What's really so bad about OAT's?

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Postby Olorin » Sat Mar 14, 2009 10:33 am

Actually, the disc is spinning on the X-Y plane while it rotates around the Z axis. It may be easier to think of airplane first. See this page on Flight Dynamics. The nose on the airplane is pointing in the same direction that the disc is flying. There are 3 aerodynamic parameters: Pitch, roll, and yaw.
Roll = Left or right side higher. Along X axis
Pitch = nose up, nose down. Along Y axis
Yaw = the spin on a disc. Along Z axis
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Re: What's really so bad about OAT's?

Postby JR » Sat Mar 14, 2009 8:39 pm

Olorin wrote:Actually, the disc is spinning on the X-Y plane while it rotates around the Z axis.


True dat. As I said I was dog tired. And any deviation of the spin from the X-Y plane is OAT. The nose of the disc can still be down or up and still spin like a flat front vs rear of the disc would without OAT. But that isn't usually good. There are also some often usable good forms of OAT. When they are planned to be utilized. Longest throws are annied steeply after the apex and the nose can be 80 degrees down on the disc rim and the disc falling from the sky. To get annied so much that the nose is so much down and having enough altitude that the disc will flex to flat and glide forward late in the throw may well need intentional OAT to have the disc flip to enough anny for the disc to avoid stalling at those high altitudes.
Flat shots need running on the center line of the tee and planting each step on the center line. Anhyzer needs running from rear right to front left with the plant step hitting the ground to the left of the line you're running on. Hyzer is the mirror of that.
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Re: The axis in OAT

Postby garublador » Sun Mar 15, 2009 6:44 am

Olorin wrote:Back to OAT-- I'm guessing that OAT is along the Z axis. Is that right?
You're part way there. Torque is a rotational foce about an axis. You are correct that it is about the Z axis in the coordinate system you have set up. Off-axis torque is any torque that is about an axis other than the Z axis. This off-axis torque will be a vector with a magnitude and a direction. Think of it as an arrow originating from (0, 0, 0) in your example pointing away from the disc in the positive Z direction, but not directly along the Z axix. The length of the arrow is the amount of torque you are applying. The direction of the OAT will have three components that can be expressed as an angle with respect to the X axis an angle with respect to the Y axis and an angle with respect to the Z axis. The component that's in the X axis is what we're talking about. It will cause the disc to act more or less "stable" than a clean throw.

There may also be a Y component that can change the pitch. For example, wrist extenstion can cause some OAT with a component in the Y direction that will cause more nose down. This type of OAT is generally not talked about a lot. It's more that people talk about things, like wrsit extension, causing more nose down, not causing OAT.
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Re: What's really so bad about OAT's?

Postby Olorin » Mon Mar 16, 2009 7:00 am

So, using the airplane analogy, the most common OAT is roll about the X axis so that the left side of the disc is higher and the right side is lower. Is that correct?

If the spinning disc is the XY plane then the disc spins about the Z axis. It seems to me that if you tilt the XY plane then the Z axis still stays perpendicular to the XY plane. Would you agree with that? If that's correct, then when you roll the disc so that the left side is higher, then the Z axis also tilts away from vertical to stay perpendicular to the plane of the disc. Would you agree with that too?
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The origin of the term OAT

Postby Olorin » Mon Mar 16, 2009 8:27 am

Who invented the term "Off Axis Torque"? It sounds like something Blake would say.
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Re: What's really so bad about OAT's?

Postby garublador » Mon Mar 16, 2009 9:30 am

Olorin wrote:So, using the airplane analogy, the most common OAT is roll about the X axis so that the left side of the disc is higher and the right side is lower. Is that correct?
Again, sort of. It's not about which side is higher, it's about how force is applied to the disc. You're right that the result is a force that pushes the left side higher.

If the spinning disc is the XY plane then the disc spins about the Z axis. It seems to me that if you tilt the XY plane then the Z axis still stays perpendicular to the XY plane. Would you agree with that? If that's correct, then when you roll the disc so that the left side is higher, then the Z axis also tilts away from vertical to stay perpendicular to the plane of the disc. Would you agree with that too?
You're right about the result, but again, it's about forces on the disc, not about disc orientation. If you throw with the left side higher that's, by definition, an anhzyer throw and doesn't say anything about the torque applied to the disc. OAT would be if you threw on a flat or hyzer line, but applied torqure about an anhyzer angle.
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Re: What's really so bad about OAT's?

