Physics questions on badminton

Discussion in 'Techniques / Training' started by fmqpt791004, Dec 28, 2011.

  1. taneepak

    taneepak Regular Member

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    Now a good test for those who claim that spin will slow down a shuttlecock how about trying this out:
    1. Try to hit a deep clear with a new shuttlecock and note the distance.
    2. Break two feathers of the same shuttle and do the same clear. You will note the obvious sharp drop in spin rate to the extent the shuttle now wobbles and has a tendency to drop prematurely to the floor. Take off a few more feathers and it will not fly at all.
    Now this loss in spin is not true spinning which many players, including coaches, wrongly believe. It is a lack of sufficient spin speed or rate that makes it wobble and fall.
     
  2. chris-ccc

    chris-ccc Regular Member

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    Yes, sometimes a short and simple question is the best question to ask. Why? Because it zooms in (into the main issue).

    From the opening post of this thread, I read the question as;

    Which is more powerful - A smash done with more spinning of the feathers, or done with less spinning the feathers?

    Some posters are saying that the shuttlecock must be spinning as it travels. But that is not the answer we want to get. It is a fact - that there is some spinning/rotation of the feathers as the shuttlecock flies.

    The question is really - Will a shuttlecock travelling with more spin travel further/stronger/faster than a shuttlecock travelling with less spin (when both are hit by the same impact force)?

    Then taneepak mentioned about 'net tumbles'. :D:D:D (which has nothing to do with the speed/velocity of a smash).

    Maybe, I shall bring in this thread that I started for BCers, to know about the terms of;

    * Sliced Flat Clear,
    * Sliced Smash, and
    * Spinning Netplay.

    Click on this link to get there;

    http://www.badmintoncentral.com/for...raining-(Strokes-Shots)?p=1648432#post1648432
    .
     
    #22 chris-ccc, Jan 3, 2012
    Last edited: Jan 3, 2012
  3. taneepak

    taneepak Regular Member

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    Well, here is one plastic/nylon shuttlecock manufacturer trying to come up with plastics that are as good as feathers, www.patentstorm.us/patents/5853340/description.html.
    Many like him have tried this before, all in vain so far. For one thing I do not believe plastics can come up with a shuttlecock that can spin on its major axis at anywhere near the speed of feathers.
    In feather shuttlecocks factories, qc requires each high quality shuttlecock to be tested for its rotational speed, the higher the higher grade it will be given.
     
  4. Andy05

    Andy05 Regular Member

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    I'll see if I can answer a few questions here about these things, in my degree I did some stuff on parabolic flight paths and air resistance created by projectiles.
    If I have managed to quote Hybriddragons picture *edit pic didn't copy* - The air placement following the shuttle does not include the air vacuum that the feathers pushing the air apart would create. This minivacuum would create turbulence behind the shuttle which is part of how a flight path is formed. Also the spin from a shuttle cannot be thought of a propulsion or decelerating force in the way hybriddragon described it earlier. Think of a shuttle as more of a watermill raising the water up a height (if that makes sense), the shuttle spinning so as not to pick the water up would spin faster and with less loss of rotational speed. Spinning so as to pick the water up would slow its rotational down as it loses energy from air resistance.
    Another thing is that shuttles DO spin in flight. A faster hit would have more spin, up to a natural maximum, from then on you need to artificially add the spin. Adding spin clockwise or anti-clockwise will slow the shot down.
    Spin when added to an object can be used to straighten a projectiles flight path, such as in rifles, however if too much spin is added the air resistance would be too great and then it becomes a decelerating force on the forwards motion of the shuttle as the shape of the shuttle and air flow both contribute to high air resistance.
    Net-spin is totally different to what is being asked in this question, as the 'spin' in this condition is used to make the shuttle tumble end over end it is not adding or subtracting speed from the shot.

    I think I covered everything I read, can't remember all of it
     
    #24 Andy05, Jan 3, 2012
    Last edited: Jan 3, 2012
  5. hybridragon

    hybridragon Regular Member

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    Yes, this is exactly what I was trying to get at. I think it's tough to test with a person as force imparted on a shuttle is subjective and not measured. It would be interesting to see the results from an objective standpoint where all the results are measured.

    @andy05~

    That was a good read. Pardon my previous drawing as I did not intend for it to show every variable. And I didn't propose the notion that spinning clockwise or anti-clockwise would create a propulsion/deceleration force, nanobatien did, which I contended against. However, I believe this part was quite important to ponder: (Which I completely agree on)




     
  6. taneepak

    taneepak Regular Member

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    Most players and coaches use the word spin differently and may I add rather wrongly.
    The major axis of spin of a feather badminton shuttlecock is the real 'spin'. 'Killing' the natural spin when doing a net tumble by saying you are spinning the shuttle at the net is not true spin, slicing a half smash or slicing when doing reverse-slice drop shots are also not true spin but additional forces brought to bear on the shuttle. That is why a badminton shuttlecock has very high Reynolds numbers and that is why it is such an interesting game. For the same reason plastics/nylon shuttlecocks have struggled for the past 50 years, always with false promises initially, but never delivered.
     
