throughout the entire stroke.  Overlapping this is the so-called, "loading move" most of which takes place as the rotational phase begins followed by the, "speed-up-and-stop" ("power-snap") which takes place largely during the latter part of the rotational phase.  One set of terms does not negate the other well publicized ones.  It all fits together, nicely.

This information represents another kind of, "blend".  The language of the lay fly caster with that of the engineer.  Kind of reminds us of Mel Kriegers teachings as he talks about the lexicon of the, "poet" and that of the, "engineer".

No matter what we call it, or, "how you cut it", all this must include SMOOTH CONSTANT ACCELERATION  to a point of rapid deceleration ("stop").

Some say, "well that's what we've been teaching for years"...."It's an answer we'd expect on an MCI exam"....etc.  What's new, then ?  

As I see it, what is new to many of us, is how we look at, "smooth constant acceleration".  Many of us took that to mean constantly increasing acceleration with no irregularities.  Now the new studies tell us that it means steady or unchanging acceleration.  A big difference.

Quantifying this as the blend of linear and angular acceleration progresses would probably require a daunting challange to our physicists and mathematicians as they try to torture enough calculus to come up with  an explanatory equation.  That equation, I think, would necessarily have many variables to fit the many casts and casting styles encountered.  Without going that route, however, Bruce Richards and Noel Perkins have demonstrated this concept well with the acceleration graphs produced by their depiction of angular change at the rod butt using the Casting Analyzer.

Gordy

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A chrismas poem sent by Capt. Jake Jordon  (One of our most valued Group contributors and FFF supporters over the years)

 

'TWAS THE NIGHT BEFORE CHRISTMAS,

HE LIVED ALL ALONE,

IN A ONE BEDROOM HOUSE MADE OF

PLASTER AND STONE.

I HAD COME DOWN THE CHIMNEY

WITH PRESENTS TO GIVE,

AND TO SEE JUST WHO

IN THIS HOME DID LIVE.

I LOOKED ALL ABOUT,

A STRANGE SIGHT I DID SEE,

NO TINSEL, NO PRESENTS,

NOT EVEN A TREE.

NO STOCKING BY MANTLE,

JUST BOOTS FILLED WITH SAND,

ON THE WALL HUNG PICTURES

OF FAR DISTANT LANDS.

WITH MEDALS AND BADGES,

AWARDS OF ALL KINDS,

A SOBER THOUGHT

CAME THROUGH MY MIND.

FOR THIS HOUSE WAS DIFFERENT,

IT WAS DARK AND DREARY,

I FOUND THE HOME OF A SOLDIER,

ONCE I COULD SEE CLEARLY.

THE SOLDIER LAY SLEEPING,

SILENT, ALONE,

CURLED UP ON THE FLOOR

IN THIS ONE BEDROOM HOME.

THE FACE WAS SO GENTLE,

THE ROOM IN SUCH DISORDER,

NOT HOW I PICTURED

A UNITED STATES SOLDIER.

WAS THIS THE HERO

OF WHOM I'D JUST READ?

CURLED UP ON A PONCHO,

THE FLOOR FOR A BED?

I REALIZED THE FAMILIES

THAT I SAW THIS NIGHT,

OWED THEIR LIVES TO THESE SOLDIERS

WHO WERE WILLING TO FIGHT.

SOON ROUND THE WORLD,

THE CHILDREN WOULD PLAY,

AND GROWNUPS WOULD CELEBRATE

A BRIGHT CHRISTMAS DAY.

THEY ALL ENJOYED FREEDOM

EACH MONTH OF THE YEAR,

BECAUSE OF THE SOLDIERS,

LIKE THE ONE LYING HERE.

I COULDN'T HELP WONDER

HOW MANY LAY ALONE,

ON A COLD CHRISTMAS EVE

IN A LAND FAR FROM HOME.

THE VERY THOUGHT

BROUGHT A TEAR TO MY EYE,

I DROPPED TO MY KNEES

AND STARTED TO CRY.

THE SOLDIER AWAKENED

AND I HEARD A ROUGH VOICE,

"SANTA DON'T CRY,

THIS LIFE IS MY CHOICE;

I FIGHT FOR FREEDOM,

I DON'T ASK FOR MORE,

MY LIFE IS MY GOD,

MY COUNTRY, MY CORPS."

THE SOLDIER ROLLED OVER

AND DRIFTED TO SLEEP,

I COULDN'T CONTROL IT,

I CONTINUED TO WEEP.

I KEPT WATCH FOR HOURS,

SO SILENT AND STILL

AND WE BOTH SHIVERED

FROM THE COLD NIGHT'S CHILL.

I DIDN'T WANT TO LEAVE

ON THAT COLD, DARK, NIGHT,

THIS GUARDIAN OF HONOR

SO WILLING TO FIGHT.

THEN THE SOLDIER ROLLED OVER,

WITH A VOICE SOFT AND PURE,

WHISPERED, "CARRY ON SANTA,

IT'S CHRISTMAS DAY, ALL IS SECURE."

ONE LOOK AT MY WATCH,

AND I KNEW HE WAS RIGHT.

"MERRY CHRISTMAS MY FRIEND,

AND TO ALL A GOOD NIGHT."

 

This poem was written by a Marine. The following is his request. I think it is reasonable.....

PLEASE. Would you do me the kind favor of sending this to as many people as you can? Christmas will be coming soon and some credit is due to our US service men and women for our being able to celebrate these festivities. Let's try in this small way to pay a tiny bit of what we owe. Make people stop and think of our heroes, living and dead,who sacrificed themselves for us. Please, do your small part to plant this small seed.