Decreasing MgR/I

[Quackadily Blip]

Hi TT. My question is about the common belief that adding lead at 12 decreases the MgR/I. I'm interested in this because I recently did an experiment with two identical leaded up racquets (check signature) except that one is 2 points more headlight that the other due to a slightly different weight distribution (Wilson quality control), same weight same gauge and type of string. I noticed the one with the 7 pts headlight balance was much easier to serve with. The other racquet with the 5 pts balance was much harder to get the ball over the net. It felt as if the tip was turning down without my control. OTOH the more hl racquet felt easier to maneuver for different spins and hit fast serves in. The common belief is that to decrease MgR/I you should add weight in the hoop, preferably close to the tip. I disagree with this for serving as gravity pulls the racquet down naturally and makes it harder to get balls over the net. I can't say if my theory applies for groundstrokes but for serving I am certain that weight in the hoop, especially at the tip increases the MgR/I for serving. My question is what should I do to decrease the MgR/I for serving only?

 

[torpantennis]

If both the racquets have same static weight, then it probably means that the more HH racquet has more weight in the hoop, i.e lower MgR/I. And lower MgR/I means "harder to get around", agreeing with your findings on serve.

To get them both feel the same, I'd try adding lead to the top of handle to 5HL racquet, and very little weight in the hoop of the 7HL racquet.

 

[Quackadily Blip]

My 5 pt hl racquet is too east to get around which is why it is too closed on contact and is making it very hard to get the serve over the net.

 

[esgee48]

I do not think you are interpreting MgR/I correctly. If I add 1 gram to the tip of my frame, my estimated MgR/I goes up. The simplest way to decrease MgR/I is to add mass to the handle. R will go down and I will remain the same. You'll make the racquet more headlight.

 

[torpantennis]

I do not think you are interpreting MgR/I correctly. If I add 1 gram to the tip of my frame, my estimated MgR/I goes up. The simplest way to decrease MgR/I is to add mass to the handle. R will go down and I will remain the same. You'll make the racquet more headlight.

Are you refering to me? That MgR/I stuff is more complicated to analyze than it seems. It turns out that any added weight in the buttcap does not affect MgR/I at all, weight in the throat increases MgR/I, and weight in the tip decreases MgR/I. I think there was an old thread that analyzed all this?

 

[esgee48]

Not you. OP. He wants to decrease MgR/I which means decreasing R, the distance from butt cap to balance point. He can do that by removing mass from grommet or hoop OR adding mass to handle.

edit: adding mass to tip certainly increases SW and corresponding I. Whether that changes MgR/I drastically depends on how much delta M and delta R, since both will also go up.

edit2: and Travlerajm does mention that you need to tune MgR/I for your own bodies' lenght, etc and says it should be around MgR/I ~21

 

[torpantennis]

But remember that decreasing R by having weight in the handle also increases mass, and it turns out M*R remains constant if the weight is added to handle. Easiest way to decrease MgR/I is to add M without adding swingweight or changing R. That'd be roughly true if you add weight to the balance point. But a better idea is to move that added weight slightly away from balance point, to the top end of the handle...

 

[Joonas]

Guys, just stick the formula in the Excel and start playing with figures

Adding mass anywhere changes:
-total weight
-balance (unless added in balance point)
-inertia ( not same as swingweight)

So normally adding weight at 12 decreases MgR/I.

 

[Mig1NC]

I respectfully disagree with your statement about gravity and the serve.

Remember that not only does gravity pull the head down over the top of the serve as you observed, but also that you are fighting gravity on the way up to the top as well and further that your racquet doesn't benefit from as much built up momentum on the way up as it does over the top.

 

[floydcouncil]

MgrI needs to be at ELEVEN!!!

 

[Mig1NC]

Twenty Eleven to be precise.