Hey folks, I'm not asking for a physics dissertation here, but how in the heck do the disc manufaturers instill that stability thing in the discs? Is it how the density is spread out through the disc? Materials? A combination of both? I can see how materials will affect speed and wear, which can in turn affect performance, but I don't see how plastic in and of itself can affect stability. Is it perhaps pure aerodynamics?

Also, is a disc's properties symetric? By that I mean if a disc were cut in half, would the two haves be identical in shape, thickness, weight, etc?

Just curious...and bored. lol

-gk-

yeah i have been wondering the same thing!! but i can still make 1.5 stability fly straight...... and an understable curve to the left! Such a wierd sport..... :p

Different plastics have different properties, because some plastics are heavier than others. This is why you dont usually see Z discs under 165 but you will see DX discs under 150. Usually, the more expensive plastics are smoother and cut through the air better.

Ok, heres the physics part. This is for a RHBH throw. Keep in mind I'm 17...

The factors in the throw are thrust, which is produced by the thrower, drag, gravity, and wind. Gravity wants the disc to come back to earth, while lift counteract and forces the disc up into the air. The balence between the two is what we call "Glide". A disc with alot of glide is a disc that produces alot of lift. A disc with little glide is a disc that does not produce as much lift.

when a disc is released, the air moving over the top of the disc causes the disc to turn right. The air moving under the disc, along the wing creates lift, as well as forcing the outside edge to point down, and the disc to turn left. Wind and thrust play a factor here. The thrust of a properly executed throw with an evenly stable disc on a windless day will make the disc fly flat. The disc is completely stable but it is really "riding the edge" of turning right and turning left as the thrust propells it forward. As the disc slows down, it will begin to tail off to the left, because the wing of the disc usually has more force than the flight plate. In theory, you could manufacture a disc that would not fade at all, but it has not yet been proved. A disc that would fade to the right would not be possible, because you would not be able to apply ANY force to it, so there would be no way of knowing.

Winds also effect the stability of discs, as you know. For example, if you are throwing a disc into a 20 mph headwind, and you apply enough thrust so that the disc is flying at 35mph, the air is moving over the disc at 55 mph. This is why discs "turn over" in a headwind. Wind is pushed over the flightplate at such a rapid rate that it forces the right edge of the disc down and causes it to turn right. This is why we throw "overstable" discs into a headwind. Because overstable discs have a wing that produces much more force than the flightplate, the force on the flightplate will not be as great and may not even be great enough to counter the force on the wing.

Drag is the force of the passing air on an object. On a windless day, the drag created by different parts of the disc determines the stability. If the flight plate of a disc creates more drag than its wing, the disc will be "understable" because the greater force on the plate will push the right side of the disc downward and force the disc right. If the wing of a disc creates more drag than the flight plate, the disc will be "overstable" because the greater force on the wing will push the left side of the disc downward and force the disc left. Evenly stable discs have wings and plates that make similar drag. Any shape of disc can be evenly stable, be it a driver, midrange, or putter, just as long as the drag is evenly ballenced.

Finally, you've probably noticed that lighter discs are "less stable" than heavier discs of the same mold and plastic. This is not really true, because if you threw the 2 of them at different weights, but at the same velocity, they would fly the same. Also, you've probably heard that "lighter discs fly further". There is not really a whole lot of truth to this either, because lighter discs can be thrown at higher velocities than heavier discs by the same player. The disc flies further, because the disc is traveling faster. Again, if you threw 2 discs at different weights at the same velocity, their flights would be very similar. (I know that a lighter disc has less mass and therefore less force is exerted on it by gravity, but it will not result in much change.) The same goes for "heavier discs are more stable/ better in the wind" because heavier discs fly slower than lighter discs and their charachteristics are more ovious, because the fade starts sooner.

No disc is perfect, and all discs come out of the mold slightly different. Weight distribution is not always equal, but when the disc is spinning, it tends to even itself out.


Phew...that was thick! Anytthing else ya wanna know? :cool:

wow..... that looks like the physic dissertation..... :p

I think you got most of that right. You sort of left out the gyroscopic forces that spin impart, though. Heavy, wide rim (wing?) with lots of spin will make a disc 'hold its line' better.
For example, if you throw a disc hard, but with very little spin, it will tend to flip over to the right (rhbh). The more spin you put on it vs speed, the less likely this will happen. :confused:

5_SEC_Rule:

A sort of thumbnail sketch is:

The wider the rim, the more overstable (rhbh left turn tendency).

