Hang time and center of mass

[Walter]

I'm surprised we rarely see discussions about center of mass when talking about the flight and hang time of the line. Usually, some point on the line like the loop or the fly is used as the measurement point to determine how fast the line is, or appears to be, falling.

I know that there is the idea that center of mass doesn't apply to fly line because its flexible but if center of mass applies to Dick Fosbury and systems of particles, I think it applies to fly line as well.

Here are some videos showing the relationship between center of mass and a "body" in flight.

The first is about the "invention" of the Fosbury Flop in high jump:



The next video shows the movement of the center of mass during a high jump. Even though the contortions of the jumper will constantly change the location of their center of mass in relation to their body their center of mass stays on the path predicted by Newtonian mechanics:



The final video is about hang time in basketball. The interesting bit starts around 4:50 showing the path of Jordan's head vs his center of gravity during his leap:



I know that there are other factors in play. In the tethered cast we have to consider tension in the rod leg and in the untethered cast there is the constant change in mass but I just wanted to show that making generalizations about the flight of the fly line by concentrating on a single portion of the line can be misleading.

[James9118]

Hi Walter,

I think it's been mentioned many times, however those that want to see lift, see lift. I see pixies.

James.

[Walter]

James,

Strangely, the purveyors of flying fly lines refused to give me a refund when I pointed out that my lines had lost their lift.

[Stoatstail50]

James,

Strangely, the purveyors of flying fly lines refused to give me a refund when I pointed out that my lines had lost their lift.

Well they wouldn’t would they….because that’s probably Piximetosis.

A course on “learning to love yourelf” should fix it.

[Graeme H]

James,

Strangely, the purveyors of flying fly lines refused to give me a refund when I pointed out that my lines had lost their lift.

If you made the common mistake of putting your fly line on the reel backwards, they take the opportunity to run away via the running line (hence the name) and the line is ruined. The bad news is that now they are free to roam in the wild, exacting revenge on their erstwhile cast-masters in the form of "wind knots" in their tippet.

The Pixie exodus from the line is a process known as Pixit.

Cheers,
Graeme

[Graeme H]

Seriously though, I believe you're right to raise the question of GoG in the line. I'm not sure what to do with the knowledge, but I'm happy to follow along.

Cheers,
Graeme

[VGB]

I believe you're right to raise the question of GoG in the line.

It’s not just GoG but also MaGoG. The Centre of Mass does give a better representation of the lines flight but focusing on bits of line does lead to caster pixcitation. Seeing pixies is better than seeing dead people though.

Regards

Vince

[gordonjudd]

It’s not just GoG but also MaGoG. The Centre of Mass does give a better representation of the lines flight

Vince,
In a uniform gravitational field I thought the center of mass was at the same point as the center of gravity.

Are your pixies messing with the distribution of gravity as well as impacting the flight of a fly line?

Gordy

[VGB]

Gordy

You should put your spectacles on before replying, "GoG" is a biblical character, not a gravity field:

https://en.wikipedia.org/wiki/Gog_and_Magog

Vince

[VGB]

While we are on the topic of gravity