Postby mark12b » Mon Mar 16, 2009 3:21 pm

Olorin wrote:If the spinning disc is the XY plane then the disc spins about the Z axis. It seems to me that if you tilt the XY plane then the Z axis still stays perpendicular to the XY plane. Would you agree with that? If that's correct, then when you roll the disc so that the left side is higher, then the Z axis also tilts away from vertical to stay perpendicular to the plane of the disc. Would you agree with that too?


off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.
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Re: What's really so bad about OAT's?

Postby Olorin » Mon Mar 16, 2009 4:22 pm

mark12b wrote:
Olorin wrote:If the spinning disc is the XY plane then the disc spins about the Z axis. It seems to me that if you tilt the XY plane then the Z axis still stays perpendicular to the XY plane. Would you agree with that? If that's correct, then when you roll the disc so that the left side is higher, then the Z axis also tilts away from vertical to stay perpendicular to the plane of the disc. Would you agree with that too?


off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.


We're dealing with precession here which can be hard to visualize and understand. But if I understand it correctly the angle that you impart in the XY plane to spin the disc sets the orientation of the Z axis. In other words, if you tilt the XY plane then the Z axis stays perpendicular to the plane and it tilts away from vertical. So the Z axis of your throwing motion always equals the Z axis of the spinning disc. I think you meant to say that with OAT the Z axis you produce tilts away from vertical. When the Z axis is vertical then you've made a flat throw. When the Z axis is at any angle other than vertical then you've got OAT.
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Re: What's really so bad about OAT's?

Postby Tree Seeking Device » Mon Mar 16, 2009 6:24 pm

Olorin wrote:When the Z axis is vertical then you've made a flat throw. When the Z axis is at any angle other than vertical then you've got OAT.


Not quite. Anhyzer and hyzer are both created when the disc's z-axis is not vertical - but it is possible to throw both with no OAT.
I think the easiest way to distill it in terms of your coordinate system: OAT is any force vector applied to the rim of the disc that is not in the XY plane.

Might be easier to think in terms of cylindrical coordinates (r, theta, z) where the z-axis is perpendicular to the flight plane of the disc. A force in the radial direction accelerates the disc. A force in the angular direction (theta) imparts spin. Any force with a non-zero z component applied away from the center of the disc creates OAT.

Yes I'm a physics geek.
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Re:

Postby rehder » Tue Mar 17, 2009 12:45 am

tumpsi wrote:I'm not sure if I understand the term OAT correctly. Could someone explain it,
really slowly, with pics 'n vids 'n shit. So, what is off axis torque, and what it
causes to a disc golf discs flight path?


holf your arm straight out in front of you like you where going to shake somebodys hand. Now roll your hand clockwise, so that the palm faces up, and the thumb sticks out to the right. Thats wrist roll. But it is only one way of inducing OAT.

It can be used well in throwing rollers, and to keep very understable discs from flipping, if you roll your wrist the other way.

The problem with it is, that is more of an advanced concept, that you should introduce once you have a solid grip on the throwing fundamentals.


What happens when newer players grab a disc that is speed overstable, is that they cant match the speed required to make it fly straight, to get it to fly straight they then introduce wrist roll to their throws, so what they do is throw s-line shots to get more distance out of the disc. Mind you they arent really throwing straight shots, they are flex-shots wich have more or less play in the left-to-right.

Now when said player has thrown a ton of these shots and wrist-roll has become ingrained in his throw, and he grabs a midrange or a putter, and the tries to throw it, it will divebomb to the right and as was said above turn into a cutroller, because these discs dont mask the OAT
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Re: What's really so bad about OAT's?

Postby mark12b » Tue Mar 17, 2009 4:18 am

Olorin wrote:
mark12b wrote:
Olorin wrote:If the spinning disc is the XY plane then the disc spins about the Z axis. It seems to me that if you tilt the XY plane then the Z axis still stays perpendicular to the XY plane. Would you agree with that? If that's correct, then when you roll the disc so that the left side is higher, then the Z axis also tilts away from vertical to stay perpendicular to the plane of the disc. Would you agree with that too?


off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.


