Coam again

[Walter]

Paul,

Exactly right. If we could reduce all the affects of drag as much as possible then there should be a significant difference in fly leg speed at the end of the cast based on the two models. Possibly casting a level sinking line (hopefully at high altitude) is what I had in the back of my mind. One of the problems is the loop. The everything gets transferred to the fly leg model without drag (I posted one above) only shows really significant difference near the end of the cast. Add air drag and the acceleration is still significant but around the point where the acceleration should be really taking off the end of the line enters the loop. In my model that doesn’t matter but in the other model I’m not sure what the people’s thoughts are about what the other model thinks because we have (I think) 2 schools of though about the loop. If it’s am is constant throughout the cast then what prevents the last bit of accelerating fly leg from physically colliding with the loop? On the other hand the idea that the am in the loop is a result of tension in the top and bottom of the loop then the loop should also accelerate appreciably but I don’t think there is consensus about the tension around the loop.

You may get to experience relativity effects in casting yet but it’s going to require a bit of practice even for you. We could attach a tiny little atomic clock to the end of your line and see if it has experienced time shift after the cast.

[Merlin]

In my model that doesn’t matter but in the other model I’m not sure what the people’s thoughts are about what the other model thinks because we have (I think) 2 schools of though about the loop. If it’s am is constant throughout the cast then what prevents the last bit of accelerating fly leg from physically colliding with the loop? On the other hand the idea that the am in the loop is a result of tension in the top and bottom of the loop then the loop should also accelerate appreciably but I don’t think there is consensus about the tension around the loop.

Walter

As the tension changes at the top of the loop, it changes from it down to the end of the line and there is no collision in the sense where the fly leg wants to push the loop thanks to its momentum. That is a misconception which does not resists N laws. All parts of the fly leg decelerate or accelerate at the same time.

You cannot decide whether or not loop AM is constant, it comes from N laws as well. The schools you are speaking about is 1) tension at top and bottom of the loop are equal (a shortcut used in many models), or 2) one uses loop AM ODE to calculate both tensions. There is a difference in the end, the flight is faster if you use loop AM ODE. In both cases loop AM varies (increases under your no air drag assumption).

Merlin

[Paul Arden]

I do notice a difference in both carry and shoot at altitude. I remember carrying the old XXD to the backing knot outside your house one year. That’s a 105’ carry and ~10’ more than at sea level for me.

Anything over about 800m I notice immediately.

Cheers, Paul

[VGB]

As the tension changes at the top of the loop, it changes from it down to the end of the line and there is no collision in the sense where the fly leg wants to push the loop thanks to its momentum. That is a misconception which does not resists N laws. All parts of the fly leg decelerate or accelerate at the same time.

Have you ever thrown a tail Daniel?

You cannot decide whether or not loop AM is constant, it comes from N laws as well. The schools you are speaking about is 1) tension at top and bottom of the loop are equal (a shortcut used in many models), or 2) one uses loop AM ODE to calculate both tensions. There is a difference in the end, the flight is faster if you use loop AM ODE. In both cases loop AM varies (increases under your no air drag assumption).

It’s nice to see (2) becoming mainstream . It’s a sign of progress since previous discussions

https://www.sexyloops.co.uk/theboard/vi ... 230#p45198

Vince

[Walter]

@Torsten,

I have found an issue with my model. As you implied I have a transformation error between two frames of reference. With the correction I am getting acceleration to infinity at the end of the cast. The issue I currently have is that my model matches the values from CoM rather than CoE. I expect I am missing something there and will continue to work at it and update if/when I make progress. Thanks for your patience.

@Paul,

Looks like we're still on for light sabers at dawn.

@ Merlin.

I think you are going to hit the wall with the second model. Good luck for writing the equations, which anyway must be the same in both cases.

Thanks for the good wishes, I have equations, thank you. Equations in two different frames of reference are not going to be the same but when we transform from one to the other we need to get the same results.

Cheers,

Walter

[Walter]

All parts of the fly leg decelerate or accelerate at the same time.

Sorry, but as one of the characters on an old time tv show used to say, "That does not compute". Can you explain it a bit more? What is the mechanism for making all of the parts of the fly leg decelerate at the same time?

fwiw, I think most people think of collisions between two objects as a physical collision between the two objects like two pool balls colliding on a table. But there doesn't need to be physical contact between the two objects. Any time two or more objects exert forces on each other for a relatively short time we have a collision. The trick is figuring out how the interaction between the two objects affects the momentum or energy of the two objects.

Thanks

[Merlin]

Hi Walter

Unfortunately I caught covid and cannot concentrate on physics.

Merlin

[Paul Arden]

Hey get well soon Daniel.

[VGB]

I do notice a difference in both carry and shoot at altitude. I remember carrying the old XXD to the backing knot outside your house one year. That’s a 105’ carry and ~10’ more than at sea level for me.

Anything over about 800m I notice immediately.

I had to take a 2nd read, I thought most people would notice an 800m carry

Get well soon Daniel, I think it's going to be a shit year for covid.

[Walter]

Get better Daniel!

I don’t expect casting physics will change much while you’re recovering.