Wednesday, January 8, 2014

The Ball Flight Laws


Do you know the ball flight laws? Do you even know what a ball flight law is? Do you believe in the old ball flight laws, or the new ones?

Ball flight laws are simply the physical laws which determine why and how a ball flies through the air. They can tell you what a ball will do in terms of height, trajectory, distance, direction and curvature (and more). They are literally the ultimate goal in golf.

This is some of the most important information you will ever learn. What can be more important that correctly diagnosing why the hell your ball flew into the trees on the left. Without the correct diagnosis, you are not going to make the correct fix. Whilst a blind squirrel occasionally finds a nut, you would be much better off to know this stuff.

Out with the old, in with the new

There has been lots of debate recently (in the last 7 years or so) on which ball flight laws are correct. The old ball flight laws stated things such as “The ball starts on the same direction as the swing path and finishes where the clubface aims”. This has been overtaken by better and more accurate information recently – most calling them the ‘new ball flight laws’.

Let us be clear though, the new ball flight laws always existed, they are a component of physics and as a result have been around for longer than trackman has been able to measure them. But it is only recently that this information has circulated and become more common knowledge (to teachers at least – hopefully). And now we are able to more accurately measure these things too.

The old ball flight laws never really existed, they were an ‘old wives tale’ created by teachers who were trying to describe what they saw and felt. And for the most part, it worked. Players never seemed to be inhibited too much by the old inaccurate information. Just because someone held a conscious belief about how something worked which was inaccurate doesn’t mean they still couldn’t get it to work. This tells us a lot about learning, subconscious mechanisms and our idea of conscious control – but those are hugely complex articles which do not entertain the majority of the public.

Nonetheless, I deem knowledge of ball flight laws as some of the most helpful bits of information you could possibly understand. If you don’t know why your ball sliced right, it will take a lot longer to fix it, if you can at all. You may even do yourself more harm by trying to fix it yourself in an incorrect way.

 Listen closely, my friends.



The ball flight laws

The ball flight laws can be categorized as path, clubface angle, strike, angle of attack, speed and loft. Sometimes angle of attack is lumped together with path (as it is effectively the vertical path of the club), and often times ‘loft’ will be lumped in with face angle – as it is effectively the face angle, but gives the shot height rather than directional control as we understand it. I have broken the terms down simply for ease of understanding.



Face angle and path

It is very difficult to talk about one without the other, as it is the combination of both which determines the direction of a shot (barring a poor strike).

The path of the club is essentially the direction the cub is swinging through impact, and the face angle refers to the direction the clubface is aiming at the point of impact. Clubface angle accounts for around 75% of a shot’s overall starting direction, with club path being only 25% (contrary to the old wives tale that the ball starts on the swing path). Although this % varies a little from club to club, face angle is the dominant influence on direction.


This is vital for a player to understand, as failing to do so can severely inhibit fixing problems. For example, the typical player hits a ball right and tries to fix it by swinging more to the left. This could potentially make matters worse (especially if club/path ratios get increasingly dissimilar).

In the below photos, the white line represents the club path, and the red line represents the target line
Square path

Left path (otherwise known as out to in)
Right path (otherwise known as in to out)


In the following photos, the red line represents the path, and the yellow represents the clubface angle.

This is a square path and face. When this happens, there is no tilting of the spin axis (fancy way of saying no curvature produced), as long as the strike was from the middle. There is a tiny bit of gear effect created from the closing of the face, but don't worry about that.

In the above picture, the clubface is open (more right of) the path. If struck from the sweet spot, this would produce a shot which starts close to the yellow line and curves further right.

In the above photo, the clubface is closed to the path. This would produce a shot which starts close to the yellow line and curves further left.

