Racquet Force swing weight...

Discussion in 'Badminton Rackets / Equipment' started by visor, Feb 9, 2020.

  1. speCulatius

    speCulatius Regular Member

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    I think that's the bigger part of it... just feeling comfortable when picking up the racket is part of it and the overall weight does play a role. So does psychology.

    YY_ZFII_LD.jpg YY_Duo_ZS_3U.jpg
    Between 89 and 90.5 for ZF II 4U (LD versions, but it should be the same racket as the regular one) vs 87 for ze Duo ZS 3U. Like you can see, there's some difference between the two 4Us they measured, so the sample size (of one) is too low and with some variances in production, your rackets might be rather close. Just measure the head weight to get a good idea of it (the difference).

    About aerodynamics, I'm still pretty sure that the strung area (head size) has by far the biggest impact on aerodynamics. Then it gets tricky, but after having tested some Adidas Überschall rackets, I'm starting to believe that the more open stringing pattern has a bigger influence than I thought. And at some point the frame shape and width comes into play. That also changes the feel as well, though.

    While overall weight and its distribution can make a difference, I think (due to my experienve choosing and recommending rackets) swing weight is a good point to start with when looking for a new racket. Once you roughly know what swing weight and stiffness you like, you can rule out a lot of rackets that you don't need to try. The rest is just trial and error. Of course it makes sense to try rackets outside of your go to specs from time to time to see if it has changed.
     
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  2. AznDude

    AznDude Regular Member

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    Generally speaking, 3U rackets hit harder than 4U rackets of the same model. 3U88D vs 4U88D etc. 3U rackets should have a higher or heavier swing weight right?
     
  3. Budi

    Budi Regular Member

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    technically its not more powerfull but heavier racket carry much more momentum force/swing weight.

    For a muscle man like me, a 3U would be a deadly weapon for me as im worthy enough in the eye of god of power but im not worthy for the god of speed, so using lighter racket wont bless me with the same power.
    Other hand my friend, not as muscley like me able to hit hard with lighter racket as he can generate way better speed than me but he totaly struggle if use my god hammer weapon.

    So its kinda complicated to tell heavier racket will hit harder than lighter one. Maybe i can say like this...
    If one can find the perfect balance in this BP & racket weight that is not to heavy yet not to light & able to achieve maximum swing speed with it, & then find a perfect sync with racket stiffness & string tension, then he would be able to perform his most powerfull stroke. But to do so is way more complicated than just saying it:p.
     
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  4. seanc6441

    seanc6441 Regular Member

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    Wow I wouldn't have imagined the 4u zf2 being much more than my 3u DZS from just swinging it at the air. My zf2 of course could be on the lower end though and close to my DZS.

    Thanks for the DZS measurement. Around 87g must be my preference too then. I think the head weight of DZS is absolutely perfect and I wouldn't want any more or any less. If I ever find any other stiff compact heads with 87g swing weight I'll be buying them because I get great balance of power and control with that racket without too much loss of agility.

    This is a long shot but do you have any TK9900 gen 3 to test out in 3u or 4u? I own the 3U version but I know it's gonna be higher swing weight than DZS and more around 4u ZF2 level. But I'm wondering if the 4U version is around 87G swing weight because that's another stiff compact racket with great handling for it's weight.
     
    #44 seanc6441, Mar 10, 2020
    Last edited: Mar 10, 2020
  5. seanc6441

    seanc6441 Regular Member

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    Also off topic a bit but do you run a store @speCulatius or do you just get access to those machines? Very nice equipment!
     
  6. speCulatius

    speCulatius Regular Member

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    That's all from the racquetforce fb page... you can see their watermark on the pictures and this thread mentions them in the title, so I forgot to give the credits to them. I just had those pictures on my laptop, because it's two rackets I have tried and I had to decide between a 3U and a 4U Adidas P8. This leads me to...
    If you want to have a back up racket, just get another Z-Strike.
    If you want more different rackets, give the Adidas P8 4U a chance. The 3U has a swing weight of 90.
    IMG-20190903-WA0002.jpg
    The overall weight difference is rather small between 3U and 4U for the P8, so it might be slightly above 87 for the 4U, but if it really should be too head heavy, you can replace the orange grommets with regular ones and reduce the weight (significantly).

