Aerodynamics stuff

[BenjiHeywood]

This is an interesting discussion. I am not sure where the idea that approximately -4 degree nose angle is somehow optimal originated. I saw Brodie Smith mentioned it in one of his TechDisc videos, but without any justification. The wind will not flip a disc up or down during the flight. Since the disc is spinning, any torque is translated into turn/fade instead. However, the change of direction of the lift and drag caused by the nose angle will make the disc change its trajectory. The extreme version of this is an air bounce, where throwing the disc on a downward trajectory with very high nose angle eventually will change the trajectory to go upwards (or vice versa, the reverse air bounce, as @sidewinder22 mentioned )

To add some quantitative data to the discussion, here is how the aerodynamic coefficients for a disc typically change around 0 degrees angle of attack (nose angle at the point of release). This data is taken from computational fluid dynamics simulations I have performed, and the trends are similar across a large range of discs.

View attachment 336192

So having nose down makes the disc behave more understable (lower moment coefficient) and reduces the lift, while the drag more or less stays the same (even a slight reduction here, but it varies between discs).

If we plug this into a trajectory simulator we can compare the flights. This is not perfect, of course, but the benefit of a simulator is that you are able to really isolate the effect of a single parameter. Here are two simulated throws, where the one with nose angle down also has a higher hyzer angle to compensate for the lower initial moment coefficient:

View attachment 336193

So why does the lower nose angle go further, even though we have reduced the lift? The answer is that by reducing the lift while maintaining the momentum and not increasing drag, we allow the disc to push more forward instead of rising up. This also makes the fade towards the end of the flight less pronounced, as you don't get as severe angle of attack towards the end of the flight. So I believe a slightly negative nose angle is beneficial, maybe especially when throwing faster, overstable discs.

Just for fun, here is an example from the computational fluid dynamics simulations. The top image has nose angle 0, the bottom nose angle -4, and the disc travels from right to left. The blue regions are low pressure and the yellow regions are high pressure.

View attachment 336194

It's maybe hard to extract something meaningful from this without digging more into the details, but we can clearly see how the pressure is higher along the top with a negative nose angle, which is reducing the lift. We also see that the wake at the back is smaller for the negative nose angle, reducing the drag, which maybe helps explain why drag stays the same overall.

This is a very interesting question, and one I really want to study more in detail. Disc golf is really unique here, I think, in that the projectile we use wears over time and that this is a beneficial effect.

I believe it's a combined effect of many separate factors. The idea that the PLH is lowered actually seems reasonable to me. Since the overall shape of the flight plate typically has some dome, it makes sense that a direct hit will push the PLH downwards most of the time. And we can already demonstrate in the simulations that this would make the disc more understable. Similarly, shaving off some of the rim bottom will also make the PLH lower (which is why beads are used to mitigate this effect), so that's clearly a contributor.

The effect of roughness, though, seems poorly understood at the moment. Maybe it could lead to an effect as I've tried to illustrate below. If the roughness introduces enough instability to make the flow near the disc turbulent, you may reduce the size of the wake underneath the flight plate. This is somewhat what some older disc designs have tried to do, with textured/dimpled rims (Latitude Missilen, Quest AT Scream DT etc). What's interesting, though, is that this is a phenomenon that depends a lot on the velocity, so the behavior could change during the flight. This might be why people say that a beat-in disc keeps its low-speed stability but loses some of its high-speed stability. It's at least a hypothesis I think is worth testing out and getting some quantitative data on. I have most of the stuff ready to test this, so hopefully I will have some data soon. Would be happy to hear some other thought on this as well!

View attachment 336824

@Eric_T has chipped in with some really excellent quantitative content on @disc-golf-neil 's grip thread. I think this stuff is worthy of its own thread, as it contains a ton of interesting things that many of us have speculated about but Eric has actual data.

 

[BenjiHeywood]

Yes, the plot I showed was actually for a pretty understable disc. Here is a comparison against an overstable one:

View attachment 336205

You see the drag behaves more or less the same way, but the overstable disc has lower lift and higher moment coefficients. You can probably design a disc that behaves differently, though. I would think that whether to throw understable or overstable depends more on the speed you throw at and what shape you want from your throw.

Oh and this one too. Very interesting.

 

[BenjiHeywood]

That last one has a graph i find very interesting.

If I'm reading it right, minimum drag happens with the angle of attack maybe 2-4 degrees below zero - but at that angle, the lift is negative. Obviously when the disc goes up and over its apex, the angle of attack is positive and the disc gets lift on the way down, but at the beginning that's not the case.

