Conceptual Disc

[gronkus]

Hi all,

Newbie to disc golf. Was watching a video on what influences a disc's "speed" rating and it got into moment of inertia. And that a lower speed disc has more mass centrally located while a higher speed disc has its mass concentrated in the rim. And while the higher speed discs, once powered up, will take longer to slow down the spin - they also are harder to snap and power up.

I was wondering what it would be like if there was a disc that had a changing concentration of mass. For instance, maybe some liquid capillaries in the plastic somehow that initially were filled towards the center of the disc but after flight the centrifugal force would squeeze the liquid (mass) outwards. Would that conceivably offer the best of both worlds?

I'm sure it would be completely non-legal and perhaps not even feasible to create, but just wondering on a slow day...

 

[dsbearsfan]

Like the thought might get way too dumpy at the end and not skip

 

[thunder3boy]

While your idea is creative, you are forgetting about conservation of angular momentum. If you start spinning a disc with it's mass centrally located and begin to move the mass away from the center, the disc will begin to slow down.

So no, it wouldn't give you the effect your are going for. But points for creativity!

 

[Aim For The Chains]

This makes me really curious how a liquid filled disc would fly.

I will disagree with the part of your post-

And that a lower speed disc has more mass centrally located while a higher speed disc has its mass concentrated in the rim.

I think the slower molds actually allow more of the weight to be naturally focused to the outside edge vs faster discs where it's more spread out through the wing.

 

[gronkus]

Aim,

I'm just going by what the video suggests here http://www.bestdiscgolfdiscs.com/speed-ratings-numbers-explanation/

 

[Old Dog]

This makes me really curious how a liquid filled disc would fly.

I will disagree with the part of your post-

I think the slower molds actually allow more of the weight to be naturally focused to the outside edge vs faster discs where it's more spread out through the wing.

If that were the case then putters would have big wide rims like drivers and drivers would have thin rims like putters.

 

[Pbmercil]

If that were the case then putters would have big wide rims like drivers and drivers would have thin rims like putters.

because a driver has a very wide wing, it has a lot of mass but much of that mass is on the interior of the wing. A putter has a very narrow wing, so all the wing mass is all all the way out on the edge of the disc.

Why do you think putters finish so straight?

 

[Aim For The Chains]

Speed and aerodynamics are the key today with drivers vs what used to be more traditional lid like shapes. There's a damn good reason why discs like the comet roc avaiar etc can fly on as-designed DG lines from 25 ft to 425 ft....

 

[Doofenshmirtz]

I was wondering what it would be like if there was a disc that had a changing concentration of mass.

Buy an Aerobie Epic. It isn't exactly what you are describing, but it is something that you might find very interesting.

 

[sidewinder22]

While your idea is creative, you are forgetting about conservation of angular momentum. If you start spinning a disc with it's mass centrally located and begin to move the mass away from the center, the disc will begin to slow down.

So no, it wouldn't give you the effect your are going for. But points for creativity!

Yep, it's spin will slow down like a figure skater arms out. And it would be harder to leverage a disc with it's mass more centered as the handle is effectively shorter.

 

[sidewinder22]

I will disagree with the part of your post-

I think the slower molds actually allow more of the weight to be naturally focused to the outside edge vs faster discs where it's more spread out through the wing.

You are thinking about it wrong. It's not about the outer most edge, it's where the rim starts/flight plate ends like a hammer. There ain't much in the flight plate of a driver compared to it's rim.

 

[Aim For The Chains]

You are thinking about it wrong. It's not about the outer most edge, it's where the rim starts/flight plate ends like a hammer. There ain't much in the flight plate of a driver compared to it's rim.

Mullen's cutting up a disc in a recent thread and posting the weight of a nuke actually was pretty surprising how much weight was in the flight plate alone.. now if you were to go just a few MM into the rim like older discs were (not 21mm+ but rather >16mm) I think you would find the amount of weight to be focused in that small area to be much greater vs that of the larger wing.

Im not thinking about it wrong at all. A disc like the polecat always has and always will be more gyroscopic vs a katana. The flight plate of the faster drivers becomes smaller too generally vs the older school large diameter stuff with fatter wing shapes.

think of it this way.. a 12 speed disc can be the same diameter as a 7/9 speed disc and many putters or mids are larger.

 

[sidewinder22]

Mullen's cutting up a disc in a recent thread and posting the weight of a nuke actually was pretty surprising how much weight was in the flight plate alone.. now if you were to go just a few MM into the rim like older discs were (not 21mm+ but rather >16mm) I think you would find the amount of weight to be focused in that small area to be much greater vs that of the larger wing.

Im not thinking about it wrong at all. A disc like the polecat always has and always will be more gyroscopic vs a katana. The flight plate of the faster drivers becomes smaller too generally vs the older school large diameter stuff with fatter wing shapes.

Cut the flight plate out the rim of a 175g katana and polecat, then weigh it. Then weigh the rims without the flight plate and tell me which has more mass on the rim.

 

[Aim For The Chains]

id have to cut the same MM from the katana as the wing of the polecat to make that even matter not just the flight plates. Very often its been found a baseline disc from the old times and even some early premium molds had thinner flight plates vs those of today which don't crack as easy.

You can cut up a dx TB or LEO vs champion and really see I difference I think someone posted here once.

 

[sidewinder22]

That's why you are thinking about it wrong.

Think about the Aerobie Ring. It has no weight at all in it's flight plate(it's a hole!) and is the most gryoscopic disc known to man. If you add a flight plate the Ring it will fly like a paper plate!

 

[Aim For The Chains]

that's more about the wing design but you are actually proving my point.

Do any disc golf disc go as far? ... yeah LMK when that ever happens with current PDGA standards'

 

[sidewinder22]

Hang on a sec... yeah it flies further part due to aerodynamics, but is still truly more gyroscopic. If you spread out the initial weight though, into the flight plate it becomes less gyroscopic as it's ratio has changed, or are we going into fantasy land and simply adding a weightless flight plate?

Your argument is wrong because you are changing the diameter(radius) in your scenario, which is like moving the fulcrum on a see saw.

 

[Improbably]

Separate from the focus of the recent few posts I have dreamt of a "rounded rectangle" disc. No not a daydream imagining, actual sleep dream with people throwing rectangular plastic tiles.

 

[armiller]

I'd love to see some mechanical/aerospace engineers do a project comparing discs. Moment of inertia, drag coefficients, performance at different rotational and linear velocities... it could potentially be very interesting. I imagine disc designers at each company take these things into consideration, but I've never seen anything written about them.

 

[BirdieMachine]

because a driver has a very wide wing, it has a lot of mass but much of that mass is on the interior of the wing. A putter has a very narrow wing, so all the wing mass is all all the way out on the edge of the disc.

Why do you think putters finish so straight?

Generally that is true but shape makes a bigger difference I think, if you've ever thrown a beefcake putter like a Vibram VP, it wants to do one thing and that is fade. Zone? Gator?

My thoughts, the larger the wing the more turn and fade you will see in general, larger wing equals more air pressure on the disc. As an avg stability high speed disc is thrown at high speed the force is higher on top of the wing then on the bottom causing the nose to tilt down slightly and due to spin tilt in the direction of the spin causing it to turn in flight. When it is slowing down it starts losing the force and starts to straighten out, by the end of the flight the force on top is so little that it starts stalling and the nose slightly raises moving the disc left. Add in some gyroscopic properties, mass and lift, blah blah. I think the air circulating inside the disc has some effect also stabilizing the flight, putters have larger inside volume. Add in the fact that the putter has a smaller rim thus bigger lever so you can throw it faster with more spin. Lots of variables.