You can see and feel these differences very easily. Beasts, Monsters and Orcs have big rims that feel 'fat' in your hand. They will tend to turn left for an average player.
Cheetahs and Leopards have much thinner rims and they are easy to turn over.

It's not that simple..... It's more like, the wider the rim, the more overstable at slow speeds. There's less area under the disc to create an air pocket, so the disc will fall quicker if not thrown at optimum speeds.

5_SEC_Rule:

A sort of thumbnail sketch is:

The wider the rim, the more overstable (rhbh left turn tendency).

You can see and feel these differences very easily. Beasts, Monsters and Orcs have big rims that feel 'fat' in your hand. They will tend to turn left for an average player.
Cheetahs and Leopards have much thinner rims and they are easy to turn over.



How do you explain demons and whippits then? A good way to tell how overstable it is is by seeing how concave the wing is. Usually, overstable discs have a flat top and a concave wing. There are exceptions, of course.

Yeah, and I specificaly did NOT ask for one! :p

-gk-

I think you got most of that right. You sort of left out the gyroscopic forces that spin impart, though. Heavy, wide rim (wing?) with lots of spin will make a disc 'hold its line' better.
For example, if you throw a disc hard, but with very little spin, it will tend to flip over to the right (rhbh). The more spin you put on it vs speed, the less likely this will happen.




I'm so glad someone else realizes this. The biggest, and most common misunderstanding in why a disc "turns over" is "it turned over because i snapped it so hard(meaning "spinned" it so hard.)" When in fact, the reason the disc "turned over" was the lack of spin to force ratio. Simple gyroscopic and aerodynamic physics and principles. :D

I think you got most of that right. You sort of left out the gyroscopic forces that spin impart, though. Heavy, wide rim (wing?) with lots of spin will make a disc 'hold its line' better.
For example, if you throw a disc hard, but with very little spin, it will tend to flip over to the right (rhbh). The more spin you put on it vs speed, the less likely this will happen.




I'm so glad someone else realizes this. The biggest, and most common misunderstanding in why a disc "turns over" is "it turned over because i snapped it so hard(meaning "spinned" it so hard.)" When in fact, the reason the disc "turned over" was the lack of spin to force ratio. Simple gyroscopic and aerodynamic physics and principles. :D



That is why you are My-Hero! :D

Don't forget the distortion to the disc/wing as it leaves the hand. There's a picture of Avery somewhere with the disc about 3 disc lengths out of his hand, and that thing is seriously warped. The disc has to recover to original shape quickly. All the engineering of the disc either has to plan for that or else overcome it through trial and error.

wow.... enlightened!!! :-) :D:D

oh, and if you some how get a disc to fly at a constant rate of mach 7, you can watch it leave the atmosphere! Good stuff to know. Make sure you don't throw anything rare over mach 7 :cool:

Wait a minute. Did I read that right? The reason that my rhbh throws are turning over is because I did not put enough spin to counter balance the forward momentum? Does that mean the reason my disc is never flat (fading left) around the 410 mark on my long drives is because I have too much spin?

Don't forget the distortion to the disc/wing as it leaves the hand. There's a picture of Avery somewhere with the disc about 3 disc lengths out of his hand, and that thing is seriously warped. The disc has to recover to original shape quickly. All the engineering of the disc either has to plan for that or else overcome it through trial and error.



I seriously doubt the disc warped when it left his hand. If you can not stretch a disc pulling between you and a friend, the force of throwing it will not distort it visibly. Most likely, the camera simply could not capture the disc in still motion when at that velocity. It'd take about 1/4000 shutter speed to capture a still disc. but if it is slower, it will record the color of the disc at the instant the shutter opened, till the shutter closed. at 75 mph....

1 mph, 1.4677777 fps.

Avery would probably throw upwards of 75mph... 110 fps

a camera taking a pretty quick action shot... shutter speed, 1/500

the disc would deform approwimately .22 inches. enough to look weird, and seem deformed, but perhaps not enough for a visible motion blur.

Good theory though... Might happen with the really gummy Champion 150 class discs.

Wait a minute. Did I read that right? The reason that my rhbh throws are turning over is because I did not put enough spin to counter balance the forward momentum? Does that mean the reason my disc is never flat (fading left) around the 410 mark on my long drives is because I have too much spin?



Did you ever think that this was occuring because the disc is slowing down?

At the local Oregon clinic/tournament, they had a radar gun set up, and we all watched Avery throw for speed. His fastest throw (trying for speed, not a golf shot) was 63 mph.

