Category Archives: Accuracy

What’s The Difference?

As tennis players, you must constantly ask “what’s the difference” when it comes to tennis racquets and string! Well, as racquet technicians we ask the same questions!

This post is intended to showcase the differences of string in testing, not playing, however, some of the data may be noticeable to the player in certain situations.

What this graph shows us, in addition to our trying to save a tree by printing on the back of previously used paper, is that each of these stings will provide almost the same performance. This is indicated by the curve and how closely related the strings are.

Tensile Strength Comparison

The differences you do see here can be attributed to the gauge, or diameter, of the string, with the largest diameter (Tour Bite) having the highest tensile strength.  Down in the “hitting” displacement range (way below the 39.9mm!), there is very little difference.

The tensile strength can be a factor as the string begins to “notch” or otherwise come apart.  Each of the strings in this graph is monofilament so notching would be the failure mode in a racquet.

 

Head Prestige Pro 2021

This years Head Prestige Pro is last years Prestige MP.  This name change was made to synchronize all the 18×20 string patterns as the “Pro” model…I think!

So, what’s in a name?  A thin beam, heavy (sort of), 18×20 pattern, players racquet, that’s what!  The Prestige Pro also includes the new Auxetic material and construction for a refined feel.

For some reason Head Prestige racquets have been called “stiff” by some and this is certainly not the case and never has been.   This racquet is not stiff! As with any racquet the string selection can have a huge effect on “stiffness” so take a look at the effective stiffness!

I believe this is going to be a “control freaks” racquet!  This racquet could also be a baseliners dream come true.  The weight will drive through the ball and the swing weight will allow for some last nano-second stroke adjustments.

Take at look at the data below then go to the Prestige 2021 Comparative Data post to see all the models in one place.

A baseliners dream!

ManufacturerHead
Racquet ModelHead Prestige Pro 2021
Reference Tension52 lbs - 23.6 kg
String
Head Reflex MLT 17
Machine UsedTrue Tension Professional
Static
ASPS, RDC53.0
ASPS, FlexFour62.5
Racquet Flex, RDC58 - After stringing
Racquet Flex, FlexFour36.0
Racquet - In Plane Stiffness326.1 lbs/Inch
Weight, Grams342
Weight, Ounces12.06

Balance, mm318
Balance, Inch12.52
Length, Cm68.6
Length, Inch27.008
Head Width9.48
Head Length13.06
Head Area, cm2627.4
Head Area, Sq. Inch97.2
Number of Main Strings18
Number of Cross Strings20
Ratio Cross/Mains.653
Main String Grid7.56
Cross String Grid10.24
Density (% of head filled with string).791
Average Cross String Space.513
Average Main String Space.417
Dynamic
Dynamic Tension, Kp, ERT35
Dynamic Tension, Lbs/in195.76
First Moment, Nm.832
Polar Moment333
Torsional Stability15
Swing Weight, Kg/cm2318
Swing Weight, Ounces11.22
Swing Weight Calculated345.8
Power, RDC45
Control, RDC56
Manueverability, RDC75
Power, Calculated 1811.5
Head Points7.87
Head Weight, %46.4%
Center of Percussion20.7
Dwell Time, ms8.74
Efective Stiffness - lbs27.7
K, Lb/In169.87
Recoil Weight157.84
Twist Weight230.87
End Weight 143.2
Tip Weight 198.9
9 O'Clock102.8
3 O'Clock100.3
Butt Cap140.3

Head Prestige 2021 Series Comparative Data

Jumping back and forth between reviews and data is not fun nor is it efficient so we have been posting comparative data. Now all the important stuff is in one place.

All of the data is based on a “play ready” racquet.  That means an overgrip and vibration damper, and unless otherwise noted…string!

As you are looking at the data try to determine which numbers mean the most to you and how you could use them.  For example, the Pro has an overall weight of 342 with a swing weight 318.  How does that compare to the MP?

Keep in mind that weight and swing weight can increased but not easily decreased.  No, making the racquet more “head light” statically does not reduce the swing weight as recorded on testing devices that grab the racquet 10cm from the end!  That is why static balance (CG) should not be used as a performance metric.

