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  #11  
Old 03-10-2009, 12:13 AM
Rameka Rameka is offline
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Originally Posted by harr0140 View Post
Wow very well explained! I understood most of it.

I do have one question. I have heard some people say to pull down on the disc as if to aim towardas the ground from your full reached back position. Is this because you will get lift on the front of the disc after it travels some distance in nose down position? Does the nose down position have less drag thus increasing distance?
This may be to reduce the wake in the initial part of the flight path while at the same time discouraging pressure build-up in the center of lift. This would cause the disc to act more understable, but it would go faster, and closer to the ground. Once the nose tips up again, the disc will pop up, glide, and finish whatever way it was built to. As far as I can tell, this technique is just to keep the disc as low to the ground as possible. I've heard a friend say that for every 10 meters of height you get on a disc, you lose 40 meters of distance; that's mostly just ballistics. Basically, what you said was correct: extremely little (even less than normal) drag in the initial part of the flight.

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Originally Posted by borndasaur View Post
Try some of these theories out on your physics advisor. You may have an interesting topic for a seminar here (not to mention a good excuse for throwing some plastic on school time!)
That's an excellent idea.
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  #12  
Old 03-10-2009, 02:29 AM
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Very informative topic here, thanks for taking the time to explain it Remeka!
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  #13  
Old 03-10-2009, 08:35 AM
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willstradamus willstradamus is offline
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Welp Im impressed! A+

Real cool of you to not only go through the trouble (or fun as you say) to put all of that together, but also answering the follow-up questions.

on a side note...
Im majoring in Accounting. Could I get any diagrams for that?
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  #14  
Old 03-10-2009, 08:38 AM
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willstradamus willstradamus is offline
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now that Im through sucking up to the professor

any Idea about what makes the disc faster? (such as the wraith being an 11 speed and the beast a 10 speed)
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  #15  
Old 03-10-2009, 09:00 AM
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Originally Posted by Rameka View Post
[I]There's one more thing I want to try explain, all the way back from Figure 2. This is partially hypothetical because I have not seen this in any research, but am merely extrapolating from my knowledge of other objects in flight. This is about why a disc becomes more understable as it "beats in". A golf ball, as we all know, has dimples. Dimples cause air turbulence around the sides of the ball, which causes the air to adhere to the sides more because of the increased surface area. In a similar way, when you beat up a disc, it gets nicks and scratches all around the outer circumference. These nicks and scratches act like dimples, and cause the points of air separation to come later, meaning that the disc has a smaller wake. This smaller wake means the ratio of pressure from the front and the back of the disc is less, causing the disc to stay fast for a longer time, just like the dimples in golf balls.

That's just my guess. If anyone else could confirm or deny this, I'd be delighted.

---

Thanks for reading. I hope this was at all informative for some of you. All the images and text is original, so I'd appreciate if you asked before quoting this or using any of the images. I'll always say yes, but I'd just like to know first. Cheers!



Sources:
www.aerospaceweb.org
www.wikipedia.org
www.odgc.ca
My understanding of this phenomenon has to do with the integrity of the disc shape, and the resulting drag caused by airflow over the surface. When a disc is new, it's shape has integrity - meaning that any cross section of the disc is the same as any other. When a disc is beat up, that integrity has been altered, and any one cross section will be different than any other. I think this is where the shape of the disc departs from that of a golf ball in it's flight characteristics. So where the dimples of a golf ball help reduce drag (due to the uniformity and distribution of the dimples around the entire surface of the object), the beat up disc does the opposite, and creates drag on the tail end of the disc.
It was explained to me that during flight, a disc has a little pocket of air that trails the disc - that is part of the natural air flow over the surface. When a disc's shape has integrity (is new) - that pocket of air is as small as it can be. As a disc gets beat up, turbulence is created on the trailing edge, causing the size of that air pocket to increase - thus causing drag. This causes the disc to slow down and turn - which is why every disc will become less stable over time.

