Smash Factor Part II

Okay, we’re onto the second (and final) part of our Smash Factor article. Are you ready? It’s a doozy!

If you didn’t catch the first article then check it out here. They work as part of a series so be sure to have read Part I before starting on Part II.

As a general summing up, however, the first part concentrated on what smash factor is and what parts are the important factor for calculations.

Now that we know what the important factors are - how do we actually calculate the smash factor?

Well, brace yourselves…

Say what?

Okay, from the important factors we discussed in Part I, let’s figure out what everything means.

m = mass of the golf ball

M = mass of a driver

e = COR

Part 1

Taking the first part of the equation…

We know that the speed of the golf club at impact imparts speed to the ball. This depends on two main things: 

• The efficiency which the ball bounces of the club face. This is given by the formula 1+ the coefficient of restitution. In a “perfect” collision this value would be 2. However, the rules of golf state that the maximum COR is 0.83. So 1 + 0.83 = 1.83. 

• The relative mass of the golf ball and the club head. This is given by the formula 1 + the mass of the ball divided by the mass of the club head. The mass of the ball is fixed at 46g by regulation while the “normal” mass of a driver is 200g. So 1 + 46/200 = 1.23. 

So we have 1.83 divided by 1.23 = 1.487.

Part 2

Second part...

We know that a perfect hit will have a club face loft of 0º. So a loft of, say 10º, will cause a less than perfect collision. The effect of this is minimal and is given by the approximation of the value of the cosine of the loft. The cosine of a 10º loft is 0.98.

Part 3

Last but not least...









This part attempts to give a value to the effect of a slight miss-hit. The formula is 1 - ( 0.12 x miss).


A miss by 1/4 inch (6 mm) would have an effect of reducing the effectiveness of the hit by approximately 3%. We find this by multiplying 0.25 (1/4 inch) by 0.12 which equals 0.03 or 3%.

The figure of 0.12 is an historic measure of the effect of missing the sweet spot. If you miss the sweet spot then your golf club will loose its effectiveness. With modern golf clubs the effect of missing the sweet spot is less than with old persimmon heads.

So, 1 - 0.03 means we have a value of 0.97 for part 3.


So for this particular example:

Okay - that’s that bit sorted.

But what does smash factor actually tell us?

The generally accepted maximum smash factor is approximately 1.50.

If you had achieved a smash factor of 1.50 this would mean that for a given club head speed the resulting ball speed will be 1.5 times faster.

So, for example, your swing speed is 90mph. With a smash factor of 1.50 your ball speed would be 135mph.

So, we’ve used smash factor to calculate the speed of our ball! Result!

But that was using the maximum accepted smash factor. What about when we use our example above?

We missed the sweet spot by 1/4” which reduced our smash factor to 1.41

So our calculation would be velocity of club x smash factor to get our ball speed.

We’re still swinging the club at 90mph and our smash factor is 1.41. That means the velocity of our ball is approximately 127mph.

Let’s say our playing partner had the smash factor of 1.50. We have 1.41. We both swing our clubs at 90mph yet our playing partner gets 135mph and we only got 127mph. All because we missed the sweet spot by a quarter inch. That sucks.

So what to do?

Let’s say I then decided to slow my swing down so I could hit more accurately. I could effectively improve my smash factor by hitting the sweet spot (or missing it by less). If I got my smash factor up to 1.5 then I could reduce my speed of club to 85mph and still get the same ball speed as I did before - 127mph.

Of course, it’s not just not hitting the sweet spot that can make a difference to the smash factor. Other things that affect the smash factor include the weight of the driver and the face angle. A smaller driver with a loft of 12º will result in a reduced smash factor thus reduced potential ball speed. Also if the face angle is open or closed in respect of the swing path of the club there will be a small reduction in the smash factor.

So what does this tell us? How can we use this to be better golfers?

Well, to be honest, for all those complex equations and mind numbing flash backs to high school math class, the point of smash factor can really be summed up quite simply.

What a measurement of the smash factor tells us is the effectiveness of the swing: The more accurate your shot, the better results you will have.

When you are practising, learn to swing in such a way that you hit the ball from the sweet spot as consistently as possible. Kind of obvious really! You may have to swing more slowly to achieve this but you will hit the drive consistently further.

Basically a slower but more consistent swing will benefit the golfer.

When a reduction of the smash factor is translated into ball speed, and by extension the length of a drive, you can see that a slower but more accurate swing can produce a longer drive.

