Disc flight science

[Doofenshmirtz]

Finally.... you brought some evidence, but doesn't really disprove anything.

I think that this is the problem with your approach. You seem to think that it is the burden of anyone who disagrees with your idea to disprove it and that you have no burden to prove anything - even though you are the one making the assertion.

I wasn't trying to "disprove" your idea. I was only pointing out that your demonstrations don't seem to prove anything other than that two different discs seem to fly differently.

I'm not tryig to assault your character or intelligence. I'll be happy to admit that you are on to something when you actually demonstrate that there is something there. You just haven't done that.

 

[blayed]

I havent seen any talk about gyroscopic precession? For spinning objects, applied forces are applied 90 degrees out of phase (90 degrees later). For a US disc air is pushed above the disc (wing pointed down), for a OS disc the air is pushed below the disc (wing pointed up). If you're throwing RHBH the disc is spinning CW. Push the disc UP at 12 o'clock, then rotate it 90 degrees clockwise to 3 o clock: Hyzer angle. Push the disc DOWN at 12 o' clock, rotate the disc 90 degrees clockwise: anhyzer angle. When discs slow down they effectively "stall out", air is pushed underneath the rim, lifting the nose up which 90 degrees later causes it to fade.

When discs beat in their edge gets blunted and angled down: pushes air above the disc and makes it behave more US. The only exception is the tilt, which will become more stable as you beat it in due to the wing shape (gets bent the OTHER way, more air going below the disc)

Here is a good visual to explain: https://www.youtube.com/watch?v=n5bKzBZ7XuM

Source: BS in Physics

 

[Sheep]

I think that this is the problem with your approach. You seem to think that it is the burden of anyone who disagrees with your idea to disprove it and that you have no burden to prove anything - even though you are the one making the assertion.

I wasn't trying to "disprove" your idea. I was only pointing out that your demonstrations don't seem to prove anything other than that two different discs seem to fly differently.

I'm not tryig to assault your character or intelligence. I'll be happy to admit that you are on to something when you actually demonstrate that there is something there. You just haven't done that.

Debate class seems to be something that isn't very common in school anymore is it?

When somebody makes a statement and you wish to debate that statement/topic.

It's helpful to bring evidence to the table to reinforce your side of the discussion against the standing topic held self evident at the time.

So, making a claim against a topic without any proof is a statement of opinion with nothing to back it up.
Different of course if you're trusted in said field and considered an expert, but that's not the case here, none of us are really experts, so we have to ignore that particular caveat.

So, we are left with 2 things here;
Ask questions, or
Counterstatement with evidence.

When its a dual of opinions, evidence is a bit different topic. but thats because its 2 opinions clashing, there is no data to be had.

This is a data driven topic, thus challenging the data must be met with a question or by evidence to the contrary to back up your theory/opinion/statement.

If you were trying to point something out, you should have formed it as a question, not a statement challenging the topic.

 

[Sheep]

The only exception is the tilt, which will become more stable as you beat it in due to the wing shape (gets bent the OTHER way, more air going below the disc)

In "theory" this sounds true.
But, in my very experienced position of throwing the tilt, a LOT.
It definitely gets more understable.
Cause mine is really really beat up at this point, (meta)
And.. It's nowhere near as overstable as it was. The only reason I know this is because I was essentially throwing a trick shot with it to hit a crazy line on a hole and over time it was not coming out of the line soon enough like it did when I started throwing it.

Now, if I could remember the effing term that I need for the air flow stability blah blah blah, it would be fantastic.
But while I don't disagree with the air above and below. The turbulence of the air is also a factor playing on the pressures of the disc as the air applies forces.

Why can I not remember this stupid term.

 

[Orchestra]

I thought this article was interesting and covered some of the turbulence effects.

Edited: wrong link. Here's the one I intended:

https://www.scientificamerican.com/...-al-rihla-has-the-aerodynamics-of-a-champion/

 

[timothy42b]

Now, if I could remember the effing term that I need for the air flow stability blah blah blah, it would be fantastic.
Why can I not remember this stupid term.

