so, again about the accelerating?

simple facts of golf swing

1. you hit a ball
2. hitting a ball slows down the club
3. slowing the club reduces clubhead speed during the time of compression

now controversial
4. supplying force during impact (not just cruising at top speed but accelerating – thats what force does) minimises deceleration

now before you all cry “thats not true” or whatever, imagine for me a club that has a hinge halfway down the shaft. the hinge is firm until the very moment of impact, but then gives way completely

this removes the ability to supply any forward force to the ball impact onwards. it doesnt change velocity

and what happens to the club. it decelerates far more than if the club was supported. in fact in my mind the club hinges completely and the ball goes max of 50 metres, probably 20

im sure there is a better way to do this that is testable, but someone tell me anything that is wrong with the thought experiment

I think what you say is 100% true – it has to be as you’re continuing to add energy to the system during impact. That extra energy creates more ball velocity, more ball spin, more sound and more heat.

My line of thinking from a similar discussion we had was does it make a significant difference? Conservation of momentum equations agree with launch monitor ball speeds when the striking mass is simply the clubhead’s mass.

But COM equations don’t take into account the continual muscular force supplied during the collision, or energy lost due to heat and sound.

If heat and sound are significant, then I would say the muscular force supplied during impact is also significant, and/or the effective striking mass is much greater than just the clubhead’s mass. Otherwise I’d expect launch monitors to show higher ball speeds. I have no idea how significant heat and sound are though.

my response to that is of course it makes a difference. in the exaggerated example i gave it made a huge difference. it is fallacious to assume that relationship stops at some cut off point

the only reason i can think of that launch monitors dont show higher ball speeds is that everyone hitting the balls are golfers. they all do supply force to some degree. the very fact the hands are both on the club provides a fulcrum of sorts

but i have never seen a comparison on launch monitor between someone who holds the lag and compresses well compared to someone who doesnt. it would be hard to do, because they would both have to swing at the same speed

if anyone has seen this, let me know. id love to see the data

The relationship wouldn’t stop at some point, but it would gradually die to become trivial. Who knows what that point is?

I would love to see a selection of pro golfers hitting the same club and looking at the ball speed versus the clubhead speed. The clubhead COR changes with swingspeed, as does the ball, but they could probably be factored in. Alternatively a small enough range of swingspeeds could probably highlight something of interest.

i would also love that

lag made some good points in the other thread (despite me trying to keep physics out of it!) re: intent and outcome

the club will always slow down, but how much it slows down will change on how the club is swung

just go watch an new golfer. my girlfriend can swing it fastish and hit the middle, and get a max of 130m with a 3 hybrid. chaining is off, no lag pressure

no other way to explain it. maybe the problem is all of the studies are done with pros!

every action has an equal and opposite reaction – newtons law

of course the club slows down and flexes, the club head striking the ball is trying to push the clubhead back the way it came.

I could guess that her lack of chaining makes her look like she is swinging it fastish, the opposite of a talented athlete who’s chaining well with the resulting rhythm making them look graceful.

And the lack of compression from a BLW from a laying-back, non trapping clubface also will kill distance.

So although compression and chaining are key, I think there are a few reasons not specifically pressure related.

It would be good if someone sold an impact bag like the martial art makiwaras with digital force readout.

SMZ

You wrote with respect to a golf club that has a hinge built into the shaft -: “and what happens to the club. it decelerates far more than if the club was supported. in fact in my mind the club hinges completely and the ball goes max of 50 metres, probably 20.”

You are totally wrong in your “thought experiment”. This has been repeatedly tested under “real life” experimental conditions. The ball goes as far because the clubhead is essentially decoupled from the shaft during impact. In fact, if you look at the Cochrane and Stubbs book, there is a photograph of a hinge-shafted club and they discuss this very issue,and they demonstrate that there is no loss in ball flight distance.

You need to read and understand these links.

Link 1

Link 2

Jeff.

Steb – you wrote-: “I think what you say is 100% true – it has to be as you’re continuing to add energy to the system during impact. That extra energy creates more ball velocity, more ball spin, more sound and more heat.”

That’s not true! One cannot add “extra” energy to the clubhead during impact because the clubshaft is decoupled from the clubhead in terms of energy transfer.

Follow this thread at brianmanzella.com (and also read those two links above).

Thread on the “heavy hit”

Jeff.

Thanks vey much for the links Jeff – they’ve revealed to me the missing link – propagation delay. Now it all adds up!

Steb

If you look at this photo series of VJ Singh you can see that his right hand is off the clubshaft at impact. He doesn’t lose any driving distance because the idea that one needs to stress the shaft at impact is Lagpressure’s personal myth, that he refuses to support with a rational argument based on solid golf physics fundamentals.

Jeff.

Here is another link to another knowledgeable person who knows a lot about the physics of the golf swing.

