Optimal Drive Angles - More Questions Than Answers

[TheBeardedFatGuy]

I've been trying to understand what the optimal pitch angle for distance should be, and I'd appreciate the input of anyone who can add insight.

It's pretty well accepted that the optimal angle of disc orientation to the plane of flight is -4 degrees - the 'nose down' angle that minimizes drag from lift, but what is the optimal launch angle that establishes that plane of flight and will give maximum distance? If we were dealing more with pure ballistics, as when launching a baseball or cannonball, instead of a spinning disc with very different flight characteristics, the established optimal angle would be 45 degrees. This is the angle that will produce the greatest possible distance. With a disc, however, 45 degrees is a very steep angle, unheard of except when throwing an extreme hyzer/anhyzer bomb or tomahawk. As the red disc in figure D shows, gyroscopic stability tends to keep the disc oriented at the same angle through the arc of it's flight, which presents more of the disc's bottom to the direction of flight, causing it to stall out and die a quick death. If the nose were constantly adjusted to keep the -4 degree orientation to the plane of flight (green disc in figure D), we might be on to something. But, again, that behavior is contrary to gyroscopic stability. I suppose it could still happen if the stability from spin was reduced steadily at just the right rate to allow the disc's airfoil characteristics to win out over gyroscopic stability. In that case, the disc would stay oriented more or less correctly, more lie a thrown paper airplane than a disc, but if you can do that you should be burned at the stake for practicing witchcraft.

(OP continues in next reply...)

 

[TheBeardedFatGuy]

The answer to this question must ultimately include the fact that the disc being thrown and the way the thrower throws it will be highly relevant to the optimal pitch angle. Some discs will have more lift, and some throws will generate more lift. I also realize that this problem is being approached from a purely 2-dimensional version, ignoring for the moment the distance that comes from things like the s-curve. If you had a reliably consistent mechanical disc thrower that you could put in an aircraft hanger to eliminate even the slightest breeze, you could dial in that perfect pitch angle, elevating it a degree at a time until you no longer saw increased distance. But I don't have one of those, and, even if I did, it's ultimately my throw I need to optimize, not some machine's.

So, thoughts on optimal pitch angle for maximum distance?

 

[Agricolae]

I think you have a problem with assuming Fig. D as a rule. Discs that don't stall nose over through their flight apex. Bullets and footballs do the same thing if their initial velocity and angle of attack are sufficient for the launch angle. I don't know the physics but I can see it happen when a QB throws a long bomb.

 

[TheBeardedFatGuy]

I think you have a problem with assuming Fig. D as a rule. Discs that don't stall nose over through their flight apex. Bullets and footballs do the same thing if their initial velocity and angle of attack are sufficient for the launch angle. I don't know the physics but I can see it happen when a QB throws a long bomb.

I'm not quite sure what you mean by 'don't stall nose over', Agricolae. Are you saying the red disc is wrong, or the green disc? I've seen both occur with a long bomb football. Those that come down from the apex of the throw with the nose oriented down are undoubtedly stalling less and presenting less surface area to the air its advancing into and so can probably travel farther. There's undoubtedly gyroscopic stability happening with a football, too, though it would be a lot less than a disc and is oriented differently with regards to the line of flight. As to why a football or bullet (spun by barrel rifling) would tip down through the apex to always be pointing in the direction of travel, the only thing I can think of is that the aerodynamics of the object exert an aligning force on it that is able to overcome gyroscopic stability. In the case of a football, gyroscopic stability would be far less than that of a disc because the skin of a football is a relatively small mass, and a bullet minus its ejected casing is a relatively solid mass (unless perhaps a hollow point). Discs, especially distant drivers, have the bulk of their mass at the outer edge, maximizing gyroscopic effects like stability.

I think we've all seen red and green disc behavior. The former is a stall and ends with the disc pitching over left (RHBH) in an early fade. The latter, as I've said, while maybe the secret to a long flight, I'm at something of a loss to explain because the aerodynamic tendency of the disc to stay relatively edge-on to the direction of travel requires a continuous change in orientation that is counter to the force of gyroscopic stability that wants to keep the disc at the exact same pitch angle through its entire flight.

 

[TheBeardedFatGuy]

Here's something else on pitch angle I've noticed in some pretty impressive drives. I don't now if it has a name, but I've taken to calling it an arm bounce. What it looks like is an air bounce, but instead of the bounce happening after the disc is snapped or released, it happens just before the snap (maybe a foot or more before the disc is released). The thrower looks like he's about to throw slightly down in a worm burner, but the arm 'bounces' up just prior to the snap creating an upward trajectory. The overall effect is a disc that is flat to the ground, but nose down to the slightly upward plane of trajectory. I've no idea if this would have any advantage over simply angling one's throw up slightly with nose down, but I've seen some pretty impressive drives done using it. I have yet to try it, but the few practice swings I've tried made it clear there's both timing and biomechanical issues with redirecting the arm mid-throw. Can anyone shed some light on this technique?