I'm no physicist- and cannot attest to the accuracy of what I was taught. Nor can I elaborate (as you have) using correct terminology about the elements affecting disc flight. It does however, make a lot of sense to me. Perhaps you can evaluate this concept for plausibility.
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Old 03-10-2009, 12:03 PM
Rameka Rameka is offline
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Quote:
Originally Posted by willstradamus View Post
now that Im through sucking up to the professor

any Idea about what makes the disc faster? (such as the wraith being an 11 speed and the beast a 10 speed)
This is from an article I read and saved some time ago:

"In terms of disc models, the putter has a more pronounced dome, and as such gets more of this kind of airfoil lift, and produces what we observe as its “floaty” behaviour when we throw it. The blunt edge however, creates more drag (having to deflect air), so that the putter has a lot of its forward momentum diffused. The driver with its much sharper edge profile, generates less lift from its flatter profile, but at the same time induces much less drag, so that it holds its speed better and the result is a flight that is more ballistic than lift-driven. The mid-range disc logically, has properties somewhere in between."

If you want me to explain that in a more rigorous, mathematical form, I can try. Just let me know.

Quote:
Originally Posted by craigg View Post
My understanding of this phenomenon has to do with the integrity of the disc shape, and the resulting drag caused by airflow over the surface. When a disc is new, it's shape has integrity - meaning that any cross section of the disc is the same as any other. When a disc is beat up, that integrity has been altered, and any one cross section will be different than any other. I think this is where the shape of the disc departs from that of a golf ball in it's flight characteristics. So where the dimples of a golf ball help reduce drag (due to the uniformity and distribution of the dimples around the entire surface of the object), the beat up disc does the opposite, and creates drag on the tail end of the disc.
It was explained to me that during flight, a disc has a little pocket of air that trails the disc - that is part of the natural air flow over the surface. When a disc's shape has integrity (is new) - that pocket of air is as small as it can be. As a disc gets beat up, turbulence is created on the trailing edge, causing the size of that air pocket to increase - thus causing drag. This causes the disc to slow down and turn - which is why every disc will become less stable over time.

I'm no physicist- and cannot attest to the accuracy of what I was taught. Nor can I elaborate (as you have) using correct terminology about the elements affecting disc flight. It does however, make a lot of sense to me. Perhaps you can evaluate this concept for plausibility.
Actually, from what I understand, discs fade as they slow down, not turn. If getting "beat in" caused discs to fade instead of turn, they would be, by definition, more overstable when beat in...which isn't the case. So, although I don't think my hypothesis is conclusive (however, I do think it accounts for some of the effect), I know for sure what you were told wasn't right.

Perhaps another effect in play is what you described about radially asymmetric cross-sections. Since the disc gets sightly bent in one or several directions, the diameter of the disc actually shrinks from this permanent distortion. Assuming the player puts the same amount of power on the disc as before, the spin speed imparted will be the same. Since the diameter of the disc is smaller, and the speed is the same, the ratio of difference between the port and starboard wing will be even higher, causing the pressure gradient to act yet even more extreme. This would cause the disc to turn, which is what we expect from beat-in discs.

Don't hold me to it, but this sounds more likely to me than what you were told.
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  #17  
Old 03-10-2009, 02:27 PM
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The speed thing makes sense, as a disc shouldn't turn if it's going slower.
But the drag thing does make sense to me - as if you increase drag - and have the same speed, this would alter the flight characteristic into a less stable flight pattern.
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  #18  
Old 03-10-2009, 03:27 PM
Omega SuperSloth Omega SuperSloth is offline
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the way it works when i throw is when the disc stops spinning then it fades so basically at that point its flying under its own power not mine anymore so the amount of spin i put on it is the amount of the flight i control the rest is up to the disc(gravity+height+disc air volume +glide+etc=glide time. anyone thats ever thrown a big anny and not gotten enough pop knows what im sayin
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  #19  
Old 03-10-2009, 03:28 PM
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ERicJ ERicJ is offline
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Hey look!!!

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time.
The period key on his keyboard does work!
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  #20  
Old 03-10-2009, 03:35 PM
Omega SuperSloth Omega SuperSloth is offline
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man you get moody on your . eric sorry.
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