Here you go:
https://theconstructor.org/fluid-mechanics/dimensionless-numbers-importance-fluid-mechanics/34265/

 

[Sheep]

Here you go:
https://theconstructor.org/fluid-mechanics/dimensionless-numbers-importance-fluid-mechanics/34265/

The funny part is. It's actually "turbulent flow" was what I couldn't remember.
But I think it was because my brain was wanting to que "laminar" flow.

Which both of these terms have HUGE impacts on the topic here.


A damaged disc creates turbulent flow. Which in turn causes different pressures on the disc to be exerted.

Where this also boils down to is that no 2 discs can ever truly be beat in the same, as disc damage is always unique.

Which is why in the case of such as my identical discs have the same flights despite vastly different wear levels.
The second one which almost looks new flies like the one that was in my bag for 4 years straight.
Despite it being in the condition of the disc I loved when it just went dead nuts straight for 300 feet before fading with no turn no fade.
This one just wants to flip.


I gotta get this deck and chicken coup finished and I can start on the Wind tunnel and we can actually pull visual data from the wind tunnel vs speculative data.

I have all the materials to do it, just have not had the time/space because I have to many projects going on, and a full size wind tunnel for this is gonna take up a TON of room as it will be around 10-15 feet long to be proper.

 

[Doofenshmirtz]

Debate class seems to be something that isn't very common in school anymore is it?

When somebody makes a statement and you wish to debate that statement/topic.

It's helpful to bring evidence to the table to reinforce your side of the discussion against the standing topic held self evident at the time.

So, making a claim against a topic without any proof is a statement of opinion with nothing to back it up.
Different of course if you're trusted in said field and considered an expert, but that's not the case here, none of us are really experts, so we have to ignore that particular caveat.

So, we are left with 2 things here;
Ask questions, or
Counterstatement with evidence.

When its a dual of opinions, evidence is a bit different topic. but thats because its 2 opinions clashing, there is no data to be had.

This is a data driven topic, thus challenging the data must be met with a question or by evidence to the contrary to back up your theory/opinion/statement.

If you were trying to point something out, you should have formed it as a question, not a statement challenging the topic.

Except this isn't a middle school debate class. Instead, it is a thread that has the word "science" in the title. If you examine the actual "debate" nature of this thread and put your post in that context, what you are doing is making an argument from ignorance (a.k.a. "appeal to ignorance"), that is, you are arguing that Sidewinder22's claims are true because of a lack of evidence against them.

Generally speaking, when a person makes a novel assertion, or any assertion really, he should bear the burden of proving it. Along with that burden should come the expectation that if he doesn't offer convincing evidence, that it is fair game for anyone to point that out.

But your reaction to my posts, which point out that the claims in the video seem to have no factual basis, is simply to argue by implication if not directly, like the person asserting those claims, that because he made the claims, it is my burden to disprove them and that if I can't disprove them, they must be true.

So, making a claim against a topic without any proof is a statement of opinion with nothing to back it up.

Have I made a false claim? Did the video not show a person comparing the flight of two different discs as an explanation as to why one of them flies differently than it used to? Did I not offer a more logical way to prove the assertion (by simply adding texture to the edge of the new disc and re-throwing it)? Wouldn't that be a better way to back up the claim than just throwing an obviously different shaped disc an comparing its flight to the beat in disc?

You speak of "data" but can you really point to any in this thread to back up what is being argued in the video. If you are claiming that the video is data, what exactly do you think it shows?

 

[jupiterboy]

Worth pointing out, too, that in an area like this (and many others that are debated on the internets) we are generally left to extrapolate from associated fields' science because nobody is going to put the money into a scientifically valid study. Beyond that, how to even construct a valid experiment becomes really murky.

 

[Sheep]

Generally speaking, when a person makes a novel assertion, or any assertion really, he should bear the burden of proving it. Along with that burden should come the expectation that if he doesn't offer convincing evidence, that it is fair game for anyone to point that out.

Pot

Have I made a false claim?

Meet Kettle.


Sidewinder, from what I'm reading, specifically stated "Finally.... you brought some evidence..."

Which he was bearing on you the burden of proving your novel assertion.



As for middle school, You're funny.
Thank you for the insult though.

