Explanation of the physics of flying discs (FIXED)

[Johnny_Crunch]

Wow, that's a lot of work

 

[blackmamba5490]

Bravo!

Rameka,
Wonderful job on your explanations and follow ups to peoples questions. As a business major and history buff, i have a hard time grasping a lot of these concepts but i have re-read your orignial post 4 times now and am getting a much better understanding. Just wanted to let you know your hard work is appreciated and well-worth it. You should make a video explaining your points so i could watch that too!opcorn:

 

[Apoth]

I had never seen this. Thanks for bumping it.

I still don't quite grasp why fade occurs, but I understand why a disc turns.

 

[Toro71]

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 curious about this too. I'd say it seems especially true with older champ plastic, that's started to break down some. Seems REALLY porous. I've always felt like, given same mold, Champ has less glide than Star. Champ's not just more OS, it slows down faster....?

 

[LoPan12]

Oh lord, not this thread again. Will no one accept my theory of turn and fade occurring thanks to the invisible Hand of God? Guess I'm the only creationist disc golfer.

I think its Nac Mac Feegles jumping up and down on one side or the other...
I'm a NE (it involved lots of fluid dynamics) and even I quit reading this after a couple pages...

 

[discgolfcrazy]

can someone explain to me how altitude and temperature effect the flight of a disc, why distance is effected?

 

[kevdiv48]

can someone explain to me how altitude and temperature effect the flight of a disc, why distance is effected?

*affect
A 2 second answer is that higher elevation should result in farther distance because the air is thinner and thus there is less drag. Similarly discs would probably flight more high speed understable.
As for temperature I am not sure. There was a thread on that a few weeks back.

 

[discgolfcrazy]

lol i thought i had it right this time, i even looked it over, affect

 

[KniceZ]

Higher Altitude lowers barometric pressure - thinner air so less drag. Lower Temperature lowers humidity - also less drag.

Lowe temp may also change the stability to some extent since the disc will shrink. But how that changes stability may vary depending on the disc design - i.e. flight plate thickness, Plc, etc

 

[BogeyNoMore]

Rameka,
Wonderful job on your explanations and follow ups to peoples questions. As a business major and history buff, i have a hard time grasping a lot of these concepts but i have re-read your orignial post 4 times now and am getting a much better understanding. Just wanted to let you know your hard work is appreciated and well-worth it. You should make a video explaining your points so i could watch that too!opcorn:

Not likely: Rameka hasn't been on this site in years.

lol i thought i had it right this time, i even looked it over, affect

The way to remember:
Affect is a verb, verbs = Action.
Effect is a noun.

 

[Olorin]

Find the wheat in the chaff.

 

[bstullis]

I have been throwing with a couple of pro (MPO ) players lately. one in particular has been frustrated with the way his discs fly here because of major loss of distance. The explaination he postulated was that the thinner air creates less lift related to the reduced molecules flowing over the top which creates a shorter throw (less air, less lift, =decreased ability for the disc to remain aloft). I was just wondering about the mechanics/mathematics on this theory. I think I agree since I seem to have been able to throw farther in Spokane (2200ft elevation) vs. here in Salt Lake (4500ft elevation), although I was just chalking it up to getting older and having less than perfect timing on my distance throws.

 

[PocketSand]

I'm almost positive that the thinner air would cause the disc to fly further because of less drag and wind/air resistance.

 

[hugheshilton]

If you believe the actual aerospace engineers who posted in this thread (look at page 11), then lift has a lot to do with disc flight. According to what I'm reading, airplanes and jets generally need more runway to take off at altitude because the thinner air provides less lift. Thus I would think we could extrapolate the decrease in lift to shorter disc flight as well.

Also, less lift means less turn at high speed since lift combined with gyroscopic progression is what creates the initial turn. So discs act more OS at altitude.

 

['ster]

My experience

I hope no one is too offended that I replied to this. I read as much as I could, but I tend to read quickly/scim and some stuff is just too mathematical for my meager mind to envision. Given that, I'd appreciate feedback on my understanding in my own words, taken from my own experiences, thoughts, and observations.

