Graphene Radical MP weight, swingweight, and stability issue
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Irvin
Talk Tennis Guru
Exactly. The more polarized the racket is (weight concentrated mainly at the ends) the higher the inertia will be around the center of mass axis. The more the weighted in concentrated toward the center of the racket the lower the inertia will be around the center of mass axis. When calculating the SW using the parallel axis theorem you square the distance from the balance point to the SW axis and multiply times the weight and add the inertia around the center of mass.
Therefore the higher the inertia around the center of mass (polarized) the higher the SW (all else being equal.)
EDIT: https://en.m.wikipedia.org/wiki/Parallel_axis_theorem
Therefore the higher the inertia around the center of mass (polarized) the higher the SW (all else being equal.)
EDIT: https://en.m.wikipedia.org/wiki/Parallel_axis_theorem
Last edited:
Irvin
Talk Tennis Guru
An easier way to understand weight, balance, and SW is this way. Say you had a 10.2 oz racket and you wanted to bring the weight up to 11.2 oz but keep the same balance. There are many ways to do that you could add 1 oz of weight at the balance point. Or you could add some weight above and below the balance point. As long as the product of the weight times the distance from the balance are the same on both sides of the balance point are the same the racket balance will remain unchanged. For instance, adding 0.5 oz above and below the balance point at the same distance maintains balance.
Inertia (and SW) is a measure of how the weight is distributed. For every different placement of weight the inertia will change. How much it changes depends on the distance from the axis. The farther the weight is from the axis the higher the inertia.
As long as the SW, TW, weight, balance, and length are all the same the rackets will feel the same when you swing the rackets. If you want the rackets to feel the same when you hit the ball the strings, tension, racket stiffness, racket vibrations, and placement of lead between the ends of the frame must be the same. I say this because if you're trying to match the Graphene and liquid metal Radicals there is always going to be some difference.
Inertia (and SW) is a measure of how the weight is distributed. For every different placement of weight the inertia will change. How much it changes depends on the distance from the axis. The farther the weight is from the axis the higher the inertia.
As long as the SW, TW, weight, balance, and length are all the same the rackets will feel the same when you swing the rackets. If you want the rackets to feel the same when you hit the ball the strings, tension, racket stiffness, racket vibrations, and placement of lead between the ends of the frame must be the same. I say this because if you're trying to match the Graphene and liquid metal Radicals there is always going to be some difference.
If weight is more concentrated towards the end, would it not lower the swing weight rather than increase it?
Irvin
Talk Tennis Guru
Just the opposite. SW (Inertia) is the sum of all mass points times the square of the distance from the axis. (Ref https://en.m.wikipedia.org/wiki/Moment_of_inertia) Let's assume you have an evenly balanced racket and you added 10 g at the butt and at the head. The 10 at the head would add 58.6*58.6*.01 or 34.3 Kg cm2. The 10 g at the butt would add 10*10*.01 or 1 Kgcm2 for a total of 35 points. If you added 20 in the center you would add 34.3*34.3*.02 or 23.5 Kgcm2. Adding weight on the ends will always have the greater change.
Thanks for the explanation. So, if I added 15g at the buttcap to any existing racket, it would still increase swingweight? (I thought the opposite would be true before).
Does adding weight to the handle still increase stability?
Irvin
Talk Tennis Guru
Adding weight anywhere on the frame adds to your SW no matter where it is added. First you must consider what SW is. The system standard for SW is the RDC and they have to hold the racket somehow. A 10 cm axis was chosen because of how the racket is held, but it is just about impossible to rotate a racket around a 10 cm axis. But what SW is doing is measuring how weight is distributed along the frame not really how hard a frame is to swing. If you want to measure how hard it is to swing a racket you need to find the axis where your racket is strung and that point will be somewhere different for most players. So you have to come up with a happy medium.
Adding weight to the butt cap actually does Increase inertia but at the same time lowers the balance. Lowering balance does have a much lower effect on inertia than raising balance. Stability is another issue and although adding mass to me increases stability many may not think it does. It all depends on your interpretation of stability. Many think stability is all about off center hits where the racket twists when the ball is hit off center. In my way of thinking any mass added increases stability as it helps to maintain momentum. Where you add weight is the biggest factor in the rackets ability to maintain momentum. Adding weight increase the amount of force needed to accelerate the racket but at the same time how much force is needed to stop the racket.