  7. taneepak

    taneepak Regular Member

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    Here is a little fun game to try out the theory of spin of a shuttlecock.
    Get a good grade goose feather shuttlecock and throw it as high and as far as you can, using your hand. Observe carefully the rotation or spin of the shuttle which is counter clockwise. Then try observing the shuttle's drift as it turns over and starts to fall down. It should drift right.
    Try the same thing with a plastic and it will not spin as much nor will it drift right at turnover as much.

    You can even put this spin/drift characteristics of clears to good use when playing the game. When clearing to the left side hit it a bit out and it will drift in. Don't try this on the right side, which will require that you clear a bit more inwards for some safety margin.
     
  8. Andy05

    Andy05 Regular Member

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    @hybridragon
    Sorry for misquoting you, I was doing a long post and forgot who had said what that I was replying to for each point.
     
  9. taneepak

    taneepak Regular Member

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    Now for all the coaches here are some simple questions:
    Why should you do a net tumble with a right to left movement instead of the other way? Has it got something to do with a shuttlecock's natural spin? What if the feathers are overlapped the other way? Will the spin be reversed from counterclockwise (as seen by the hitter) to clockwise?
     
  10. chris-ccc

    chris-ccc Regular Member

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    .
    If you would start threads on these topics (one thread for one topic), I would participate in them.

    But for this thread question:

    Question: Which is more powerful? - A smash done with more spinning of the feathers, or done with less spinning the feathers?

    My answer is: A smash done with more spinning of the feathers will be slower and will have less power.
    .
     
    #30 chris-ccc, Jan 5, 2012
    Last edited: Jan 5, 2012
  11. visor

    visor Regular Member

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    you guys should play with plastic more often, don't have to worry and think so hard about spinning less or more ... just smack it hard. :p :D
     
  12. chris-ccc

    chris-ccc Regular Member

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    You have reminded me of this:

    The current plastic shuttlecock will travel faster than a 'feathered shuttlecock' in a smash because of these reasons;

    * Without spin, the plastic shuttlecock (compared to the feathered shuttlecock) will travel faster in a smash.
    * With less rigidity of the plastic 'skirt' (compared to the stiff feather shaft), the plastic skirt collapses (folding inwards).

    Therefore, a smash with a plastic shuttlecock is usually faster and/or more powerful than a smash with a 'feathered shuttlecock'.

    Maybe, this is another topic... And perhaps, we can start another thread on this one.
    .
     
    #32 chris-ccc, Jan 5, 2012
    Last edited: Jan 5, 2012
  13. taneepak

    taneepak Regular Member

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    The title of the thread covers more than the questions being asked. To fully understand the correct answers to your questions, a more detailed explanation is helpful.

    Answers to your questions are straightforward :

    1. Yes, a smash will have a high spinning rate of the shuttle, with the jump smash the highest followed by ordinary smash.

    2. A spinning shuttle, that is spinning on its axis, will go a longer, much longer, distance than a non-spinning shuttle. It is impossible for a shuttle, whether feather or plastic, not to spin when being hit with some force.

    3. Almost all smashes on oncoming shots are hit against an incoming spinning shuttlecock. The speed of your smash is dependent on your skill. No, a smash will not cause a 'smashed' shuttlecock to stop spinning unless it has fallen to the floor.


    BTW, plastics are not true badminton shuttlecocks as their behavior is closer to a round/spherical ball, especially with hard shots.
     
  14. taneepak

    taneepak Regular Member

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    Frankly, I am flabbergasted by so much misunderstanding of a feather shuttlecock's spin. Even 'experts' get confused and start talking about spinning the shuttle with sliced drop shots, sliced smashes, reversed-sliced drops, and spinning the shuttle at the net. Now if all these 'spinning' can be done, pray please explain the direction and nature of such spins.

    Put simply, a shuttlecock has to spin on its axis to go from one point to another point. Without this spin it is like a runner without legs. The spin is fast for fast shots and slower for slower shots. The spin is always counter-clockwise, as seen from the hitter after he has hit the shot (seeing from the back of the shuttle).

    Now to put to rest this nonsense about more spin means slower speed :
    As mentioned earlier try throwing a feather shuttlecock up and forward but slowly. Note the spin rate.
    Next use the same shuttle and do the throw again but with increased speed. Notice the faster spin? Now tell me which one spins more and which one travels faster and with greater stability?
     
