#11  
Old 06-30-2020, 07:12 PM
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  #12  
Old 06-30-2020, 08:30 PM
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Originally Posted by dewflicker View Post
Do the disc ratings for turn and fade reverse if I am throwing sidearm?
Might depend on how much OAT you've got going on

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Originally Posted by BogeyNoMore View Post
The numbers don't change. They describe disc flight relative to other discs.

You can expect discs to behave as if the turn and fade #'s differ for FH vs BH, but you can still use the #'s to get an idea of how other discs will fly for that same type of throw. Does and glide really shouldn't seem too different.


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Also, Bogey, what’s the “travel tag” thing you mention in your sig?
I'm living proof that Bogey lost his tag! (get a new one! maybe TimG will even give you the same number you lost?) However, I did make his list of DGCR members he has played with. It's currently my biggest DGCR achievement.

I've only swapped once sadly. But it was fun. And I'd probably be swapping more if I were traveling more. Check the DGCR Travel Tags page out.

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Old 07-01-2020, 08:42 AM
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Hmmmm....this is a pretty good question. I don't think RHBH and RHFH are mirror images. In my experience a forehand imparts considerably more spin on the throw, given equal ability with both throws. This extra spin would make the disc seem less stable in flight. A -1 turn might be a fairly stable, straight BH disc, while it would likely have a nice R>L turn during flight for the FH. I find that most FH players of my skill level will throw considerably "beefier" discs than I do.

There are certainly some factors that could come into play, though. Like "off axis torque" of the FH player. A pretty common FH technique/error.
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Old 07-01-2020, 09:55 AM
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Originally Posted by ru4por View Post
This extra spin would make the disc seem less stable in flight.
...
There are certainly some factors that could come into play, though. Like "off axis torque" of the FH player. A pretty common FH technique/error.
Is the first part (more spin = less stable) the general consensus on this? My first thought was that I would think that extra spin would just magnify whatever characteristics the disc had. Although, that is based on two assumptions on my part.

Assumption 1 is that the basic flight characteristics of stability and end of flight fade come from the disc dragging air in its spin. (Bull**** sophomore physics follows: Like the curve of baseball, the end of flight fade comes air building up on the forward spin side of the disc. A baseball moves away from the buildup of air, but a disc moves into it, because that side of the disc would lose lift and subsequently tilt in that direction.) Understable discs must be doing something with the spin to counter act that? I would assume that would increase as well. So, whatever happens, it would happen more with more spin.

Assumption 2 is that, given that forehands don't go as far as backhands, they aren't thrown with as much forward speed. If they have more spin, that's more spin relative to apparent air speed. We know that throwing into a headwind, which decreases spin relative to apparent air speed, will make the disc less stable. So forehands with more spin and less speed should be more stable, not less.

That said, it sure is easy to turn over a forehand, but I was assuming that was a combination of it being difficult to get very much hyzer on a disc, the tendency to then throw with anhyzer, and the ease of imparting OAT when your arm/wrist goes from hyzer to anhyzer through the throw.

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Old 07-01-2020, 11:05 AM
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Originally Posted by ru4por View Post
I don't think RHBH and RHFH are mirror images..
I also believe this. And RHBH is not the same as a LHFH.

You might be able to get similar results, but the flight paths (at least for me) are not the same.

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Old 07-01-2020, 11:59 AM
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Originally Posted by Rastnav View Post
Is the first part (more spin = less stable) the general consensus on this? My first thought was that I would think that extra spin would just magnify whatever characteristics the disc had. Although, that is based on two assumptions on my part.

Assumption 1 is that the basic flight characteristics of stability and end of flight fade come from the disc dragging air in its spin. (Bull**** sophomore physics follows: Like the curve of baseball, the end of flight fade comes air building up on the forward spin side of the disc. A baseball moves away from the buildup of air, but a disc moves into it, because that side of the disc would lose lift and subsequently tilt in that direction.) Understable discs must be doing something with the spin to counter act that? I would assume that would increase as well. So, whatever happens, it would happen more with more spin.

Assumption 2 is that, given that forehands don't go as far as backhands, they aren't thrown with as much forward speed. If they have more spin, that's more spin relative to apparent air speed. We know that throwing into a headwind, which decreases spin relative to apparent air speed, will make the disc less stable. So forehands with more spin and less speed should be more stable, not less.

That said, it sure is easy to turn over a forehand, but I was assuming that was a combination of it being difficult to get very much hyzer on a disc, the tendency to then throw with anhyzer, and the ease of imparting OAT when your arm/wrist goes from hyzer to anhyzer through the throw.

Man, I talk a lot, don't I?
I am not the aerodynamics guy. Though some here are very much into that, maybe they will chime in. I am only basing by post on observation and anecdotal experience.
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Old 07-01-2020, 02:09 PM
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Regardless of the type of throw,...

Spin is what gives a disc stability. If you push a disc off a table with some velocity and zero spin, it has no stability. At any given velocity, less spin will make the disc less stable. More spin will make it more stable.

The greater the stability, the more it will resist turning, and the better it will hold a line.

OS and US are relative terms intended to describe how much spin that mold requires for a stable (basically straight) flight, at it's intended speed.

