Is side spin real?

[chemclub]

I have heard it before "There is no such thing as side spin" but I think that side spin can actually be a very informative (if simplified) metric for gauging how your swing path and club face interact.

 

I won't deny that there is only one axis of spin for the golf ball, but when a launch monitor like Skytrak spits out two numbers for backspin and side spin these numbers are not incorrect if they are interpreted correctly (see below).

 

 

(a) a perfectly flushed, on-line shot will have the axis of spin perpendicular to the target line. This is a shot that will go dead straight (no wind). Shots like these are what keep us playing the game.

 

(b ) when the face and club path are not aligned, it creates what has popularly been called "off-axis spin" or a tilted spin. But this tilted off-axis spin can be broken down into two components: (i) pure backspin, and (ii) pure side spin. The tilted off-axis spin is a linear combination of these two spins.

 

I always understood those numbers from the Skytrak to be components of the true tilted spin (but this is an assumption, I don't know if this is right so please correct me if I am wrong). So for me it always seemed strange to hear there is no such thing as side spin. There has to be side spin or the ball wouldn't curve. I believe the launch monitor is simply measuring the component spins, or is measuring the tilted spin and pulling the component spins apart. This is a common analysis in physics or linear algebra.

 

So I always like to know my side spin component because it is simply easier to understand how it relates to the direction and flight of my ball rather than trying to visualize tilted off-axis spin. Consider an example to explain what I am talking about. 

 

 

Pretend someone wants to fly in the air from x to y. You could say to them, "It's easy. Just fly –27 degrees off axis from true North for 4.47 miles." 

 

Or you could say, "Fly due North for 4 miles then due West for 2 miles, can't miss it."

 

The component route (due North then due West) is not actually the best way to get there but it is far easier to understand and does a really good job at communicating to the traveller that the final result, y, is 2 miles left of the due North target line.

 

Maybe I am wrong in my interpretation, but I still maintain that side spin is real.

[apprenti23]

I Have zero intention of reading your thesis but there is no such thing as side spin.

[chemclub]

I Have zero intention of reading your thesis but there is no such thing as side spin.

 

 

May I ask why you are so sure there is no such thing as side spin? Because someone told you there was no such thing as side spin?

[chemclub]

I did say that this was all murky reasoning and assumption on my part. If I am wrong just show me why.

[revkev]

It's semantics -

 

If you'd like to called the ball spinning on a slightly tipped axis side spin what harm is there?  Just so long as you realize that the ball isn't spinning two different ways at the same time.

[chemclub]

Actually, I would say it is spinning two different ways at the same time. If you add a backspin to a side spin they combine to give a tilted off-axis spin. (Tilted away from the pure backspin straight shot)

 

For a given tilted spin... If you had a sensor that could only measure pure backspin, it would register backspin. If you had a sensor that could only read pure side spin, then it would register side spin. Those two spins both add together to create one tilted off-axis spin rate that is greater than both pure back- and pure side spin individually (just like in my air travel example above: back (4), side (2), off-axis (4.47). For every 4 revolutions back there is 2 revolutions sideways, but to our eyes it looks like 4.47 revolutions that rotate 27 degrees off axis).

 

But I totally agree that it is semantics. People talk about "there is no side spin" like they are trying to wake the sheeple from a viscous conspiracy. It doesn't matter if you think about spin as a tilted off-axis spin or a linear combination of back- and side spin components. Whatever is simplest for you. But realize that a tilted off-axis spin necessarily has the ball spinning to the side to some degree. 

 

Any ball mechanics out there want to set me straight, I am all ears.

[hckymeyer]

The ball can only spin in one direction.  Period end of story.  It would be more accurate for a launch monitor to give the spin rate and axis of the spin, but for simplicity sake they give a backspin and a side spin number.

 

However you want to think of it to help yourself make sense of it, doesn't matter to me.  Just understand that there is only one direction a ball can spin at a time.  I guess if you could somehow spin it all the way past a 45 degree axis then you could call it side spin and there would be no backspin

[apprenti23]

So does our planet have side spin? Honest question.

 

Ball has to have backspin or it will never go up. It can only go in one direction before it stops to spin the other direction. Pure backspin on an axis. Pure side spin or it wouldn't climb. In this case, I am sorry but your work seems to be all for naught. The world is still flat in the case of golf ball back spin. I do like crow so if you get published or something be sure to drop a pm.

[chemclub]

So does our planet have side spin? Honest question.