Smash factor is important but you have to consider it in the context of other aspects of swing performance such as launch angle; spin rate; club choice; fitness and course conditions. The list goes on…

So, there is no need to sit there with a scientific calculator either on the golf course or when you get home. When smash factor is translated into ball speed, and by extension the length of a drive, you can see that a slower but more accurate swing can produce a longer drive. The point of calculating the smash factor is then really just a tool by which we can validate that the better your swing, the better your game.

And that, ladies and gentlemen, is Smash Factor. I think I need a lie down!

What's on this weekend?

I always like to do a quick run through of what’s coming up at the weekend in terms of tournaments. There are always so many tournaments and tours to choose from that I thought it might be fun to share what’s going on in golf this coming weekend.

PGA Tour

The PGA tour heads of to Malaysia this week for the CIMB Classic at Kuala Lumpur Golf Club.

Ryan Moore defends his title which he won last year in a play off against Gary Woodland. 

Others in this years field are Garcia, Westwood, Ishikawa, Matsuyama, Dufner and Love III.

This is a great international field playing for the $1.26m winners prize.

Guan Tianlang (just turned 16) is a sponsor exemption hoping to do well.

This is a co-sponsored event with the PGA Asia Tour.

European Tour

The European Tour Final Series gets underway with the BMW Masters at Lake Malaran in Shanghai.This is the start of the four tournament run which finishes with the DP World Tour Championship in Dubai.

The race to finish as the top European golfer is well and truly on as Rory McIlroy, the current Race to Dubai leader, is on a short playing hiatus until the Dubai tournament and therefore can be toppled by several players should they play to their best abilities.

European Seniors

With last week’s Dutch Open (won by Ian Woosnam) now over, there is a break on the tour until December 12th when the MLB Tour Championship will be held in Mauritius. A 5 week holiday and then a trip to the sun. It’s hard to understand why, as I sit here staring at the pounding rain and grey skies of autumn in Scotland, I might be a teeny bit jealous!

PGA Champions Tour

The Champions Tour heads to the Charles Schwab Cup Championship at Desert Mountain in Scottsdale, Arizona this weekend. If it’s possible, this sounds even more wonderful than Mauritius! Bernhard Langer has already secured the overall Schwab Cup with a tie for 6th place in last week’s AT&T Championship in Texas. Colin Montgomerie is currently in second place overall in the Schwab Ccup points race however there is still plenty to play for - the lower places and pride, of course.

Australian Tour

The Aussie Tour heads from Perth (where Thorbjorn Olesen was the winner by 3 in the ISPS Handa Perth Championship) to Kalgoorlie for the WA PGA Championship. This one is deep in the Australian outback so if you lose your ball, that’s it gone for good, I would imagine!

Ladies PGA

The Ladies PGA tour is in Taiwan for the Futon LPGA Championship this weekend.

Current world number 4, Suzann Pettersen, defends her title and is looking for three in a row on the tour. That would be quite an achievement and I have my fingers crossed for her.

So that’s what’s on this weekend. Now that I think about it - if it continues to rain here, I will have lots of excuses to sit in an enjoy the golf instead of doing chores round the house or in the garden. Good times.

Quote of the Week

My Putters: A Love Story

I continually complain that I cannot putt very well yet I have not changed my putters in 40 odd years.

Why is that? And why am I not likely to change them even now?

Well, I believe that putting is so much a mental game that I would rather try to practice enough to get a sound method and good tempo than paying out money (sometimes lots of money) to acquire a new wand.

Also, I am a typically frugal Scotsman and spending money is to be avoided where possible!

Besides, to tell the truth, I like my putters. They are like old friends. When you bring them out after 6 months in the cupboard (aka winter) it brings a smile to my face to see them again.

My number 1 go-to putter is a Ping Anser.

It has a great feel and although it has been through the golfing wars it is still as good as new.

My second string putter is a John Letters "Golden Goose". This putter has been drilled and otherwise messed with in order to meet with my teenage requirements. It is great for fast greens and is what I would describe as a 'feel' putter.

I would love to hear about what kind of putters you use and why you like them. Feel free to send me the story of your putters. Take pics - I like pics!

Also, a little putting tip to end. Remember, the living room carpet is a great place to practice putting over the dark winter months. Spouse permitting, of course!!

GSA Pro: A Review

I visited the local driving range yesterday and took along a gismo from GSA Pro to test with my swing. Well, I do love my gadgets and hardly need an excuse…

The GSA Pro is a tiny device that fits on the grip end of the golf club. When you swing the club it records, and sends to a phone, information about each golf swing.