David Tutelman

Note what he states at the end of his paper -: ‘The time constant of the “plucked driver assembly” is about 40 milliseconds. That’s almost 100 times longer than the contact between clubhead and ball. So anything that happens at the grip of the club during contact has no more chance of effecting the ball than if the club were being swung on a string.”

Here is a link to another one of his papers.

http://www.tutelman.com/gol...

Here he states-” “Strength or weight of the golfer holding the club: Simply not a factor! If the golfer couldn’t convert strength and weight into clubhead speed, then there’s nothing that they can do during impact to increase distance. As we saw in the section on vibrational frequency, the clubhead is swinging free at this point, with little more connection to the grip than if it were on a string. Actually, that’s an overstatement. The shaft is infinitesimally stiffer than a string. If you do something at the grip during impact, 1/10,000 of that effect will reach the clubhead while the ball is still there. But that’s all.”

Jeff.

jeez jeff

stop it. ive seen them

they are baloney

it doesnt make sense. ive explained why for nm

for mandrin – so his assumption is that for kinetic chaining to occur a wave of force must propogate up the shaft to the golfer, and back down the shaft to the ball? and this must be done with a 43 inch shaft? and pre-stressing the shaft will not alter the equation in any way?

his words
“the head is decoupled because of time and flexibility”

the answer
-flexibility of the shaft is grossly decreased if it is stressed. all that energy has stretched it to its limits. it cannot stretch further, in an exaggerated example, no matter how much force the ball supplies

so there goes flexibility

time – that doesnt even make sense. why does there need to be a wave in the first place. i dont disagree it could ‘help’ if a well timed wave snapped back, but the force of the collision – all of the equal and opposites – are in play already

the only one he is talking about is the additional elastic potential that comes from the collision into the shaft

and when the shaft is fully stressed it has no elastic potential

that said i would like to see that book. link? scan it up? im sure they did something wrong. i have read part of it and the certainly dont like quotations do they? nothing is referenced at all!

anyway, regarding the point they make (which i think is somewhat irrelevant anyway), pressure plays a huge role in impact wave propogation, and a stressed (pressured) shaft will transmit that sort of wave faster than an unstressed one

there are many articles written about baseball and such and they all never make mention of pre-stressing a shaft. they all try to be reproducible by using machines, but then aim for velocity not acceleration

in an unstressed test the mass of a baseball bat isnt even fully transferred, only part of it is. begs the question why we even use bats? my hypothesis (i will call it that because i have never seen it tested) is a stressed bat/club will supply greater force than an unstressed one

it supports experience and thus far is not disproven, that i have seen

its the same as everyone thinking for years backspin equalled distance with a driver. backspin = lift. makes sense, but doesnt work experimentally

so i will keep an open mind that i could be wrong. you should too

Just a few interesting thoughts,(at least to me), for discussion.

1. Many talk of a prestressed golf shaft, there is some evidence that the golf shaft is actually bent forward by the time that the club head gets to the ball. For a tubular shape that is bent, (stressed), one side of the shaft is in compression and the other is in tension. So does it make a difference which side of the shaft is compressed and which side is in tension in relation to the direction of the strike of the ball? If so, why?

2. Any object that is traveling in an arc is accelerating because there is a change in direction, in this case it happens to be a constant change in direction. Is this type of acceleration with a constant club head rotating velocity (rpm) enough of an acceleration to have a positive influence on a golf ball’s initial velocity?

good questions

very good

1. it is true in many slow mo videos the clubs flexes forward. the question as to whether this happens for everyone, including those who subscribe to and exemplify ‘hold the lag’ has never been tested as far as i know

it should be

the other important factor is this can be an optical illusion, some of what we see as forward flex is actually toe droop, and the 2d image is a misrepresentation of a 3d action

as to 1 part 2, it depends what hypothetical effect you are discussing. if you believe a pre-stressed shaft supplies mass and acceleration to the ball, then yes it does matter, because only a shaft flexed backwards has resistance to further flex in that direction

if you are talking about what jeff raised, the back and forth standing wave formed at contact (i dont think it would change performance myself) then i suppose just flex in itself is what alters speed of wave propagation. direction is less important

2. you are correct the clubhead is always accelerating. i hadnt ever considered this before, because it is easy to assume the direction of acceleration is perpendicular to impact. of course it isnt, or every club would be a putter. it explains much better (for me) why the ball moves up the clubface, why it gets into the air, and why it spins backwards

it also explains why the steeper the swing, the more the spin and loft, because the steeper the swing the more upward (toward the axis of rotation) acceleration

great thoughts hacking

Soul,
My first question pertains to a stressed shaft supplying mass and acceleration to the ball. Why do you believe that a backward stressed shaft would have more resistance than a forward flexed shaft to more flex?

