"Climbing loop" / Acceleration

Walter & Group...

As some of you know, Phil Gay has spent years as a military jet pilot and Navy aircraft carrier commander. Here is what he has to say:

Gordy,

 

    The jet pilot in me has to weigh in on the lift issue again!

 

    The fly line in itself can not generate lift.  Lift is caused when air comes across a fixed airfoil.   The air separates at the front of the airfoil and has to travel faster across the top because of the camber in the airfoil.  Even if you want to make the loop an airfoil in order for lift to work both legs must be static.  When shooting neither leg is static and when not shooting only the bottom leg is static.  A rising loop is caused most like from trajectory not true aerodynamic lift.  Remember the Bernoulli principle is that as a fluid (air) accelerates the pressure drops.  That is why an aircraft is sucked up into the air not really lifted from under the wing.

 

    Let's put this fly line lift issue to bed.

 

Phil

 

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Phil,

 

This makes sense to me.

 

While we can't deny the "climbing loop", it can't really be caused by LIFT defined in aeronautical physics.

 

To my list of things which I think might explain this phenomenon, I should have added TRAJECTORY or LAUNCH ANGLE.

 

As my old chemistry professor once said as an experiment he was demonstrating turned out with an unexpected result, "IT'S THE NATURE OF THE BEAST ! "

 

Gordy

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COMMENT:   I recall a paper by Caroline Gatti-Bono (I think a physics student of Noel Perkins at the U. of Mich.) entitled: EFFECT OF LOOP SHAPE ON DRAG-INDUCED LIFT OF FLY LINE ..

 

This appeared as an attachment to a message in Al Crise's CCI Study Group this morning.  Unfortunately, the attachment didn't contain the equations or diagrams.

 

I remember this paper well.  My take was that the authors were using the term "LIFT" to mean elevation due to other factors, not LIFT in an aeronautical sense.

 

I'd archived it, but lost it in a computer crash a while back.  I'll try to get it and if successful, will post it as an attachment for those interested.       G.

 

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                                                                     ACCELERATION

 

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Returning to Mark Milkovitch's excellant question, we now have comments by Bruce Richards. Bruce's answers are preceded by ****.  I've also highlighted them in RED :

 

From Mark Milkovitch...

In Bruce Richards' comments on the Kyte & Moran "Elite Caster" study (I'm

sure he means the one entitled, "Going For Distance"), he makes the point

that the best casters have "a constant rate of acceleration".

Does this mean that no matter how fast the rod tip is moving there is a

constant amount of force on it to move it even faster ?

 

****I suspect this is true, but would have to confirm to be sure.       B.

 

... And is it the case that a constant rate of acceleration is more

effective than an increasing rate of acceleration ?

 

*****No question about this one, yes! If the acceleration is exponential

there is little rod bend initially, a lot later, which results in tailing

loops eventually.    B.

 

Bruce