Drift

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I'm confused, what are you trying to say here? That drift is not due to the magnus effect and due to the seam presentation effecting the laminar flow over the ball?

edit: then why do those toy balls for babies that do not have seams, drift and not swing. I have bowled with a light soft ball filled with spongy foam as well those light plastic balls that are in those pools of balls for kids and they drift. They only do drift as it the ball begins to fall I've noticed.

edit2: I've just thought of this, wouldn't bowling the ball perfectly square seam cancel the effect of the swing in the ball, and somehow allow for the drift to happen more readilly.

I've always struggled with why with an outswinger for a right handed batsmen swings out and bowling an overspun leg break which has the seam presented in the same direction doesn't behave the same way. The only difference is they spin in the opposite direction, swing bowler has back spin on it.

I can kind of see that generally for and outswingeer that because of the off spin component of the ball, the magnus effect would not hinder the swing because it should "curve" in the same direction.

So do we generally accept that there are two competing forces with an overspun leg break, one from the laminar flow over the seam of the ball becoming turbulent as it hits the seam creating a wake, and the other the magnus effect caused by the overspun rotation of the ball and therefore why we do no see it happen so often with a cricket ball.

Is the effect of the swing created by seams on a ball stronger than the effect of the spin (magnus effect) on a ball?
 
funk192 said:
I'm confused, what are you trying to say here? That drift is not due to the magnus effect and due to the seam presentation effecting the laminar flow over the ball?

edit: then why do those toy balls for babies that do not have seams, drift and not swing. I have bowled with a light soft ball filled with spongy foam as well those light plastic balls that are in those pools of balls for kids and they drift. They only do drift as it the ball begins to fall I've noticed.

edit2: I've just thought of this, wouldn't bowling the ball perfectly square seam cancel the effect of the swing in the ball, and somehow allow for the drift to happen more readilly.

I've always struggled with why with an outswinger for a right handed batsmen swings out and bowling an overspun leg break which has the seam presented in the same direction doesn't behave the same way. The only difference is they spin in the opposite direction, swing bowler has back spin on it.

I can kind of see that generally for and outswingeer that because of the off spin component of the ball, the magnus effect would not hinder the swing because it should "curve" in the same direction.

So do we generally accept that there are two competing forces with an overspun leg break, one from the laminar flow over the seam of the ball becoming turbulent as it hits the seam creating a wake, and the other the magnus effect caused by the overspun rotation of the ball and therefore why we do no see it happen so often with a cricket ball.

Is the effect of the swing created by seams on a ball stronger than the effect of the spin (magnus effect) on a ball?
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Strewth! I've been looking through all those phsysics papers, looking at Laminar flow and the magnus effect, I looked at Pencil Crickets blog where he's put in a massive effort to shed some light on the matter and just now I've looked at Woolmers book "The Art and Science of Cricket". Now... Bob Woolmer was a man with a lot of connections in cricket and there's a pretty extensive list of people that helped him on that book along with a massive bibliography that cites all sorts of sources. But despite this when it comes to both seam bowling and swing and more so in the case of 'Drift' he concludes with the fact that there isn't enough scientific data to actually pin down either of these phenomena and explain fully why they happen.

Dip and the ball staying in the air with back-spin - that's kids stuff, I can't see why anyone would dispute that and it's easy to put into practice and see it happen, but drift, with the ball drifting in the opposite way to the way that it spins... that's just screwed. What doesn't help either - and I don't know if anyone else sees it in the same way as me, but the illustrations in Woolmers book in the spin section seem to completely miss the relevance of the seam with regards to the direction the ball is spinning? So on that note I declare that I've given up on trying to get my head round this whole issue and join the 'Spin hard' brigade and hope that it drifts!;)

Maybe I'll engage with discussions on empirical observations, Woolmer in his analysis of Warnes BoC proposes that the ball was spin at almost 90 degrees to the direction of flight and that the axis of the spin was either tilted upwards or downwards which if was the case, kind of ties in with some of the data I found on the effects of laminar flow, but still goes nowhere near explaining drifts direction being opposite to the spin direction.
 