So the value of a negative nose angle is in minimising drag early, when the speed is very high*, so that you can get the disc up in the air with minimal losses. It's potentially not so much about the angle it glides down at, or how much of the top of the flight plate you can see in flight, which is probably what i would have thought was important.

Would you say that the correct nose angle for max distance when gliding is going to be whatever keeps the disc straight (which will depend on overstable/understable), and the correct angle out of the hand is whatever minimises drag early? And then the best choice of disc and/or launch angle for max distance is going to be whatever hits the best combination of initial angles and gliding angle, given your mph and rpm etc.

Or am i talking nonsense? That is of course very possible.

*Incidentally, do you think the drag varies with velocity or with velocity squared, Eric? I dunno what the Reynolds number is etc etc. If it started as v2 early but was v later in on the flight, that would really emphasise the importance of nose angle early.

 

[Eric_T]

CoeffThat last one has a graph i find very interesting.

If I'm reading it right, minimum drag happens with the angle of attack maybe 2-4 degrees below zero - but at that angle, the lift is negative. Obviously when the disc goes up and over its apex, the angle of attack is positive and the disc gets lift on the way down, but at the beginning that's not the case.

So the value of a negative nose angle is in minimising drag early, when the speed is very high*, so that you can get the disc up in the air with minimal losses. It's potentially not so much about the angle it glides down at, or how much of the top of the flight plate you can see in flight, which is probably what i would have thought was important.

Would you say that the correct nose angle for max distance when gliding is going to be whatever keeps the disc straight (which will depend on overstable/understable), and the correct angle out of the hand is whatever minimises drag early? And then the best choice of disc and/or launch angle for max distance is going to be whatever hits the best combination of initial angles and gliding angle, given your mph and rpm etc.

Or am i talking nonsense? That is of course very possible.

*Incidentally, do you think the drag varies with velocity or with velocity squared, Eric? I dunno what the Reynolds number is etc etc. If it started as v2 early but was v later in on the flight, that would really emphasise the importance of nose angle early.

Thanks for creating a separate thread on this!

I'd say that the benefit of a slightly negative nose angle is not only the lower drag (the difference in drag is not massive), but also the fact that you trade lift for more forward momentum, which translates to longer distance. Max distance has many parameters to consider, so it's hard to come up with general rules. I actually have written an optimizer for this, maybe I will share some results from that here as well.

Regarding the drag, the drag force definitely varies with velocity squared. The drag coefficient has been shown to be relatively independent of the velocity.

 

[BenjiHeywood]

Thanks for creating a separate thread on this!

I'd say that the benefit of a slightly negative nose angle is not only the lower drag (the difference in drag is not massive), but also the fact that you trade lift for more forward momentum, which translates to longer distance. Max distance has many parameters to consider, so it's hard to come up with general rules. I actually have written an optimizer for this, maybe I will share some results from that here as well.

Regarding the drag, the drag force definitely varies with velocity squared. The drag coefficient has been shown to be relatively independent of the velocity.

So even at the end of the flight, it's still velocity squared? That's interesting.

Anyway, I'm thinking, in a back of the envelope style, that the v-squared thing explains why pure distance lines are so high - we get out of the VERY high drag phase (the square of a very high speed) earlier, by throwing upwards (such that gravity, as well as drag, slows the disc down) but then we use the gravitational potential energy to counteract the drag on the way down, maintaining a slower but more stable velocity for longer and thereby travelling further - even though the disc has to travel a longer overall path by going so up and down instead of flatter.

But i lack the maths skills to work out whether that's just nonsense.

 

[Eric_T]

Yes, it's about trying to spend as much time as possible in "glide-mode", letting the disc drift with high lift force throughout the flight. Here is one of the optimized throws I was talking about, throwing a nuke at 70 mph (with the usual caveats about uncertainties etc):




This is thrown with a high hyzer angle, letting the disc flip up and then ride to the right before fading out. I would say this looks very similar to what the pros throw in distance competitions. Of course they also try to exploit the wind, ideally you want tailwind to hit the disc in the glide phase, so going over your shoulder from left to right.

So as you say you want to get the disc high quickly (but this is done mostly by the lift, not by throwing upwards), and the ideal way to do this is with negative nose angle initially, as that has lower drag. But you don't lose that much by having a higher nose angle, as long as you also compensate by throwing lower and with less hyzer.

