Disc Golf Course Review OAT is a stupid concept
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#101
03-29-2013, 08:57 PM
 sidewinder22 * Ace Member * Join Date: Nov 2008 Location: Creeping Creek DGC Years Playing: 10.7 Courses Played: 174 Posts: 10,740 Thanked 123 Times in 104 Posts

Quote:
 Originally Posted by Dave242 Pretty cool that you were at Bose. They are in several of the buildings vacated when the company I worked for out of college (Prime Computer) went belly up. I wonder what your AP Physics teacher and MIT professors would think of the concepts put forth in this paragraph: I'm not arguing that gyro doesn't resist oat here on earth, but in outer space it's another story. All that video shows is that the imparted gyro effect is greater than the relative gravity. Gyro is a counterbalance and actually requires a reference to ground to work it's little parlor trick. Drag amplifies the gyro effect on a disc. Gravity is not really even a force, it's an observed effect or pseudo force at best.
I'm fairly sure Einstein would agree.
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#102
03-30-2013, 10:04 AM
 BionicRib * Ace Member * Join Date: Jun 2011 Years Playing: 16.9 Courses Played: 194 Throwing Style: RHBH Posts: 2,214 Thanked 5 Times in 5 Posts

I was gonna post last night after I read this and then I passed out after paragraph 3, but to sum up my opinion, I do understand where you are going with this Dave242, but you are arguing semantics IMO.

Here is a good definition of OAT I found by Bradley Walker.

"Of axis torque
-
this is the condition that results from the hand not perfectly
tracking around the nose
within the plane of the disc into the extremely powerful snap. Think of the top if you wrapped the string
askew at some odd angle. The harder the string is pulled the more wobble will be induced."

IMO if I you really wanted a clearer term than OAT......you could call it OIAT......(Off Ideal Axis Torque), but IMO that just doesn't sound as cool as "OAT".

PS. Dave if you haven't delved into technique yet, I would strongly recommend starting here, then after you read this "summary if you will" you may be able to coexist with the word OAT.

http://ripsychotherapy.com/pdf/RightPecDrill.pdf

....lots of good stuff in there
#103
03-30-2013, 11:19 AM
 sidewinder22 * Ace Member * Join Date: Nov 2008 Location: Creeping Creek DGC Years Playing: 10.7 Courses Played: 174 Posts: 10,740 Thanked 123 Times in 104 Posts

Yeah, I was gonna say part your issue with this concept probably has to with your disc throwing theory. There is no way to throw without oat, however comparing a gyro to throwing is not apples to apples. The goal of throwing is not to spin it, but it's to leverage it to its home. Part of our goal is to change the disc's cog so it can be leveraged like a hammer, and a gyro's goal is to maintain it's cog. Part of the problem with the gyro is that you are only applying another force after it's spun and it's cog is stable, where a disc's spin is more of a byproduct from being leveraged and it's cog is not stable until well into flight where drag dominates any gyro.

Check this puppy out, and it uses drag to stabilize the easier model from the wobble/oat.
#104
03-30-2013, 03:13 PM
 Dave242 * Ace Member * Join Date: Aug 2007 Location: Lake Forest, IL Years Playing: 22.8 Courses Played: 381 Throwing Style: LHBH Posts: 4,504 Thanked 0 Times in 0 Posts

Quote:
 Originally Posted by BionicRib Here is a good definition of OAT I found by Bradley Walker. "Of axis torque - this is the condition that results from the hand not perfectly tracking around the nose within the plane of the disc into the extremely powerful snap. Think of the top if you wrapped the string askew at some odd angle. The harder the string is pulled the more wobble will be induced."
Excellent! Thanks for posting this. It really helps me for the first time understand the axis of the torque that the "OAT" is referring to which is off-axis from the ideal. Very helpful. That explanation is really the first thing that has clicked with me this whole thread in this regard.....I am probably a little dense in picking up the concept if others have tried getting the same point across in different terms.

That said, I think it is those who have the concept of a disc obtaining its spin the same way as a top are the ones that over-inflate the impact of OAT. Interesting that SW22 posted this right after yours:

Quote:
 Originally Posted by sidewinder22 Yeah, I was gonna say part your issue with this concept probably has to with your disc throwing theory. There is no way to throw without oat,...... The goal of throwing is not to spin it, but it's to leverage it to its home.
If I have time, I will make a quick youtube video explaining my take on BionicRib's explanation.....and why I still think OAT is a misdiagnosis of what it going on: I still do not think the Torque of OAT carries into the flight....rather it is the motion of the levers (all the moving body parts) leading up to the release that really matters.

At the end of the day, I believe that the result of OAT in the planes of the levers have the same effect on the flight as people claiming tourque imparted on the disc has.....so like BionicRib adeptly says: I am now "able to coexist with the word OAT."