 

[RowingBoats]

I honestly think some of these mysteries are what make this sport so cool lol. I'm positive lots of y'all are capable of pulling data from wind tunnel experiments, and that data is probably useful...

But none of that data changes the fact that a wraith can go from useless to amazing in one tree hit, and fully modeling that will always be impossible.

 

[Sheep]

I honestly think some of these mysteries are what make this sport so cool lol. I'm positive lots of y'all are capable of pulling data from wind tunnel experiments, and that data is probably useful...

But none of that data changes the fact that a wraith can go from useless to amazing in one tree hit, and fully modeling that will always be impossible.

Comment of the day!

Take that, Tree!!!

 

[Eric_T]

I'm late to the party here, but came across this post now. I'm one of the authors of one of the papers cited by the OP (thanks, btw!). I also have a wind tunnel, see the picture below Hope I can find some more time to spend on disc golf aerodynamics research, in the mean time I would be happy to discuss some more here.

 

[Sewer bill]

I'm late to the party here, but came across this post now. I'm one of the authors of one of the papers cited by the OP (thanks, btw!). I also have a wind tunnel, see the picture below Hope I can find some more time to spend on disc golf aerodynamics research, in the mean time I would be happy to discuss some more here.

View attachment 335368

You should absolutely discuss more here.

 

[HyzerRoc]

Just focusing on the first part of the video here. The taller cup gets pulled to the right when thrown with enough velocity. Does this apply the same and explain why taller putters have that drift to the right when thrown with enough speed? A mercy is quite OS for a putter but when driving with it it drifts to the right, not even turning much, just drifting.

I'm late to the party here, but came across this post now. I'm one of the authors of one of the papers cited by the OP (thanks, btw!). I also have a wind tunnel, see the picture below Hope I can find some more time to spend on disc golf aerodynamics research, in the mean time I would be happy to discuss some more here.

Thats really cool, researching frisbees and having your own wind tunnel and all that.

Can you talk a bit about what you learned about disc selection through your research?

What do you think about the characteristics of flat vs. domey discs? I have heard here and there that domey discs behave more squirrely.

And what is the difference between discs designed with flat vs. concave lower rims? Example would we a River (concave) vs. a Hawkeye/old FD which has a flat lower rim. Both discs fly fairly straight. I have noticed that Trilogy tends to design even their understable discs with a concave lower rim while Innova has chosen to make some discs with a flat lower rim and toyed with convex lower rim designs (for example the Innova IT).

 

[Brychanus]

I'm late to the party here, but came across this post now. I'm one of the authors of one of the papers cited by the OP (thanks, btw!). I also have a wind tunnel, see the picture below Hope I can find some more time to spend on disc golf aerodynamics research, in the mean time I would be happy to discuss some more here.

View attachment 335368

YW and awesome to see you here!

 

[Eric_T]

Thats really cool, researching frisbees and having your own wind tunnel and all that.

Can you talk a bit about what you learned about disc selection through your research?

What do you think about the characteristics of flat vs. domey discs? I have heard here and there that domey discs behave more squirrely.

And what is the difference between discs designed with flat vs. concave lower rims? Example would we a River (concave) vs. a Hawkeye/old FD which has a flat lower rim. Both discs fly fairly straight. I have noticed that Trilogy tends to design even their understable discs with a concave lower rim while Innova has chosen to make some discs with a flat lower rim and toyed with convex lower rim designs (for example the Innova IT).

Sure. About flat vs dome, it actually varies depending on the disc. Typically, we can say that dome increases glide (I don't like glide as a flight number, but that's a different discussion...). It also generally makes the disc more understable, as it pushes the parting line down compared to a flat disc. There are exceptions, though. I have a Wraith with a very pronounced dome in the center of the disc, but the parting line is still higher than a flatter Wraith. So it has more glide, but is also more overstable. From what I understand, this is an attractive feature in certain Destroyer runs (I don't throw hard enough to know ). I have simulated a comparison of different plastics, using the Alfa Discs Cosmic disc. These discs had a very pronounced difference in dome, and the parting line was a bit lower for the domey disc. You can see the result of this comparison below, both in terms of aerodynamic coefficients and typical flight shapes with low and high throwing speed ("beg"=beginner, and "pro"). You see that the domey disc has higher lift, and is also more understable (lower moment coefficient). This will make the disc more squirrely, as you say, as it will be more affected by the wind and also off-axis torque in your throw.



