OAT Vs. turn over

[Apothecary]

Also wrong. What we call turn is more properly called negative roll (though that depends on convention) and is caused when the differential between the center of gravity and the center of lift creates a pitching moment (that is, a torque about the pitch axis - pushing the nose either up or down). Because the disc is a spin-stabilized wing, gyroscopic effects dictate that moments on an input axis normal to the angular momentum vector also cause motion on a mutually perpendicular output axis.

http://www.discwing.com/research/aerodynamics.html
http://en.wikipedia.org/wiki/Gyroscope

The only variables that truly matter to disc flight that are not the product of the aerodynamics of the disc itself are release angle, angular velocity / directional velocity (more properly, a quantity called the advance ratio), and and off-axis moments applied to the disc at release.

Rolling your wrist under -> spike hyzer because the moment applied along the roll axis forces the nose up. Rolling your wrist over similarly forces the nose down. Both affect the angle of release as well.

In this context, a hyzer flip is simply a throw with a high enough directional velocity to force a strongly nose down pitching moment, and the proper angular velocity to avoid ultra-stability (spin too high - too stable), and turn-and-burn (spin too low - not stable enough).

Here's where I'm stuck - wobble causes turn-and-burn, but why? Using the above model, the effect should be nothing more than a sequence of pitches with the same magnitude but opposite direction, and not actually affect the flight, unless the transient characteristics as the disc leave the hand dominate its later motion...

Maybe it's correlation and not causation, because putter flutter doesn't seem to result in under-stability inside the circle, so maybe wobble is just something that you see when you don't apply enough spin for the amount of armspeed (in dg terms), not something that actually causes under stable characteristics.

dang them are some dandy terms.

/me wishes i had taken a few physics classes in college.:\

 

[Pwingles]

Spin makes a disc more stable, like a top. Which is why forehand throwers need more stable discs since they usually have less spin.

imo FH throwers have more snap/spin required and that is why they need more stable discs, less stable discs are more difficult to throw accurately FH

 

[tom8658]

Im not disputing your explanation of the physics btw, just confused as to how throwing a speed 7 (for example) disc like a TB with lets say 400 ft of power (for example) This disc needs to be thrown harder then its power requirement to get to 400, agreed? Assuming there is no wind, and elevation change and you arent doing anything out of the ordinary here, a flat smooth throw at its requirement is not going 400. So when you add power the you have to compensate both your arm speed and release angle. We happen to know that the TB will have to have the port wing at about 8 o clock or maybe more at release because at 400 ft of power the physics you describe take over and the disc will want dip the starboard wing. This is why youve compensated by already dropping the port wing. How is this not OAT?

OAT is a moment applied to an axis not parallel to the angular momentum vector. Release angle is not OAT, it is release angle. OAT is when you roll your wrist, either over, under, backwards, or forwards, or have a release that isn't clean and causes the disc to roll as it leaves the hand.

 

[Pwingles]

Here's where I'm stuck - wobble causes turn-and-burn, but why? Using the above model, the effect should be nothing more than a sequence of pitches with the same magnitude but opposite direction, and not actually affect the flight, unless the transient characteristics as the disc leave the hand dominate its later motion...

i dont think this is true across the board, flutter or wobble can also cause the disc to go nose up and die, i think the only thing about wobble that is true no matter what is that it causes a loss in distance, no matter what

 

[Apothecary]

in terms of disc physics bh or fh should have no bearing on how the disc flies once its out of the hand.

 

[Apothecary]

OAT is a moment applied to an axis not parallel to the angular momentum vector. Release angle is not OAT, it is release angle. thrower OAT is when you roll your wrist, either over, under, backwards, or forwards, or have a release that isn't clean and causes the disc to roll as it leaves the hand.

fixed.

 

[Pwingles]

OAT is a moment applied to an axis not parallel to the angular momentum vector. Release angle is not OAT, it is release angle. OAT is when you roll your wrist, either over, under, backwards, or forwards, or have a release that isn't clean and causes the disc to roll as it leaves the hand.At an angle and speed not intended by the thrower usually

fyp
your wrist shouldnt be relevant its a flaw that causes something, not the something itself. Even when the wrist is where you want it, its possible to have OAT

 

[optidiscic]

a FH throw is more likely to wobble as the snap of the wrist and arm movement are easier to misallign and mistime

 

[tom8658]

in terms of disc physics bh and fh should have no bearing on how the disc flies once its out of the hand.

