Polarised Rackets

[Veninga]

Guys,

Lately there has been much talking about (de)polarised rackets. Depol makes modern spinny way of playing more easy. Pol makes the more traditional more flat way of playing more easy.

If i understood it right, a depol racket has on both ends of the racket (cap and top) more weight than a pol one. In other words in a polarised racket the weight is more even distributed along the vertical axis.

The balance rating is of course something else. This number is saying more about the weight distribution in vertical axis. More at one of the other side.

My questions:
- what are typical polarised rackets?
- which numbers on TWU are saying something about (DE)POL

On the second question. Does plowthrough and or hittingweight in the top of the stringbed compared with the lower part of the stringbed something?

Anyone?

Ciao from Holland

[spaceman_spiff]

You've got it switched around. A polarized frame will have more weight at the top and down in the handle, whereas a depolarized frame with have more weight concentrated around the neck and lower part of the hoop.

A good example of a polarized stock frame is the Youtek Extreme Pro. It's relatively light, has a headlight balance, and yet has a rather high swingweight. A good example of a depolarized frame with similar weight and balance is the Youtek Speed MP 18x20. Although it has the same unstrung weight and similar balance as the Extreme Pro, it has a much lower swingweight.

You can use the hitting weight comparison tool to see the difference between the two. The Extreme Pro has much more weight around the top and sides of the hoop, wherease the Speed has more weight around the bottom of the hoop.

[Veninga]

oh, yes i swithed them around.

but thanks for the answer.

following your answers, a polarised racket has a higher swingweight and a higher hitting weight at the top (when all other specs are more or less the same).

The SPEED is more depolarised, the EXTREME more polarised and the RADICAL has a pretty high SW compared with the SPEED, but a normal HITTING weight. So its between.

Clear. Therefore a dunlop 500t is much more polarised than a 300.

And is SPEED ELITE more polarised than the SPEED 300.

[Veninga]

little correction. the radical has almost the same hittingweight as the extreme. based on these stats both are polarised. extreme has a more open stringbed, so probably even more spinny.

on the twu tools, there is also one called racket speed. this one shows the speed when you hit the ball at the top or in de the center. Ill guess these number and the comparison between top/center, would even be a better stat to look at. because it also take the real static weight into account and makes it up to ball speed when. a more polarised racket should have a higher number than a depolarised one.

the radical scores really low on this particular number. so does all the wilsons and the speed 300. extreme scores higher, babolats also (with exception of the storm). feels like how it should be.

do you agree?

[Bartelby]

The prestige pro versus the midplus are good examples of the difference.

[olliess]

There have been a few threads where people have computed various numbers to estimate "polarization" -- they might be worth searching for if you're interested in this topic.

One way to is to divide the moment of inertia of the racquet (swing weight around the balance point) by the mass of the racquet. This number is bigger for more polarized racquets, since their weight is moved out toward the ends.

By this metric, the racquets that are polarized vs. non polarized tend to be pretty much the ones you think, although there are a few surprises. Also note that I got all the specs from TW play tests where available, and the published specs on TW otherwise.

YouTek Prestige MP and Mid are not very polarized (.844 and .848 ). Prestige Pro (.855) is only slightly more polarized than those two.

BLX 6.1 Tour (0.841) is surprisingly even slightly less than Prestige MP, although it's commonly known that the first thing to be done to the 6.1 Tour is to cram lead under the head guard.

Head IG Speed MP (.863) is nore polar but still not much.

BLX 6.1 95 18x20 (.874) a bit more still.

Babolat Pure Drive Roddick GT Plus is a step up in polarization (.912), although some of this is also an effect of the extra length.

Aero Pro Drive GT (.934) is way up there.

But the biggest surprise for me anyway is that the most polarized racquets I've seen are not the APDGT, but the YouTek Radical MP (.939) and Radical Pro (.949).


For comparison, the Pro Staff 85 (.808 ) is the least polarized that I could find specs for.

[Veninga]

Originally Posted by Bartelby

The prestige pro versus the midplus are good examples of the difference.

You mean the pro is more polarised than the mp? Because the racket speed in the top compared to the center is higher?

