Why does "beat in" = less stable.

[The dude on the bike]

Maybe all of these things are factors but the only one that is easily demonstrated is the busted nose factor as stated by Mashnut. I use dx destroyers on certain water holes, sometimes when I get a new one I need to bend down the nose a bit to get the exact flip I want. The spaces on the picnic table tops work great for this. Discs don't really go fast enough for some of the stuff guys come up with to be significant.

 

[tampora]

I originally said that the curveball effect would increase a disc's understability. If you equate understability with going right (for a right handed player) then this holds true. If you require the disc to also angle itself into an anhyzer tilt, then this isn't true. However, I don't think it is the main reason the disc goes right.

I now agree with another poster who said that the differences in lift on the left and right edges are the main factor to consider in what makes a disc go right.

So, both of these effects happen: it curveballs and tilts. But, curveballing has a much less dramatic effect on a discs flight since the surface area impacting the air is so small.

I think this might give an explanation as to why taco'ing a disc also increases understability: Any deviation from the perfectly-symmetrical original form of the disc, such as a taco'ing, is either going to increase or decrease the height of the profile of the disc. Just like changing the angle of attack of a wing, this is going to change the amount lift generated by the disc. When the lift is changed, the amount of tilting does as well.

Increasing the domeyness by bending the nose down in most areas will greatly increase the profile height. This should result in more drag as well as more lift.

 

[justactnormal]

I've read all this, and I can hardly believe that I have, but I'm more the man for it, I suppose. I have often wondered about a great deal and I appreciate all the knowledge bombs that got dropped on the subject, but I still have a couple of related questions that I don't think have been touched on yet.

1. Why are champ/Z molds so much more overstable than their counterparts in other plastics? I've taken apparently identical PLH teebirds and champ is way more overstable than star or DX. Way more overstable. What gives?

2. How are drivers designed to be more understable from the get go? You can look at mids and see that a rhyno or even a drone will be beefy, but a buzz or stingray not so much. But drivers are a different thing altogether. I'm thinking Mamba, here. It's wing has to be designed in such a way as to provide more lift on the left side than the right when spinning, no? The leopard has that wierd notch on the wing, and it has way more turn than a teebird which doesn't. These flight characteristics have to be designed into the disc wing somehow, but how?

On a side note, the mamba was only released in the most stable and durable plastic, champ, and for good reason. It's flight properties should remain fairly consistent for a long time. Could you imagine the flip you'd get with a beat dx one? But how does the wing design overcome the inherent stability added by that plastic blend?

 

[The dude on the bike]

I've read all this, and I can hardly believe that I have, but I'm more the man for it, I suppose. I have often wondered about a great deal and I appreciate all the knowledge bombs that got dropped on the subject, but I still have a couple of related questions that I don't think have been touched on yet.

1. Why are champ/Z molds so much more overstable than their counterparts in other plastics? I've taken apparently identical PLH teebirds and champ is way more overstable than star or DX. Way more overstable. What gives?

2. How are drivers designed to be more understable from the get go? You can look at mids and see that a rhyno or even a drone will be beefy, but a buzz or stingray not so much. But drivers are a different thing altogether. I'm thinking Mamba, here. It's wing has to be designed in such a way as to provide more lift on the left side than the right when spinning, no? The leopard has that wierd notch on the wing, and it has way more turn than a teebird which doesn't. These flight characteristics have to be designed into the disc wing somehow, but how?

On a side note, the mamba was only released in the most stable and durable plastic, champ, and for good reason. It's flight properties should remain fairly consistent for a long time. Could you imagine the flip you'd get with a beat dx one? But how does the wing design overcome the inherent stability added by that plastic blend?

Different plastics cool to their respective shapes differently even though they come from the same mold. as far as comparing discs to round balls or fixed wings, don't, it is not the same at all.

 

[Nick481]

Well, everybody so far is clueless. The question is why does a beat in disc become less stable.
You PLH people are the most annoying, although its true PLH can initially determine stablilty, beating in a disc does not necessarily mean the PLH comes down.
The nick and surface camp makes sense, but it still doesnt explain why a disc thats repeatedly taco'd into a tree, but has no extreme surface damage, can still fly less stable than a new version.

