If tennis racquets could play each other without the help, or hindrance, of a human, I wonder how they would do?

When we finish a series of racquets for a client, we have data that detail the properties, so, why not use this process to see how two (2) different racquets compare and, what, if anything, would contribute to one racquet “beating” another. We have this data for each client, so, we could play one client racquet against another! Of course to the player this is subjective but let’s look at a quick comparison and discuss what could make a difference and what that difference may be.

Property	Head Prestige Mid	Yonex VCore Pro 97	Difference	What it Means
Main String	MonoGut ZX	MonoGut ZX
Cross String	MonoGut ZX	MonoGut ZX
End Weight	146.4	147.2	-.8 grams	Nothing
Tip Weight	206.0	205.4	.6 grams	Nothing
Overall Weight	352.4	352.6	-.2 grams	Nothing
Swing Weight	343.0	340.0	3 Kg/cm2	Very Little
Polar Moment	358.0	358.0	0.0	Nothing
In Plane Stiffness	411.0	352.9	58.1 Lbs/Inch	Resistance to "Squeezing"
Static Balance	321.8	321.1	.7mm	Nothing
Stability	15	18	-3 units	Less Stable
Position 1 - Butt Cap	137.6	141.3	-3.7 grams	Less weight in the grip
Position 2 - 9 O'Clock	108.1	105.1	3 grams	More weight on the left
Position 3 - 3 O'Clock	106.5	104.6	1.9 grams	More weight on the right
CheckSum	352.2	351	1.2 grams	Confirmation
RDC Stiffness	59	60	-1	Nothing
FlexFour Stiffness	41	45	-4	Less stiff in the shaft
SBS - RDC	66	58	8	Different testing methods
SBS - FlexFour	70.5	66.0	4.5	Different testing methods
SBS - Lbs/Inch	225.9	211.5	14.5 Lbs/Inch	Tighter String Bed
COF= Main	.387	.392	-.005	Nothing
COF = Cross	.397	.342	.055	More Ball Grip
Peak Load	218.0	231.0	-15.1	Softer String Bed @ big hits
Head Weight %	47.05%	46.94%	.11%	More weight toward head
Dwell Time	5.4 ms	4.9 ms	.5 ms	Longer ball contact
Length - Unstrung	68.5 cm	68.5 cm	o.o cm	Nothing
Head Size - Calculated	92.4 Square Inch	95.8 Square Inch	-3.4 Square inch	Higher String Bed Stiffness
Head Width	9.2 Inch	9.6 Inch	-.4 inch	More Twisting

As you can see, there is little difference in these racquets so it could be concluded that they will play the same. However, let’s start at the top and look at the properties that could make a difference.

MonoGut ZX String is quite “soft,” and both racquets were strung at the same reference tension so not much there.

The End, Tip, and Overall Weight are virtually the same as is Swing Weight and Polar Moment.

In Plane Stiffness is the racquets resistance to becoming more narrow when cross strings are tensioned, or wider when main strings are installed. In Plane Stiffness can contribute to a more “firm” or more “flexible” string bed.

Static Balance is the same, but Stability is higher for the Yonex, and I contribute this to the slightly “wider” head. The farther the sides are from the neutral axis, the more stable. However, the Head has a higher 9 and 3 O’Clock weight which should contribute to stability.

Position 1, 2, and 3 are weights taken at three locations on the racquet. Places 2, and three on the Yonex could be increased slightly to increase swing weight.

The checksum is there for me to confirm entries.

RDC and FlexFour stiffnesses indicate that the Yonex should be a little more “powerful” (≈13%) which is confirmed in another piece of data not included here.

SBS RDC and FlexFour are different tests of the string bed. The FlexFour data is used to calculate SBS Lbs/Inch. This data would suggest the Yonex racquet would generate a little more “grunt.”

COF=Main: is the resistance of a ball sliding up the main strings.

COF=Cross: is the resistance of a ball sliding across the cross strings. So, if the ball can catch the string (higher number) the more quickly the ball will begin to rotate. At this moment the coefficient of friction of “string on string” will take over.

“String on String” coefficient of friction is recorded in another data base and can be used to choose complimentary strings for any occasion.