NEW TWU (1-30-13): Spin & Steams, Spaghetti, Diagonal, etc.

[TW Professor]

A new TWU experiment is now up. It investigates spin and rebound angle from spaghetti-type patterns, Wilson Steam 16x15, PowerAngle 16x16 diagonal, and standard 16x19.

It comes in two parts:

1. The experiment writeup: Spin and String Patterns Old, New, and Illegal: Spaghetti, Diagonal, Open and Closed Patterns
2. A companion database and image gallery: Spin Database and Impact Image Gallery

Lot of fun stuff like these:




And, of course, lots of information, data, graphs, photos, illustrations, analysis, etc.

[Buford T Justice]

This is incredible stuff Prof!

[Federerkblade]

its way over my head

[db10s]

Ahh yes... This looks like fun...

[Anton]

Flippin Awesome

[sureshs]

You still need to take the 99S string pattern into account into your trajectory calculator, as I said previously

[mikeler]

Executive Summary Needed!

[dmcb101]

Anyone ever try stringing spaghetti style? Does it hurt the frame to do that?

[sureshs]

Originally Posted by mikeler

Executive Summary Needed!

Steam S open patterns produces more spin and bigger rebound angle.

[corners]

Originally Posted by sureshs

You still need to take the 99S string pattern into account into your trajectory calculator, as I said previously

Patience Sureshs.

[Automatix]

Fantastic stuff. Too bad you didn't check the spin of multis considered the best in this department such as Head RIP Control and Tecnifibre X-One Biphase.

But still, I wouldn't dare to ask for more considering the amount of work you've done already.

[McLovin]

[mikeler]

Originally Posted by sureshs

Steam S open patterns produces more spin and bigger rebound angle.

That is pretty much what I got out of a quick skim.

[TW Professor]

Originally Posted by mikeler

Executive Summary Needed!

I don't know if this qualifies as "Executive," or even "summary," but here you go ...

When the ball bounces from a racquet, the ejection force is not evenly distributed across the ball. Instead, the sum of all the local forces from the strings ends up to be in front of the center of the ball as it slides across the stringbed. This off-center force pushing up in front of the ball tries to create backspin. The distance offset in front of center is called "D". So, the force that creates your "power" is also a topspin inhibiting force. That's not good . . . that's bad.

When main strings move sideways with the ball, they bunch up in front of the ball and push up from there. This adds to the counter-topspin effect. That's not good either. Bad.

But the sideways movement also stores sideways elastic energy, which, upon snap-back, pushes the ball backwards (slows it down, creating high launch angle) and adds topspin. That's good. -- (The amount of energy given back is summarized as a sort of "sideways power". I suppose we could also call this "Spin Power". But we don't. We call it eT.)

Both D and eT can be measured or calculated. They are quantifiable. That means we can compare. That is good too.

Good against bad. Which wins? In this case we have a ratio of the pro-spin to anti-spin agent: eT/D. That ratio ends up with funny dimensions - 1/mm - so we multiply by the constant R (33 mm, radius of ball) to get a nice, neat dimensionless ratio of spin-influencing agents: eT * R / D.

We call this ratio "Spin Number." As spin number goes up, spin and launch angle increase.

D and eT tend to move in the same direction but not by the same percentage amount. If you have a working knowledge of these relationships, then, as a player, stringer, coach, retailer, or manufacturer you can design, string, recommend, choose, etc., racquet setups to customize factors that influence eT and D in ways optimizing the end result. This is a stringer's dream come true -- it's and extra arrow in the quiver, tool in the tool-belt, when promoting your customizing/optimizing skills. You can then make recommendations based on patterns, tensions, materials, gauges, stiffnesses, friction numbers, etc. that will change eT compared to D in ways beneficial to the customer. You don't actually have to know these numbers, you just have to know how altering different variables might change their relationship.

The image database and the experiment write-up offer both visual and cognitive approach to these concepts.

But concepts aside, of the patterns/strings tested, the basic ranking of spin/launch angle from high to low is: spaghetti, Steams (16x15), diagonal, polyester, nylon, zyex.

[mikeler]

Originally Posted by TW Professor

I don't know if this qualifies as "Executive," or even "summary," but here you go ...

When the ball bounces from a racquet, the ejection force is not evenly distributed across the ball. Instead, the sum of all the local forces from the strings ends up to be in front of the center of the ball as it slides across the stringbed. This off-center force pushing up in front of the ball tries to create backspin. The distance offset in front of center is called "D". So, the force that creates your "power" is also a topspin inhibiting force. That's not good . . . that's bad.

When main strings move sideways with the ball, they bunch up in front of the ball and push up from there. This adds to the counter-topspin effect. That's not good either. Bad.

But the sideways movement also stores sideways elastic energy, which, upon snap-back, pushes the ball backwards (slows it down, creating high launch angle) and adds topspin. That's good. -- (The amount of energy given back is summarized as a sort of "sideways power". I suppose we could also call this "Spin Power". But we don't. We call it eT.)

