Thursday, 14 September 2017

Skytrak vs R Motion Part 1

Introduction/Disclaimer:
I did not purchase my R Motion unit, I was asked to use the device and provide feedback to Rapsodo. Getting injured greatly slowed this process down but I have now managed to capture some data and compare it to my Skytrak.

Accurate simulation golf is expensive with the ST marking the current entry point. The R Motion is significantly cheaper and does not measure the ball launch characteristics. It is a clip based system which is attached to the club before the ball is hit.

Can the very affordable R Motion provide sufficiently accurate data to TGC in order to dramatically lower the barrier to entry into simulation golf?
Can it provide additional data which could be used to supplement the highly accurate ball data provided by the ST?

Method:
Within the limitations of my setup I tested by capturing 5 solid shots (not blatant mishits) with multiple clubs. Shots were struck from a soft range mat. Using this mat I have noticed shots launch higher and travel less distance compared to a firmer mat or turf. Spin rates are also higher and less variable than those encountered playing 'real' golf.

R Motion version was 1.3.0
ST version was 2.6.5

The ball used was:
Callaway Chrome Soft

The clubs used were:
PW (45°)
7 Iron (31°)
5 Iron (24°)
3 Iron (19°)

The clip position was measured on each club and the actual lofts were also entered into the R Motion configuration to provide maximum accuracy.

Results and Analysis:
In order to accurately simulate the shot outcome the R Motion needs to capture/calculate the basic launch parameters and I think it does an excellent job.
Ball speed is calculated well. As previously noted fractional mishits reduce ball speed slightly and I think this  explains why the R Motion ballspeed is generally a little higher. Of additional interest are the three shots where I caught the mat first. It wasn't sufficient to drop ball speed drastically but the R Motion could not tell when strike occurred which led to a large difference.

Excellent correlation with ST.



The result of these measurements
The R Motion sets its target line at the start of the takeaway (where the clubface is pointing). Obviously this can vary from the ST target line but in general they show a good correlation.


An aggregated summary:
I think this is impressive. In terms of simulation golf you need to know where the ball would have gone. The R Motion is within 3 yards of the Skytrak for L/R and within 3% of the Skytrak for carry distance.

Source data can be found here.

Conclusion
"Can the very affordable R Motion provide sufficiently accurate data to TGC in order to dramatically lower the barrier to entry into simulation golf?"
I think the above proves it can. I dont think this is a game improvement tool like the Skytrak but it is a simple to use entry point into golf simulation.

"Can it provide additional data which could be used to supplement the highly accurate ball data provided by the ST?"
I hope so and this is what really interests me. In theory data from this (or a Skypro etc) could be merged with the Skytrak data to provide accurate ball and club data. At this point it could become a component of a hugely powerful game improvement tool.

Monday, 4 September 2017

Chrome Soft vs TP5 vs TP5X

Introduction
As previously stated I love the Callaway Chrome Soft and it is my normal ball. My previous testing has suggested (others have concluded similarly) that a premium ball is a premium ball and you should make your selection based on other factors such as cost, feel, colour etc.

The TP5/TP5X balls appear a little different. TM claim they launch higher with lower spin on full shots whilst maintaining the high spin character of a premium ball on shorter shots. If true this is really interesting.

For my skill level I get too much spin with a premium ball which increases the amount of curvature I get. If I could get a ball which exhibits consistently (wet vs dry etc) lower spin with longer shots it might help. An additional benefit of consistently lower spin would be better performance in the wind.

Hypothesis
TM claim the TP5 should launch higher with lower spin on longer shots. The TP5X should launch higher still with even lower spin and increased ball speed. Performance on short shots should be unaffected.

I have recently switched to CF16 irons in an attempt to reduce spin, is it possible the TP5/X balls will exhibit too little spin when paired with these irons?

Method
Within the limitations of my setup I tested by capturing 5 solid shots (not blatant mishits) with each ball and multiple clubs. Shots were struck from a soft range mat. Using this mat I have noticed shots launch higher and travel less distance compared to a firmer mat or turf. Spin rates are also higher and less variable than those encountered playing 'real' golf.