[Veninga]

Originally Posted by olliess

There have been a few threads where people have computed various numbers to estimate "polarization" -- they might be worth searching for if you're interested in this topic.

One way to is to divide the moment of inertia of the racquet (swing weight around the balance point) by the mass of the racquet. This number is bigger for more polarized racquets, since their weight is moved out toward the ends.

By this metric, the racquets that are polarized vs. non polarized tend to be pretty much the ones you think, although there are a few surprises. Also note that I got all the specs from TW play tests where available, and the published specs on TW otherwise.

YouTek Prestige MP and Mid are not very polarized (.844 and .848 ). Prestige Pro (.855) is only slightly more polarized than those two.

BLX 6.1 Tour (0.841) is surprisingly even slightly less than Prestige MP, although it's commonly known that the first thing to be done to the 6.1 Tour is to cram lead under the head guard.

Head IG Speed MP (.863) is nore polar but still not much.

BLX 6.1 95 18x20 (.874) a bit more still.

Babolat Pure Drive Roddick GT Plus is a step up in polarization (.912), although some of this is also an effect of the extra length.

Aero Pro Drive GT (.934) is way up there.

But the biggest surprise for me anyway is that the most polarized racquets I've seen are not the APDGT, but the YouTek Radical MP (.939) and Radical Pro (.949).


For comparison, the Pro Staff 85 (.808 ) is the least polarized that I could find specs for.

Thanks a lot, makes sense. And yes, some surprises there. For example the radical MP. Can you tell me wich stats u mean and where you have find them (in wich tools)?

And what is the score for the Dunlop Bio 300?

[olliess]

Oops, sorry, I had a typo in the formula when I got those numbers.

What you need are the racquet mass (m), balance point (x), and swing weight (SW). Then you can get the moment of inertia (I) using
SW = I + mr^2 = I + m(x - 10 cm)^2. The 10 cm is just because the balance point is measured from the butt end, but the SW is measured 10 cm from the end.

Then I just divide out the mass and call the ratio I / m the polarization ratio. Maybe it should just be called polarization number or something, since it isn't really a "ratio." (If you use mass in g and swing weight in kg cm^2, you get even funnier units like I did, but you can just multiply everything by 1000 if you prefer). This is one way to try and measure polarization, but it is by no means the only way.

The idea of polarized racquets is basically to give you big swing weights (and hence more power/spin) with for a given mass / head heaviness, and you can see that reflected in the numbers here.

Here is a corrected table (accuracy still not guaranteed!):

Dunlop Bio 300: 0.4208
Head IG Speed MP: 0.4342
Pro Staff 6.0 85: 0.4536
YouTek Prestige MP: 0.4596
YouTek Prestige Mid: 0.4640
Bio 300 Tour: 0.4660
YouTek Prestige Pro: 0.4712
YouTek Radical Pro: 0.4726
YouTek Radical MP: 0.4768
PDR GT Plus: 0.4932
BLX 6.1 Tour: 0.4997
BLX 6.1 95 (18x20): 0.5010
APD GT: 0.5054
LM Radical MP: 0.5087

[Veninga]

Originally Posted by olliess

Oops, sorry, I had a typo in the formula when I got those numbers.

What you need are the racquet mass (m), balance point (x), and swing weight (SW). Then you can get the moment of inertia (I) using
SW = I + mr^2 = I + m(x - 10 cm)^2. The 10 cm is just because the balance point is measured from the butt end, but the SW is measured 10 cm from the end.

Then I just divide out the mass and call the ratio I / m the polarization ratio. Maybe it should just be called polarization number or something, since it isn't really a "ratio." (If you use mass in g and swing weight in kg cm^2, you get even funnier units like I did, but you can just multiply everything by 1000 if you prefer). This is one way to try and measure polarization, but it is by no means the only way.

The idea of polarized racquets is basically to give you big swing weights (and hence more power/spin) with for a given mass / head heaviness, and you can see that reflected in the numbers here.