At the local Oregon clinic/tournament, they had a radar gun set up, and we all watched Avery throw for speed. His fastest throw (trying for speed, not a golf shot) was 63 mph.



Makes me wanna get "clocked". I know it would be no wear near Avery, but I'm curious none the less!

Theo brings the gun to events and charges $1 per throw. All of the proceeds go to support Oregon's first Supertour event this year. It's a lot of fun. People enjoy seeing how fast they can throw, and which discs go the fastest out of the ones in their bags. It is always interesting to watch people throw as fast as they can. The form is sort of different then throwing as far as you can.

If you want to see how much a disc warps at 60 MPH just drive in your car at 60 MPH and hold the disc out the window at various angles. They warp like crazy and the Pro and Z plastic warps MORE than DX plastic!!!

I did think that as the spin died off, the lift on the left side of the disc diminished which resulted in the fade and subsequent crash to the ground. I have been trying to increase the amount of spin in an effort to try and get more glide which would result in less fade. Is that not the correct approach?

"In response to a question on the spirits stability from our discussion board"
How the weights effect high speed drivers.
I am not an aerodynamicist, but I did stay at a holiday inn last week.
Actually the flattest flying brand new Spirit I have thrown so far was a 185 S.
2 main factors effect a discs over stability when they begin to loose revolutions and velocity.
Assuming you threw the disc with proper technique, trajectory and angle in relation to YOUR revolutions and velocity ( hard enough to get on a flat flying plane for a long time enough to get forward penetration)
1) The main one; is deflection angles of the wing.
No matter what weight the disc is if there is more angle( concave radius) on the wing than the dome on the flight plate( anything above the parting line) it will begin to fade left as soon as the velocity begins to decrease.
example a Sabre has less or close to equal angle on the wing than on the dome which is why it is one of the best Gliding and landing discs on the market.
The speed Demon has a very long and fairly concaved wing which is a lot more angle( resistance) than the flatness of the top.( that�s why they cut back so hard even before declaration!)
2) The 2nd factor is gyroscopic weight distribution or ration of weight between flight plate and rim.
In the 185g Spirit I flew dead straight right out of the hopper, a lot of plastic got pushed into the flight plate making the ration of weight from rim to flight plate lean more towards the flight plate than in the 175 gram ones we ran after we got the profile of injection lined out.
The 175 and 185 were made from the same weighted batch of plastic, just pushed around differently by Temperature, Pressure and Speed!
Being that the Speed Demons and Spirits have the greatest difference of ratio between flight plate and rim( in a 175 gram Spirit or SD the ration would be rim= 120 and flight plate 55) This along with the ow overall height and sharpness on the nose is why our disc is the fastest on the market. Besides the Epic our 2 High Speed Drivers have the MOST gyroscopic weight distribution which allows it to SPIN FASTER AND LONGER.
Check out any competitive YO-YO or ask someone who competes about revolutionary designs in the past few years!
Just like the angles of wing deflection ,the close in balance the rim to flight plate ration is, the straighter the disc will fly on deceleration. Back to the reason why the Sabre flies so straight, the ration between rim to flight plate in a 175 gram Sabre is about 95=rim to 80= flight plate.

Hmmm....

my head is spinning..... frisbee golf is the sport of intellectuals.....
That would be fun clocking a disc with a radar gun to see how fast its going....... I hear the crush is the fastest........ ANd the new discraft FLASH is supposed to be faster!

way to deep of a conversation for my shallow mind :confused:,i'll leave this one up to the experts :D

We get to do speed throw contests with a radar gun at ZLT10's all the time. :)

Move to Texas.

i am orginally from Houston..... would be nice to do speed tests in Tulsa..... :-) I wonder if there are any cops on the TDSA thought would clock our discs..... :-P instead of my truck when i am driving!!!!!!! :D

No disrespect intended but Graham's explanation is basically incorrect. There is a lengthy thread on this exact subject that I can't find right now... :cool:Here's a basic summation: A flying, spinning disc acts like a gyroscopic wing.