 

To hit a straight shot is easy (in theory) – just get the clubface and swing path aiming in the same direction (preferably towards the target) at the point of impact. But what happens if they are not aimed together?
The rule to remember here is

“The ball starts roughly on the line of the clubface and then curves away from the path”

For a practical example, imagine a player swings the club and at the point of impact the clubface aims 2 degrees left of the target and the club is swinging 12 degrees left of the target. In this scenario, the ball would start about 4 degrees left (close to the face) and curve away from the path (to the right).

How much would it curve? This is dependent on a multitude of factors. In general, the bigger the difference between the path and the face, the greater the curvature. Also, the less loft used (all other things being equal) the more the ball will spin to the right. Also, the further you hit the ball, the more chance it has to curve offline. So next time your ball starts left and curves way off to the right, you know that the clubface was left, and the path was even MORE left.

Another definition I like to use is the following

If the face is more right of (open to) the path, the ball will curve right. If the face is more left of (closed to) the path, the ball will curve left.

This definition can also serve purposes. The first definition implicitly covers this idea, but it is also worth remembering. For example, if your swing path is to the right by 10 degrees (in to out) and your clubface aims only 2 degrees right, the ball will start to the right (close to the clubface). As the clubface is CLOSED TO THE PATH, the ball will curve left.

ball started right and curved left. Face must have been aiming right at impact, and the club path was much FURTHER RIGHT.

Ball started straight and curved right. Clubface must have been pretty square/slightly left at impact, and path was much further left.






Strike

This is likely the single biggest factor in your golf, and is one of the ONLY common denominators amongst all tour pro’s. They all strike the ball on the sweet spot. The sweet spot is the point on the face (usually the middle of the grooved area, somewhere about the 3-5th groove up from the bottom) where it feels great when you hit it.

sweet spot


If you hit below this point, the ball will tend to fly lower and have more spin. Hitting above this point will tend to produce a slightly higher shot with less spin. Hitting more towards the toe end of the club (the far end – think of a foot), the ball will start more to the right (and  have more draw spin) and a shot hit more towards the heel will tend to start more to the left and have more fade spin (unless you completely shank it – hit it from the hosel). In all cases, shots which do not come from the sweet spot will send more vibration/twisting up through the shaft, which you will feel as a not very pleasant sensation and a shorter distance.  Great players can identify the difference in these vibrations and relate them to which part of the clubface they have hit – this is something which almost every good player develops automatically over time, although I see most poor players have no clue.

My top drill for building up this awareness (and skill at the same time) is to mark the golf ball with a dot of ink from a dry erase market pen. Line the dot up to the back of the ball and hit. You will leave a mark on the clubface as to where the ball contacted the face. Through doing this drill, you will start to develop a much better feel and will be able to identify the strike without even seeing the mark eventually. As a teacher who sees people hit the ball poorly all day (pun) I am so practised at this that I can identify which part of the club the ball has come from simply from the sound of the strike. You will too, if you use this drill.

Mark the ball

                                                                             tee it up
see where you hit it




Angle of attack and loft

These two terms are the vertical equivalent of ‘path and face’. Angle of attack refers how steep or shallow the club attack the ball. Think about a nail angled through a golf ball. If the nail was quite parallel with the ground, we would consider this a shallow angle of attack. If the nail was angle 20 degrees into the ground, we would call this a steep attack angle.
Steep angle of Attack

Shallow angle of attack

This one starts out steep, then shallows at the last second.
 The ball will react to what is happening at impact (shallow)


Let’s get something straight. No good player hits up on a golf ball (driver and putter being the only exception). Every tour pro hits their shots with a slightly descending blow, as this is the only way to purely and consistently strike the ball from the ground. How do you make sure you do this? Go out onto the grass, draw a line on the ground (chalk/spray paint/scrape a line with a stick) and place the ball on the line. Now proceed to hit the shot and make a divot which starts on the line (or slightly in front of it) and continues forward on the target side of the line. This will guarantee you have hit the ball with a descending blow.
Spray paint a line on the ground (if allowed)


The divot should come AFTER the line (target is above in the picture)



The loft refers to how much angle is on the clubface at impact. The more angle, the higher the ball will launch (all other things being equal). We normally present a different loft angle to the ball by simply changing our club (a 4 iron has 24 degrees and a 9 iron has 44). However, it is possible to change the loft angle at impact (called dynamic loft angle) by changing the shaft angle at impact (if it leans more forwards at impact there will be less loft on the club, and vice versa) or by aiming the face in a different direction we can also manipulate loft angle. A clubface which is more closed tends to fly lower, and a clubface which is more open tends to fly higher.