    Stiff, compact head, great racket.
     
  7. Ch1k0

    Ch1k0 Regular Member

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    Science has replied. 3UG6 JP code NF800 with plastic wrap and original grip still on. Weight is 89.68g and head weight is 38.87g.

    Sent from my SM-G975F using Tapatalk
     
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  8. visor

    visor Regular Member

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    Very nice! That head weight is almost exactly what I'm looking for! Around 0.5g more than my current 4U 88D, which imo is already one of the higher head weights I've seen in a 4U 88D.

    Sent from my SM-G965W using Tapatalk
     
  9. Ch1k0

    Ch1k0 Regular Member

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    Eh. If that actually catches your eye then the RF data for swing weight is 86.0 for an 89.2g weight racket with plastic on.

    Sent from my SM-G975F using Tapatalk
     
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  10. terrynguyen121988

    terrynguyen121988 Regular Member

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    Please! Test nanoray z-speed racket
     
  11. Budi

    Budi Regular Member

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    most of the data is provided by RF & as its old generation racket, doubt they had it on stock to test.
     
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  12. terrynguyen121988

    terrynguyen121988 Regular Member

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    In Vietnam, Z speed is still on available ^-^. (new batches)

    It's about 80 dollars, too cheap to a good racket.

    p/s: I have a friend who is a racket seller and he has a machine to test racket (like the pictures on this topic).
    Unfortunately, the city was locked down now, he cannot go to his shop to make a test for me.
     
    #52 terrynguyen121988, Apr 5, 2020
    Last edited: Apr 5, 2020
  13. Prince Light

    Prince Light New Member

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    According to Badminton Racket Review Astrox 55 has a swingweight of 88 kgcm2. Stiffness of shaft is 1.18, which is rated as 'Stiff', but not overly stiff. For a lower end racket with similar specs there is the Astrox 38 D (swingweight 88 kgcm2, stiffness 1.08 (medium)).
     
    #53 Prince Light, Apr 15, 2020
    Last edited: Apr 15, 2020
  14. Prince Light

    Prince Light New Member

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    In the Ph.D. Thesis 'Designing the World’s Best Badminton Racket' (Kwan, 2010) there is some interesting numbers for aerodynamics. According to this, around 75% of the drag is from the strings alone, 20% from the head frame and 5% from the shaft. Changing strings from the thicker 0.68-0.69 mm. to a very thin 0.61 mm. string would then give approx. 7-8% reduction in total air resistance for the racket. Worth considering :)
     
    #54 Prince Light, Apr 15, 2020
    Last edited: Apr 15, 2020
  15. Budi

    Budi Regular Member

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    but thicker string carry more weight on the head & so does lower tension as there is more string on the frame.:p

    For 20% frame, it really feel faster than using thinner string. For example when im experimenting with thin 0.66 string (where before i would go 0.68 or 0.70), i find it much more repulsive yet didnt feel significant faster swing (at least for me to feel it). Other hand, when i use my AVP (compare to all my previous boxy frame racket), my swing feel light & faster as if it cut through air, tho it still feel wierd on impact like im missing something in my stroke. The feedback not as solid & satisfying like box frame.
     
  16. speCulatius

    speCulatius Regular Member

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    Well... no.

    First of all, thanks for the title is the thesis, a link to it would have been much appreciated.

    I might be too skeptical, especially when engineers attempt to do research, but let's start with something that bothers me.
    PSX_20200416_105356.jpg Before we get to the part that I highlighted, he wants to use a motion sensor that alters the racket's properties "to sidestep the inconveniences of using an elaborate camera system." As long as it's more convenient, we don't need the best measurements?!?

    Now to the highlighted part. Note that he didn't define g and normally, g is used for the unit gram, a weight unit, not acceleration. Obviously, he is referring to the gravitational acceleration which should be somewhere between 9.76 m/s² and 9.83 m/s², but it's not a defined unit. Before you say that the difference is not big, multiply it with 50. A physicist might have written, "50 * 9.81 m/s² with 9.81 m/s² being the assumed average gravitational acceleration on earth."