Both D and eT can be measured or calculated. They are quantifiable. That means we can compare. That is good too.

Good against bad. Which wins? In this case we have a ratio of the pro-spin to anti-spin agent: eT/D. That ratio ends up with funny dimensions - 1/mm - so we multiply by the constant R (33 mm, radius of ball) to get a nice, neat dimensionless ratio of spin-influencing agents: eT * R / D.

We call this ratio "Spin Number." As spin number goes up, spin and launch angle increase.

D and eT tend to move in the same direction but not by the same percentage amount. If you have a working knowledge of these relationships, then, as a player, stringer, coach, retailer, or manufacturer you can design, string, recommend, choose, etc., racquet setups to customize factors that influence eT and D in ways optimizing the end result. This is a stringer's dream come true -- it's and extra arrow in the quiver, tool in the tool-belt, when promoting your customizing/optimizing skills. You can then make recommendations based on patterns, tensions, materials, gauges, stiffnesses, friction numbers, etc. that will change eT compared to D in ways beneficial to the customer. You don't actually have to know these numbers, you just have to know how altering different variables might change their relationship.

The image database and the experiment write-up offer both visual and cognitive approach to these concepts.

But concepts aside, of the patterns/strings tested, the basic ranking of spin/launch angle from high to low is: spaghetti, Steams (16x15), diagonal, polyester, nylon, zyex.

Great write up, thanks. Interesting that nylon is above zyex.

[yonexRx32]

Originally Posted by TW Professor

I don't know if this qualifies as "Executive," or even "summary," but here you go ...

When the ball bounces from a racquet, the ejection force is not evenly distributed across the ball. Instead, the sum of all the local forces from the strings ends up to be in front of the center of the ball as it slides across the stringbed. This off-center force pushing up in front of the ball tries to create backspin. The distance offset in front of center is called "D". So, the force that creates your "power" is also a topspin inhibiting force. That's not good . . . that's bad.

When main strings move sideways with the ball, they bunch up in front of the ball and push up from there. This adds to the counter-topspin effect. That's not good either. Bad.

But the sideways movement also stores sideways elastic energy, which, upon snap-back, pushes the ball backwards (slows it down, creating high launch angle) and adds topspin. That's good. -- (The amount of energy given back is summarized as a sort of "sideways power". I suppose we could also call this "Spin Power". But we don't. We call it eT.)

Both D and eT can be measured or calculated. They are quantifiable. That means we can compare. That is good too.

Good against bad. Which wins? In this case we have a ratio of the pro-spin to anti-spin agent: eT/D. That ratio ends up with funny dimensions - 1/mm - so we multiply by the constant R (33 mm, radius of ball) to get a nice, neat dimensionless ratio of spin-influencing agents: eT * R / D.

We call this ratio "Spin Number." As spin number goes up, spin and launch angle increase.

D and eT tend to move in the same direction but not by the same percentage amount. If you have a working knowledge of these relationships, then, as a player, stringer, coach, retailer, or manufacturer you can design, string, recommend, choose, etc., racquet setups to customize factors that influence eT and D in ways optimizing the end result. This is a stringer's dream come true -- it's and extra arrow in the quiver, tool in the tool-belt, when promoting your customizing/optimizing skills. You can then make recommendations based on patterns, tensions, materials, gauges, stiffnesses, friction numbers, etc. that will change eT compared to D in ways beneficial to the customer. You don't actually have to know these numbers, you just have to know how altering different variables might change their relationship.

The image database and the experiment write-up offer both visual and cognitive approach to these concepts.

But concepts aside, of the patterns/strings tested, the basic ranking of spin/launch angle from high to low is: spaghetti, Steams (16x15), diagonal, polyester, nylon, zyex.

Awesome! Where did you get your engineering or physics degree from?

[corners]

Originally Posted by mikeler

Great write up, thanks. Interesting that nylon is above zyex.

Keep in mind that the zyex string tested was Dynamite, which has a braided nylon jacket that effectively prevents the main strings from sliding and snapping back. Of all the strings tested, Dynamite was the the closest to a stringbed where the strings were locked or bonded at the intersections. Zyex monogut zx, being a zyex monofilament with a surface more slippery than many polys, would perform very differently than Dynamite. Dynamite looks great for a flat hitter looking for a little extra pace.

[Anton]

I'm trying to figure out which string setup would give me the most spin with lowest launch angle...is there a way to maximize this or the two simply go hand in hand?

[corners]

Originally Posted by Anton

I'm trying to figure out which string setup would give me the most spin with lowest launch angle...is there a way to maximize this or the two simply go hand in hand?

Looking at the graphs in section 2b4 it appears that cyclone 18 would be the best choice from among the strings tested.

[Mongolmike]

Awesome stuff, thank you... but now I have to go nap-nap time.

Oh... and if I strung a Steam 16x15 spaghetti style I could launch full swing moonballs that would bounce into the court with about 3000 rpm?