With a certain combination of spin and velocity...
A "stable" disc will fly straight and then fade.
An OS version of the same disc requires less spin to acheive stable flight.
An US version of the same disc requires more spin to achieve stable flight.

US discs have a tendency to turn because most players don't impart enough spin at the thrown velocity to provide sufficient stability to turning. That's not a knock on players. US discs are designed to turn... for most players.

But since different players impart differing ratios of spin vs speed, the same disc may fly differently for different players.

Most players generate less spin FH than they do BH. If you have a disc that rarely turns BH, but tends to turn FH, it's because your BH throw generates more spin than your FH throw. The additional spin provides the stability to resist turning. Same velocity with less spin, will allow the disc to turn.

Last edited by BogeyNoMore; 07-01-2020 at 02:13 PM.
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  #18  
Old 07-05-2020, 09:02 AM
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Quote:
Originally Posted by ru4por View Post
Hmmmm....this is a pretty good question. I don't think RHBH and RHFH are mirror images. In my experience a forehand imparts considerably more spin on the throw, given equal ability with both throws. This extra spin would make the disc seem less stable in flight. A -1 turn might be a fairly stable, straight BH disc, while it would likely have a nice R>L turn during flight for the FH. I find that most FH players of my skill level will throw considerably "beefier" discs than I do.

There are certainly some factors that could come into play, though. Like "off axis torque" of the FH player. A pretty common FH technique/error.
I agree that they are not mirror images. My assumption has always been the opposite. I.e. forehand imparts LESS spin but is easier for a new player to impart more velocity or speed overall. Think of how backhand has more levers and pivot points compared to forehand. (E.g. backhand has core, shoulder, elbow, and wrist all coiled up and then "unleashed" to impart lots of spin, whereas the forehand "spring" is not nearly as coiled up.) A greater amount of spin actually makes the disc turn LESS and fade LESS, if all other things are the same. As you mentioned with OAT, that can make discs behave differently.

As a beginner, they are "opposites" in the sense that one fades right and one fades left. That's because of the direction of the disc's spin (clockwise for RHBH, counter-clockwise for RHFH). It's very useful to have a right finishing shot and a left finishing shot, for sure.

Quote:
Originally Posted by Rastnav View Post
Is the first part (more spin = less stable) the general consensus on this? My first thought was that I would think that extra spin would just magnify whatever characteristics the disc had. Although, that is based on two assumptions on my part.

Assumption 1 is that the basic flight characteristics of stability and end of flight fade come from the disc dragging air in its spin. (Bull**** sophomore physics follows: Like the curve of baseball, the end of flight fade comes air building up on the forward spin side of the disc. A baseball moves away from the buildup of air, but a disc moves into it, because that side of the disc would lose lift and subsequently tilt in that direction.) Understable discs must be doing something with the spin to counter act that? I would assume that would increase as well. So, whatever happens, it would happen more with more spin.

...
I like how you're thinking, but I think both of your assumptions are wrong. Regarding assumption 1, yes fade comes from the air, but it's specifically the torque caused by where the center of lift (aka aerodynamic center) acts on the disc. This is affected by the disc's shape. This location also changes with angle of attack, which is lower at the beginning of the throw and gradually increases.

Regarding assumption 2, I'll just say that the mechanics of FH and BH are very different. A well thrown backhand actually can have more velocity AND more spin (or angular velocity), but that requires a lot of practice to achieve. For beginners, especially athletic people with baseball or football experience, I do think their forehand has MORE velocity at the beginning and hence gives easier distance. Have you ever noticed that forehands tend to fade more if thrown a similar distance? I would contend this is actually because they have LESS spin.

There are a number of good threads about disc physics, and here are some of the main ones. They're not super easy to follow, and of course there is some wrong info sprinkled in there. One problem is that some of us get obsessed about this and start asking questions, but not all of us are obsessed at the same time. Also, there are lots of "common sense" things that end up being less helpful to understanding disc flight. E.g. the magnus effect is less significant with discs than with balls, and the idea of one side of the disc having more lift than the other due to forward or backward rotation doesn't play much part.

There are some classic research papers out there, and some good ones are linked in the threads below. A lady named Hummel did a nice paper using the Ultrastar (ultimate lid), and then the Potts and Crowther group in England did some nice work which also used some other discs. One paper did some wind tunnel work using Aviar, Buzzz, Wraith, and Flick, with some others. Anyway, we all tend to get very long-winded on these things, partially because it's just not easy to convey some of these thoughts on a forum like this.

Here are some of those threads that have most of the DGCR wisdom, though there are surely others out there.
Explanation of the physics of flying discs (FIXED) - this is probably the original
Disc Golf / Frisbee Physics 101 - this is a newer one that has some links to threads
Disc Physics...??? - this one may be less helpful because of 15 pages of back and forth, but may be helpful too

I'm sure I'm wrong on some of this stuff, but I do have a background in engineering and a decent fundamental understanding of physics.

Quote:
Originally Posted by BogeyNoMore View Post
Regardless of the type of throw,...

Spin is what gives a disc stability. ...
I can't find anything to disagree with here. As usual, nice post BNM!

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