 

[hook_nuts]

So, thoughts on optimal pitch angle for maximum distance?

Since you aren't a machine and there are so many variables from person to person, disc to disc, and environment to environment, don't you think a stack of plastic in a field under all weather conditions would answer this best?

A quarterback doesn't complete a pass by knowing the exact angle. A basketball player doesn't make a basket by knowing the exact angle. Etc. It's all about repetition.

 

[DiscFifty]

I have yet to try it, but the few practice swings I've tried made it clear there's both timing and biomechanical issues with redirecting the arm mid-throw. Can anyone shed some light on this technique?

I don't know what it's called, but I do this myself and see other people do it quite often. I use it in a head wind and also when I need a nice low drive through trees, or if I need a disc to hit the ground sooner when it starts to fade. Usually it's released very flat in this shot.

 

[Agricolae]

I'm not quite sure what you mean by 'don't stall nose over', Agricolae. Are you saying the red disc is wrong, or the green disc?

My comment, "Discs that don't stall nose over through their flight apex" is meant to be read as, "Discs that don't stall [pause] nose over through their flight apex." This is shown by the green disc in your Fig. D. Apologies, I was reading on a phone and missed the green disc in that figure.

So, your question is ... What is the optimal launch angle for the trajectory? ... What is the optimal angle for the disc with respect to the trajectory (you've already answered that)?

Again, as far as discs and footballs are concerned, I can't explain mathematically *why*, on "good" throws, they maintain a slight nose down orientation with respect to their forward vector (your green disc) through their entire flight but I do know that is key. I can take a stack of Rocs and show you the flight of the red disc in your figure and the flight of the green disc. As a *practical* matter, when I throw those shots, I think I'm controlling both the nose angle of the disc with respect to the forward vector AND the amount of power (velocity) out of my hand ... could be wrong about how it really works but I practice both to use them effectively on the course.

 

[DG_player]

I hate to bring up ball golf, but this has been rather extensively dissected in that regard, and the implications are similar.

In a vacuum a 45 degree angle would provide the maximum distance. When you add in atmosphere, and the drag it causes this drops the optimal launch angle to around 35 degrees. However this is much different from what is observed. A golf ball generates significant lift due to backspin. This is added lift changes the optimal launch to 10-15 degrees, depending on the amount of backspin and lift generated.

I would guess that a disc generates as much or more lift as a golf ball, so I would suspect the optimal launch angle to be in that range or lower. Obviously there would be other factors that would effect it that depend on the thrower and the desired shot shape.

 

[lyleoross]

I hate to bring up ball golf, but this has been rather extensively dissected in that regard, and the implications are similar.

In a vacuum a 45 degree angle would provide the maximum distance. When you add in atmosphere, and the drag it causes this drops the optimal launch angle to around 35 degrees. However this is much different from what is observed. A golf ball generates significant lift due to backspin. This is added lift changes the optimal launch to 10-15 degrees, depending on the amount of backspin and lift generated.

I would guess that a disc generates as much or more lift as a golf ball, so I would suspect the optimal launch angle to be in that range or lower. Obviously there would be other factors that would effect it that depend on the thrower and the desired shot shape.

Somewhere in the last month there was an inevitable thread on disc flight mechanics. One of the players with flight mechanics knowledge commented extensively on lift and precession on that thread in a very clear way. There is a center of gravity, fixed, and a center of lift, changes over the flight of the disc. The angle of attack, wind, forward speed, disc shape etc. determines where the lift is, front, back, center. All of that is very different from the flight mechanics of a golf ball and the lift given from flow over the dimples due to spin.

The optimum drive angle would depend on the disc and where the center of lift will be at the release. That will impact the path the disc will take, stability, and the distance it will fly. If I understand correctly, it will be different disc to disc and shot to shot.

 

[lyleoross]

That there is a range of angles over which you can be effective as a thrower is clear, but that depends on what you are trying to accomplish. I might want the disc to stall and dive left to throw around a clump of trees, therefore a high angle of release that is going to give me a short flight with a hard stall is essential. On the other hand, there are other ways to accomplish the same shot with a lower angle of release. Aka, the Dave Feldberg method of lining your body up on the target and throwing at an angle that goes around the clump. That methodology puts the disc, naturally, on a pathway that intersects the target, yet still goes around the trees. don't ask me why, Dave says it does, and in practice, for me, it works.