Click here to see the data!

 

 

Head Prestige Tour 2021

This racquet has the potential to be the hottest new Prestige in a long time. The “Tour” series is not new to the Prestige line but this one has some differences that are meaningful, we think!

This new Tour is a 16×19 string pattern inserted into a 95 square inch hitting area! Compare that to the previous Tour with a 18×19 string pattern in a 99 square inch head(now the new Prestige MP)…so you can see where this one is headed!

All of the new Prestige 2021 racquets will come with the full cap system that has become the “iconic” Prestige accoutrement.  

Also included in the Prestige Tour is the Auxetic material and construction that is intended to provide a better feeling impact and maybe a little more “energy”.  The shaft has a slightly different geometry and is a little shorter than some other models, however, the graphics indicate the shaft is “elongated”.

The “box” beam is a relatively constant 22mm from start to finish and is beautifully done in matt black transitioning into the Prestige maroon.

ManufacturerHead
Racquet ModelHead Prestige Tour 2021
Reference Tension53 lbs - 24.0 kg
String
Victrex 7718 (PEEK)
Machine UsedTrue Tension Professional
Static
ASPS, RDC50.0
ASPS, FlexFour63.5
Racquet Flex, RDC63 - After stringing
Racquet Flex, FlexFour42.5
Racquet - In Plane Stiffness384.6 lbs/Inch
Weight, Grams336
Weight, Ounces11.85

Balance, mm326
Balance, Inch12.83
Length, Cm68.5
Length, Inch26.968
Head Width9.406
Head Length12.78
Head Area, cm2608.9
Head Area, Sq. Inch94.4
Number of Main Strings16
Number of Cross Strings19
Ratio Cross/Mains.620
Main String Grid7.20
Cross String Grid9.125
Density (% of head filled with string).695
Average Cross String Space.464
Average Main String Space.445
Dynamic
Dynamic Tension, Kp, ERT34
Dynamic Tension, Lbs/in190.16
First Moment, Nm.844
Polar Moment347
Torsional Stability16
Swing Weight, Kg/cm2331
Swing Weight, Ounces11.68
Swing Weight Calculated357.1
Power, RDC53
Control, RDC47
Manueverability, RDC66
Power, Calculated 1968.0
Head Points5.20
Head Weight, %47.6%
Center of Percussion21.1
Dwell Time, ms9.00
Efective Stiffness - lbs27.9
K, Lb/In160.26
Recoil Weight161.61
Twist Weight223.59
End Weight 136.8
Tip Weight 200.6
9 O'Clock99.5
3 O'Clock101.4
Butt Cap134.9

 

What Can String Failure Tell Us?

Well, in the simplest terms, failure tells us it is time to have the request strung! However, there may be subtleties in string failure that can help us in our quest for tennis racquet performance.

Such as?

Is the failure shear related or tensile strength related? Was friction the major contributor to the failure? Where did the failure occur (on the racquet, not the court)? Was the failure during play or in the bag?

Shear-related failure is when the string breaks very near the racquet frame. This failure is called a mis-hit or shank! It is like cutting the string with a pair of scissors!

Shear Failure

Friction Failure

Friction failure is caused by just that, friction!  Friction is caused by the string moving on each other. That rubbing creates friction and notches the string where it will fail.

If the racquet failed during play and it is not shear-related, the tensile strength of the string was exceeded. If a string has a tensile strength of 120 pounds and the tension is 60 pounds leaving 60 pounds to be used to hit the ball. Some big hitters can generate at least that much force on a solid forehand!

The graphs show the tensile strength and relative elongation of different material.

This graph shows the tensile strength of the string to be about 115 pounds.  Given the movement of this string-on-string, the frictional notching can contribute to relatively early failure based on the hitters force.

This graph shows the tensile strength of the string to be about 155 pounds but it has to travel (stretches) further to reach that force.

So, you can see, with this information we can make better decisions when asked to suggest a string, or strings, for a client!