We're dealing with precession here which can be hard to visualize and understand. But if I understand it correctly the angle that you impart in the XY plane to spin the disc sets the orientation of the Z axis. In other words, if you tilt the XY plane then the Z axis stays perpendicular to the plane and it tilts away from vertical. So the Z axis of your throwing motion always equals the Z axis of the spinning disc. I think you meant to say that with OAT the Z axis you produce tilts away from vertical. When the Z axis is vertical then you've made a flat throw. When the Z axis is at any angle other than vertical then you've got OAT.


the z-axis of your disc/wrist doesn't necessarily match the z-axis of the rest of your body. that's one place off-axis torque comes from. it's like if you've ever spun a top and not gotten a clean release, the top goes wobbly because of the different forces in play. but a gyroscope can't really have OAT because it's basically is a top on a fixed axis.

with a disc you can have a clean release where the forces all line up like a gyroscope, but it's totally possible to mix them up too, e.g. if you roll your wrist over at the same time you're snapping it you can end up with something like that wobbly top.

off-axis torque has nothing to do with whether or not the z-axis of the disc is vertical -- you can have a clean OAT-free hyzer, a clean, OAT-free nose-up stall-out, etc. otoh you can have a shot that's flat but wobbly from OAT.
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Re: What's really so bad about OAT's?

Postby garublador » Tue Mar 17, 2009 6:47 am

mark12b wrote:off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.
This is a good way to put it.
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Re: What's really so bad about OAT's?

Postby Olorin » Tue Mar 17, 2009 9:35 am

mark12b wrote:off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.


I'm still trying to understand this, and I'm not trying to be argumentative, but some of things y'all are saying still don't make sense to me. Maybe I'm just obtuse.

1) I understand your explanation of wrist roll as OAT and why new players do it. I just sat here with a disc in my hand and rolled the disc. But when I use my wrist to tilt a stationary disc so the the left side is up I've tilted the XY plane that it will spin on, and I've also tilted the Z axis.

2) When you hold the disc in your hand, prior to release it isn't spinning. You will always impart spin to the disc on the XY plane. If you have positive roll about the X axis so that the left side of the disc is up the disc is still spinning about the XY plane, but the Z axis is tilted from vertical. Your throw creates this angle. It seems to me that the Z axis of your throwing motion must create the Z axis of the spinning disc; they cannot even be 2 different things.

Y'all seem to be envisioning things differently. Am I missing something? I'm totally open to being corrected because I just want to understand this, but I'm about to give up. Either I can't see what you're trying to say, or you don't have it quite right. At the moment I can't really tell which is which, but all I can go by is what I understand that I've explained above.
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Re: What's really so bad about OAT's?

Postby cmlasley » Tue Mar 17, 2009 10:53 am

Olorin wrote:
mark12b wrote:off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.


Y'all seem to be envisioning things differently. Am I missing something?


Look at the above quote from mark12b. He's talking about two separate Z-axis that don't match - that of the thrower's rotation and that of the spinning disc. I think that is what you are missing. I could be wrong, though.
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Re: What's really so bad about OAT's?

Postby mark12b » Tue Mar 17, 2009 12:14 pm

Olorin wrote:
mark12b wrote:off-axis torque would be when the z-axis of your throwing motion doesn't match the z-axis of the spinning disc.


I'm still trying to understand this, and I'm not trying to be argumentative, but some of things y'all are saying still don't make sense to me. Maybe I'm just obtuse.

1) I understand your explanation of wrist roll as OAT and why new players do it. I just sat here with a disc in my hand and rolled the disc. But when I use my wrist to tilt a stationary disc so the the left side is up I've tilted the XY plane that it will spin on, and I've also tilted the Z axis.

2) When you hold the disc in your hand, prior to release it isn't spinning. You will always impart spin to the disc on the XY plane. If you have positive roll about the X axis so that the left side of the disc is up the disc is still spinning about the XY plane, but the Z axis is tilted from vertical. Your throw creates this angle. It seems to me that the Z axis of your throwing motion must create the Z axis of the spinning disc; they cannot even be 2 different things.

Y'all seem to be envisioning things differently. Am I missing something? I'm totally open to being corrected because I just want to understand this, but I'm about to give up. Either I can't see what you're trying to say, or you don't have it quite right. At the moment I can't really tell which is which, but all I can go by is what I understand that I've explained above.


think about that wobbly top -- yes it has a z-axis that the top is spinning around, but the axis itself is rotating around a single point...
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