To demonstrate, spin a disc clockwise on your finger. Lightly tap the front rim of the disc. Note that the disc wobbles and turns to the right. Repeat, but this time tap the back rim. It should tilt left. You've just simulated a moving center of lift on a rotating wing and incidently the flight path of a disc. Why does it do this? :confused:

Let's tackle the wing part first. All discs have a dome and a rim. If the rim is wider, there is less overall drag and the disc will retain speed longer. Lift is generated by the disc displacing air unevenly as it travels: Air passing over the dome must move farther than air passing under the rim, creating lower pressure over the top of the wing and higher pressure under the bottom. The center of lift on any wing tends to move dependant on the relative velocity of the wing. Generally speaking, the center of lift moves back at higher velocity and forward at lower. Airplanes compensate for this by using flaps to change the wing configuration, making it wider and taller at low speeds and narrower and shorter at high speeds. Unfortunately, flying discs don't have this option, so we get a variable center of lift.

This brings us to rotational dynamics (the gyroscope part)
The center of lift (c.o.l.) is not in line with the center of gravity (c.o.g.) This imbalance of forces, in combination with the principle of angular precession (what keeps you upright on a bicycle) causes the disc to turn. When the disc is at high speed, the center of lift is behind the center of gravity and the force is transferred 90 degrees in the direction of the spin (clockwise) to push the left side of the disc up and make the thing fly to the right. When the disc slows down a bit, the center of lift moves through the center of gravity and the disc flies straight. When the disc really slows down, the c.o.l is in front of the c.o.g. and the forces act to push the disc to the left.

This brings me to what we all really want to know: How do I make these things fly straight? The X factor is rotational momentum, and lots of it. All things being equal, if a disc is spinning faster and/or is heavier, it will resist the precessional (turning) forces more. Getting more spin on the throw is the key to keeping a disc straight and in the air for as long as possible. Pick a disc that matches your throwing speed and the wind conditions. That means that if Disc X flies overstable at lower speeds, try throwing it into a headwind. If Disc Y turns and burns for you, try it with the wind over your shoulder. Beat up discs tend to fly farther, possibly because the nicks and dings act like the dimples on a golf ball and reduce drag. :D

about the whole beat up discs flying farther???? i dunno bout that fact for drivers but the midranges that is true! :D

<font color="blue">Kenja said "Airplanes compensate for this by using flaps to change the wing configuration, making it wider and taller at low speeds and narrower and shorter at high speeds. Unfortunately, flying discs don't have this option, so we get a variable center of lift."</font>


Kenja, I'm not convinced we are without options in this field of study. I'll reference the Dunipace patent <font color="red">(#5,531,624 - July 2, 1996)
</font> a few times to support my theory(ies), beginning with <font color="red"> "The present inventor has recognized there is still room for additional improvement in the design of flying discs." </font>

Grip enhancement is, or should be, obvious to the CHING Excelerator Concept (http://www.chingdiscgolf.com/discs.htm).

http://www.chingdiscgolf.com/concept/excelerator.jpg

As Dunipace states, <font color="red">"...and it is preferred that it be sufficiently thin and flexible that the disc will bend on impact and allow the user's thumb to be pressed into the plate 20 when gripping"</font>

Small dimples to reduce surface friction/drag may be ineffective, however less obvious may be the aerodynamic stability improvement for a longer consistent flight based on rotational dynamics and speed sensitivity in a complex contoured flight deck.

http://www.chingdiscgolf.com/concept/excelerator-flow.jpg

Observed in a stationary position, this mini shows a simple Excelerator pattern.

http://www.chingdiscgolf.com/concept/mini-01.jpg

This is basically a spoiler around the entire circumference of the disc with some parts filled in - not unlike the patented ThumtracTM disc.

http://www.chingdiscgolf.com/concept/thumtrac.jpg

When the mini is spinning faster and faster, a virtual groove is generated which offsets the tendency to turnover by keeping the rear of the disc down for stability - especially when it is most vulnerable to undesireable turnover from hyperspeed.

http://www.chingdiscgolf.com/concept/mini-02.jpg
http://www.chingdiscgolf.com/concept/mini-03.jpg
http://www.chingdiscgolf.com/concept/mini-04.jpg

<font color="red">" On the trailing edge, the raised ridge may look like a spoiler and it is believed that raised ridge with its transition point may function as a rear control or deflection surface."</font>

The limitations of prior technology include a fixed location for the spoiler near the rim (since grip improvement may be the primary design consideration) and no speed sensitivity. Excelerator technology allows the stabilization to diminish with the slowing spin/speed of the disc so it doesn't turn toward the direction of spin prematurely. Also improved is the ability to selectively locate the width and intensity of the virtual groove, spreading it out over a larger portion of the flight deck to reduce flutter and adjust to the shifting lift forces.