Then again maybe I haven't given up, I'm just wading through Vaughan Roberts and so far I'm making sense of it and I've just ordered Brian Wilkins book for a few quid off Amazon... The research continues!
 
someblokecalleddave said:
Strewth! I've been looking through all those phsysics papers, looking at Laminar flow and the magnus effect, I looked at Pencil Crickets blog where he's put in a massive effort to shed some light on the matter and just now I've looked at Woolmers book "The Art and Science of Cricket". Now... Bob Woolmer was a man with a lot of connections in cricket and there's a pretty extensive list of people that helped him on that book along with a massive bibliography that cites all sorts of sources. But despite this when it comes to both seam bowling and swing and more so in the case of 'Drift' he concludes with the fact that there isn't enough scientific data to actually pin down either of these phenomena and explain fully why they happen.

Dip and the ball staying in the air with back-spin - that's kids stuff, I can't see why anyone would dispute that and it's easy to put into practice and see it happen, but drift, with the ball drifting in the opposite way to the way that it spins... that's just screwed. What doesn't help either - and I don't know if anyone else sees it in the same way as me, but the illustrations in Woolmers book in the spin section seem to completely miss the relevance of the seam with regards to the direction the ball is spinning? So on that note I declare that I've given up on trying to get my head round this whole issue and join the 'Spin hard' brigade and hope that it drifts!;)

Maybe I'll engage with discussions on empirical observations, Woolmer in his analysis of Warnes BoC proposes that the ball was spin at almost 90 degrees to the direction of flight and that the axis of the spin was either tilted upwards or downwards which if was the case, kind of ties in with some of the data I found on the effects of laminar flow, but still goes nowhere near explaining drifts direction being opposite to the spin direction.
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Its exactly the same thing as dip. Spin it forwards, it will move downwards, ie dip, spin it sideways, it will move sideways, ie drift. I don't see the confusion?


The direction the ball spins off the ground and the direction it moves are always opposite. Think of a backspinner: it drifts towards the batsmen, but its spinning away from them.
 
SLA said:
Its exactly the same thing as dip. Spin it forwards, it will move downwards, ie dip, spin it sideways, it will move sideways, ie drift. I don't see the confusion?


The direction the ball spins off the ground and the direction it moves are always opposite. Think of a backspinner: it drifts towards the batsmen, but its spinning away from them.
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No - not at all. I was thinking along the same lines. But, if you think in terms of the ball going away from your down the wicket with top spin the ball will dip because of the magnus effect. Now think in terms of the ball spinning turned on its side so the seam is rotating around the middle of the ball like the equator round the earth, if it's spinning anti-clockwise (leg break style) the rotation will make it veer to the left (off-side) not the Leg-side. Vaughan Roberts calls this 'Swerve' and this is easily explaned because it's the magnus effect and the seam is still arranged in such a way that it doesn't cause an in-balance of the air-flow over the ball. Roberts maintains that the most dramatic kind of change in the trajectory of the ball would be with the use of this 'Swerve' (Dip turned on its side), but that wouldn't be much cop as the seam would be in the wrong place to get any purchase off the wicket. Do you have the Brian Wilkins book as Roberts cites this as part of his research into Drift?
 
someblokecalleddave said:
Strewth! I've been looking through all those phsysics papers, looking at Laminar flow and the magnus effect, I looked at Pencil Crickets blog where he's put in a massive effort to shed some light on the matter and just now I've looked at Woolmers book "The Art and Science of Cricket". Now... Bob Woolmer was a man with a lot of connections in cricket and there's a pretty extensive list of people that helped him on that book along with a massive bibliography that cites all sorts of sources. But despite this when it comes to both seam bowling and swing and more so in the case of 'Drift' he concludes with the fact that there isn't enough scientific data to actually pin down either of these phenomena and explain fully why they happen.

Dip and the ball staying in the air with back-spin - that's kids stuff, I can't see why anyone would dispute that and it's easy to put into practice and see it happen, but drift, with the ball drifting in the opposite way to the way that it spins... that's just screwed. What doesn't help either - and I don't know if anyone else sees it in the same way as me, but the illustrations in Woolmers book in the spin section seem to completely miss the relevance of the seam with regards to the direction the ball is spinning? So on that note I declare that I've given up on trying to get my head round this whole issue and join the 'Spin hard' brigade and hope that it drifts!;)

Maybe I'll engage with discussions on empirical observations, Woolmer in his analysis of Warnes BoC proposes that the ball was spin at almost 90 degrees to the direction of flight and that the axis of the spin was either tilted upwards or downwards which if was the case, kind of ties in with some of the data I found on the effects of laminar flow, but still goes nowhere near explaining drifts direction being opposite to the spin direction.
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well! I have understood the drift from the book also.I do bowl it at will.Now spinning the ball hard,today started getting curve.it is very hard to explain.you said"tilting upwards and downwards".The upwards is correct but downward would drift the other side as upwards tilt,Like a wrong 'un.But it wont spin.I have not bowled but is it.
 