 

Ball has to have backspin or it will never go up.

 

As we define it, yes, our planet has side spin in that we define north and south as up and down and the earth spins around that axis (spinning at the equator).

 

Trivia time: people who live at the equator (furthest from the spin axis) are moving faster than people who live at higher and lower latitudes (closer to the spin axis). It is the reason we launch space ships as close to the equator as possible. They are simply already moving faster there so we don't have to put in as much energy to get them up to speed.

[chemclub]

Also, having side spin does not mean you can't have backspin at the same time. The physics of spin is such that you can add the axis of backspin and the axis of side spin together to end up with one single direction of spin. It is completely valid to think of them as two separate spins or one apparent spin.

hckymeyer is right in that if you were to fly behind a ball in the air as it travels it would only look like it is spinning in one direction. But if you stopped and pondered for a while you would see a dimple rotate backwards towards you and sideways to your left or right in one smooth motion (viola, your component spins at work).

 

If you think about it, one direction of spin makes complete sense (despite trackman telling us this) since we see the ball curve left or right on a stable flight, and we can even predict where it will finally land. This is consistent with a single axis of spin. If the ball had multiple axes of spin then it could end up having a corkscrew flight. It is not immediately obvious to me why a golfball only has one axis of spin. Maybe it has something to do with a flat club face. Can you throw a baseball with multiple axes of spin? Not really sure if it is at all possible.

 

Go home nerd

[apprenti23]

Hahaha

[Kor.A.Door]

Here's my take, in order to have to different spins at the same time the ball must be struck in 2 different places at the same time, so in your theory, the ball was struck at 90* from the bottom and at 0* at the same time, in order to create both the back spin and the lateral (side) spin. Since we know that for every action there is an equal and opposite reaction and we are contacting the ball in one place, I say the spin that is out in the ball is from where the club made contact with said ball. The reaction of spin is equal to where the ball was struck, it was not struck in 2 places, it was struck in one place either to the left, center, or right parts of the ball, so the spin is an opposite and equal reaction to that.

[DaveP043]

It's semantics -

 

If you'd like to called the ball spinning on a slightly tipped axis side spin what harm is there?  Just so long as you realize that the ball isn't spinning two different ways at the same time.

Its more than semantics, this is the way most engineers think of any kind of motion, or force, or whatever.  Its really difficult mathematically to describe stuff as acting in a single line (or around a single axis in the case of rotation) when other stuff is acting along different lines.  So we separate the motion into orthogonal components (vectors), each along a standard direction (or axis)  that can be combined to show the true 3-D motion, or force, or acceleration, or whatever.  Then we can actually work the math.

 

I'll agree that its virtually impossibly to have only sidespin (i.e. the axis of rotation is vertical) for a golf shot, but for almost all of us the axis of rotation is tipped slightly, .  Its also nearly impossibly to have "overspin" on anything other than a cold top, but we often hear players talking about a ball rolling out better because of the overspin.

[revkev]

Engineers to the right of me, engineers to the left of me here I am stuck in the middle with you! What a perfect answer to read on the day that my son was discharged from the Navy and enrolled in a mechanical engineering program at Thomas Edison. My Dad was an engineer, his Dad was as was my maternal grandfather. I don't know what happened to me.

 

At any rate is course you are correct so how about if I alter my statement to read that to the laymen it's fine to say......

 

 

 

Sent from my VS986 using MyGolfSpy mobile app

[cwojtowicz]

Side spin is the spin vector projected onto the axis that is perpendicular (I call it the x-axis) to the target. If you want to calculate ball flight, you can either use a fixed coordinate system or a rotating coordinate system. Your idea of breaking it up into components is correct.

[cwojtowicz]

So does our planet have side spin? Honest question.

 

Ball has to have backspin or it will never go up. It can only go in one direction before it stops to spin the other direction. Pure backspin on an axis. Pure side spin or it wouldn't climb. In this case, I am sorry but your work seems to be all for naught. The world is still flat in the case of golf ball back spin. I do like crow so if you get published or something be sure to drop a pm.

 

The answer to your question is it depends on your coordinate system, if you were to rotate the coordinate system then you would have a spin component along two axis. Likewise, if you lined up your coordinate system so that one of your axis was parallel with the earth's spin, then yes, you would have spin on only one axis.

[808nation]

Let me Google this...

