Golf Simulator Forum is the center point for discussion on golf simulator products, brands, manufacturers, launch monitors and everything else related to golf simulation.
If this is your first visit, be sure to
check out the FAQ by clicking the
link above. You may have to register
before you can post: click the register link above to proceed. To start viewing messages,
select the forum that you want to visit from the selection below.
Wow, thanks James^2 for this! I suspected all along that the SkyTrak offline measurements were too punishing - and I think this proves it. I just read elsewhere about "spin decay" possibly being a factor that SkyTrak has not considered? My guess is that's the answer. I have a GCQuad on order and was going to do this same sort of comparison to my SkyTrak to see what gives?
Great write up and thanks for taking the time to compare.
I saw you mention something about ball setting in trackman. " In Trackman ball conversion terms they are the equivalent of hard (reduced spin with short irons, elevated spin with long irons/woods)." Do you really need to do ball selection type there? This measures the entire flight outside correct, why would that matter? I might not understand the ball comment correctly.
Ball speed, LA, Total Spin, Back Spin, Flight time all look very good.
Normalisation can also change the other parameters (ball speed, spin, launch etc) which would then give imply the ST was wrong when it was actually spot on.
This is also why people shouldn't read much into the calculated figures (carry, total etc) because that isnt a fair test. The parameters which interest me are the measured ones and not surprisingly the ST is near faultless.
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; t...
I think I have managed to explain most of the difference in the offline figure between ST and TM (an alignment difference of circa 1.5deg), but I dont think alignment plays any part on spin axis? What confuses me is the spin axis chart clearly shows the ST and TM tracking each other with an offset so the ST is measuring the spin axis reliably???
I'm guessing alignment does play a part on spin axis - if the ST unit is leaning towards the ball, or away from the ball, it might skew the spin axis. You might try leaning it 10 deg towards the ball, hit five or ten shots, then lean it 10 deg away from the ball, hit another five or ten, to verify that hypothesis.
- Ron at GunghoGolf.com - we specialize in TrackMan, FlightScope, Foresight, Uneekor, SkyTrak, Garmin, Bushnell, TGC, and E6 Connect. 512-861-4151 or email hello AT gunghogolf.com.
Amazing analysis James James. Your are clearly our resident sim PhD =)
As for comments on your analysis:
- I tend to draw the ball so sometimes think that ST over-exaggerates the side RPM and spin axis to the left so sometimes turning draws into hooks. But I really wonder if this is true on fades and slices? In part 2 of your analysis, you said: "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." Do you have the data from Player B showing this reverse skew in positive (instead of negative) direction?
- Also what happened w Player A's 3 wood? This is the only club where ST shows a less negative side RPM and spin axis than Trackman.
Again, thanks for the great analysis. Super helpful to me, and I'm sure to all.
The side spin number are very interesting. Over the past month or so (I can't remember exactly how long), the side spin seems to have increased significantly on my Skytrak. Up till now, I thought it was my swing but now I'm questioning my Skytrak or at least the software. Did re-installing the software have any impact? I also see higher side spin numbers when I'm playing sim software so I'm not sure if the increase is related to my swing, Skytrak hardware, Skytrak firmware, or other software.
I have been looking through my data today and I am not happy with it so don't feel it is worth publishing in the same way. During my part of the testing Trackman missed a couple of shots and ST missed 1. I therefore have some offsets in the shot-by-shot analysis that I cannot reliably eliminate (you can kind of see it in the chart above) so I would rather rerun my part of the testing at some point in the future than publish questionable data.
I might well publish the summarised data if I am confident the quality isnt affected.
James, that's some really great data and write-ups there ! (I think I've finally found someone more analytical and geeky than myself on golf...)
I've had my unit over 2 years now and hit regularly on TM and FS, as well as used to hit on GC2 quite often. I know my numbers pretty well.
I've long held the opinion that the raw speed and spin data was extremely accurate on the Skytrak, but the ball curvature of the flight model over exaggerated shape. I have an almost dead straight flight on the range and on course, but have always seen a consistently wider dispersion pattern on the Skytrak range.
Your suggestion that Spin axis is somehow over calculated makes total sense to me; I sometimes struggle to believe the spin axis readings I get on Skytrak.
Having said that, I'd rather have the error be that way and be straighter on the course than I am when practicing, than the other way round...
But we don't calculate spin axis. It is a measured parameter. It's effect on curvature lines up extremely close to Optimal Flight and other flight models. It is odd though looking at James's analysis that the measured axis is that much more extreme. Still makes me wonder about wind though. I know wind is super-temperamental with our robot testing with Trackman.
SkyTrak_Seth In your experience are there any things which can affect the measurement of Spin Axis that we should be mindful of? The bit I struggle with is the accuracy with which total spin and launch direction are measured suggests the spin axis should also be spot on?
James James , yeah definitely. If you are doing this sort of detailed testing, always make sure that a clear black mark (line is best) is facing the SkyTrak unit. Especially outdoors, the dimples can get washed out pretty easily making it much harder for us to track the spin.
Comment