These results make it possible to say something about what disc to throw for max distance, as long as you have consistent form. You should throw the fastest disc that lets you get a similar flight path to the one shown above. So the slower your arm speed is, the more understable you should throw. And if you throw nose up, you should lower your pitch angle (throw flatter) and also reduce the hyzer angle. Throwing flex shots with an overstable disc will lose you some distance, both because most people throw a bit slower on anhyzer and also because you "use up" some of that glide mode early in the flight since your disc is already turned over.

Obviously the usual recommendation that you throw slower discs as a beginner still apply, as you will be punished harder for inconsistencies with fast drivers, and throwing very understable discs are more likely to flip over in the wind etc.

 

[BenjiHeywood]

Great stuff. I've been thinking for quite a while about the way the disc flies, and in particular why the disc needs to be turned in the glide phase. You can let me know if what I'm thinking makes sense!

At first glance to you would think that wings-level would be the most efficient glide phase angle, right? That way all the lift is acting vertically, directly against gravity, rather than having some component of the lift pushing sideways. But experience tells us that gliding with a bit of turn results in far more distance.

The simplest explanation would be that the disc constantly fades during the glide phase, so starting with a bit of turn allows it to pass through the wings-level position and thereby maximises the overall lift in the vertical direction. We're basically saying that the equilibrium for maintaining wings-level glide is so unstable that we're better off starting overturned and passing through flat rather than trying to stay flat throughout.

But that doesn't really match experience. The longest throws have a very long turn phase followed by a pretty sharp flare-out, rather than a smooth, constant decline in the amount of turn.

I think what's going on has a lot to do with the left-to-right movement, and its effect on the axis of turn/fade. And in particular, on how the 'nose' moves around the disc. Let's define the 'nose' as the part of the disc hitting the air (as usual) and define the 'target-nose' as the part of the disc closest to the target - which is obviously not the same thing, whenever the disc moves sideways.

If the disc is in the glide phase, moving from left to right (rhbh) then the nose is slightly to the right of target, and turn/fade will happen about that axis - which means (with the disc fading) that the 'target-nose' will be pushed down slightly. And then as the disc comes out of the turn, and the nose starts to align more with the target-nose, that new nose is now lower than it otherwise would have been, so the angle of attack is lower and the disc stalls less.

Once the disc starts to curve right to left - the flare-out stage - the target-nose will be pushed upwards, and from the thrower's point of view the disc will seem to stall sharply.

Basically, i guess, when the disc is fading and changing direction, the fade axis related to the current position of the nose causes the future position of the nose to be lower, which partly compensates for the overall high angle of attack and extends the flight.

Does ANY of that make sense?

 

[Eric_T]

The simplest explanation would be that the disc constantly fades during the glide phase, so starting with a bit of turn allows it to pass through the wings-level position and thereby maximises the overall lift in the vertical direction. We're basically saying that the equilibrium for maintaining wings-level glide is so unstable that we're better off starting overturned and passing through flat rather than trying to stay flat throughout.

Thanks for the input. It's an interesting theory with the nose angle, but I think what you say here is actually sufficient to explain the optimal trajectory. Like you say a wings-level approach would be optimal, so we need to try to approximate that. By having the disc at an anhyzer angle and balancing against the fade as the disc slows down we keep the disc closest to the optimal throughout the flight. The sharp flare-out you describe is maybe just an optical illusion of sorts. The hyzer angle does gradually change smoothly thoughout the flight, but it happens even as the disc is still moving towards the right. When it finally starts actually fading towards the left it will maybe look like a sharper flare-out than it really is.

 

[disc-golf-neil]

Anyone have insight on how the nose angle changes during flight. I've heard things like initially nose down doesn't stay nose down and it starts to level out.

Also, how detrimental is too much nose down? I'm wondering if too much nose down will level out faster lose the "too much" nose down quickly and not be that bad as long as it's not a really low launch angle.

For example, -4 nose and 10 degree launch angle vs -8 nose and 10 degree launch angle and holding other things constant, like they both turn gently a similar amount before fading.

According to tech disc (in the field simulator), the too much nose down is robbing at least 100 feet at 65 mph, 1200 spin, 5 wobble, 14 hyzer with a disc (11, 5, -1, 2.25) 172g.

The -8 nose version makes the disc turn way more initially, but even if you adjust the hyzer to get a similar amount of turn it's still at least 100 feet less (420 vs 320).