Same with concave/convex/flat lower rims, it is difficult to compare different discs since the overall design is different so you can't really isolate just the effect of the rim profile. For the River/FD, the River has a more pronounced curve on the shoulder of the disc, which together with the larger dome adds to the glide and understability. But I think this is a really interesting comparison, since it's two very different designs with the same goal of a glidey, straight disc. I will run it through my simulation setup and report back with more details.

For the convex rim, I do have an example in my article, comparing a Firebird against a Roadrunner. This was chosen as an extreme example on purpose to really highlight the differences. A different version of that comparison is shown below, with arrows indicating the wind pressure pushing on the disc. You see that for the concave rim, the disc is pushed up on the nose, making it more overstable. The convex rim is more neutral. There is also a big difference towards the back of the disc, where the air pushes more upwards on the Roadrunner, making it more understable. But again, this is the overall design, not just the rim shape.

 

[HyzerRoc]

I have a Wraith with a very pronounced dome in the center of the disc, but the parting line is still higher than a flatter Wraith. So it has more glide, but is also more overstable. From what I understand, this is an attractive feature in certain Destroyer runs (I don't throw hard enough to know ).

Yeah the dome of a destroyer is not gradual but pops up, leaving a depression between dome and rim. I noticed that about the Time Lapse: its dome does not pop up but is more like a continuation of the shoulder/rim.

Same with concave/convex/flat lower rims, it is difficult to compare different discs since the overall design is different so you can't really isolate just the effect of the rim profile. For the River/FD, the River has a more pronounced curve on the shoulder of the disc, which together with the larger dome adds to the glide and understability. But I think this is a really interesting comparison, since it's two very different designs with the same goal of a glidey, straight disc. I will run it through my simulation setup and report back with more details.

Other candidates that would come mind here would be a Ti Buzzz (others have a more pronounced shoulder) vs. a Mako3 as those also have similar profiles but the Buzzz rim is concave while the Mako3 is convex/flat. The new FD also features a more concave rim.

What I wonder here is what the tradeoffs are in the design of the discs. Obviously the molds here are all very popular, achieving a similar purpose but are designed very differently.

For the convex rim, I do have an example in my article, comparing a Firebird against a Roadrunner. This was chosen as an extreme example on purpose to really highlight the differences. A different version of that comparison is shown below, with arrows indicating the wind pressure pushing on the disc. You see that for the concave rim, the disc is pushed up on the nose, making it more overstable. The convex rim is more neutral. There is also a big difference towards the back of the disc, where the air pushes more upwards on the Roadrunner, making it more understable. But again, this is the overall design, not just the rim shape.

View attachment 335376

I stumbled over this figure of yours but struggled understanding it. The way you explain it makes a lot of sense so thanks for that.

This might just be rewording what you already said, but I guess the disc with a flat rim would raise its nose angle later in the flight than the one with a concave rim as it doesnt have the same pressure on its nose while also having some pressure on its back so the nose stays down. In regards to the River/old FD comparison this would mean that the old FD has a later/less fade than the River. The River likely makes up for that with a lower parting line and as such will have more turn during its flight. So an old FD would be straighter while a River would fly more from side to side.

 

[Eric_T]

Yeah the dome of a destroyer is not gradual but pops up, leaving a depression between dome and rim. I noticed that about the Time Lapse: its dome does not pop up but is more like a continuation of the shoulder/rim.

Yes. Here is a slice through a 3D scan of that Wraith, you can clearly see the funky shape of the flight plate.

 

[Sheep]

I'm late to the party here, but came across this post now. I'm one of the authors of one of the papers cited by the OP (thanks, btw!). I also have a wind tunnel, see the picture below Hope I can find some more time to spend on disc golf aerodynamics research, in the mean time I would be happy to discuss some more here.

View attachment 335368

Yeaaaah my wind tunnel is not going to be that fancy when finished. hahaha.