The balls were:
Callaway Chrome Soft
Taylormade TP5
Taylormade TP5X

The clubs were:
60° wedge (goal was a 50 yard pitch)
9 Iron (40°)
7 Iron (31°)
5 Iron (24°)
3 Iron (19°)
Driver (9.5°)

Results and Analysis

Subjective:
Nothing feels as soft as a Chrome Soft but the TP5 is noticeably softer than the X.
The TP5/X balls are also more clicky sounding.
During testing I noticed the TP5 ball initially seemed to get a little 'hairy'. This wore off after a few more shots and all of the balls appear durable. After completing my testing the Chrome Soft is in the best condition although the difference is minor.

Data:

60 Degree Wedge (Target 50 Yards):
Launch Angle was way higher with the TP5/X. I was hitting into a net and the launch angle was so steep I had to move my mat closer to avoid hitting the top!
 Spin rate was lower with the TP5/X, it averaged approx 1000rpm lower.


 9 Iron:
Launch Angle for the TP5 was similar to the chrome soft, but the TP5X launched significantly higher.
 Spin rates comparable.
 Average carry distance slightly longer for TP5/X.

7 Iron:
 Launch angle higher for TP5, higher still for TP5X.
 Spin rate comparable between Chrome Soft and TP5. TP5X substantially lower spinning.
 TP5 peak height > Chrome Soft. TP5X higher still.
 Carry distances similar.

 5 Iron:
 TP5X launches slightly higher.
 TP5 spin rate slightly lower than Chrome Soft. TP5X substantially lower.

 TP5X carry distance higher than Chrome Soft/TP5 by approx 5 yards.

3 Iron:
TP5X ball speed higher.
 TP5X launch angle > TP5.
 TP5/X spin rate < Chrome Soft.

 TP5/X carry distances longer than Chrome Soft.

Driver:
Ball speed highest with TP5X. Better than Chrome Soft by 3mph and TP5 by 2mph.
 Launch Angle highest with Chrome Soft (overridden by strike?)
 Spin rates comparable, controlled by strike.

 TP5X longer than Chrome Soft by 11 yards on average.



Raw data can be found here.


Do the TP5/X launch higher?
Yes, although most surprisingly with a 60deg wedge. In general the X launches higher than the 5.

Do the TP5/X spin less?
Yes, especially in the middle irons? On the 50 yard shots the TP5/X balls had a significantly lower spin rate

Is ball speed higher with the TP5/X
In the case of the X yes, but not by much.


Conclusion
The TP5/X are interesting balls; they actually appear to be doing something differently. They launch higher, spin less and travel slightly further. It is great to see TM taking a different direction with their ball design and I am keen to test these on course in the near future.


Update 07/09/17:
I have now managed to test on course and the results were interesting (and mostly subjective).

  • Off the tee I hit both balls, the TP5X went further on 4 occasions and the Chrome Soft went further on 3. 
  • When the TP5X was longest it tended to be by a greater amount than when the Chrome Soft was longest.
  • On approach shots the TP5X went further on 3 occasions.
  • Both balls appeared to stop equally well (distance between pitch mark and resting place).
  • The TP5X launched and flew visibly higher with iron shots. 
  • The TP5X appeared to be affected less by the wind.
  • The TP5X felt much harder than the Chrome Soft.

Strike is king. I believe the TP5X does behave differently to other premium balls, but fractional mishits vs flushed shots still count more than relatively minor differences between the balls.





Thursday, 4 May 2017

Chrome Soft vs Chrome Soft X

Introduction
I love the Callaway Chrome Soft, without doubt my favourite ball. The introduction of an X version meant I had to test it.

Hypothesis
This is an interesting one. My previous testing with premium balls and indeed other comparisons between these models suggests there will be no difference. However, Callaway claim the X version should fly lower and spin slightly more whilst feeling slightly firmer.

A excellent review here.
GolfWRX review here.

Method
Within the limitations of my indoor setup I tested by capturing 5 solid shots (not blatant mishits) with both balls and multiple clubs. Shots were struck from a soft range mat. Using this mat I have noticed shots launch higher and travel less distance compared to a firmer mat or turf. Spin rates are also significantly higher and less variable than those encountered playing 'real' golf.