Correct. Certain throws just have different characteristic advance ratios that are useful to talk about. Forehand throwers tend to be more directional velocity dominant, which those who learn the DGR "hammer pound" forehand and backhand throws will be more angular velocity dominant. People who are "muscling" the disc are throwing with more directional velocity than the amount of angular velocity applied dictates.

It's also important to note that OAT, as we speak of it, is something that happens as the disc leaves the hand. There are all sorts of off-axis moments that occur when the disc is in flight, which is why they don't all go in straight lines and suddenly drop.

EDIT: Apoth just pointed this out

 

[CwAlbino]

Also wrong. What we call turn is more properly called negative roll (though that depends on convention) and is caused when the differential between the center of gravity and the center of lift creates a pitching moment (that is, a torque about the pitch axis - pushing the nose either up or down). Because the disc is a spin-stabilized wing, gyroscopic effects dictate that moments on an input axis normal to the angular momentum vector also cause motion on a mutually perpendicular output axis.

http://www.discwing.com/research/aerodynamics.html
http://en.wikipedia.org/wiki/Gyroscope

The only variables that truly matter to disc flight that are not the product of the aerodynamics of the disc itself are release angle, angular velocity / directional velocity (more properly, a quantity called the advance ratio), and and off-axis moments applied to the disc at release.

Rolling your wrist under -> spike hyzer because the moment applied along the roll axis forces the nose up. Rolling your wrist over similarly forces the nose down. Both affect the angle of release as well.

In this context, a hyzer flip is simply a throw with a high enough directional velocity to force a strongly nose down pitching moment, and the proper angular velocity to avoid ultra-stability (spin too high - too stable), and turn-and-burn (spin too low - not stable enough).

Here's where I'm stuck - wobble causes turn-and-burn, but why? Using the above model, the effect should be nothing more than a sequence of pitches with the same magnitude but opposite direction, and not actually affect the flight, unless the transient characteristics as the disc leave the hand dominate its later motion...

Maybe it's correlation and not causation, because putter flutter doesn't seem to result in under-stability inside the circle, so maybe wobble is just something that you see when you don't apply enough spin for the amount of armspeed (in dg terms), not something that actually causes under stable characteristics.

I've read through your explanation and see no difference between yours and the one I quoted. Regarding my education, it's self done through reading etc so my knowledge is only as good as my sources. I'm actually a Comp Sci Major but have a love for physics for some odd reason.

The gyroscopic effect tries to keep the disc stable, and fighting turn. I think the difference is, where is the nose? The nose of a wing would be the frontside, where the wing collides with the air. Wouldn't the "nose" of the disc due to the gyroscopic effect, be the left side of the disc? Where it comes around and connects with the air at it's greatest velocity. This would make the tail end of the "wing" or disc the right side of the disc. Pushing up or down on each side of course is what would then create the turn or negative roll.


Another thing that would come into account with lift and pressure would be the concavity of the wing edge itself. Or a bead.

 

[tom8658]

fyp
your wrist shouldnt be relevant its a flaw that causes something, not the something itself. Even when the wrist is where you want it, its possible to have OAT

I think you're misunderstanding what I wrote.

When you intentionally roll your wrist on release, that is still OAT. The good kind. The kind that you can control to throw spike hyzers and short turnovers.

You can also cause When all of your fingers don't release cleanly, or your thumb comes off first, etc etc.

 

[Apothecary]

Wouldn't the "nose" of the disc due to the gyroscopic effect, be the left side of the disc? Where it comes around and connects with the air at it's greatest velocity. This would make the tail end of the "wing" or disc the right side of the disc.

i completely agree and this is something i stress when teaching noobs. gotta think about aiming with and throwing the NOSE of the disc, the leading edge/left (rhbh) side (both in driving and putting).

 

[tom8658]

I've read through your explanation and see no difference between yours and the one I quoted. Regarding my education, it's self done through reading etc so my knowledge is only as good as my sources.

Your explanation was incorrect in that the airspeed over the disc does not vary from side to side, only from front to back. A disc correctly called an axi-symmetric spin-stabilized wing.

