Spin & Stability

[Mike C]

I want to start a discussion on spin and stability, and how the two are related.

Specifically lately I've been thinking about how spin affects the stability of FH throws.

I've heard my whole DG life "Throw more overstable plastic when you throw FH because a FH throw generates so much spin that it makes a disc fly more understable."

Now, I always thought this was bullshit. I thought people just had shitty FH form and that's why discs didn't fly as stable for them compared to BH. I used this theory to explain why I noticed the same effect myself, that a lot of discs that flew good for my BH weren't flying so great FH.

The other day I did an experiment which I suspect has solved the issue for me. I was throwing my 2nd shot on a long hole at my home course, and that shot as about a 120' FH upshot with a putter. It got turned over hard by the wind and carried for over to the left. Confused, because I knew even in this 10mph headwind a 120' approach is no issue for my putter, I tried again. For some reason the second time I snapped it much harder and it held the line beautifully.

The problem was not that a FH throw generates so much spin it makes a disc fly understable, the problem was the opposite (At least for me it was, I don't know if this is universal). I was generating such little spin on my forehand throws that this was causing them to fly understable.

So I repeated my test and got the results I expected. When I compacted my FH throwing movement and focused entirely on wrist and finger movement to generate high levels of spin, my discs flew much more true. Finally I was able to flick my neutral mids and putters into a headwind and have them hold hyzers the entire way. Another thing I noticed is before when I tried to FH a putter really hard it would turn over easily. It was because I was trying to speed up my whole arm and not focus on spin. Now when I try to flick a putter hard, I can make it fly straight like a bullet and it's beautiful to watch, because I'm putting enough spin on the disc to stabilize it.

I'm going back out today to play around with this theory some more. But from what I've seen the past few days I am inclined to believe the following:

-Unusually understable disc flights can be caused by a lack of spin imparted on the disc at release.
-Discs will hold their line better, fight wind more and glide further when they are given an increased amount of spin.
-There are no differences between BH and FH throwing that make discs fly inheritly different for a given throwing style (Something I've always felt but could never explain why I think it's true).

If you think any of this is wrong or right I'd like to hear why. I know there are much more experienced FH players on here than me and while this subject isn't exclusive to FH throwing a lot of my observations have been related to it.

[kern9787]

More spin cannot be generalized into more or less stable. It will equate to straighter in general, more HSS, less LSS. I can't expand on it right now, but I will in a little bit. Look up moment of inertia if you're curious in the meantime.

[fanter]

Mike, because I've seen your FH grip (which looks exactly like mine)...

I don't think this grip imparts much spin in general. It lacks a "pinch point" because the thumb is behind the two fingers. While working with that grip, I felt like I was more "pushing the disc out" than spinning it. I didn't turn anything over without a good amount of torque.

Based on my experience with it, I wouldn't call it an optimal grip for throwing far, but it works fine for shorter, controlled shots, which I think is what you are describing.

My big point is that grip plays an important role in how much spin the thrower imparts on the disc. It's kind of a secondary point, though. I'll be interested to see where this thread goes, but I think it might go straight to gyros pretty soon.

[Mike C]

One thing that is difficult to tell from the photos is I get a good pinch between my thumb and the last joint in my index / middle finger. I'm not putting pressure on the fingertips like it might appear. Do you know of a better distance grip?

[Dbuntu]

"Throw more overstable plastic when you throw FH because a FH throw generates so much spin that it makes a disc fly more understable."

I think you've been told this because overstable plastic corrects sloppy form. What I mean is that when most people crank their flick up trying to really lauch it they will roll their wrist and elbow as they sling it out. That rolling puts the release on an angle. Because the throw comes out of a roll not a flat snap, it's not being thrown like a disc, but more like a baseball. So it's got a lot of force behind it but the force isn't in the spin. It's in the foward motion. So you've got a disc that's moving foward at a high velocity with lower spin and the overstablity of the disc pulling it back to a flatter line. If that same throw is done with a neutral disc, it's taking a quick and ugly dive into the dirt.

[Triflusal]

One thing that is difficult to tell from the photos is I get a good pinch between my thumb and the last joint in my index / middle finger. I'm not putting pressure on the fingertips like it might appear. Do you know of a better distance grip?

an ideal grip has the pads of at least one of your fingers on the rim. Putting the side of your finger against the rim (pads on the flightplate) limits wrist movement and can result in wrist roll.



your grip with the pads of your fingers on the flightplate facing up



compared to a grip with the pads on the rim facing the direction the wrist naturally likes to move.



this is avery's grip which is also pretty common in my experience.

[Mike C]

I tried those grips in the past, and the peqce sign grip, and the one I use in the picture gave the best results. I've been thinking about trying those two grips again because like you say looking at the wrist movements it kind of makes sense. I was playing with the motions inside and it seems like it could give more snap.

[kern9787]

More spin cannot be generalized into more or less stable. It will equate to straighter in general, more HSS, less LSS. I can't expand on it right now, but I will in a little bit. Look up moment of inertia if you're curious in the meantime.