http://www.chingdiscgolf.com/concept/disc-01.jpg
http://www.chingdiscgolf.com/concept/disc-02.jpg
http://www.chingdiscgolf.com/concept/disc-03.jpg

Profile is significantly more influential in defining the general flight characteristic of each model (as should be apparent comparing an overstable Rhyno to an understable Wolf - both sharing the 'spoiler' design but with dramatic flight differences) but measurable benefits in control, distance, and accuracy will be available when Excelerator technology is unleashed later this year. :cool:

Holgate,

This is an interesting and novel way to rework the flight plate of a flying disc. There seems to be number of recent innovations in disc technology -- discwing has some sort of deeply grooved inner rim in the works, aerobie had the spoiler rim and epicyclic design (which IMO made the Epic the worst of all possible discs -- high speed extremely understable, low speed extremely overstable)

Without making anyone sign an NDA, can you give us any proof to back your claims re: the Excelerator? Has Ching done anything to address the bottom part of the disc -- which is where the majority of the drag occurs, if you think about it. I can almost imagine disc golf designers working as the Wright bros. did, making tiny scale models for a windtunnel. BTW, was anyone aware that they actually tested hundreds if not thousands of possible wing configurations in a wide range of airspeeds?

How do you test a disc in a wind tunnel? If you nail it in the center and spin it like that college did way back when, the top caves in due to lift on the disc and the center being locked down. That doesn't tell you anything real world.

Putting some kind of spreader to lock in the bottom of the rim would be better, but it seems that would dramatically interrupt the air flow on the inderside and thus again move away from real world behavior.

Is there a way to stablilize a spinning disc in a wind tunnel and gather useful info? An airplane wing is a lot different in that it doesn't spin, so you can just hold it there and blow the wind.

How do you test a disc in a wind tunnel? If you nail it in the center and spin it like that college did way back when, the top caves in due to lift on the disc and the center being locked down. That doesn't tell you anything real world.

Putting some kind of spreader to lock in the bottom of the rim would be better, but it seems that would dramatically interrupt the air flow on the inderside and thus again move away from real world behavior.

Is there a way to stablilize a spinning disc in a wind tunnel and gather useful info? An airplane wing is a lot different in that it doesn't spin, so you can just hold it there and blow the wind.


Oh great..............another dimple disc............ :eek: :D

Without elusive industry standardized automation, empirical data for golf disc testing remains subjective for all manufacturers. But the countless random participants we�ve solicited for feedback (a wide range of skills, strengths, and techniques) on a methodical journey of discovery and aggressive execution of the design process verify our claims � claims which are built upon the logical body of knowledge widely accepted from the industry authority and algorithmically taken to the next level...




...ok, I threw a couple in the backyard. /msgboard/images/graemlins/smirk.gif

How do you test a disc in a wind tunnel?



Embed magnets in the rim. Set up a rig inside the wind tunnel that would both spin the disc and hold it in the air using the magnets. Simple, really.

Actually, I have no idea if this is possible.

I was thinking more on the lines of wing configuration testing with a nonspinning disc, just to measure where the lift is occuring. Of course, this ignores both the gyroscopic effect and the vortex of air trapped under the dome. Rather than 'thumbtacking' a disc to a test rig -- I'd envision some type of free moving arm assembly like they use to test airfoils. Distortion could also be minimized by using more rigid materials like polycarbonate. The trick is to maintain constant rotation, which could be achieved through magnets (the weight of which might affect the test) or simply spinning the sucker and trying to get measurements before it slowed down. As a thought experiment, a slow, straight flyer like the Roc or Cobra should have a very wide range of 'stable airspeeds' -- where the center of lift is closest to the center of gravity.

Wait a second, I don't need a wind tunnel to prove that those discs fly far and straight. :D

Ah, screw it -- the best way to test is to throw em around in the backyard. /msgboard/images/graemlins/smirk.gif

so how thick is that tape around your glasses??? :D :Dand do you use those spandex headband to keep your glasses on when you play???? :D :D :D

hehe I have glasses made out of candy rhynos, doncha know? :D :D :D

LMAO lol lol :D:D:DI have tears coming from my eyes

symmetrical.

One: Just hold it there and blow the wind. Pin through the center that also adjusts to lift will work. The pin could be attached to a lightweight arm to avoid the disc caving in, or
it could be designed to telescope up and down with the lift.

Two: Hold it there and spin the hell out of it and blow the wind. Same pin arrangement through the center of rotation will do fine.
There are several ways to impart the spin. A powerdrill
attached to the pin would be one of the simplest methods.