Big Question #1 after Backhand Fundamentals 201 - What causes spin?

[timothy42b]

Okay 201 isn't out yet, but I'll be ready.

What really really causes spin? And how do we know that's the right answer? (If it is just one answer; I can think of about four possible contributors).
What are the forces that causes the disc, and where are they applied? I haven't seen a convincing answer. Maybe I'm the only one who doesn't know.

I know some obvious theories about ball golf have turned out to be wrong. The golf ball spin (average player, about 3300 rpm, tour player about 2700) is not caused by friction on the grooves, but by the moment induced by striking the ball below the center of mass.

FWIW, I didn't see an answer in the Hummel thesis from 2003. The bent arm throws she measured were what they'd call a pass in ultimate, or an up shot in disc golf. Energy for linear velocity was about 14.1 joules and rotational was 2.54. Josh from Overthrow with that high tech disc posted throws averaging 53.48 mph and 1086.65 rpm, which is 50.013 joules linear and 15.215 joules rotational. (feel free to check my math.) I used Josh because he's not an elite thrower but not a novice either, and he just posted the data from his new toy.

Will it help me throw better? Probably not, but it relates to a couple things discussed recently.

 

[Sewer bill]

Asymmetrical leverage is what causes spin, same way an engine crankshaft converts linear motion into rotational motion. Delving deeper starts getting into serious geometry and physics really fast.

 

[BruisedOoze]

It would be instructive to know where you felt the force from grip, and resultant torque, failed to describe the cause of spin? Besides gravity, there is no other considerable fundamental interaction with the disc during the throw itself (usual air resistance caveates).

 

[HyzerRoc]

In the same vein: I wonder what the relationship between spin, speed and distance looks like. There was a reddit thread a while back in which a company advertised themselves, measuring ejection speed and spin (sorry about the bulky insert):



They measured that backhand throws generate more spin in relation to ejection speed than forehand throws and claim that more spin at the same ejection speed results in more distance. At one point they posted numbers, sadly I can't find them anymore on their website.

Adding on to that: can we increase spin without increasing ejection speed with certain techniques?

 

[Sheep]

Okay 201 isn't out yet, but I'll be ready.

What really really causes spin? And how do we know that's the right answer? (If it is just one answer; I can think of about four possible contributors).
What are the forces that causes the disc, and where are they applied? I haven't seen a convincing answer. Maybe I'm the only one who doesn't know.

I know some obvious theories about ball golf have turned out to be wrong. The golf ball spin (average player, about 3300 rpm, tour player about 2700) is not caused by friction on the grooves, but by the moment induced by striking the ball below the center of mass.

FWIW, I didn't see an answer in the Hummel thesis from 2003. The bent arm throws she measured were what they'd call a pass in ultimate, or an up shot in disc golf. Energy for linear velocity was about 14.1 joules and rotational was 2.54. Josh from Overthrow with that high tech disc posted throws averaging 53.48 mph and 1086.65 rpm, which is 50.013 joules linear and 15.215 joules rotational. (feel free to check my math.) I used Josh because he's not an elite thrower but not a novice either, and he just posted the data from his new toy.

Will it help me throw better? Probably not, but it relates to a couple things discussed recently.

Spin and spin control have to do with "how" you leverage the disc.

This is something I wanna do a bit of study on, but need to take some video to do the research and get the studio set back up, and... yeah.
Not a priority.

But what we are doing is turning a bunch of energy into the disc acting as a lever out of our hand, which creates the spin, as the disc litterally spins and rips out of our hand.
There are techniques to get "more" spin on the disc as well. As you see a lot of tour pro's who throw and their disc sits up by the basket spinning on the ground.

This is another reason why simon does dumb things like throws glitches 400 feet. He can impart enough spin on the disc while giving it speed to get it to stay stable enough.

So our ability to impart spin has a lot to do with the stability of the disc and how it acts as well.

I don't think the pro's know enough to talk about it, but we look at ball golf and there are different shot types (swings) to produce a few different variables into the disc.
I think pro's do this, but they dont really talk about it, mostly because they dont understand enough, they just know what they are doing and how to do it.

I had a video on this a long time ago, but will be making another video on it at some point.
Because I want the math on how much we are leveraging the disc, not just "guesses" which is what we mostly make now.


As for the device thing, I'd not trust half that data as "actual" but more as a "use to adjust what your'e trying to do with THAT sensor"

if that makes sense.
I think it gives you data, but its like running a vehicle on a dyno. Not all dyno's give the same data.
So you want to always use the same dyno when you make changes to see if you lost or gained power. It doesn't matter if the power number is accurate, it just matters that you see a result. Same for the sensor.
I'd not really trust some of that data at all for accuracy, but it gives you a baseline to work off of.

 

[Sheep]

They measured that backhand throws generate more spin in relation to ejection speed than forehand throws and claim that more spin at the same ejection speed results in more distance. At one point they posted numbers, sadly I can't find them anymore on their website.

Yes, I fully believe that forehands have less disc leverage than backhands.
On a half guess without the data I want to collect, I figure were leveraging around 25% of the disc on a forehand, and around 40-60% on a backhand.

And, regardless of "thinks" when you have math, you... have answers.
But we can see that forehand throws do not fly the same as backhand throws. Same disc, close speeds, forehands flippier on throws than backhands. Why is that? Spin.
The rotation of the disc helps with its resistance to forces imparted by the pressure of flying through the air. Basic gyroscope things. more spin = more stability.
Which is why you can take super flippy discs and throw crazy shots that dont flip if you know how to really control spin/velocity vs a player who doesn't who will turn it into instant rollers.

Adding on to that: can we increase spin without increasing ejection speed with certain techniques?

Yes, How we pocket the disc is one of the largest factors in spin control.
And, I have no way to prove this, but in my experience, a wide rail throw gives more spin.
But I think that has to deal with the mental game of how i'm pocketing the disc vs a straight backswing.

How we control our wrist in the throw is another way we can impart spin.
Watch paul and simon on upshots. They use a LOT of wrist movement and not a lot of anything else, They are building a strong chain to throw, but heavily focusing on spin to keep the disc stable to control its flight, vs trying to grip and rip.