Why do discs hyzer/anhyzer?
Spin/Speed. A RHBH throw spins in the opposite direction as a RHFH throw, and consequently, the former fades to the left and the latter to the right. A disc turns over when the speed it is traveling forward exceeds the force generated by the speed a disc is spinning. That is, a disc with greater spin will resist the forces generated by forward speed. In my experience, the stronger my grip (which is best asserted with the thumb), the greater the effect of hyzer. Conversely, the looser my grip, the more likely my disc is to anhyzer. Two new, identical discs thrown at the same angle and speed, but with different spins will hyzer at different points in their flight, the one with less spin hyzering later than that with more spin. Which means that a player who lacks the arm speed to produce speeds greater than a disc's rating will get more distance with less spin, while a player who can produce forward speeds greater than a disc's rating will get the greatest distance by imparting an equally great spin. As a RHFH dominent player, I've hypothesized that RHBH players, who have more grip, tend to achieve greater distance because they can more easily impart greater spin, and thus force a 'flippy' driver such as a Valkyrie to better resist the force of the disc's forward speed. I realize this isn't phrased in a mathematical way, but I believe it does explain the effects as I've observed them.

What is "beating?"
I'd also like to offer the following thoughts on the effects 'beating' imparts on discs. As I believe someone mentioned and as is directed on the packaging of Aerobie's "Epic," bending a disc face plate to face plate with increase its stability while bending it rim to rim will decrease its stability. What I believe makes a disc more or less stable is a disc's tendency to be affected by spin imparted on it. A disc that is more affected by spin is overstable, while a disc that is less affected by spin is understable. I've 'tuned' many discs using the "Epic" instructions – it works on all drivers that bend without breaking – when a disc is bent face to face consistently all the way around so that it will still lie completely flat on a smooth surface, more the rim plate is exposed, which, in turn, increases the effect spin imparts on a disc's flight, making it more overstable. When a disc is bent rim to rim, less of the rim plate is exposed, decreasing the effect spin imparts, making the disc more understable. I don't believe scratches or even chips out of a disc make a significant difference in flight. A disc tends to beat to understable because, when a disc strikes an object, it is more likely to give in a rim-to-rim manor, following the natural curve of the original dome.

Nose-up/Nose Down effects? A disc throw nose-up not only rises as it "bounces" it also experiences more effect of spin, as air is hitting more of the rim-plate than if the disc were released flat. Inversely, a disc thrown nose-down will not only hit the ground, it will anyhzer sooner, as more air hits the face place than flat, and thus, loses the effects of spin.

More on Spin/Speed:

Observationally, discs continue to spin until they are stopped. The effect of spin increases as the disc's forward speed decreases. A disc is not limited to the speed at which it is rated. The speed at which a disc is rated is relative to the other specs rated on the disc. A disc rated 7, 5, -1, 2, will, when thrown at 7 speed, anyhzer to -1 at the point of 5 glide, then fade to the degree of 2 as it slows down. Of course, none of that takes into account the spin imparted on the disc, which is why any two players with the same arm speed can achieve different distances with the same disc in the same conditions. A player could through a disc rated 7 at a speed rating of 14, but it will lose its speed sooner than a disc rated a faster speed. Additionally, as a disc continues to travel above its rating, the greater the amount of spin will need to be imparted to maintain the ratings. A disc rated at 7 speed, traveling at 9 speed will need be exponentially more spin to stay flat than the same disc traveling at 7.5 speed.

 

[hugheshilton]

Oh here we go again opcorn:

Why do discs hyzer/anhyzer?

You're going to encounter quite a number of people on here who absolutely insist that it's all about gyroscopic precession. Personally, I don't think precession explains all of what you see. (For example, why do you get more turn when throwing into a headwind since the headwind doesn't produce any more spin and thus shouldn't produce any extra precession?) However, I no longer think it's really worth arguing with anyone about that. Everyone is entitled to their own opinion. However, since you asked for comments about your theories, I'll offer some comments.

That is, a disc with greater spin will resist the forces generated by forward speed.

So you're going with the theory that the spin stabilizes the disc. That one is common and seems plausible. Spin also seems to stabilize off axis torque (OAT) produced by bad form during the initial phase of flight.