Sounds like fun.


The objective of the device is to assist you in swing analysis and improvement. I certainly need all the help I can get.

First things first, the GSA Pro fits easily int the grip of the golf club. It is so light and does not, in my opinion, interfere in any way with the swing which is obviously so important.

The app for the phone is free and really easy to set up. I used an iPhone and was completely happy with the interface.

The app itself shows a variety of pieces of information and allows you to choose a best swing for comparison purposes. You can also take a video of your swing for more realistic reviews. Once you have completed a swing the gizmo automatically sends thousands of data points to the GSA Pro phone app which is analysed and presented on the phone screen.

Info includes:

Club head speed

Force applied

Ball speed

Carry distance

Tempo

Back swing and downswing time

Face angle

Swing path


In the above screen shot I have compared my swing with an included pro's swing (the green figures). I found the comparison interesting and it has given me several points to work on including attaining a flatter swing plane.

After many swings I can say that the face angle and swing path statistics are a good representation. and the tempo seems pretty accurate. The ball speed is calculated by an algorithm which takes the speed at the grip end and calculates the resulting ball speed. The carry distance is similarly based on an algorithm based on the club loft and assumes a solid hit from the sweet spot. (For more on this, see our blog on Smash Factor).

I think the ratio of the club head speed to ball speed may be a little high but I don't think this matters as the GSA Pro is a tool for comparison and improvement, not for achieving absolute numbers.

This screen comparison with the pro golfer shows a couple of things.

I have a faster backswing and it is too upright which makes it difficult to get inside on the downswing.

My objective is to flatten the swing and improve tempo.

Overall, I really enjoyed playing with this little gadget and feel that not only are the stats interesting but it actually gives you something to work towards in terms of your swing.

I would rate this device at 9/10 and recommend it to any golfer interested in the stats of their swing.

For more information, click here.

Quote of the Week

Golf Grooves - What do they do?

I was reading an article about the recently changed rules regarding grooves on golf clubs and it made me think about what the change in the size of the grooves actually does. 

The general reasons stated for the rule changes were to reduce the spin that a golfer can achieve when hitting out of rough. 

Ok, that sounds realistic.

The reason for this is to counter the recent trend of hitting a long, but not necessarily accurate, drive and being able to make a controlled recovery shot from the rough. The proper thinking being, when you hit onto the rough, you should suffer some sort of consequence.

So, what is the story about grooves? 

I always thought they were there to impart backspin which doesn’t really tally with the reason for the rule change. 

Time to do some experiments.

What would happen if you hit a ball with a club with no grooves?

I couldn't find a golf club with a smooth face (so no grooves) so I could not make my own comparison. However, I did find a book (Search for the Perfect Swing by Cochran and Stobbs) which discusses grooves.

Their argument is that the grooves do little to increase backspin. Indeed, a ball hit with a smooth faced club will fly with similar spin and distance compared to a grooved club.

How can this be? 

Collision theory is the culprit.

When the club makes contact with the ball, the ball starts to skid up the club face but soon the effect of friction between the ball and clubface takes over and the ball starts to spin.

Because of the forces involved at impact, (and at impact the ball is only in contact with the clubface for .45 milliseconds) the ball will, by force of nature, be spinning when it leaves the club face.

A study by the USGA indicated that square grooves give a negligible spin increase when a ball is hit from a dry fairway but give substantial spin increase from wet rough. In fact, spin rates increased 25%-50%.

So grooves are not there to impart spin they are there to get rid of any liquid which gets trapped between the ball and clubface (e.g. wet grass). Just like the tread on car tyres is there to disperse water, not to give grip.

A wedge hit from the fairway will perform similarly, with or without grooves.

A wedge with no grooves hit from the rough would, the theory goes, give virtually no control over the shot whereas one with grooves will provide more control. Essentially making a difficult shot easier.

Grooves do provide a more consistent hit and also the psychological positives of feeling that there is more control, but too rough a face can actually reduce the spin. This assertion is complex and frankly beyond me but Cochran and Stobbs outline the physics and maths for those who are interested.

Just to prove this, note that some drivers have no grooves in the sweet spot area but you still achieve spin. Interesting.

My conclusion is, therefore, that we do not need to become fixated on the shape or depth or distance between the grooves but that, if like me you live in the rough, you should always make sure you grooves are clean!