swing weight discrepency

[highsierra]

I have noticed a number of discrepencies in the racket swing weight on the TW site. I don't know if the numbers are provided by the manufacturers or came from tests done by TW.

For example, here're two Wilsons per the TW site:

nCode SixOne 95
weight 12.2. oz
balance 10 pts HL
length 27"
swing weight 330

PS 6.0 85
weight 12.6 oz
balance 8 pts HL
length 27"
swing weight 329

How can the heavier PS 6.0 85 that's less head light have a lighter swing weight than the nCode one? It's just mathematically impossible. I don't think the headsize makes a difference. There are other discrepencies like this between rackets of same headsize too.

 

[spinbalz]

SW is not only a matter of weight and balance, it is also a matter of weight distribution.

You can obtain the same balance point, and weight for 2 racquets even if they have 2 different mass distributions, for exemple one racquet will have a high % of its mass distributed near the balance point, and the other will have a higher % of its mass placed near its extremities, then their swingweights will differ.

 

[man-walking]

SW is not only a matter of weight and balance, it is also a matter of weight distribution.

No, AFAIK SW is a simple formula based by weight and balance as variables.

You can obtain the same balance point, and weight for 2 racquets even if they have 2 different mass distributions, for exemple one racquet will have a high % of its mass distributed near the balance point, and the other will have a higher % of its mass placed near its extremities, then their swingweights will differ.

Yes, this explains why *felt* swingweight is always different from calculated one.

 

[spinbalz]

No, AFAIK SW is a simple formula based by weight and balance as variables.

ABSOLUTELY NO, The SW formula is not simple at all, it is a formula based on weight/Balance/and weight distribution, the weight distribution factor makes almost impossible to write the SW as an exact true equation, because writing the exact weight distribution in an equation is almost impossible, it would make the writing of the equation almost endless ; so sometimes a simplification is used to calculate the SW by avoiding the weight distribution factor in the formula, but then the result is always wrong, this way the result is just an approximation.

The only way to know the real SW of a racquet is to use a machine, a machine that will move the racquet (circular/rotational movement) and will provide the SW based on the force/power needed by the the machine to achieve the circular racquet movement at an invariable speed, or based on the racquet speed that the machine was able to generate by using an invariable amount of power.

 

[man-walking]

You are right, I meant the RDC calculated one, the standard one ... and it's the only one that we (can) obtain.

(ATM there's no need for such complex inertia machine to determine the "real" one, because our arm is enough)

so sometimes a simplification is used to calculate the SW by avoiding the weight distribution factor in the formula, but then the result is always wrong, this way the result is just an approximation.

Not sometimes, this is just the SW formula used by RDC, used to calculate any value you read anywhere.

I'm talking about *ordinary* swingweight, you are talking about *real* swingweight but of course you won't find it ever written/calculated anywhere.

 

[spinbalz]

you are talking about *real* swingweight but of course you won't find it ever written/calculated anywhere.

I don't exactly know what method uses TW to measure the SW they publish, but since it exists some sophisticated machines that can mesure the real SW/Dynamic inertia, by making a real live test, and not by just apllying a formula, then it is possible that TW has one of these machines and publishes the real SW. Perhaps Sysop can answer that?