TechDisc

techdisc.com

 

[Nick Carroll]

I have many of the same nose down questions, now that I'm finally able to have nose down throws. I think playing with the simulator might provide some insight, to set some parameters, and then throwing in a field with similarly spec'd discs and try those changes. You'd have to develop a feel for launch and nose angles, but ultimately a Tech Disc might actually be useful in those real world tests because you can get the actual statistics from the disc, then see it fly. But I think you'd have to find out what the disc actually flies like in terms of flight numbers, then set the simulator effectively.

Not sure the juice is worth the squeeze here, but research is often tedious and not immediately rewarding.

 

[disc-golf-neil]

I have many of the same nose down questions, now that I'm finally able to have nose down throws. I think playing with the simulator might provide some insight, to set some parameters, and then throwing in a field with similarly spec'd discs and try those changes. You'd have to develop a feel for launch and nose angles, but ultimately a Tech Disc might actually be useful in those real world tests because you can get the actual statistics from the disc, then see it fly. But I think you'd have to find out what the disc actually flies like in terms of flight numbers, then set the simulator effectively.

Not sure the juice is worth the squeeze here, but research is often tedious and not immediately rewarding.

After reading this, I was wondering why I haven't thrown the TechDisc for real in the field and then I remembered it's because I got a beefy 12 speed one and I almost never throw beefy discs on anhyzer release angles for max distance. I throw less stable discs on hyzerflip-to-S-curve lines.

So I'm not that tempted to throw the tech disc for real. I just didn't get to choose the stability IIRC, just the speed and I chose 12 speed since it's the more challenging rim to grip so I wanted more practice with that.

 

[Nick Carroll]

After reading this, I was wondering why I haven't thrown the TechDisc for real in the field and then I remembered it's because I got a beefy 12 speed one and I almost never throw beefy discs on anhyzer release angles for max distance. I throw less stable discs on hyzerflip-to-S-curve lines.

So I'm not that tempted to throw the tech disc for real. I just didn't get to choose the stability IIRC, just the speed and I chose 12 speed since it's the more challenging rim to grip so I wanted more practice with that.

lol yeah I've been averse to throwing mine in a field, but it is an Undertaker, and I have a noodle arm. I also worry about the likelihood of damaging it.

 

[sidewinder22]

Anyone have insight on how the nose angle changes during flight. I've heard things like initially nose down doesn't stay nose down and it starts to level out.

Also, how detrimental is too much nose down? I'm wondering if too much nose down will level out faster lose the "too much" nose down quickly and not be that bad as long as it's not a really low launch angle.

For example, -4 nose and 10 degree launch angle vs -8 nose and 10 degree launch angle and holding other things constant, like they both turn gently a similar amount before fading.

According to tech disc (in the field simulator), the too much nose down is robbing at least 100 feet at 65 mph, 1200 spin, 5 wobble, 14 hyzer with a disc (11, 5, -1, 2.25) 172g.

The -8 nose version makes the disc turn way more initially, but even if you adjust the hyzer to get a similar amount of turn it's still at least 100 feet less (420 vs 320).

TechDisc

techdisc.com

From what I think I understand, the pitched attitude(relative to ground/horizon) from release doesn't change.

The AoA changes due to change in relative airflow direction as the disc rises or falls. So as the disc is falling the relative airflow is more upward so the relative nose is more up, it's not that the nose/attitude actually moved up.

The nose also moves around the disc as it turns/fades changing trajectory left/right. It's kind of weird because the disc doesn't have a defined nose like an airplane.

Too much nose down will create negative lift pushing the disc down.

 

[Sewer bill]

[COLOR=var(--text-lighter)]The nose also moves around the disc as it turns/fades changing trajectory left/right. It's kind of weird because the disc doesn't have a defined nose like an airplane.[/COLOR]

If the disc is traveling faster than the cruising speed, aka fast enough to turn, for a rhbh person the center of pressure moves clockwise which is what causes the disc to turn, when the disc slows down and fades the center of pressure moves counter clockwise and the disc moves left.

 

[sidewinder22]

If the disc is traveling faster than the cruising speed, aka fast enough to turn, for a rhbh person the center of pressure moves clockwise which is what causes the disc to turn, when the disc slows down and fades the center of pressure moves counter clockwise and the disc moves left.

Not sure that is 100% true. Understable discs are designed for the Center of Pressure to be on the backside of the disc at their relative cruising speed which is why they turn easily.

 

[Sewer bill]

Not sure that is 100% true. Understable discs are designed for the Center of Pressure to be on the backside of the disc at their relative cruising speed which is why they turn easily.

