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Trackman: Optimal numbers for driver fitting.

post #1 of 26
Thread Starter 

Via John Graham's blog (http://johngrahamgolf.com/blog/) -- the following data courtesy of Trackman based on their own experience.

 

Screen-shot-2011-05-21-at-7.29.46-AM.png

 

Found several things interesting. One was the relatively small variation in optimal backspin for widely different swing speeds. Less than 300rpms at any AoA between a 75mph swinger and a 120mph swinger! When you think of all the time spent obsessing over "spin-killing" shafts and driver heads on Internet golf forums...

 

Another was the spin loft numbers. As I understand it, spin loft is dynamic ("actual") loft at impact less the angle of attack. So, if we take the flat hits (0 degree AoA) in the chart, then the optimal spin loft in those cases should roughly equal the theoretical optimal face loft for the driver itself, surely? And those seem way high? Nine to 13 degrees for a 120mph swinger? (In practice it might be even more because if we assume hands ahead at impact, that will be additionally delofting the club a degree or so.) Maybe I'm reading this wrong or not understanding the basic relationships correctly?

 

(EDIT: Realized I wasn't including the shaft bend contribution to the dynamic loft, but pretty sure that rarely adds more than about 1.5 degrees.)

 

Anyway, at minimum probably also some useful reality-check numbers for all those discussions about driving distance. a2_wink.gif


Edited by Stretch - 5/21/11 at 10:18am
post #2 of 26

I think a lot of the obsession over spin-killing shafts is from people, like myself, who hit down on the ball to much, which kills distance. I'm still more willing to fix my swing rather than my shaft at this point though. 

post #3 of 26

I hit way too down on the ball. Probably the last 2 months i have been hitting my driver only about 220m when i used to easily hit it 240+ . I went on a launch monitor the other day with my titleist driver, and had numbers like 104 club speed, 150mph ball speed 14-15 launch angle and 4000 spin. Obviously I am spinning the crap out of the ball at least 1200 rpm and launching it way to high to start off with. This was with my old shaft in it (Tour AD DI) which is supposed to be mid/high launch and the same shaft I have used for about 12 months. I tried putting in my old prolaunch red(when I was hitting the ball too low) and I am hitting it almost as high and clearly spinning just as much too with the ballooning effect. I thought the PL Red would surely lower the flight but alas it did not. I am annoyed because the monitor didn't have an attack angle reading which I thought was strange. 

 

So my question after all that rambling is: How do I fix this? The way I see it I can flatten out my attack angle(even though I do not know what it is exactly but it must be pretty steep) or put in a different shaft/get different loft?

post #4 of 26
Thread Starter 
Quote:
Originally Posted by michaeljames92 View Post

I hit way too down on the ball. Probably the last 2 months i have been hitting my driver only about 220m when i used to easily hit it 240+ . I went on a launch monitor the other day with my titleist driver, and had numbers like 104 club speed, 150mph ball speed 14-15 launch angle and 4000 spin. Obviously I am spinning the crap out of the ball at least 1200 rpm and launching it way to high to start off with. This was with my old shaft in it (Tour AD DI) which is supposed to be mid/high launch and the same shaft I have used for about 12 months. I tried putting in my old prolaunch red(when I was hitting the ball too low) and I am hitting it almost as high and clearly spinning just as much too with the ballooning effect. I thought the PL Red would surely lower the flight but alas it did not. I am annoyed because the monitor didn't have an attack angle reading which I thought was strange. 

 

So my question after all that rambling is: How do I fix this? The way I see it I can flatten out my attack angle(even though I do not know what it is exactly but it must be pretty steep) or put in a different shaft/get different loft?


If you are launching at 14 to 15 degrees with a 9.5 degree driver, then it's hard to see how you can be hitting down on the ball at impact. Let's say for argument's sake you were catching it a touch high on the face on the monitor and the true loft at point of impact was 10 degrees. The nominal launch angle for a 10 degree lofted club is 8.8 degrees -- given the normal friction loss of energy in the impact collision -- and you can calculate your angle of attack by subtracting this from your actual measured launch angle. In your case: 14.5 - 8.8 = 5.7 degrees UP. The average shaft bend contribution to dynamic loft is between one and two degrees, so for symmetry lets just call it 1.7 degrees in this case. That still has you at a four degree positive angle of attack. But then, going back to the Trackman chart, at your swing speed we'd expect you to be carrying it 255ish with around 2700RPM of spin. So I don't know what the answer is, but one possibility (not intended to be a slam and I have precisely no actual qualifications in this area) would be that you are flipping. Seems to me that you could be coming down into the ball steeply, but if the head was passing your hands it would stilll be adding significant dynamic loft at the point of impact, yielding both weak contact (high spin loft) and excessive backspin.

