Disc Golf Course Review Explanation of the physics of flying discs (FIXED)
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#21
03-10-2009, 03:24 PM
 Rameka Par Member Join Date: Jan 2009 Location: British Columbia Years Playing: 11.8 Posts: 115 Niced 4 Times in 3 Posts

Quote:
 Originally Posted by craigg 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.
But that in itself seems paradoxical to me because drag is conducive to slowness. All other variables left the same, you can't increase drag without lowering the rate at which the disc slows down. Interestingly, (I just found this information now), a higher drag, in airfoils, reduces the pitching moment (the angular momentum resulting from the radially asymmetric center of lift that I described). This isn't, however, because of a tail-drag. It's actually because of a head-drag. From what I gather, this head-drag causes the center of lift to actually be pushed back, so precession is retarded.

Figure 6: Discs from side-view, flying to the left.

This actually gets back to willstradamus' question as well, about speeds. It explains why "slower" (more blunt/rounded edges) discs turn over when given too much power. Precession isn't permitted to be as dominant in these situations, because of the compensatory properties of the disc, such as having rounded edges. This is something I didn't really explain in my first post, only vaguely touched upon.

So yes, craigg, you were partially right. Sorry for the confusion.

On a side note, I'd like to add something to my reply of harr0140's question about nose-down release. Since turn and lift are directly associated, throwing a nose-down disc will cause it to go fast, and consequently turn, and as a consequence of that, lift. The downward tendency imparted from the nose-down release and the lift should cancel eachother out, leaving the disc to turn, level to the ground, without banking right into a roller.
Obviously, the path will change for different stabilities, but that's the general effect.

On another side-note: ERicJ and Omega SuperSloth, let's please keep on topic. Cheers

Last edited by Rameka; 03-10-2009 at 03:28 PM.
#22
03-10-2009, 03:33 PM
 Rameka Par Member Join Date: Jan 2009 Location: British Columbia Years Playing: 11.8 Posts: 115 Niced 4 Times in 3 Posts

Quote:
 Originally Posted by Rameka All other variables left the same, you can't increase drag without lowering the rate at which the disc slows down.
Sorry, craigg; what I meant to say here is that, all other variables left the same, you can't increase drag without speeding up the rate at which the disc slows down.

I really hate the 5-minute edit function on this forum.
#23
03-10-2009, 04:50 PM
 Omega SuperSloth Banned Join Date: Jan 2009 Location: Houston,TX Years Playing: 19.3 Courses Played: 12 Throwing Style: RHBH Posts: 2,081 Niced 1 Time in 1 Post

yo doc ur makin this to complicated with your big words and long paragraphs basically spin fights the drag created by air the faster u throw the more drag u get, the air wants to stop ur spin so it can take over so the more spin the farther it goes before the drag stops the spin and your disc fades. spin(right)no spin(left) it dosnt take a phd to watch a disc fly it just takes a brain and some eyes put down the book and go play
#24
03-10-2009, 06:07 PM
 Jungle Tim Birdie Member Join Date: Sep 2008 Location: San Francisco Years Playing: 14.1 Courses Played: 27 Posts: 348 Niced 2 Times in 2 Posts

Rameka

Good stuff, im not sure if you are aware but the founder of Discwing discs, Dr. Johnny Potts, actually got his doctorate researching disc flight physics. Much of his research information is avaliable at the Discwing website.

I have a question too, how can you explain discs like the Tee-Bird which is a speed 7 disc, but reportedly doesn't turn till you throw it over 450ft??
#25
03-10-2009, 06:14 PM
 Rameka Par Member Join Date: Jan 2009 Location: British Columbia Years Playing: 11.8 Posts: 115 Niced 4 Times in 3 Posts

Quote:
 Originally Posted by Omega SuperSloth yo doc ur makin this to complicated with your big words and long paragraphs basically spin fights the drag created by air the faster u throw the more drag u get, the air wants to stop ur spin so it can take over so the more spin the farther it goes before the drag stops the spin and your disc fades. spin(right)no spin(left) it dosnt take a phd to watch a disc fly it just takes a brain and some eyes put down the book and go play
I'm certainly not a doctor; in fact, I don't have a degree of any sort. I simply enjoy dissecting certain phenomena I see in the real world to get a better understanding of them. As I said earlier in this thread: if nobody gets anything out of this except me, it still won't have been a waste, as I enjoyed writing it. I prefer to explore both practice and theory in a given area of interest.