I think the physics paper I read about center of pressure and cruising speed was based on a lid type disc so I could be wrong about how a golf disc behaves and if those characteristics found in the paper apply to all round flying wings.

 

[Eric_T]

Anyone have insight on how the nose angle changes during flight. I've heard things like initially nose down doesn't stay nose down and it starts to level out.

Also, how detrimental is too much nose down? I'm wondering if too much nose down will level out faster lose the "too much" nose down quickly and not be that bad as long as it's not a really low launch angle.

For example, -4 nose and 10 degree launch angle vs -8 nose and 10 degree launch angle and holding other things constant, like they both turn gently a similar amount before fading.

According to tech disc (in the field simulator), the too much nose down is robbing at least 100 feet at 65 mph, 1200 spin, 5 wobble, 14 hyzer with a disc (11, 5, -1, 2.25) 172g.

The -8 nose version makes the disc turn way more initially, but even if you adjust the hyzer to get a similar amount of turn it's still at least 100 feet less (420 vs 320).

TechDisc

techdisc.com

I did a few more simulations of this, and the results are pretty interesting. As you say, the disc will level out during the flight. Think of an air bounce throw, for instance, even with an extremely high nose angle the disc will eventually change its trajectory and start flying more straight. Some players, Matty O comes to mind, has a small amount of air bounce in his throw, meaning he throws a bit "nose up", and he can still throw very far. I think the reason is that he compensates for the nose up by lowering his launch angle and reducing his hyzer angle.

I don't know how the tech disc simulator compares to my simulator, but from a few tests it looks very similar. Here's an example where I only adjust the nose angle, keeping all other aspects of the throw the same:

So as we expect, with a very high nose angle the disc rises quickly due to the higher lift (see the bottom plot which shows a view from the side), and fades out sharply due to the higher moment on the disc. Vice versa, with a very low nose angle the disc is pushed downwards and turns to the right.

However, if we optimize the launch angle and the hyzer angle based on the given nose angle, and also adjust the yaw angle (the left-right direction of the throw) to keep the landing position the same, we end up with almost identical throws:


We see that with a very low nose angle we need to throw with a higher launch angle (and more hyzer, which is not illustrated here). This makes the disc quickly adjust to a similar trajectory as the 0 nose angle, and we only lose a few feet of distance due to the higher initial drag.

These results seem to suggest that maybe the nose angle is really not so critical As long as we are consistent in our throws we should be able to compensate by adjusting launch and hyzer angles correspondingly. In my initial test in one of my previous posts I just manually adjusted the angles to get a similar throw, which made the effect seem more pronounced.

One thing worth noting here, though, is that I have not taken into account the biomechanical aspects of the throw. Probably some angles are easier to get high speed out of. My guess would be with some amount of hyzer, which would need a lower nose angle to get the proper flight, but this is probably individual as well.

 

[disc-golf-neil]

I did a few more simulations of this, and the results are pretty interesting. As you say, the disc will level out during the flight. Think of an air bounce throw, for instance, even with an extremely high nose angle the disc will eventually change its trajectory and start flying more straight. Some players, Matty O comes to mind, has a small amount of air bounce in his throw, meaning he throws a bit "nose up", and he can still throw very far. I think the reason is that he compensates for the nose up by lowering his launch angle and reducing his hyzer angle.

I don't know how the tech disc simulator compares to my simulator, but from a few tests it looks very similar. Here's an example where I only adjust the nose angle, keeping all other aspects of the throw the same:
View attachment 338739
So as we expect, with a very high nose angle the disc rises quickly due to the higher lift (see the bottom plot which shows a view from the side), and fades out sharply due to the higher moment on the disc. Vice versa, with a very low nose angle the disc is pushed downwards and turns to the right.

However, if we optimize the launch angle and the hyzer angle based on the given nose angle, and also adjust the yaw angle (the left-right direction of the throw) to keep the landing position the same, we end up with almost identical throws:

View attachment 338740
We see that with a very low nose angle we need to throw with a higher launch angle (and more hyzer, which is not illustrated here). This makes the disc quickly adjust to a similar trajectory as the 0 nose angle, and we only lose a few feet of distance due to the higher initial drag.

These results seem to suggest that maybe the nose angle is really not so critical As long as we are consistent in our throws we should be able to compensate by adjusting launch and hyzer angles correspondingly. In my initial test in one of my previous posts I just manually adjusted the angles to get a similar throw, which made the effect seem more pronounced.

One thing worth noting here, though, is that I have not taken into account the biomechanical aspects of the throw. Probably some angles are easier to get high speed out of. My guess would be with some amount of hyzer, which would need a lower nose angle to get the proper flight, but this is probably individual as well.