Higher loft


Lower loft, same club

The ball will respond mostly to the loft. Just like launch direction is mainly influenced by the face angle, the loft produced at impact will largely dictate where the ball launches. A lower loft will launch the ball lower, and a higher loft will launch the ball higher (all other factors being equal).

The difference between the loft at impact and the angle of attack is called "spin-loft". In general, a higher spin loft will produce more spin and will tilt the spin axis into a more neutral position. This will make the ball curve less and have more backspin. This is why clubs with higher loft tend to hit the ball straighter.



Often people ask me, “How do I make the ball spin back?”. Well, there are lots of things which have to go into this. A good quality and clean strike is essential, with lots of speed (the more speed, the more spin). But you can also increase spin by increasing the difference between the loft and angle of attack. As a rule of thumb, the greater the difference, the more backspin (although there is a law of diminishing returns with this). We refer to the difference between loft and angle of attack as ‘Spinloft’.



Speed

This is going to be easy – All things being equal, the faster the clubhead is moving, the further the ball will go. It does other things too, it will increase the rate of spin, and also bring up the % which the clubface becomes dominant regarding start direction (although it is too small an issue to worry yourself with).
This clubhead is moving REALLY fast.


As a side note, acceleration does nothing calculable to the ball flight. For example, a shot which has the same clubhead speed at impact but one club is accelerating and the other is decelerating into impact, they would both do the same thing (if everything else was equal).

The higher the speed, the further the ball goes, but you had better have good control of the face angle and path.  A ball which goes further also goes further offline.



Take home notes

So there you have it, the ball flight laws. At the very least, I hope you picked up one bit of new information. But keep coming back to this page and re-learning it. You have to be able to self-diagnose, as most of the time you will be alone practicing. The first step in changing something is to become aware of it. In Randy Pausch’s book ‘The last lecture’ he said

“It’s an accepted cliché in education that the number one goal is to help the student learn how to learn. However, my number one goal was to help the student evaluate themselves. Do they recognise their own abilities, their own flaws, were they realistic about how others viewed them. Feedback is important.”


I tend to agree. I have found so much value in understanding the ball flight laws personally, and understanding that the ball has no bias on whether you are 6 foot 9, or 5 foot 1, 220pounds of muscle, or a 130 pound soaking wet stick. The ball does not even know if you are a weekend warrior, or Tiger Woods, it just knows what the clubhead does to it at impact, and responds accordingly. Read that last line again and let it sink in. In fact, I will write it again here.

“The ball does not know if you are a weekend warrior, or Tiger Woods, it just knows what the clubhead does to it at impact, and responds accordingly.”

There are other more intricate concepts involved with ball flight laws, such as gear effect, coefficients of friction, groove effect, ball slippage etc. But for now, these above definitions should be enough to set you on a good path of understanding. Contact me at Adamyounggolf@gmail.com for more information, or to look at booking a lesson so we can work on your ball flight factors and get that ball under control.

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4 comments:

  1. Very good. But the dynamic lie is missing

    ReplyDelete
    Replies
    1. Hi Oliver - actually, dynamic face plane tilt is an integral part of the clubface vector. So, Dynamic lie is already accounted for.

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Currently working for the World famous Turnberry Resort at the Golf Performance Academy. I am a golf coach who specialises in not only what to learn, but 'how' to learn. I am always looking to further education of myself and others, and improve knowledge and understanding so that we can be better golfers and coaches