someblokecalleddave said:
No - not at all. I was thinking along the same lines. But, if you think in terms of the ball going away from your down the wicket with top spin the ball will dip because of the magnus effect. Now think in terms of the ball spinning turned on its side so the seam is rotating around the middle of the ball like the equator round the earth, if it's spinning anti-clockwise (leg break style) the rotation will make it veer to the left (off-side) not the Leg-side. Vaughan Roberts calls this 'Swerve' and this is easily explaned because it's the magnus effect and the seam is still arranged in such a way that it doesn't cause an in-balance of the air-flow over the ball. Roberts maintains that the most dramatic kind of change in the trajectory of the ball would be with the use of this 'Swerve' (Dip turned on its side), but that wouldn't be much cop as the seam would be in the wrong place to get any purchase off the wicket. Do you have the Brian Wilkins book as Roberts cites this as part of his research into Drift?
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Yeah, swerve is when the ball is spinning sideways with the axis vertical, and drift is when the ball is spinning like a corkscrew with the axis along the line of the pitch. But (even neglecting this bend) a cricket ball does not move in a straight line - gravity kicks in.

The swerve will make the ball bend sideways the whole length of the delivery, the drift will only make the ball bend sideways during the portion of the delivery where the ball is descending. If the ball only ever travelled horizontally, the corkscrew spinning ball would not bend at all. It is only when it starts to descend that corkscrew spin starts to look like sidespin and the Magnus force kicks in.
 
I really don't rate Woolmer's description of the magnus effect and drift. It strikes me he simply hasn't got his head round it himself, and given the pace-crazed times he coached in, and the lack of any great spin tradition in South Africa where he did a lot of coaching, I'm not surprised the subtleties of spin didn't permeate. Watching his videos it's clear in the sections on spin bowling that he's happy to let the (relative) experts do the talking. Also to be fair, trying to get across a very three-dimensional concept on a two-dimensional page is a pretty tough task at the best of times.
 
Spiderlounge said:
I really don't rate Woolmer's description of the magnus effect and drift. It strikes me he simply hasn't got his head round it himself, and given the pace-crazed times he coached in, and the lack of any great spin tradition in South Africa where he did a lot of coaching, I'm not surprised the subtleties of spin didn't permeate. Watching his videos it's clear in the sections on spin bowling that he's happy to let the (relative) experts do the talking. Also to be fair, trying to get across a very three-dimensional concept on a two-dimensional page is a pretty tough task at the best of times.
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I knew you'd be tempted to join in at some point. Yeah Woolmers attempts are a bit Wooly and don't really go anywhere hence the caveat at the end I suppose where he says that it's not the definitive explanation. I wouldn't say it was pretty tough taks, it looks to me like a nigh on impossible task! I'll have to wait for my book and see if that throws any light on it. I've contacted Vaughan too and I'm trying to get the full document rather than the sections as posted on the net.
 
SLA said:
Yeah, swerve is when the ball is spinning sideways with the axis vertical, and drift is when the ball is spinning like a corkscrew with the axis along the line of the pitch. But (even neglecting this bend) a cricket ball does not move in a straight line - gravity kicks in.

The swerve will make the ball bend sideways the whole length of the delivery, the drift will only make the ball bend sideways during the portion of the delivery where the ball is descending. If the ball only ever travelled horizontally, the corkscrew spinning ball would not bend at all. It is only when it starts to descend that corkscrew spin starts to look like sidespin and the Magnus force kicks in.
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That's interesting - but can you go on to say why the magnus force comes into action as the ball drops because of gravity and does the axis remain constant or does it tilt as the ball starts to descend?
 
Shivam_ipl said:
well! I have understood the drift from the book also.I do bowl it at will.Now spinning the ball hard,today started getting curve.it is very hard to explain.you said"tilting upwards and downwards".The upwards is correct but downward would drift the other side as upwards tilt,Like a wrong 'un.But it wont spin.I have not bowled but is it.
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Shivam tell me what it is you're doing exactly especially as you're saying that you can bowl with drift at will. You're the first person I've ever heard say that they're able to do this and this is one of my main questions early in the quest for the facts on drift?
 