Concerning the pictures of the golf shaft at impact, I agree with you that it is possible that the pictures are misleading. What is really interesting to me is that some very good pictures seem to show that the shaft near the handle is still lagging, but that towards the club head, the shaft is leading. I would like to know if this is reality or not and it could be very interesting to find out that the shaft is lagging and leading at the same time.

I am not into physics in a big way but would like to throw this little thought out there.

The lagging clubhead stays that way until the wrist is uncocked.
The later that happens the more acceleration is available at the latter part of the swing. Therefore a later release has to have more going for it than an earlier one where the shaft may have that forward bowing look.

Also we are only talking here about a FLW release, not a hackers BLF delivery where all of the forces are out with the bath water.

The videos that I am talking about are all pros. I am not talking about throw away. Good golf swings only, I couldn’t care less what happens in a bad golf swing.

I will try and find some videos in youtube that show what I am talking about, if people care. These questions have always bothered me, so I would like to here others thoughts.

so, again about the accelerating?

simple facts of golf swing

1. you hit a ball
2. hitting a ball slows down the club
3. slowing the club reduces clubhead speed during the time of compression

now controversial
4. supplying force during impact (not just cruising at top speed but accelerating – thats what force does) minimises deceleration

now before you all cry “thats not true” or whatever, imagine for me a club that has a hinge halfway down the shaft. the hinge is firm until the very moment of impact, but then gives way completely

this removes the ability to supply any forward force to the ball impact onwards. it doesnt change velocity

and what happens to the club. it decelerates far more than if the club was supported. in fact in my mind the club hinges completely and the ball goes max of 50 metres, probably 20

im sure there is a better way to do this that is testable, but someone tell me anything that is wrong with the thought experiment

SoulmanZ,

I think you need to study conservation of momentum a little more in depth.

The greater the clubhead slows down ie more decceleration,the more momentum is passed onto the golf ball.Why would you want to “resist deccelaration” in a collision event such as a golf strike?Remember we are not slinging the golf ball like a slingshot or an arrow,it is a collision.

I can understand the golfer trying to “put more weight” via the shaft into the clubhead during the strike but the ball does not stay on the clubface long enough for that to happen significantly.

man

i want to answer these questions simply but the maths is crazy. the shaft can do all sorts of things because elastic materials can set up standing waves, certainly getting outside my understanding though

might have to wait till tomorrow, im at work 13 hours today. will try to nut it out

edit:

dap, not true. misuse of terms maybe. by supplying force you are accelerating the clubhead. rather than resisting deceleration you are supplying a positive point to start from, more space to decelerate without losing velocity

makes sense?

SoulmanZ,

Don’t overcomplicate things.Clubhead striking a ball is a collision.Use conservation of momentum laws.

Supplying force via the shaft is insignificant due to the small amount of time the ball is in contact with the clubhead.

Makes sense? :)

yep its a collison

a collision of multiple elastic systems

you talk momentum but then discuss acceleration – you are the one who brought force into it. momentum can be used. force can be used. energy can be used. who cares? the only reason we use momentum in collisions is because it is the only way to approximate the ‘moment of collision’ using impulse. everything else gets too complicated

but we arent throwing numbers around, we are talking concepts

tell someone who is shot that the application of force is irrelevant because the bullet only hit them for a short time

by your reasoning supplying a force via a clubhead is insignificant due to the small amount of time of contact. so how does the ball move?

Soulmanz,

Please use your calculations to determine how long the bullet was in contact with the person who was shot,assuming the bullet logded in the body.That is a ridiculous analogy.

The ball moved because of conservation of momentum.The momentum lost by the clubhead was gained by the ball.

I did not say “supplying force via the clubhead”....i said “via the shaft”.

i know you didnt

thats why i did

time is irrelevant to all or to none

“the ball moved because of conservation of momentum”

thats a fallacy. straight up

the ball moved because the clubhead exerted a force on it

the clubhead slows because the ball exerted a force on it

conservation of momentum is one (approximate) way to describe it

let me pose this to you. a small guy swings a hard stick at 80mph into your chest. a giant swings a tree trunk into your chest at the same speed

now according to golf and baseball research, both of these objects are ‘disconnected’ from their mass. according to the research into collisions the parts hitting you are the same size, or very similar

if the masses are the same the momentum is the same. but the force required to swing the tree trunk is far greater

so which one hits harder?

time is irrelevant. an impact is an impact. an application of force. that is all

Another ridiculous analogy.

We are not swinging a stick and then a tree trunk.Golf clubs are all essentially roughly the same weight.If you can swing a tree trunk to 100mph then good on you.

It’s all about using force to accelerate the clubhead to your potential maximum velocity at impact to maximise your potential distance.Velocity is all that matters.If you can generate more force you will generate more velocity if all other things being equal.

The point of discussion here is whether or not you can make any difference to the outcome during the time the ball is in contact with the clubhead.