The only real answer is, and I dont know why 3P hasnt piped up yet , repeated impacts change the properties of TPE's at a molecular level.
If we had any physics smarties that participated here, they could tell the rest of us exactly whats happening here, on a molecular level, to cause the changes.

My guess is the TPE's become less dense, due to more air between molecules as it gets crashed, thereby becoming less gyroscopic.

Okay, thats my BSOMA theory, you guys can tear it down.

You are right that it is changing the molecular makeup of the thermoplastic elastomers which would cause certain areas around the outer rim of the disc to either become less or more dense because the molecular structure is being crushed, in turn changing the gyroscopic properties of the disc. However, this would do nothing to cause a linear off balance of the disc.

Let's put it as only one side of the disc had hit a tree and caused a molecular off balance on that side of the disc which made that side more dense. When the disc is in it's flight and say at one moment in it's flight the more dense side is on the left. It may cause the disc to naturally want to tilt left at that moment, but as the disc rotates another 180 degrees it will do the same on the right side countering any effect it had. This would essentially just be like an extremely rapid teeter totter that you could not notice in real speed. So, the internal molecular structure of the plastic and specific location density would not have any effect on left to right turn.

 

[bikinjack]

Both the turn (understability at speed) and fade (overstability at the end of the flight) are caused by precession. As a disc turns, the center of lift is behind the center if rotation. Due to the conservation of angular momentum, the disc precesses and turns to the right (for rhbh). As the discs forward air speed slows the center of lift moves forward relative to the dire:|ction of travel. When the center if lift moves in front of the center of rotation, the disc begins to fade. This is also due to the conservation of angular momentum and the precession that ensues.

 

[atvan]

So is what you are saying that beat in discs have a farther aft mean CoL? Why is this?

 

[Anselm]

Dimples on a golf ball reduce the surface area of the ball affected by wind resistance. Think of it this way, as the ball or disc is spinning it is disrupting the air surrounding the ball or disc, cutting through the air with the entirety of its surface and creates drag along it entire surface as well. Now let's say for the sake of argument that a golf disc has a circumferance of 20" (I have no idea what it really is and I'm not going to measure) when that disc leaves your hand and begins rotating and cutting through the air it is creating drag along the entirety of the wing. Now when a disc is "broken in" it will typically have quite a few dings and nicks along its wing let's say for example there are four 1/4" nicks in the side of the disc. We have reduced the drag on our disc by one full inch which will allow the disc to spin faster for a longer period of time thus prolonging the hss phase of flight which in turn makes the disc more understable. Dimples and nicks reduce surface area which reduces drag. Make sense?

Dimples and nicks increase the surface area of a disc (or any object, for that matter). Unless you chop the disc in half and throw away one of the halves.

 

[bikinjack]

So is what you are saying that beat in discs have a farther aft mean CoL? Why is this?

As best as I can figure, it has to do with a combination of the lower PLH, loss of flashing/bead, and forward speed of the disc in flight.

 

[The Hammer]

We need DJJeramiahJ to come back and settle this!!

 

[captain jack]

1. Why are champ/Z molds so much more overstable than their counterparts in other plastics? I've taken apparently identical PLH teebirds and champ is way more overstable than star or DX. Way more overstable. What gives?

Density. Dave has explained this on the PDGA forum.
Its also the reason why they cant mold certain discs in light weights, with the premium plastics.

Both the turn (understability at speed) and fade (overstability at the end of the flight) are caused by precession. As a disc turns, the center of lift is behind the center if rotation. Due to the conservation of angular momentum, the disc precesses and turns to the right (for rhbh). As the discs forward air speed slows the center of lift moves forward relative to the dire:|ction of travel. When the center if lift moves in front of the center of rotation, the disc begins to fade. This is also due to the conservation of angular momentum and the precession that ensues.

Thank you for the lesson professor, but, this fails to address the question in any way. :|