Its simply just tilting the axis upwards with more revs.I just come to my stride and and bowl the side spin with little tilt upwards.The wrist should be cock on the other to make it drift.No one tells you how to drift the ball.in books either.May be it is my own invention
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Its simply just tilting the axis upwards with more revs.I just come to my stride and and bowl the side spin with little tilt upwards
 
Shivam_ipl said:
Its simply just tilting the axis upwards with more revs.I just come to my stride and and bowl the side spin with little tilt upwards
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Did you mean spinning the ball up? Theoretically drifting the ball at will is almost impossible unless you are bowling into the wind and giving it a massive rip. You must also have perfect body alignment.
 
someblokecalleddave said:
That's interesting - but can you go on to say why the magnus force comes into action as the ball drops because of gravity and does the axis remain constant or does it tilt as the ball starts to descend?
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Let x be the alignment of the pitch, y be the alignment of the crease, and z be height off the ground.

The ball is spinning with magnitude s. The angle of the spin axis is parallel to the ground in the x direction (s, 0, 0) - and this stays constant while the ball is in the air.

The angle of the spin axis relative to the path of the ball varies however, because the path of the ball varies with respect to the ground. In simple terms, first it goes sideways, then down. The velocity vector is (vx, 0, vz) where vx is constant and vz is g^2 /2t.

While it is going purely sideways (ie z component of velocity is still negligible), there is no Magnus force acting on the ball because (s, 0, 0) x (v, 0, 0) = (0, 0, 0) Once it starts to drop, then z component of velocity is no longer negligible and the cross product of the path vector and the spin vector (s, 0, 0 ) x (vx, 0, vz) becomes non zero, and a Magnus force force is resultant of (0, s.vz, 0). If the spin is clockwise (from the bowlers viewpoint), the force will be to the left. If its anticlockwise then the force will act to the right.

So as the ball drops, the Magnus force will increase from 0. Hence the reason you only really see visible drift over roughly the last 1/3 of the flight of the ball.
 
someblokecalleddave said:
That's interesting - but can you go on to say why the magnus force comes into action as the ball drops because of gravity and does the axis remain constant or does it tilt as the ball starts to descend?
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The axis of the ball should stay virtually constant. Since it's spinning it acts like a gyroscope and has a lot of stability. As it drops though, while the axis of spin stays the same the direction of motion changes, so the axis of spin relative to the airflow does change and this is what causes drift in the downward part of the flight.
 
Spiderlounge said:
The axis of the ball should stay virtually constant. Since it's spinning it acts like a gyroscope and has a lot of stability. As it drops though, while the axis of spin stays the same the direction of motion changes, so the axis of spin relative to the airflow does change and this is what causes drift in the downward part of the flight.
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Yeah I got that from Vaughans work - but just wanted someone else to say the same thing and confirm it's the case.
 
SLA said:
Let x be the alignment of the pitch, y be the alignment of the crease, and z be height off the ground.

The ball is spinning with magnitude s. The angle of the spin axis is parallel to the ground in the x direction (s, 0, 0) - and this stays constant while the ball is in the air.

The angle of the spin axis relative to the path of the ball varies however, because the path of the ball varies with respect to the ground. In simple terms, first it goes sideways, then down. The velocity vector is (vx, 0, vz) where vx is constant and vz is g^2 /2t.

While it is going purely sideways (ie z component of velocity is still negligible), there is no Magnus force acting on the ball because (s, 0, 0) x (v, 0, 0) = (0, 0, 0) Once it starts to drop, then z component of velocity is no longer negligible and the cross product of the path vector and the spin vector (s, 0, 0 ) x (vx, 0, vz) becomes non zero, and a Magnus force force is resultant of (0, s.vz, 0). If the spin is clockwise (from the bowlers viewpoint), the force will be to the left. If its anticlockwise then the force will act to the right.

So as the ball drops, the Magnus force will increase from 0. Hence the reason you only really see visible drift over roughly the last 1/3 of the flight of the ball.
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Sorry SLA your advanced years demonstrate how good the education was back in the day, unfortunately maths was never my strong point and the main reason for starting this thread was so to look at the potential of describing these factors in a way that someone like me could comprehend. Any chance you could somehow simplify that?:confused:
 
Just that drift is the same as swerve except swerve affects the ball when its moving horizontally, and drift affects the ball when its moving vertically.
 
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