i recognise this, intuitively rather than from an understanding why point of view, its pretty much what i always considered 'fast' to be!

im liking this, AA+ERN+Q factor = 'feel', bit of refinement and a few disagreements needed before that is even close to being accepted, but i think it explains something as practically important as it is interesting.

I'm not sure that there is a practical home test that you could use to define Q but it should be do'able for industry.

i just like the sound of Q factor

actually there is a very practical thing going on here, 'feel' in fly casting is such a vague term that it becomes useless, yet its a practical necessity and where we get a great deal of satisfaction in fly fishing, bit like art, casting is aesthetic as much as it is technical in that we respond to what we feel, we just neglect that bit because we don't have the language to discuss it.

im not proposing we do by the way

On a very similar vein, this thread explains resonance far better than I have:

rod recovery / low frequency resonance damping

I'm coming to the firm conclusion that rod builders know more about this stuff than anyone else, they have a common language perhaps and just work with these things,

this is possibly what i always found missing from sexyloops, great understanding and instruction confused by scientific formulas that would be easier to just say.

I suspect that casters tend to be less analytical because generally you are talking about production kit so the cast is the main variable. Builders are often trying to make something unique or personal with many physical variables, so they use a common language to talk about the rods over the internet

This is a very thoughtful read, takes a while:

Untitled

I mentioned critical damping as going into the dark places earlier in this thread because I could not think of an analogy that worked and the associated maths is horrible. However, this week I listened to the Gary Loomis podcast ( 20 Dec 2009) on the itinerant angler:

The Itinerant Angler

As well as being hugely entertaining it is very informative in a accessible way. He uses a great analogy of a diving board for a rod that allows me to explain damping. Please remember this only applies to the sprung portion of the cast.

We are looking to get the maximum energy from our rod (diving board) to the line (diver) by bouncing on the board (each end of cast). The board is clamped at one end by our hand.

If the diver cannot flex the board he cannot launch - underlined, rod too stiff, not enough acceleration in the cast - the system is under damped and operating near to natural frequency

A lot of energy is required to launch the diver becasue either the board flexes too much or the diver is of a generous girth - overlined, rod too soft, overpowered cast - the system is overdamped and the system is operating below natural frequency and is unresponsive.

The diver achieves a 1.5 somersault with pike - the line weight, rod stiffness and acceleration are all perfectly balanced - the system is operating at its resonant frequency

Hope it works for you

this doesn't strike with my understanding! suspension on a cargoes up and down, undamped the car would bounce off the road, but damper spring controls the rebound,

in rod terms, a badly made bamboo rod counter flexes almost to the same degree as it bent in loading - no damping,
high modulus carbon loads deep but the tip straightens without excessive counter flex, i.e.. crisp recovery without continuing to then bend in the opposite direction, damped.

is that the same thing?

Not really. In your examples you are comparing different stiffness of the board. Your high modulus carbon rod would be overdamped if rated for a 2 wt line and you strung an 8 wt through it. Critical damping is all about matching the rod stiffness, line weight and energy input.

Using your damper spring underdamped gives you a hard ride and overdamped it would wallow. The reason I liked the diving board is that the input is rythmic, like a casting stroke. If it made sense, then in conjunction with Gary Loomis explanation of blank properties and the diving board, it would give you how fast and slow actions are achieved and how they are affected by other factors including casting tempo.