The balls were:
Callaway Chrome Soft
Callaway Chrome Soft X

The clubs were:
LW (60°) (goal was a 36 yard pitch)
SW (52°) (goal was a 90 yard pitch)
6 Iron (29°)
3 Iron (21°)
3 Hybrid (21°)
2 Hybrid (18°)

Results and Analysis

Subjective:
The X ball is superb/weird. It felt very similar-slightly firmer to me but made a noticeable click compared to the duller thud of the normal chrome soft. I really like the click and soft feel of the X, but I also really like the thud and soft feel of the normal ball!

Data:
These are screenshots, the first club is the normal chrome soft, the second is the X.


As usual, raw data can be found here.

Does the X fly lower?
Not the way I hit it!

Does it spin more?
Technically I think it might a little; with the exception of the 36 yard pitch every single club did spin slightly more. However, I dont think a few hundred rpm of additional spin is going to affect my scores!

Conclusion
I think this was as expected. There may be differences between these balls if you are a tour player but as an amateur a premium ball is a premium ball. I would and will happily play either chrome soft model.

Next Steps
Once I get a setup capable of withstanding 3W/Driver shots repeat the testing.

Tuesday, 21 March 2017

Efficiency & Spin Axis

As someone who finds the maths and physics of Golf almost as interesting as playing I read and watch a lot in an attempt to improve my understanding. This led me to dig a bit deeper into my driver data, specifically efficiency and spin axis.

ST does not measure clubspeed it is calculated (with good accuracy). It measures ball speed with high accuracy. I therefore extracted my data and calculated bsCarryEfficiency, bsTotalEfficiency, csCarryEfficiency and csTotalEfficiency.

The PGA tour measures carry and total efficiency comparing clubspeed to carry and total distance.
For carry efficiency the 2017 range is 1.918-2.616, my average across my ST data is 2.4
For total efficiency the 2017 range is 2.391-2.936, my average across my ST data is 2.63
Fig 1
Figure 1 shows my bsCarryEfficiency distribution. The mean is 1.64, Q1 is < 1.6 and Q4 is > 1.69. It therefore seems reasonable to conclude anything at or above 1.69 is an efficient drive.

Having watched numerous youtube videos of various professionals I noticed a number of them were posting driver data with significantly greater carry distances than myself despite a similar or lower ballspeed. Spin rates and launch angle were similar so the distances should have been comparable. I therefore looked at other launch parameters and once again found myself looking into Spin Axis:
Fig 2
Figure 2 compares spin axis with ball speed carry efficiency for my driver data. PGA tour style carry efficiency would be better but I didnt want to rely on a calculation and using ball speed reduces (not eliminates) the effect of strike on the data. Within this data there is a curve (albeit with a low r2 value of .3397); increasing spin axis (left or right) generally reduces efficiency which makes sense. Using this data an efficienct drive requires a spin axis of +- 20deg (+-700rpm of side spin). My normal dynamic loft is 15.5deg so I need the face and path to be within 4.5deg of each other to hit an efficient drive (data taken from trackman university). The low r2 value will be the effect of strike and delivery, so you can have a low efficiency straight drive but you cant have a high efficiency crooked one (from the perspective of carry).

Skytrak, Trackman, GC2/GCQ
Going back to my youtube comment I decided to add some extra data; I added my trackman data from my recent Skytrak vs Trackman test, and manually captured data from youtube to see how the data compared. All of this data was produced on GC2/GCQ from various pros and also some amateurs:
Fig 3
Figure 3 shows the bsCarryEfficiency for Skytrak, Trackman and GC2/GCQ. Trackman shows a wider range which makes sense, it is measuring actual ball flight and there are lots of variables at play (open data). However, I think the GC2/GCQ data proves my observation that the youtube carry distances posted are significantly higher than ST and Trackman. This means for every mph of ball speed you put in a GC2/GCQ will likely calculate a more generous carry distance than a ST or a TM would observe.