That is, angle of release is a tool, personally, viewing it as some optimal value is a mistake. I work a number of angles depending on what I need.

 

[DG_player]

Somewhere in the last month there was an inevitable thread on disc flight mechanics. One of the players with flight mechanics knowledge commented extensively on lift and precession on that thread in a very clear way. There is a center of gravity, fixed, and a center of lift, changes over the flight of the disc. The angle of attack, wind, forward speed, disc shape etc. determines where the lift is, front, back, center. All of that is very different from the flight mechanics of a golf ball and the lift given from flow over the dimples due to spin.

The optimum drive angle would depend on the disc and where the center of lift will be at the release. That will impact the path the disc will take, stability, and the distance it will fly. If I understand correctly, it will be different disc to disc and shot to shot.

I'm not talking about lift as it relates to precession/turn/fade etc. I'm talking about it solely in the aspect that it counteracts gravity. In this respect it doesn't matter how it's generated, lift pushes up, gravity pushes down.

 

[DG_player]

That is, angle of release is a tool, personally, viewing it as some optimal value is a mistake. I work a number of angles depending on what I need.

I took the OP to mean optimal as in optimal for max distance.

 

[TheBeardedFatGuy]

The optimum drive angle would depend on the disc and where the center of lift will be at the release. That will impact the path the disc will take, stability, and the distance it will fly. If I understand correctly, it will be different disc to disc and shot to shot.

I've no doubt this is absolutely true, but it does nothing to satisfy my need for a magic wand solution. Heh. Well, maybe not a magic wand, but a starting place and basis for understanding would be nice.

 

[sidewinder22]

Here's something else on pitch angle I've noticed in some pretty impressive drives. I don't now if it has a name, but I've taken to calling it an arm bounce. What it looks like is an air bounce, but instead of the bounce happening after the disc is snapped or released, it happens just before the snap (maybe a foot or more before the disc is released). The thrower looks like he's about to throw slightly down in a worm burner, but the arm 'bounces' up just prior to the snap creating an upward trajectory. The overall effect is a disc that is flat to the ground, but nose down to the slightly upward plane of trajectory. I've no idea if this would have any advantage over simply angling one's throw up slightly with nose down, but I've seen some pretty impressive drives done using it. I have yet to try it, but the few practice swings I've tried made it clear there's both timing and biomechanical issues with redirecting the arm mid-throw. Can anyone shed some light on this technique?

In ball golf or a hyzer swing it's called the bottom of the swing arc.

 

[sidewinder22]

I've no doubt this is absolutely true, but it does nothing to satisfy my need for a magic wand solution. Heh. Well, maybe not a magic wand, but a starting place and basis for understanding would be nice.

djjeremiahj is your Gatekeeper.

 

[puck'n'disc5]

I'm going to invent a disc and call it the protractor. So that way you can play disc golf while using your protractor simultaneously.

 

[TheBeardedFatGuy]

I'm going to invent a disc and call it the protractor. So that way you can play disc golf while using your protractor simultaneously.

I like your angle. Heh If you can add an accelerometer, altimeter, gps and a plumb bob I'd buy it.

Michael

 

[mittbull]

So when I go out and do some field practice today on an flat (assume windless) football field, if I can pull my tern on a straight line with the nose angle parallel to the ground I should see the disc rise from lift correct?
For maximum distance I would actually want the nose of the disc to be angled slightly down 4 degrees while throwing the disc on ~an upward trajectory of ~10-15 degrees?

Would a putter need more or less upward trajectory? Should the nose angle be closer to parallel as there is less of a wing/less lift?

I need someone to dumb this down for me.

 

[TheBeardedFatGuy]

So when I go out and do some field practice today on an flat (assume windless) football field, if I can pull my tern on a straight line with the nose angle parallel to the ground I should see the disc rise from lift correct?
For maximum distance I would actually want the nose of the disc to be angled slightly down 4 degrees while throwing the disc on ~an upward trajectory of ~10-15 degrees?

Would a putter need more or less upward trajectory? Should the nose angle be closer to parallel as there is less of a wing/less lift?

I need someone to dumb this down for me.

Correct. How much lift you see depends on the disc's nature, but lift has been pegged as a bad cause of drag and so bad for distance. The -4 degree nose down angle is supposed to reduce drag from lift and so cut through the air easier. Problem is, thrown flat with no lift, gravity will end the flight sooner than if the disc had some altitude. Which is why I'm hunting for that sweet spot angle of trajectory that will take the disc farther.

I've no idea how this affects putters, sorry.