    Interestingly, I did not find the numbers you mentioned either. I didn't even find any measurement of drag. I only found this in the appendix:
    PSX_20200416_111000.jpg
    PSX_20200416_111034.jpg
    Based on a rather rough model where they just assumed a value for the drag coefficient. It's not a measurement.
    Even if that value was true, how do you come up with the assumption that for dynamics like that, the drag only depends on the cross section. There's so much going on, you need to consider all the turbulences a string causes. They couldn't do that, that's why they made an assumption for the drag coefficient (for the entire strung area, not for a single string). How did you do it? Where does it show in your consideration.

    If anything at all, this is evidence for what I've been saying all along. A smaller head (less strung area) has a much bigger impact on the aerodynamics of a racket than the frame profile and even the frame thickness. You might also argue that less strings will most likely cause less drag (look at Babolat and Adidas rackets if you need examples).

    Each of those aspects would yield enough content for an own Phd thesis or at least a very throughout paper and that leads to one of my problems with engineers attempting to do research. This thesis is trying to solve all the problems at once. The goal is to make something, to produce something. The value of research is to look at a part of it, make an assumption and try to prove this assumption wrong. As long as you cannot prove it wrong, you keep assuming it. With this, you need to look at all the different aspects and when there's enough evidence that supports the assumptions (by not proving them wrong), you can start putting the pieces together. That's not what Kwan is doing and you're simplifying it even more. Simplyfying it to a degree that's so far from reality that it's useless. Talking about the drag of strings, even their surface might have a bigger impact than the diameter (at least in some conditions). Probably not, but it needs to be considered. Making bold statements doesn't help anybody if there's nothing to back it up.

    Please don't take it personal. It's not.
     
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  17. Prince Light

    Prince Light New Member

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    @speCulatius I was basically trying to tell you, that your assumption about the racket head area by far accounts for the biggest share of drag, is supported by the data in the mentioned thesis. And it makes sense ofc.

    The data for drag in the diagrams in the appendix of the thesis looks to be calculated from a model using the elements strings, head frame, shaft and handle. The drag coefficients and cross-section areas for each of the elements are then used to calculate their contribution to the drag force, also taking into account the variations in air velocity along the length of the swinging racket.

    All things considered, that sounds plausible to me, even when it is omitting many small details in the racket geometry, like cross intersections of the strings, grommets etc. Which btw. all tends toward higher total drag for the racket.

    The values of drag components I mentioned are read off the diagrams in the appendix. I would have guesstimated a bit lower values for the strings and a bit higher for the head frame, but 75% for the strings, 20% for the head frame and 5% for the shaft still looks plausible to me. I understand that these are not exact numbers ofc., they might be 5-10% off, but the general picture remains.

    As for the difference in drag between a thick and a thin string, both with the same (circular) shape, it is proportional to the cross-section area, so it is hardly an assumption.

    About your scepticism toward the thesis in general, I don't think you are being fair. It is fx. not relevant if the author use '50 g' instead of an exact value of acceleration, when all he is trying to do is to explain why certain types of accelerometers are hard to find. A critical approach is a good thing, but I think you are over the top here. This thesis by Kwan is one of the more thorough out there.
     
  18. Prince Light

    Prince Light New Member

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    @visor The above swingweight values from Badminton Racket Review are with strings, so these are not directly comparable with swingweight values without strings.
     
  19. Prince Light

    Prince Light New Member

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    True, not by much though, around 20% or 0.7 grams if you compare 0.68 mm. strings with 0.61 mm. strings, assuming same material/density and circular shape.

    True, but this is such a small difference that it is not worth considering :)
     
  20. speCulatius

    speCulatius Regular Member

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    I don't think I'm unfair. A Phd thesis should show research, even the title of this thesis shows that this is not about scientific research. That's something for a very different discussion that I'm not gonna get into.

    If it was that easy, why didn't they use the value for one string and calculate it? How do different strings deform at the intersecting she how does that change the real cross section?
    You're assuming that intersecting strings don't cause any different turbulences than just parallel strings or even just one string. And again, how does the surface of the string factor in?

    That's guessing territory, nothing else.

    I'm pretty sure a weight difference of 0.7 g and all of that in the head makes a bigger difference.

    PSX_20191009_233752.jpg

    I'm out.
     

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