Returning to Spin Axis
I then decided to reproduce the spin axis chart with the additional data and see how it compares:
Fig 4

Figure 4 shows the efficiency vs spin axis plot for the 3 data sets and I this this illustrates a few things:
1. The TM efficiency data is comparable to ST except the spin axis values are generally smaller. This was already noted in previous testing.
2. The range of spin axis measurements for ST and GC2/GCQ are comparable (more extreme than TM) so perhaps the ST isn't exaggerated compared to GC2/GCQ? Much more data would be required to prove this.
3. The GC2/GCQ is significantly more generous in its carry calculation, to the tune of 10 yards at my average ball speed of 155mph.

Thursday, 9 March 2017

Flightscope Trajectory Optimizer - Launch Angle

http://flightscope.com/products/trajectory-optimizer/

This is a great tool and I use it frequently to assess my launch conditions against a different flight model (Flightscope instead of Skytrak or Trackman), and also to experiment with different parameters so I can analyse how they affect distance.

I launch my driver quite high, on average between 14.5-16 degrees. Trackman suggests the optimum for my ball speed is closer to 13 degrees so I wanted to assess the impact and it turns out the results are quite interesting.


The coloured columns are carry, total (hard), total (soft).
This suggests high launch is not a big issue, and strongly indicates it is better to err on the side of launching too high vs too low. According to this launching at 17deg is optimum for carry, but even launching at 25deg will only cost you 6.5 yards of carry and approx 10 yards of total distance in hard conditions. Conversely reducing launch angle to 9 degrees will cost you 10 yards of carry. From this point carry distance drops rapidly with decreasing launch.

N.B. the dip in the curve for total (hard) at 10 degrees launch.

133mph ball speed
I thought it might be interesting to compare this with a lower ball speed (the average ball speed of player a from our Skytrak vs Trackman test).

A similar pattern emerges and optimum launch increases to a whopping 20-22deg. How many amateurs launch their driver at 20-22deg???

The dip in the curve for 10deg launch is much more pronounced. Not sure what this indicates???

Friday, 3 March 2017

Skytrak vs Trackman Pt 2 - Shot by shot Player A

Introduction
After the first part I wanted to try and illustrate the data captured on a more blow by blow basis so this is that attempt; this will therefore be a very chart heavy! Each chart shows the Skytrak and Trackman data, aligned shot by shot.

This is the actual Trackman data with no normalisation. Differences in calculations from the ST flight model should therefore be expected (but I still expect it to follow the measured data (e.g. short shot = short shot etc).

Summary data is useful but I think the below shot by shot charts illustrate just how accurate the ST is.

Ball Speed

I think this is highly impressive and shows excellent correlation between both systems. The difference is normally negligible peaking at approx 7.7mph in the worst case.

Club Speed
As a calculated parameter this is surprisingly close to the measured Trackman value.


Vertical Launch


Horizontal Launch


I think this shows the subtle difference in alignment between the 2 units. If you subtract approx 1.5 deg (turn the ST 1.5deg left) they match even more closely. I do not believe these 1.5deg affect the spin axis measurement but they do affect the offline projection.

Total Spin

I think this is the most impressive chart of all, Skytrak can measure spin rate with phenomenal accuracy. It is this which makes me think the Spin axis deduction is not calculating as expect (as opposed to capture). The sizeable deviations are caused by Trackman not returning total spin.

Spin Axis

As previously noted this is the only troublesome measured parameter. I think this chart clearly shows the Skytrak is measuring Spin axis (I would even say accurately) but for this player it is predominantly skewed in a negative direction. For myself (Player B) I am pretty sure we will see the reverse (skewed positively) because our shot shapes are opposing.

Flight Duration

A calculated parameter for Skytrak. This is impressively close considering we were hitting range balls with a slightly reduced distance.

Descent Angle
A calculated parameter for Skytrak, impressively close to Trackman for the majority of shots.

Peak Height

A calculated parameter for Skytrak, impressively close to Trackman for the majority of shots.

Smash Factor

A calculation based on a calculation so potentially risky. However, it seems impressively close to the Trackman value. 

Offline


As previously noted the wind was slightly helping and from the right. You would therefore expect the ST shots to finish right of the actual TM shots? However, if you take into account the circa 1.5deg alignment difference between the units (ST alignment approx 1.5deg right of TM target) I think these are almost identical.

Carry Distance

Carry distance looks spot on considering they were range balls.

Total Distance

As before total distance also tracks as you would expect (for a range ball).