.....OK, OAT is not a stupid term like I put in the thread's title. Misleading, but not stupid.
#105
03-31-2013, 01:20 AM
 BionicRib * Ace Member * Join Date: Jun 2011 Years Playing: 16.9 Courses Played: 194 Throwing Style: RHBH Posts: 2,214 Thanked 5 Times in 5 Posts

FWIW I still don't think its misleading.....I think you need to warm up a pot of coffee and spend a day or two reading some of the forums on technique on DGR. I'm still learning how to execute everything I have learned, but atleast now I understand what I am doing wrong and what I am doing right, and most importantly I know why its wrong or right.

We don't live to far away from each other, maybe we can meet up sometime for a round and some good ol fashioned oat discussion.......without the gyro's of course
#106
03-31-2013, 03:17 PM
 jtencer Eagle Member Join Date: Mar 2010 Location: Albuquerque, NM Years Playing: 12.8 Courses Played: 56 Throwing Style: RHBH Posts: 921 Thanked 0 Times in 0 Posts

Quote:
 Originally Posted by Dave242 But, assuming the that flight plates are the same weight, wouldn't a narrow rim disc have more angular momentum since the rim weight is concentrated closer to the edge of the disc (a smaller cross-section triangle)? I suspect the wider rims provide more stability due to the aerodynamics of a wider wing.
Haven't read the whole thread, but I wanted to jump in and correct this. The flight plates aren't the same weight. Flight plates on wide-rimmed discs tend to be thinner to compensate for the extra mass at the edge. The plastic density is what's generally common across molds.

The aerodynamics of a wider wing (mostly the decreased drag) don't have a huge effect. Some wide wings generate more lift -> more turn but others are designed not to generate as much lift and are thus more HSS. It seems like most of the newer ones released are leaning more toward the more lift / less stable variety though.
#107
03-31-2013, 03:36 PM
 jtencer Eagle Member Join Date: Mar 2010 Location: Albuquerque, NM Years Playing: 12.8 Courses Played: 56 Throwing Style: RHBH Posts: 921 Thanked 0 Times in 0 Posts

Quote:
 Originally Posted by Dave242 If I have time, I will make a quick youtube video explaining my take on BionicRib's explanation.....and why I still think OAT is a misdiagnosis of what it going on: I still do not think the Torque of OAT carries into the flight....rather it is the motion of the levers (all the moving body parts) leading up to the release that really matters. At the end of the day, I believe that the result of OAT in the planes of the levers have the same effect on the flight as people claiming tourque imparted on the disc has.....so like BionicRib adeptly says: I am now "able to coexist with the word OAT."
The Torque doesn't carry into the flight. After the disc has left your hand, it's all just momentum conservation. But the torque provides the initial condition and in that sense it propogates into the flight.

If you assume a prescribed throw to be the nominal throw, you can imagine that small pertubations in the initial conditions (linear speed, rpms, hyzer/anhyzer angle, nose up/down, and OAT) will result in changes in the flight path. The flight path varies pretty smoothly and predictably with most of these parameters but OAT can be a little less intuitive.

Orient yourself in the plane of the disc. The axis of the disc is normal to the plane and through the center of the disc. Forces in the plane result in torques about this axis (or any other axis normal to the plane). An earlier post seemed to contradict this by talking about the location of the axis in the plane being important. Off-axis-torque is cause by forces normal to the plane that do not act through the center of mass of the disc. This is energy that you're expending that is neither causing the disc to spin in its intended plane nor propel it towards its intended destination. It also causes the characteristic wobbling which as you may imagine can seriously effect your aerodynamics if it isn't quickly damped out.

Sometimes the pertubations are small and get damped out (wobble that goes away). Sometimes they don't (wobble that causes turn-and-burn).
#108
04-05-2013, 05:17 PM
 Tmart Eagle Member Join Date: Jun 2009 Years Playing: 8.7 Courses Played: 13 Throwing Style: RHFH Posts: 583 Thanked 0 Times in 0 Posts

It would be impossible to throw a disc forward if it was rotating on the Z axis, a disc thrown flat rotates on the Y axis.

That xylo in the video above rotates on the Z axis though.
#109
04-07-2013, 04:30 PM
 jtencer Eagle Member Join Date: Mar 2010 Location: Albuquerque, NM Years Playing: 12.8 Courses Played: 56 Throwing Style: RHBH Posts: 921 Thanked 0 Times in 0 Posts

Quote:
 Originally Posted by Tmart It would be impossible to throw a disc forward if it was rotating on the Z axis, a disc thrown flat rotates on the Y axis. That xylo in the video above rotates on the Z axis though.
????

The definition of your reference frame is arbitrary. Also convention normally dictates that z denote the vertical axis. The way we've been talking, we've been using a moving reference frame and defining the z-axis to be normal to the top of the disc.

#110
04-07-2013, 04:40 PM
 jrawk * Ace Member * Join Date: Oct 2009 Location: Lexington Park, MD Years Playing: 7.7 Courses Played: 83 Throwing Style: LHBH Posts: 5,449 Thanked 0 Times in 0 Posts

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