The impact of spin on dignics 09c and fastarc G1 with angles calculated [video]

[palguay]

This time, attempted spin, with a few modifications from a video shooting standpoint, including increased lighting and slow-motion footage captured with a mobile camera. Additionally, data was collected and added some charts at the end of the video.

Excited to be going to WTT Goa next week

 

[SFF_lib]

Very interesting. As a person with a mathematical mind I appreciate your effort.

The ball 1 in G1 is the odd one out. Outgoing spin was reduced by 20x. The greatest reduction out of all six tests.

Having said that it proves that G1 is a better blocking rubber than 09C.

 

[dingyibvs]

This time, attempted spin, with a few modifications from a video shooting standpoint, including increased lighting and slow-motion footage captured with a mobile camera. Additionally, data was collected and added some charts at the end of the video.

Excited to be going to WTT Goa next week

Great improvements over the first video! However, it really needs a more realistic blocking angle. At positive angles (as defined by the video) the spin is reversed, as may be seen in the video where all the outgoing balls have backspin, which is not realistic. Place the racket in a more realistic blocking angle so that the incidence angle is negative, then we'll have a topspin ball after a block and get a better idea.

Very interesting. As a person with a mathematical mind I appreciate your effort.

The ball 1 in G1 is the odd one out. Outgoing spin was reduced by 20x. The greatest reduction out of all six tests.

Having said that it proves that G1 is a better blocking rubber than 09C.

That's may not the way to look at it. Just my theory, but I think it may be more important to look at the difference between the spin than the ratio. For that particular ball, the incoming spin was the highest at +2966, while the outgoing spin is also the highest at -105 (negative as it's backspin), a difference of 3071. The difference for the other 2 balls for the G1 were 3166, and 2997, so it falls right in the middle. The average was 3078. For the D09C the differences were 3192, 2988, and 2902, an average of 3027.

Also, I'm not sure it's been decided yet whether retention of spin or not, or whether higher or lower angle change is better for blocking.

 

[yoass]

So — this is about measuring spin sensitivity. I like it, but since raw data is always in want of interpretation, what's your take, @OP?

 

[latej]

So — this is about measuring spin sensitivity. I like it, but since raw data is always in want of interpretation, what's your take, @OP?

I was thinking that if that is the objective, then many same shots should be fired on the 2 rubbers, to have some averaging for that particular shot, with intended speed, rps, angle. And then do the same for another shot. So far it seems there is too few data, if I understand correctly.

Another minor point about angles, I'd prefer instead the angle to be against the normal of the bat plane.

 

[palguay]

So — this is about measuring spin sensitivity. I like it, but since raw data is always in want of interpretation, what's your take, @OP?

As I had mentioned earlier, the first few videos are for us to understand this process and figure out what data makes sense to collect, once we have a better understanding then we can look at analysing the data

 

[DukeGaGa]

This is how all reviews should be, an objective analysis of characteristics of the stuff one is reviewing.

 

[palguay]

Great improvements over the first video! However, it really needs a more realistic blocking angle. At positive angles (as defined by the video) the spin is reversed, as may be seen in the video where all the outgoing balls have backspin, which is not realistic. Place the racket in a more realistic blocking angle so that the incidence angle is negative, then we'll have a topspin ball after a block and get a better idea.


That's may not the way to look at it. Just my theory, but I think it may be more important to look at the difference between the spin than the ratio. For that particular ball, the incoming spin was the highest at +2966, while the outgoing spin is also the highest at -105 (negative as it's backspin), a difference of 3071. The difference for the other 2 balls for the G1 were 3166, and 2997, so it falls right in the middle. The average was 3078. For the D09C the differences were 3192, 2988, and 2902, an average of 3027.

Also, I'm not sure it's been decided yet whether retention of spin or not, or whether higher or lower angle change is better for blocking.

Yes, I think that a video with a different angle would be an additional data along with this. Thanks for the suggestion. I am trying to figure out these things as we go along. Hopefully as we keep iterating we learn together and help us understand this better

 

[brokenball]

I found the audio a little low. I had to turn up the YouTube volume and computer speaker volume to max.
Use revolutions or radians per second. Use MKS units. It will be easier to do do the energy calculations later.

Even if the ball had no spin at contact, it would have spin afterwards since the angle of incidence is not 0.
I would measure the speed in meter per second before and after. This way the translational and rotational energy before and after can be measured. Also difference in elevation is a difference in potential energy. The difference in potential energy should be small but not ignored. The difference is how much energy the rubber and blade absorbed. The rubber and blade that absorb the least amount of energy is overall the faster rubber

I forgot to add that some energy will be lost due to air resistance. It would be nice to have the speed, rotation and elevation measured frame by frame. Still, the energy before impact should be constant ( minus air resistance ) and greater than the energy faster impact.

 

[palguay]

I found the audio a little low. I had to turn up the YouTube volume and computer speaker volume to max.
Use revolutions or radians per second. Use MKS units. It will be easier to do do the energy calculations later.

Even if the ball had no spin at contact, it would have spin afterwards since the angle of incidence is not 0.
I would measure the speed in meter per second before and after. This way the translational and rotational energy before and after can be measured. Also difference in elevation is a difference in potential energy. The difference in potential energy should be small but not ignored. The difference is how much energy the rubber and blade absorbed. The rubber and blade that absorb the least amount of energy is overall the faster rubber

I forgot to add that some energy will be lost due to air resistance. It would be nice to have the speed, rotation and elevation measured frame by frame. Still, the energy before impact should be constant ( minus air resistance ) and greater than the energy faster impact.

Thank you , I forgot the mic when doing it. I am looking for help in these calculations as I do not have the necessary background and hopefully will have some help and can start putting out these units.

Thanks for the explanation on the energy absorption, this was clear and insightful for me.

 

[brokenball]

This site has the formulas for both translational and rotational energy. MKS units should be used and omega is the angular frequency in radians per second, not hours.

Rotational energy - Wikipedia

en.wikipedia.org

The potential energy is mgh. h is the elevation in meters.
If you want to do research, you should use the MKS system of measurements.