Golf Physics - Please Explain

[Jensen]

So, after watching some vids on You Tube I have started to work on taking a divot with my irons. Before I was a sweeper or would nip it pretty clean off the turf.
Now I've watched a video that states by hitting the irons with a descending attack the club is still accelerating before it levels out, where at the bottom of the arc it starts to decrease in speed.

So all you Einsteins and Newtons out there, if this is the case, as I can see and agree, then why do we hit the driver on the up ?
As per the above theory with irons, at this point the swing speed would be starting to slow down beyond its optimum point, so we would be better to hit driver on the downswing. However I know that by hitting driver on the downswing that this merely makes the ball balloon.

Whilst I accept the principle, could somebody please explain the logic and reasons behind it ?

Thanks

 

[Alex1975]

Hit the driver on the way up as it has very little loft so you are better off helping it launch and you would also like it not to spin too much so your not looking to trap it.

Also you want to hit driver higher on the face as it has more loft at the top of the face and less at the bottom of the face because of the face roll.

 

[Deleted Member 1156]

I'm not totally convinced that if you are swinging correctly the club is decelerating that early in the swing. I thought it was still accelerating through the impact point?

 

[Foxholer]

I'm not totally convinced that if you are swinging correctly the club is decelerating that early in the swing. I thought it was still accelerating through the impact point?

If the club is descending, gravity is helping. If swing is ascending, gravity is working against you.

However, with the angles involved, between 2 and 8 degrees, the component due to gravity is actually quite small. Muscular torque is more significant than gravity through the impact zone.

And if muscular torque is applied properly through that zone, the clubhead speed is increasing for both bith irons (descending) and Driver (ascending).

 

[duncan mackie]

I'm not totally convinced that if you are swinging correctly the club is decelerating that early in the swing. I thought it was still accelerating through the impact point?

I'm totally convinced there's no fundamental reason it does ie I agree with you!

 

[Jimaroid]

Now I've watched a video that states by hitting the irons with a descending attack the club is still accelerating before it levels out, where at the bottom of the arc it starts to decrease in speed.

The problem is that you're believing what golfers on the Internet have said. And in no other pursuit but golf has so much nonsense been said about physics.

Imagine trying to hit golf ball in space. What is up and what is down, and where is the club travelling at it's maximum velocity? The point at which your clubhead is going to be travelling at the greatest velocity is going to depend on your technique. Back on the ground, the point where the clubhead reaches maximum velocity can be pretty much anywhere your technique dictates. Gravity is an opposing force but there's no reason why the maximum velocity can't be on the upswing, like when you're using a driver.

The reason angle of attack is important is because of how the ball reacts in terms of its initial direction, spin and how it flies aerodynamically. Hitting the ball cleanly will also impart most energy to it. If you hit the ground first, that's a lot of energy wasted and not going into the ball.

 

[the_coach]

the difference is the location of the ball relative to the golfer.

the iron is striking a ball on that's sitting on the ground normally - (but when on a tee this is also the reasons why the ball should be teed down so the cup of the tee is touching the ground)

the driver is striking the ball some 3" to 4" up on a tee.

both swings when done efficiently to produce the best contact for energy transmission from face to ball to produce the optimum ball speed are both producing the optimum & fastest club head speed for that particular swing motion at impact.

the player in both instances, iron & driver, has to have the intention in their mind that they are looking to produce the fastest swing speed in the area directly after impact to be able produce that optimum speed at collision at impact.

the same intention in producing efficient motion that allows a martial artist to smash through a solid object.

 

[Nosevi]

It's all to do with controlling your spin loft - understand that and you've got it sorted. Nothing more to be said.........

For the OP though......

Putting it another way, you're trying to do entirely different things with a driver swing than with an iron shot - a driver you're trying to limit the spin for a given trajectory to maximise your distance off the tee, an iron you want control into a green so you want that spin to be there and you sacrifice some distance to get it.

With a driver you hit up on the ball for one reason - to minimise spin for a given initial trajectory. You could hit down on the ball and get the same trajectory by using a club with more loft but by doing this you would impart more spin on the ball and more spin equals less distance. That 'ballooning' of the ball with a driver is when you impart too much backspin to the ball, causing it to climb them stall, and in so doing you kill your distance. Take that spin off and you have a more neutral ball flight (a nice curve looking from the side with no 'stall') and you gain distance. By teeing the ball up you can hit up on the ball, take the spin off and get that distance.

With an iron again you're 'controlling' the spin but you're doing it in a different way. In order to get maximum distance for a given spin you need to be maximising your smash factor. You don't just do this for fun, a ball struck well holds its line better and is a more controlled shot both in the air and into the green. Now this is going to be difficult to describe without drawing it but see if you can follow this through......

In order to strike an iron efficiently you need to have forward shaft lean (sure you've heard that before) BUT your hands aren't stationary at a point ahead of the ball when you strike it with the club literally rotating around them and so down into the ground, they are moving forwards and so the vector of the force applied by the club is not at right angles to the shaft (down into the ground if the shaft is leaning forwards) but is 'less steep' than that or to put it another way, more through the ball. Rotating your hips shallows out you swing for a given shaft lean as it moves your hands forward through impact.

The result of all this 'geekery' is that the force transferred by the club to the ball is greater and you get a lower flighted, higher spinning ball, and this is a good thing for an iron shot into a green as it gives more control. Clearly in order to benefit from this you have to hit ball then turf or all bets are off as any benefit you get from a bit of forward shaft lean has just created a more impressive divot rather than a better shot if you hit the ground first.

Hope that kind of makes sense. Essentially driver - hitting up to minimise spin and so maximise distance, iron - forward shaft lean but actually hitting down less than 90 degrees to the shaft angle as your hands are moving forwards to use your spin loft to control your ball flight.

 

[JustOne]

then why do we hit the driver on the up ?

The ball is on a tee.

That said, the PGA tour average used to be -1.3° (that's hitting the driver on the way down). Not sure if there are any newer stats for 2014.

http://trackmangolf.com/media/a0015...070a/9qh0WA/PDF/3. Newsletter/newsletter6.pdf

 

[Jensen]

Thanks all for the replies, but particularly Nosevi for a very detailed and lengthy reply - extremely helpful

 

[SocketRocket]

These videos may help your understanding:

[video=youtube;BMWLSVeFy6c]https://www.youtube.com/watch?v=BMWLSVeFy6c[/video]

 

[SocketRocket]

Heres one for the driver:

[video=youtube;8Z5860T8Dec]https://www.youtube.com/watch?v=8Z5860T8Dec[/video]

 

[Nosevi]

These videos may help your understanding:

[video=youtube;BMWLSVeFy6c]https://www.youtube.com/watch?v=BMWLSVeFy6c[/video]

Great vids mate. Make what I was saying above far clearer I think. Thanks