Here is a corrected table (accuracy still not guaranteed!):

Dunlop Bio 300: 0.4208
Head IG Speed MP: 0.4342
Pro Staff 6.0 85: 0.4536
YouTek Prestige MP: 0.4596
YouTek Prestige Mid: 0.4640
Bio 300 Tour: 0.4660
YouTek Prestige Pro: 0.4712
YouTek Radical Pro: 0.4726
YouTek Radical MP: 0.4768
PDR GT Plus: 0.4932
BLX 6.1 Tour: 0.4997
BLX 6.1 95 (18x20): 0.5010
APD GT: 0.5054
LM Radical MP: 0.5087

Very nice work. Very useful. Hopefully TWU is reading this too and can give the number in their specs.

I tried to recalculate with your formula...

Radical MP.
- swingweight 324
- weight 312
- balance 33,2.

Can you show us the first steps? The I/M is not difficult.. Thanks

[Veninga]

first steps to calcuate the I.

Like sw x mass = outcome a
outcome a / balance = outcome b
etc.

[olliess]

From the expression above (post #9):

SW = I + mr^2 = I + m(x - 10 cm)^2,
so
I = SW - m(x - 10 cm)^2.

For your Radical MP,
I = 324 kg cm^2 - .312 (33.2 cm - 10 cm)^2
= 156 kg cm^2.

I / m = 156 kg cm^2 / 312 g * 1000 g/1 kg = 500. cm^2.
or same as 0.500 in my funny units of 1000 cm^2 (I didn't multiply by the final 1000).


BTW, I can't take credit for this, as several others have already shown calculations like this.

Anyway, this is all fun to play with, but you don't want to get too embroiled in the specs. They're just made up measurements that help explain why some racquet A plays differently from some other racquet B, but they don't help you play!

[Veninga]

Originally Posted by olliess

From the expression above (post #9):

SW = I + mr^2 = I + m(x - 10 cm)^2,
so
I = SW - m(x - 10 cm)^2.

For your Radical MP,
I = 324 kg cm^2 - .312 (33.2 cm - 10 cm)^2
= 156 kg cm^2.

I / m = 156 kg cm^2 / 312 g * 1000 g/1 kg = 500. cm^2.
or same as 0.500 in my funny units of 1000 cm^2 (I didn't multiply by the final 1000).

BTW, I can't take credit for this, as several others have already shown calculations like this.

Thanks a lot!! Makes sense now.

[guitarplayer]

This thread is polarizing.

[Veninga]

I must admit some outcomes are really surprising. Speed 300 should be less polarised (because advertised as more spinny) than the radical. Same for Extreme. Hmm, doesnt sound like logic?

[Veninga]

Originally Posted by guitarplayer

This thread is polarizing.

Can you please depolarize?

[olliess]

Originally Posted by Veninga

I must admit some outcomes are really surprising. Speed 300 should be less polarised (because advertised as more spinny) than the radical. Same for Extreme. Hmm, doesnt sound like logic?

The physics seem to indicate that a racquet with a bigger swing weight will tend to produce more power and spin, given a similar pre-impact velocity.

Polarized racquets have more swing weight for given a mass and balance, so they should therefore produce better power and spin.

I didn't do the calculation for the IG Speed 30, only the 18x20. But the 300 (.454) does come out to be slightly more polarized than the 18x20 (.434).

On the other hand, string pattern is also a big factor. Open string patterns seem to produce more spin and closed string patterns less. The IG Speed 300 has a 16x19 pattern, which should make most of the difference in spin compared to the IG Speed 18x20.

[travlerajm]

I think a better measure of the polarization is Ic/(MR^2), where Ic is the recoil weight (moment of inertia about the balance point), M is the mass, and R is the distance from butt to balance point.

Ic = SW - M(R - 10)^2, where SW is the swingweight abou the 10cm axis.

[Veninga]

Originally Posted by travlerajm

I think a better measure of the polarization is Ic/(MR^2), where Ic is the recoil weight (moment of inertia about the balance point), M is the mass, and R is the distance from butt to balance point.

Ic = SW - M(R - 10)^2, where SW is the swingweight abou the 10cm axis.

I = SW - m(x - 10 cm)^2.

its the same?

[travlerajm]

Originally Posted by Veninga

I = SW - m(x - 10 cm)^2.

its the same?

Yes. But divide I by MR^2 instead of M, otherwise you are effectively just measuring the balance rather the the degree of polarization.