In my experience, the stronger my grip (which is best asserted with the thumb), the greater the effect of hyzer. Conversely, the looser my grip, the more likely my disc is to anhyzer.

I'm not really sure that gripping harder or looser always produces faster spin. I definitely think gripping too hard OR too loose can produce OAT. It can also change your hit point, causing you to release slightly earlier or slightly later or even to roll your wrist. Generally gripping harder is going to cause a later release and more wrist roll. Would have to see you throw to really trust I knew what you were doing.

Two new, identical discs thrown at the same angle and speed, but with different spins will hyzer at different points in their flight, the one with less spin hyzering later than that with more spin.

Here's where I definitely disagree with you. In my experience when people get more spin on the disc, it tends to hold the line and stay in the air longer. It resists fading for longer.

Which means that a player who lacks the arm speed to produce speeds greater than a disc's rating will get more distance with less spin

Noodle arms can maybe help answer this question. When you get less snap on the disc, does it go FARTHER for you? Personally, I'm pretty sure more snap and more spin causes the disc to turn a little more, to stabilize from OAT more, and to stay in the air longer. Maybe I'm wrong though.

while a player who can produce forward speeds greater than a disc's rating will get the greatest distance by imparting an equally great spin.

Here I don't quite understand you. You think there's some magic speed where the affect of more spin on the disc reverses? You think when a disc is thrown slower, spin affects it in totally the opposite way than when the disc is thrown faster? That doesn't make any sense to me, sorry.

I agree with you that generally forehand throws get less spin on the disc. The spin is what stabilizes any OAT on the disc. Even professional players with very clean form have some amount of OAT if you watch slow-mo videos of them driving. Thus in order for a forehand player to not turn and burn their drives, they generally use a much more overstable disc to counteract the fact that they don't have as much spin on the disc as backhand dominant players.

I've 'tuned' many discs using the "Epic" instructions – it works on all drivers that bend without breaking

I think you're probably right about tuning and the way discs bend when they beat in. However, I think the reason it works is because as the disc bends inwards, the wing height of the disc is lowered. Everyone knows that within the same model/plastic of disc, a disc with a higher PLH or wing height will fly more overstable than one with lower PLH. Thus when you tune a disc inwards or as the disc beats in, the wing height is getting lower. I'm not sure I buy your explanation for WHY that matters, but it definitely matters. I'm also pretty sure that chips and gouges do affect flight as well. You could test that though by buying a disc, throwing it a couple times, then gouging the heck out of it and seeing if it flew the same.

Observationally, discs continue to spin until they are stopped.

My observation is that spin gets slower the longer a disc is in the air. It may not stop before it hits the ground, but it definitely seems slower than when it was released.

The effect of spin increases as the disc's forward speed decreases.

Disagree again. I think the affects of spin decrease as the spin decreases, which makes a lot more sense. Generally I observe that getting more spin on a drive causes the disc to hold the line longer and fade later because it's spinning faster through more of its flight.

Of course, none of that takes into account the spin imparted on the disc, which is why any two players with the same arm speed can achieve different distances with the same disc in the same conditions.

I think how clean their form is has a lot more to do with it. Less OAT means that the disc doesn't lose as much of its spin at the beginning of the flight and thus it spins faster throughout the flight which delays the fade for longer. Also, how the heck do you know for sure that 2 players were driving with the same speed and the same release angle? Have you pointed radar guns at different players when they were driving to actually test this because I don't think just eyeballing 2 people is going to tell you that they are throwing at the same speed.

 

[Savage Henry]

I have a headache now. And also a BS that took lots of physics and maths. And still a headache.

 

[Savage Henry]

Lets do a thought experiment. Imagine throwing a disc under water.

 

[hugheshilton]

I have a headache now. And also a BS that took lots of physics and maths. And still a headache.

Lol nice. I have a BS in computer science which took quite a bit of math, and I took some physics as well. However I think disc flight would be a fairly specialized branch of physics, probably related to aeronautics and I took nothing related to that so there you go. Mainly everyone on here is just BSing anyway.

 

[PMantle]

lowers humidity - also less drag

Are you sure?