 

 

 

 


Edited by Stretch - 5/21/11 at 1:35pm
post #5 of 26

Hmm yeah well thats what I was thinking, but even hitting driver shots while holding the flying wedge and the same spin was occuring. I'm going to have to video myself face on and see what is happening.
 

EDIT: I forgot to mention that quite often the ball starts reasonably low-mid height and then balloons into the air and basically fall straight down and doesn't roll at all.

Quote:
Originally Posted by Stretch View Post




If you are launching at 14 to 15 degrees with a 9.5 degree driver, then it's hard to see how you can be hitting down on the ball at impact. Let's say for argument's sake you were catching it a touch high on the face on the monitor and the true loft at point of impact was 10 degrees. The nominal launch angle for a 10 degree lofted club is 8.8 degrees -- given the normal friction loss of energy in the impact collision -- and you can calculate your angle of attack by subtracting this from your actual measured launch angle. In your case: 14.5 - 8.8 = 5.7 degrees UP. The average shaft bend contribution to dynamic loft is between one and two degrees, so for symmetry lets just call it 1.7 degrees in this case. That still has you at a four degree positive angle of attack. But then, going back to the Trackman chart, at your swing speed we'd expect you to be carrying it 255ish with around 2700RPM of spin. So I don't know what the answer is, but one possibility (not intended to be a slam and I have precisely no actual qualifications in this area) would be that you are flipping. Seems to me that you could be coming down into the ball steeply, but if the head was passing your hands it would stilll be adding significant dynamic loft at the point of impact, yielding both weak contact (high spin loft) and excessive backspin.

 

 

 

 



 

post #6 of 26

When I hit it strait I have this issue. So I started hitting a 15ish yard fade as my stock driver shot and I gained quite a bit of distance and roll.

post #7 of 26

 

Quote:
Originally Posted by Stretch View Post

If you are launching at 14 to 15 degrees with a 9.5 degree driver, then it's hard to see how you can be hitting down on the ball at impact. Let's say for argument's sake you were catching it a touch high on the face on the monitor and the true loft at point of impact was 10 degrees. The nominal launch angle for a 10 degree lofted club is 8.8 degrees -- given the normal friction loss of energy in the impact collision -- and you can calculate your angle of attack by subtracting this from your actual measured launch angle. In your case: 14.5 - 8.8 = 5.7 degrees UP. The average shaft bend contribution to dynamic loft is between one and two degrees, so for symmetry lets just call it 1.7 degrees in this case. That still has you at a four degree positive angle of attack.


Stretch, check this out a little more. I think there's more to this than that.

post #8 of 26
Thread Starter 

Quote:
Originally Posted by iacas View Post

 


Stretch, check this out a little more. I think there's more to this than that.


Yeah, I'm going to ask some fitters I know here. Although the dots connect up fine, it just doesn't feel like we end up in quite the right place I agree.



Quote:
Originally Posted by michaeljames92 View Post

Hmm yeah well thats what I was thinking, but even hitting driver shots while holding the flying wedge and the same spin was occuring. I'm going to have to video myself face on and see what is happening.
 

EDIT: I forgot to mention that quite often the ball starts reasonably low-mid height and then balloons into the air and basically fall straight down and doesn't roll at all.


OK, let's think about this some more. We know that you're getting too much backspin on some drives both from the monitor readings and your description of the downrange ball flight. The two primary factors that determine the amount of backspin are loft angle and swing speed. The higher the loft, the more backspin for any given swing speed. The higher the swing speed, the more backspin for any given loft. A guy with your 105mph swing speed would expect to see about a 260rpm change in backspin for each degree increase/decrease in loft angle. So, again, it seems like the most obvious explanation is that you are somehow adding loft at impact. The other, lesser, factors that would be in play are the shaft bend profile and your driver's face roll radius. Both of these are probably contributing, but likely far less than any changes in effective loft as a result of individual swing characteristics.

 

Again, I'm no expert. Just kind of noodling here in the hopes it might be helpful. 