  15. taneepak

    taneepak Regular Member

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    I hope the simple home shuttle throwing test suggested earlier will be an eye-opener to a better understanding of a shuttlecock's spin.

    However, to help avoid any more misleading 'expert' opinions in the future may I point out the following untrue claims:

    1. "The way the feathers are over-lapping with a clock-wise spin (travelling from you) of the shuttle will mean it will travel faster.........."

    This is wrong. All current feather shuttlecocks have their feathers overlapped in the same direction and they will all spin counterclockwise, not 'clock-wise' (travelling from you).


    2. "Never heard of a spinning shuttle will travel faster and go further".

    The proof can be found in your simple home shuttle throw test to debunk this.

    3. "Smashing with a slicing action (in generating more spin) the forward velocity will decrease".

    Smashing with a slicing action is a 'moderated' smash with less power and speed but it reduces the spin or rotation rate, not increasing it. The slicing action does not in any way create any additional spin. In fact it 'moderates' the spin rate which means a reduced spin rate.


    4. "A smash done with a spinning of the feather will be slower and will have less power".

    All shots, smashes, clears, drives, drops will generate spin. The slower the spin the easier it is for the human eye to discern, the faster the spin the more difficult to observe. It is this detectable spin that fools 'experts' into believing they have added more spin to say a sliced smash. This is not true.
    Again, the more powerful the smash the faster the spin rate.
     
  16. uselessmail

    uselessmail Regular Member

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    Physics explained

    After reading quite a few 'expert' opinions which are by nature contradictory, I thought I'd give some definite points which can be used too further fuel this wonderful discussion. There has been a lot of speculation on this board on the effect of spin (whether it is counterproductive or not and by how much?). There is a paper available online from the ISB Journal of Physics on 'Deceleration of a Shuttlecock' wherein they have explained the concept quite minutely and have given a valid formula that one can use in the calculation. You can find it here-- http://www.isb.ac.th/HS/JoP/vol4iss2/Papers/1Badminton.pdf

    Admittedly, there isn't much information regarding the effects of 'more' spin in the research but one can at least get a fair idea of the physics of the decelerating shuttle in a normal circumstance. In fact there is always some spin when the shuttle leaves the racket after its hit (One can see any of the numerous slow motion videos posted by Yonex marketing dept. to see that).

    Let the discussions continue...
     
  17. OhSearsTower

    OhSearsTower Regular Member

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    jeez im getting a headache here
    i think i must leave this forum as im afraid i read so much bs on topics im unsure about and read so much wrong stuff

    here is your answer, its very simple:

    more spin on a smash = less speed q.e.d.
    that is because the feathers widen more the more they do spin and therefore have more air-resistance which makes the shuttle slower


    all comparisons with other sports are ridicolous as the badminton shuttlecock is such a unique sport item
     
  18. mindfields

    mindfields Regular Member

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    Hmm, Not sure if I agree with all of the explanations given.

    There's a few fundamentals that need to be realised.

    1. There are two processes which impart spin on the shuttle. Spin imparted by the racquet & spin imparted by the airflow due to drag over the feathers.

    2. Propellers add forward thrust as they "bite/screw" into the air due to their shape. Shuttle cocks do not have this shape & cannot impart forward thrust.

    3. The spin on a shuttle will always settle on the path of least resistance (i.e. least drag)

    So. . .
    The faster you hit it the more natural spin will be on the shuttle due to drag over the arranged feathers. The natural spin is dictated by the speed not the other way round.

    If you hit the shuttle with more/less spin than the natural for that particular speed you add more drag. If you cut the shuttle to take away spin the air resistance will speed up the rotation. If you cut the shuttle to add more spin air resistance will slow the rotation.

    Rather than thinking of a propeler on a plane think of a sail boat.
    If the wind is 10 mph & your drifting at 5 mph raising your sails will speed you up.
    If your travelling at 20mph on the engine then switch it off & stick your sails up the sails will act like a airbrake & slow you down to 10mph.

    tanepeeks pretty much got it on the money apart from making the distinction between the two ways that spin is put on the shuttle. In his example's he's only really talking about spin from air drag.

    Using his example You should notive this effect:
    If you try & throw a shuttle with lots of spin it will slow down it's rotation.
    If you try & throw a shuttle with no spin it will speed up it's rotation.

    Any change in spin speed is due to drag. Any energy required to slow/speed up the spin is sacrificed from forward speed.
     