 

Sent from MyGolfSpy mobile

[RookieBlue7]

Spin is not omnidirectional. It is one direction and the axis tilts. You can not spin 2 directions without impact in 2 separate places and even then a single fixed object can not spin 2 directions. Physics say it is impossible. Engineers are always funny though, I almost went to school for engineering. Then they told me I had too much common sense for that.

 

If you want to get technical, the hairy ball theorem (that's what it's called) says it is possible in 4D. Euler's theorem has proven that wrong in 3D.

[sp0rtsfan86]

Two thoughts: One you can't have two spins, I think you guys have done a good job with that. The question is what is side spin? I think it's made up in a way, but explains the tilt and angle of the axis without having to actually put that into a formula. I'm not sure but wow what a great question.

[mjkladis]

It's not literally spinning in two different directions. The vectors are just the component of the spin to give you the picture of the ball flight. Heck it could just says the ball was spinning at X RPMs with a (+/-)Y* axis tilt. It would mean the same thing.

 

 

-MK

[cwojtowicz]

It's not literally spinning in two different directions. The vectors are just the component of the spin to give you the picture of the ball flight. Heck it could just says the ball was spinning at X RPMs with a (+/-)Y* axis tilt. It would mean the same thing.

 

 

-MK

 

Exactly. We split up the spin into different components to match the desired coordinate system. For ball flight, like other projectile motion problems, it's easiest to just use the Cartesian coordinate system (x, y, z) where the xy plane lies on the ground and z is distance above the ground. If you really wanted to, you could define the coordinate system so that one of the axis was always in the same direction as the spin vector but I'd rather keep a coordinate system that has gravity pointing in the -z direction and the ground as the xy plane.

[numberonecoog]

No. Side spin isnt real. Its all backspin and the tilt of the axis of the ball. It drives me nuts when I see side spin and back spin on a LM. Then it says total spin. Drives me nuts

[silver & black]

Well, my head hurts now! I just want to know how to hit "stay in the fairway" spin.

[chemclub]

Well, my head hurts now! I just want to know how to hit "stay in the fairway" spin.

 

Make sure your component of side spin is a lot less than your component of backspin. Easy game.

[chemclub]

No. Side spin isnt real. Its all backspin and the tilt of the axis of the ball. It drives me nuts when I see side spin and back spin on a LM. Then it says total spin. Drives me nuts

 

I think we have to be clear that none of us are suggesting there is more than one axis of spin. In my very first post I agreed that the ball is only spinning on one axis that tilts (again I will cite my post #10 above that the flight of the ball indicates only one axis of spin even before trackman jumped on the scene). But I was trying to clarify that it shouldn't "drive you nuts". It's physics.

 

What the launch monitor is doing is breaking the overall (single axis) spin into two components. The pure backspin component is directly aligned with the initial ball path (from my triangle example, 4 miles north). The pure side spin component is 90 degrees (orthogonal) to the backspin component (from the triangle example, 2 miles west). These two "projections" of the true spin axis onto the north and west axis can be added together to produce the true spin axis (often called vector addition). They aren't incorrect.

[chemclub]

But I will agree that it is extremely difficult to imagine how this component of side spin looks on a ball. Visualizing one axis of  backspin that is tilted is so much easier for us to visualize, but breaking it into components might be so much easier for the launch monitor to measure. It makes sense if you look at the vector addition, and a few folks who are engineers on here seem to have backed up my analysis.

 

In fact, I guarantee the conversation between the engineers who developed launch monitors that show separate side and back spin went something like this.

 

ENGINEER1: Phew, thinking about tilted (off-axis) spin can get pretty complicated.

 

ENGINEER2: Let's break the single tilted spin into vector components.

 

E1: Yeah, since we understand vector component addition, I bet everyone else does too!

 

E2: Just dandy. Now lets get back to building this widget so passionate people can argue about the best way to hit little balls using their metal stick thingys.

 

E1: Tinker tinker. Work work work

 

Revkev, this is your son in a few years.

 

So here is my best attempt at explaining the pure backspin and pure side spin components of an off axis spin that is tilted by 45 degrees. 

 

 

Side spin is actually hidden in the tilted spin!

 

A tilted spin is made up of pure backspin and pure side spin that combine together to give the tilted off-axis spin. So in the same way that many say, "there is no such thing as side spin", I respond that side spin is real if you think about it in the correct way. 

 

Side spin is what determines the angle of the spin away from pure backspin! So your launch monitor isn't lying to you.