 

post #9 of 26
Quote:
Originally Posted by Stretch View Post

Via John Graham's blog (http://johngrahamgolf.com/blog/) -- the following data courtesy of Trackman based on their own experience.

 

Screen-shot-2011-05-21-at-7.29.46-AM.png


I have seen an studied this table before, and I like it ...... but I have some doubts .......

 

First : It is almost as like the values have been calculated in a software model, rather then being form actual measurements, I am finding it more or less theoretical, than real values.

 

Second : I find it hard to understand the angle of attack to differ so much, I personally would think the variances to be smaller ......... is there also real data available on actual angles of attack ?

 

Third : as slower swingspeed golfers have trouble getting a ball launching high, it is hard to believe that a 75 mph swing at a zero angle of attack launches 16.3 deg.

 

We all look at how to get to 300 yds off the tee, but apart from giving a theoretical insight this table sounds more like marketing to me ...... g1_wacko.gif

 

post #10 of 26

 

Quote:
Originally Posted by Gerald View Post

Second : I find it hard to understand the angle of attack to differ so much, I personally would think the variances to be smaller ......... is there also real data available on actual angles of attack?

 

These aren't the same golfers... I figure you probably know that, but just checking...? It's relatively easy to get amateurs at +5 and -5... or worse.

post #11 of 26

The charts fit pretty good when I was trying out clubs. At first I was hitting 5º down on the ball, launching it low with high spin and poor distance. During the session I got it down to 0º on some swings, and the distance increased. Never got it over on the plus side, but I'm sure I would have gotten more distance out of it by achieving a 2-3º positive angle.

 

I think the charts are pretty important to understand when trying out drivers. You can look at spin rate, launch angle, AoA etc. to find the cause for the distance, instead of just hitting hundred balls and see if you can hit it farther. Very few hit the ball with optimal launch conditions. Many try to swing faster to hit it farther, but a better place to start would be better launch conditions.

post #12 of 26
Quote:
Originally Posted by Gerald View Post

Third : as slower swingspeed golfers have trouble getting a ball launching high, it is hard to believe that a 75 mph swing at a zero angle of attack launches 16.3 deg.

 



The launch angle is just the angle at which it leaves the club. This chart does not speak to how long it maintains that angle.

 

I agree on the computery look to this, but computers.. they got a funny way of being right.

post #13 of 26

The chart info from Clubhead Speed = 90 MPH matches pretty much what I got when testing for a driver back in 2008.

 

Here are numbers of Callaway 10.5* HyperX Tour CH w/ R flex, midkick shaft: CH speed = 84 mph, had 13* launch angle, ball speed 124 MPH, and ball spin just at 4000 ( a bit high, may explain why I got less roll than chart said I would)

 

Adjustments this season: As per a Hank Haney tip (GolfD, June 2011, p. 46), I tee ball lower for driver with top of ball even with top of driver crown. Haney says better players can tee up a "half ball higher," but for average players this leads to more mishits with sidespin. Since I tried this, my drives appear to be hotter and a bit lower. Can't tell overall distance benefit until the fairways dry out from perpetual rains and I get a little roll.

 

Some charts like this give you a good start, other ones are way off. Just have to pick and choose.

 

post #14 of 26
These optimal #'s look great but how much trouble did you go through to get close to them given your swing speed?
post #15 of 26

TRACKMAN launch monitors are pretty much dead on. It is no marketing gimmit.

post #16 of 26

Here's an interesting thought however - if you look at the ubiquitous Trackman optimal numbers, then not one of them has an optimal smash factor of 1.50. Which begs the question, are they really as optimal as they could be? Anyone who knows anything about fitting knows that hitting the middle of the club face yields the best ball speed. And ball speed is everything.

post #17 of 26
Quote:
Originally Posted by Nemicu View Post

Here's an interesting thought however - if you look at the ubiquitous Trackman optimal numbers, then not one of them has an optimal smash factor of 1.50. Which begs the question, are they really as optimal as they could be? Anyone who knows anything about fitting knows that hitting the middle of the club face yields the best ball speed. And ball speed is everything.

Who's getting a smash factor of 1.50? Maybe the pros?
post #18 of 26
Quote:
Originally Posted by colin007 View Post


Who's getting a smash factor of 1.50? Maybe the pros?

 

1.485 led in 2013: http://www.pgatour.com/stats/stat.02403.2013.html .

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