    #38 mindfields, Apr 23, 2012
    Last edited: Apr 23, 2012
  19. Pakito

    Pakito Regular Member

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    Pakito's Theory of Relativity on Shuttle Spin

    Hey guys, I am no scientist, and frankly all this quantum physics has made me all 'corkscrew'y in the data processing machine seated in my skull. :D

    Let me chip in on my theory of the spin. As of now, one says that the spin slows down the shuttle, the other vice versa.

    While it is true (I feel) that the shuttle does spin on its own irregardless of whether it is sliced or not, I feel that the spin is indeed really a 2 faced coin.

    Spinning is in fact aroused and heightened by both speed and slice. But the fact for me is this: ever notice that the shuttle starts out fast and speedy on alot of spin, then it's like those Dragsters' sports where the dragster fires out a parachute and severely slows the speed of the dragster? Well, this is what happens in theory of the spin. And to cement this theory, virtually all fast spins (spins due to tremendous input power and slice from the racket) are all shots that land at the frontal area of the court, never the baseline. This is because its starts out fast by input of strength of hit by the player, and then sliced at the same time. The high input of kinetic force forces the shuttle to spin faster, boosted by the slicing motion of the racket on the shuttle (think snooker), and for the first part of the shuttle flight trajectory, it travels fast indeed, fooling the player to stand closer to the baseline. Almost in a quick milliseconds later, the shuttle suddenly lands nearer to the frontal area of the court. This where majority of the shots are used to fool their opponents. This effect cannot be achieved (at least in my theory) for lobs, lifts because palyers don't sliced them for a full perfect high lift. You can sliced a jab or a push a little, but not a lift, because the lift will fall low and fall short. This is why intense shuttle spinning (revolutions per second) happens a lot on downward trajectory shots ie the smash, half-smash, sliced fast drop (there is a distinction between a slow falling drop and a sliced fast drop).

    So why fast at the beginning and slowing down at the end? Because the spin is a mechanism that needs slicing and kinetic force to start up, but once it's started up, spin speed increases till it comes to a break point when the feathers open up (think of a peacock) and causing more resistance and thereby, intense speed reduction.

    Don't get me wrong, a shuttle does spin even with a full smash down the line without a slice, but compared to the smash coupled with a slice, the straigh smash spins slower.

    PS: Shuttle spin (rotary motion) and shuttle tumbling motion (horizontally and vertically orientation) are both different aspects of defination of the motions defined.

    Why I say this theory is a 2 faced coin?

    Speed and sliced ---> increased the spin of the shuttle ----> increasing spin creates a vacuum in front of shuttle head (think of turbo engine) ------> shuttle speed increases even more -------> shuttle spins reached a criticial level where the feathers has to opens due to outward spinning momentum of the feathers ------> feathers opening outward increases friction on flight trajectory (think parachute) ------> as speed decreases so does the spinning (this is why commentators can see the spin when is slow, but not on initial flight straight from the racket because its too fast for the eye to define) ----->shuttle falls short of its intended length and drops in front of the opponent. Opponent is tricked.
     
    #39 Pakito, Jul 22, 2012
    Last edited: Jul 22, 2012
  20. taneepak

    taneepak Regular Member

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    So much theory about spin and still getting confused.
    Here is from a shuttlecock manufacturer's brief explanation. When we make shuttlecocks we have to test all shuttlecocks for rotational speed (spin) and stability on a special machine. This machine is different to another machine that tests shuttlecock's speed and distance. An average non-nylon shuttlecock has a rotational speed or spin of about 320 revolutions/minute, plus/minus 5 revs/m, with an average stability. A higher grade could be as high as 480 revs/m, plus/minus 5 revs/m, with very high stability.
    The higher quality shuttlecock can spin/rotate faster and still maintain very high stability at such high rotational spin because of its higher quality feathers and shafts. Obviously, winter goose feathers are the best.
    The faster a shuttle is hit the faster the spin/rotational spin, limited by the shuttle's spin limit. A duck feather shuttlecock has no hope of reaching a 480 revs/m and will travel at a spin of 320 revs/m when hit with power, which will collapse the feathers inwards a bit because the shafts are not strong enough, resulting in having higher wear and tear and loss of speed over a relatively short period of time.
    The bottom line , insofar as shuttle manufacturing is concerned, is that the best shuttle must have very high rotational speed with very high stability when hit with power.
    Now, you don't want to buy shuttlecocks with slow spin/rotational spin when hit with power.
    Stroke techniques such as slices and so called "net spins" affect the shuttle's rotational spin by slowing it down in both speed and its natural rotational spin. In other words, the faster a shuttle's rotational spin the faster and the more stable the shots.
    What happens is subject to 2 forces, gravity(pulling down) and air resistance (pushing up), that will affect its motion.
     

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