Expanding on this, angular momentum is the spinning equivalent to momentum. Meaning the more angular momentum a disc has, the more force it takes for it to tilt in flight, whether that be high speed turn, or low speed fade. Angular momentum is defined by how fast the disc is spinning, and its moment of inertia.

Moment of inertia is an equivalent to mass when talking about momentum. It is not only defined by mass, but the distribution of the weight. For example, a ring (essentially a disc shape with all of its weight on the outer rim) has a greater moment of inertia than a disc with equal weight distribution. (This is essentially the concept behind more "gyroscopic" discs, such as MVP discs. This is also how Aerobie rings achieved records for longest thrown object without velocity aiding features.)

High speed stability and low speed stability can be defined for a particular disc by velocity. High speed turn will kick in when above x mps. Low speed fade will kick in when below y mps. To my knowledge, and physics buffs, step in if I'm wrong, spin does NOT effect the speeds at which high speed turn and low speed fade occur. What does occur is, as spin increases, the rate at which a disc turns or fades decreases.

What this means is that if you throw a disc fast enough with not very much spin, it will likely turn over uncontrollably in its high speed turn. If you throw that same disc the same speed, but with a substantial amount of spin, the turn will be slowed down greatly. This can be the difference in a disc turning and burning or standing up gently from a hyzer and locking in on a straight line.

[kern9787]

-There are no differences between BH and FH throwing that make discs fly inheritly different for a given throwing style (Something I've always felt but could never explain why I think it's true).

Theoretically, this true and, the only difference is the spin direction causes precession in the opposite direction.

Practically speaking, it depends on the person and the throw. For most people, its easy to throw fast with a forehand. They typically don't get the same amount of spin on the disc as a similar backhand throw, at least not without practice. If somebody does manage to throw with the same amount of velocity and amount of spin, backhand and forehand, then essentially they would be able to throw mirror image throws.

[Mike C]

Expanding on this....spin does NOT effect the speeds at which high speed turn and low speed fade occur. What does occur is, as spin increases, the rate at which a disc turns or fades decreases.

Great post, you explained everything well. You are correct, what I was watching is more a straightening of the disc than making it fly more overstable, I kdidn't explain myself very well.

Played during a tornado warning today so I got to do a lot of experimenting in 25-50mph winds. Was interesting. One thing I tried after I played a few rounds was doing towel snap drills on BH, FH, OH and roller throws. I tried to not focus on the towel and instead just throw how I would normally throw. What I found out was that if I "threw" the towel like I would a 100' hyzer putter approach, I snapped it, but if I "threw" a 350' Predator line drive I didn't snap it. I also noticed a lack of towel snap on distance FH rollers. BH felt good at least.

[JHern]

Isaac Newton figured this out centuries ago. The faster the spin, the slower the rate of change of hyzer angle. Angular momentum is key.

The problem with FH throws is that they have less spin and also usually have more wobble, both of which make the disc fly more understable. Clean up the wobble and get more spin, and the disc will hold the line.

Anyways, by being a bit of a scientist yourself, and experimenting with spin, you've discovered the right answer...

[garublador]

I agree with most of the observations, but I'm not convinced people can isolate and control how much spin they get on drives. You can fix things that will help you get more spin, but they'll also change the velocity at which you're throwing so much that you won't be able to actually isolate either variable.

It's much easier to control on approach shots, though.

[kern9787]

I was thinking about this a little more today.

One of the biggest problems I see with newer players and their approach shots is that they try to keep the same mechanics as the drive but slow everything down to lessen their power. As a result, they do lower velocity, but the velocity they are getting is coming mostly from their arm speed and their wrist mechanics break down and they lose a strong disc pivot. They lose a lot of spin on their discs and as a result, the shots are more errant, turning or fading a lot more than intended and not gliding very well. It becomes much harder to throw a straight shot. I would imagine this is part of the reason why players prefer throwing drivers instead of midranges or putters for approaches. They aren't traveling fast and thus fly overstable. To them, this is the most predictable shot they can throw.

Compare that to a better player's approach shot. Its usually a compact throw without much reach back. A significant portion of the velocity comes from good overall mechanics and the disc pivoting out of the hand just like it would a drive. This results in a much more controllable shot. Understable mids/putters will have a predictable turn. Straight/stable mids/putters will have a predictable fade (or lack of). Discs also don't need quit as much velocity as a comparable shot for the "beginner" approach because the disc will glide better.

I'm sure this is something we've all noticed, I know I have. I've just never given it too much thought.

[Mike C]

That's a good point. I used to struggle in the 120-180' range with my approaches because I wasn't sure how to scale down my power with back hand form. I tried to give it half snap but keep the same body motions. It works much better to compact the form down and snap it just as hard but use less reach back, body rotation, height on the shot etc.

Another thing that's really been blowing my mind with this is headwind putts. If you go throw a few putts that are straight lobs at the basket with as little spin as possible, then throw some very high spin "putts" from the same distance, the difference in line-holding is quite drastic.

[JR]

There are at least anatomical differences between FH and BH throws. Wrist motions are faster and stronger Fh than BH and the forearm muscles and tendons stay looser FH. FH has two fingers on under the disc usually and most use four fingers for BH. Guess which is stronger and resists slipping before a full pivot has occurred better?