No one's forcing you to read and/or learn it.

To Jungle Tim: I didn't know that. That's very interesting, and I'll look into it. Thanks! As for the Teebird question, this is where my knowledge wanes--I really have no idea. I am curious, though, and I'll let you know if I figure it out.

Last edited by Rameka; 03-10-2009 at 06:17 PM.
#26
03-10-2009, 06:30 PM
 skurf * Ace Member * Join Date: Jan 2009 Location: Austin, TX Years Playing: 18.1 Courses Played: 28 Posts: 2,101 Niced 52 Times in 31 Posts

My friend who got a degree in aerospace engineering did one of his final papers on the physics behind a golf disc. Didn't understand it then, and don't understand it now, but I did help him test his hypothesis's on the course and in open fields. Maybe I could get his paper and post here to see how closely it relates to your theories.
#27
03-10-2009, 06:50 PM
 ERicJ * Ace Member * Join Date: Mar 2008 Location: Houston, TX Years Playing: 12.8 Courses Played: 256 Throwing Style: RHBH Posts: 4,064 Niced 8 Times in 7 Posts

Travis Greenway did his Master Thesis on "A BIOMECHANICAL ANALYSIS OF THE BACKHAND DISC GOLF DRIVE FOR DISTANCE".
#28
03-10-2009, 06:56 PM
 sidewinding * Ace Member * Join Date: Jul 2008 Location: The Milky Way Years Playing: 12.7 Courses Played: 81 Posts: 2,817 Niced 7 Times in 7 Posts

It is obvious that discs of the same mold but different plastics have different flight characteristics but I have noticed something. It may just be coincidence but I have noticed that a plastics ability to absorb permenant marker seems to be directly proportional to it's drag. If you take two discs of the same mold like a champion wraith and a dx wraith and write your name on them with a sharpie and then use acetone to remove the sharpie, the disc with the least amount of sharpie left in it (DX plastic) will fly farther and have less fade than the other one(Champion plastic).

My theory is that at a microscopic level air will absorb into the plastic just as the sharpie ink did and adhere better and therefore slow the disc down faster.

So if this is true, if you could create a plastic that sharpie will not stick to then you would have the ultimate long flying plastic.

 Niced: (1)
#29
03-10-2009, 07:08 PM
 Omega SuperSloth Banned Join Date: Jan 2009 Location: Houston,TX Years Playing: 19.3 Courses Played: 12 Throwing Style: RHBH Posts: 2,081 Niced 1 Time in 1 Post

[QUOTE=Rameka;40121]I'm certainly not a doctor; in fact, I don't have a degree of any sort. I simply enjoy dissecting certain phenomena I see in the real world to get a better understanding of them. As I said earlier in this thread: if nobody gets anything out of this except me, it still won't have been a waste, as I enjoyed writing it. I prefer to explore both practice and theory in a given area of interest.

No one's forcing you to read and/or learn it. : if my dyslexia would let me read your charts and long paragraphs i would probally agree with your science just dumb it down a little for us 8th grade graduates

#30
03-10-2009, 07:14 PM
 trifocal Eagle Member Join Date: Jun 2008 Location: Madison, Wisconsin Years Playing: 12.3 Courses Played: 12 Posts: 743 Niced 57 Times in 26 Posts

Quote:
 Originally Posted by sidewinding It is obvious that discs of the same mold but different plastics have different flight characteristics but I have noticed something. It may just be coincidence but I have noticed that a plastics ability to absorb permenant marker seems to be directly proportional to it's drag. If you take two discs of the same mold like a champion wraith and a dx wraith and write your name on them with a sharpie and then use acetone to remove the sharpie, the disc with the least amount of sharpie left in it (DX plastic) will fly farther and have less fade than the other one(Champion plastic). My theory is that at a microscopic level air will absorb into the plastic just as the sharpie ink did and adhere better and therefore slow the disc down faster. So if this is true, if you could create a plastic that sharpie will not stick to then you would have the ultimate long flying plastic.
I'm thinking....wipe all my discs with acetone or only write my name in shaprpie on discs that I want to be understable.......the beat in part of this thread peaks my curiosity. One thing pitchers know.....a ball with scuffs will behave less predictably than a fresh baseball. Pitchers like that. Golf ball dimples....beat in discs.....where we going?