Interesting, two simulations now pointing to the fact that the nose angle is not as important as people may have thought and that the more important thing is that the other angles work with the nose angle.

But as you said, maybe the nose down throw biomechanics could be easier to recruit power into.

 

[BenjiHeywood]

From what I think I understand, the pitched attitude(relative to ground/horizon) from release doesn't change.

I'm still pretty convinced that it does change attitude during flight. It might not be an enormous amount, in normal conditions, but i think the
[COLOR=var(--text)]effect is there.

Again (in my own opinion, obviously) the nose itself doesn't move up and down per se, but as the disc turns and fades, and then the nose moves around the disc, the 'nose' has definitely moved up or down.

I was out the other day, in a 20 mph right-to-left wind, with a disc that is a different colour on top and bottom so it's easy to see when it changes orientation.

When i threw something with a bit of turn, nose up (so i could initially see only the top of the disc), it clearly transitioned in flight so that i was looking at the bottom of the disc. It was probably moving sideways at a combined 25mph (wind+turn), so it's hardly surprising that the orientation (from the thrower's perspective) would change quite significantly.

When it faded out, it very much faded forwards (towards the target) and i saw the bottom even more.

I'm still fairly sure there's something going on when a disc turns that helps keep the nose (relatively more) down, whereas a hyzer tends to flare and stall much more. That bottom graph in Eric's last post doesn't always reflect how the height changes in flight. It feels like (at the very least some of the time, for some throws) that the disc can lose height fairly rapidly during turn and then significantly reduce its rate of fall - sometimes even 'bouncing' actually upwards - as it fades and the nose rises again.

We've probably all seen throws that look to be turned and burned, dropping rapidly almost to the ground, but then just get out of it in time and actually travel another 150 feet. Right? Or am i imagining these things?

I feel it's clearest with absurdly fast and un-stable discs (Epic, Bohrium - easy to turn over but also a rapid fade) where they flip quickly from turn to fade, and hence the nose moves a long way round the disc quite quickly. But if it's happening there then it must also be happening on other throws i guess.

Anyway, I'm waffling. Do people think the height graph in Eric's last post is how your longest throws actually behave? Or does the optimal real-world throw tend to have a flare/bounce at the end?[/COLOR]

 

[sidewinder22]

I'm still pretty convinced that it does change attitude during flight. It might not be an enormous amount, in normal conditions, but i think the
[COLOR=var(--text)]effect is there.

Again (in my own opinion, obviously) the nose itself doesn't move up and down per se, but as the disc turns and fades, and then the nose moves around the disc, the 'nose' has definitely moved up or down.

I was out the other day, in a 20 mph right-to-left wind, with a disc that is a different colour on top and bottom so it's easy to see when it changes orientation.

When i threw something with a bit of turn, nose up (so i could initially see only the top of the disc), it clearly transitioned in flight so that i was looking at the bottom of the disc. It was probably moving sideways at a combined 25mph (wind+turn), so it's hardly surprising that the orientation (from the thrower's perspective) would change quite significantly.

When it faded out, it very much faded forwards (towards the target) and i saw the bottom even more.

I'm still fairly sure there's something going on when a disc turns that helps keep the nose (relatively more) down, whereas a hyzer tends to flare and stall much more. That bottom graph in Eric's last post doesn't always reflect how the height changes in flight. It feels like (at the very least some of the time, for some throws) that the disc can lose height fairly rapidly during turn and then significantly reduce its rate of fall - sometimes even 'bouncing' actually upwards - as it fades and the nose rises again.

We've probably all seen throws that look to be turned and burned, dropping rapidly almost to the ground, but then just get out of it in time and actually travel another 150 feet. Right? Or am i imagining these things?

I feel it's clearest with absurdly fast and un-stable discs (Epic, Bohrium - easy to turn over but also a rapid fade) where they flip quickly from turn to fade, and hence the nose moves a long way round the disc quite quickly. But if it's happening there then it must also be happening on other throws i guess.

Anyway, I'm waffling. Do people think the height graph in Eric's last post is how your longest throws actually behave? Or does the optimal real-world throw tend to have a flare/bounce at the end?[/COLOR]

IDK, like I said it can weird talking about where the nose is because it's changing with the trajectory and moving around the disc. I was trying to separate attitude from nose which I think is AoA. Think about an overhand shot that barrel rolls, is the attitude changing or is it just rolling over or both, IDK?