I'm actually a Comp Sci Major

Me too! :hfive:

The gyroscopic effect tries to keep the disc stable, and fighting turn. I think the difference is, where is the nose? The nose of a wing would be the frontside, where the wing collides with the air. Wouldn't the "nose" of the disc due to the gyroscopic effect, be the left side of the disc? Where it comes around and connects with the air at it's greatest velocity. This would make the tail end of the "wing" or disc the right side of the disc. Pushing up or down on each side of course is what would then create the turn or negative roll.

No. The nose of the wing is the part of the disc which hits the air first, so it must be along the directional velocity vector. Since the disc is axi-symmetric, it makes no sense to talk about sides, only axes - the fact that the disc is spinning does not affect it's aerodynamic characteristics, only its responses to pitch and roll inputs.

Read the paper I posted, after you slog through the aeronautics jargon, things become a lot clearer. There is also wind-tunnel test data.

 

[Pwingles]

I think you're misunderstanding what I wrote.
I understand, but to me thats only a portion of OAT examples and I know that there are more examples and reasons of why it happens and its not solely as the disc leaves the hand or wrist roll.

To me this is a rectangle is a square but not the other way around sort of thing (might be backwards ) OAT can be caused BY wrist roll, but wrist roll is not OAT, its wrist roll.

Your wrist can be perfect and if youre leaning back to throw an anny shot and it dumps, thats still oat.

 

[tom8658]

i completely agree and this is something i stress when teaching noobs. gotta think about aiming with and throwing the NOSE of the disc, the leading edge/left (rhbh) side (both in driving and putting).

That's a slightly different concept, but exceedingly useful.

 

[Apothecary]

That's a slightly different concept, but exceedingly useful.

is it? i dont understand a lot of these physics terms. my teaching method is all based on experience. it seems to me that if you instruct to aim with the leading edge (read: left side (rhbh)) of the disc, they can aim (and miss) a lot smaller.

 

[tom8658]

I think you're misunderstanding what I wrote.
I understand, but to me thats only a portion of OAT examples and I know that there are more examples and reasons of why it happens and its not solely as the disc leaves the hand or wrist roll.

To me this is a rectangle is a square but not the other way around sort of thing (might be backwards ) OAT can be caused BY wrist roll, but wrist roll is not OAT, its wrist roll.

Your wrist can be perfect and if youre leaning back to throw an anny shot and it dumps, thats still oat.

Semantics

Wrist roll is wrist roll, but it applies an "off-axis" moment to the disc upon release, so causes OAT.

I suppose you could cause OAT by, for example, arching your back as you accelerate your arm, causing your arm to not only lift but move in towards your body (I understand this is how some people throw rollers). However, putting too much anhyzer angle on a shot and snapping hard on release is not OAT, but will still give you "turn and burn" flight.

 

[CwAlbino]

Your explanation was incorrect in that the airspeed over the disc does not vary from side to side, only from front to back. A disc correctly called an axi-symmetric spin-stabilized wing.



Me too! :hfive:



No. The nose of the wing is the part of the disc which hits the air first, so it must be along the directional velocity vector. Since the disc is axi-symmetric, it makes no sense to talk about sides, only axes - the fact that the disc is spinning does not affect it's aerodynamic characteristics, only its responses to pitch and roll inputs.

Read the paper I posted, after you slog through the aeronautics jargon, things become a lot clearer. There is also wind-tunnel test data.

I did? :-/ I'm pretty sure I meant to say it DOES vary from side to side.

The left side is going much much faster because of the spin of the disc + the velocity.

The right side is going slower than the center of the disc, and much much slower than the left side of the disc.

Maybe I'm not understanding what you are trying to correct me on.

 

[CwAlbino]

I also read your gyroscopics wiki (not thoroughly) and I believe Torque-Induced Precession is what would explain the flutter

http://en.wikipedia.org/wiki/Precession

 

[Pwingles]

Semantics

Wrist roll is wrist roll, but it applies an "off-axis" moment to the disc upon release, so causes OAT.

I suppose you could cause OAT by, for example, arching your back as you accelerate your arm, causing your arm to not only lift but move in towards your body (I understand this is how some people throw rollers). However, putting too much anhyzer angle on a shot and snapping hard on release is not OAT, but will still give you "turn and burn" flight.

semantics yes, but its sort of an important distinction and one that ive been trying to make for a few pages now

You dont call the chickenpox the flu right? but they are a virus. You can have a virus and it may happen to be the flu, but the flu didnt cause the virus because the virus is the virus, see