Do you have a GCQ with Club Data? Please read...strange club vs. ball flight data

[DirkDigglr]

Hi everyone, thanks for reading as I would like to solicit views/help from the group.

I have owned my GCQ for about a year and my GCQ appears to me to be measuring inaccurate club data that I wanted others views on. I have a decent understanding of ball flight rules but others will know more.

I use FSX Pro to capture my data and I download each session into Excel so I can track all the historical data. I have noticed several instances where the face-to-path data doesn't match up to the ball spin axis.

1. I have logged 5955 shots of IRONs only (clubs with no bulge or roll). Excel sheet is attached for any data nerds like me!
2. In that data set, 550 shots have a NEGATIVE face-to-path yet a POSITIVE ball spin axis. 112 shots have a POSITVE face-to-path yet a NEGATIVE ball spin axis.

so in total, 662 shots of the 5955 shots (11%) are showing club data and ball data not consistent with simple ball flight rules. Now I fully agree that some of these shots can be explained by where the ball was impacted on the face (gear effect etc) so this test isn't perfect. However, I generally hit the ball in the middle of the face and my lie angles are generally good. I also acknowledge that some of these odd readings are very minor (under 1%) which may be within the GCQ measurement tolerances (I don't know what the stated tolerances are).

I have sent several shot data to Foresight Canada who are trying to determine if the machine is mis-reading or not. So far they don't believe the machine is NOT faulty which is why I am soliciting views from this group.

My personal view is that the ball data is being captured correctly and its the club data that is being misread. But these shots are all indoors so I can't compare to actual ball flight experienced.

any thoughts or views from this group is appreciated. Is my understanding of ball flight data incorrect, are these shots of concern within tolerances or does the machine have a problem?

the shot data is attached for anyone that is interested to see. Please note the excel sheet does NOT contain all 5955 shots as the file was too large to upload so I had to delete some shots from this.

thanks in advance.

[Tom Howarth]

I am waiting for my Quad to be delivered. It's back ordered. So my opinion has little value. Could it be the positioning of the stickers on your club face?

[andygg1986]

Just a quick observation without going through too much. I think the lie angle at impact is the source of what you are seeing. Just eyeballing averages, your 58 degree wedge is about at -4, 54 degree wedge is at -6, 50 degree wedge is at -3, 9 iron is -5, 7 iron is -3. I can't remember how positive and negative numbers relate to in-to-out path, face pointed right or left, and toe up or toe down. But if your face is slightly closed to the path but a short iron is toe down 5 or more degrees, you are still going to hit a cut because lie angle becomes much more significant with more lofted clubs.

[DirkDigglr]

Ok that’s interesting and helpful. I have noted some shots where my lie angle is flat and yet the similar ball flight / club data is observed. I have captured those shots and sent to Foresight as i wanted to send them data on shots where lie angle was near perfect to show them. Maybe I am seeing ghosts?!? But your thoughts are helpful for me to do more research on.

[DirkDigglr]

further to the post from andygg1985 about lie angle being a possible cause, I re-cut the data to remove any shot with a lie angle less than -2* or greater than 2*. this resulted in total shots to analyze of 2568 (from 5955). clearly, I need to work on lie angle...but that's another issue.

in the new data set, 259 shots have a NEGATIVE face-to-path yet a POSITIVE ball spin axis. 32 shots have a POSITIVE face-to-path yet a NEGATIVE ball spin axis. total of 291 odd shots..

interesting that 291 / 2568 is 11%. still the same percentage as my original analysis.

so lie angle could be a cause but at +/- 2* I would think this shouldn't be too much of an issue to cause these odd ball/club data discrepancies.

anyone else have other ideas to consider here?

updated data is attached if anyone is interested.

thanks again.

[pma99car]

Great topic! I love things like this, and even better there is some actual data to explore!

Plotting FaceToPath against SpinAxisTilt (attached: FaceToPath) you can easily see the relationship you'd expect. The outliers you've described are all visible too - these are the points that are either in the top left or bottom right quadrants of the chart. I guess the interesting thing is that you only tend to see these outliers when FaceToPath isn't taking an extreme value.

I looked to see if there was a change in the relationship between Lie Angle and Spin Axis Tilt at different ranges of of FaceToPath and Dynamic Loft but honestly couldn't see any discernible patterns / changes. The average dynamic loft of the outliers is slightly above that of the expected results, but only by less than 2% - I don't know if this is statistically significant but it does align with the concept that lie affects spin at higher lofts. I'll keep looking and report back if I see anything further.

BTW OP - your lie angle with the Srixon irons is much better than it is with the JPX.

[DirkDigglr]

Love it! I assume your analysis would be the same with the updated population of shots where i removed all shots outside of the +/-2* lie angle. My biggest issue remains confidence in the GCQs measurement. I want to believe the unit is working correctly but i do have some nagging concerns given the percentage of shots is 11%.

[pma99car]

Yep, that is one of the things I looked at and it didn't change what I saw unfortunately.

I think I understand what is going on... although I haven't read the foresight manual so maybe someone will correct me. I think spin axis tilt is measured relative to the target line. If you hit a shot on a path 5 degree to the right of target with a perfect 0 degree face to path (and lie, strike being perfect etc). the ball would fly perfectly straight 5 degrees to the right. However the quad would show that as having some positive side tilt axis (I don't know if it would be 5 degrees or not).

[DirkDigglr]

I think your explanation about how spin axis is measured may in fact be the best answer. Your explanation to me makes very good sense - provided that is how the GCQ measures spin axis. If anyone else knows for sure how spin axis is measured, please post. Thanks so much for thinking about this and offering additional insight! Always good answers in this forum.

[sinkingputts]

Make sure you unit is at the exact height of your hitting mat. And change balls

[ElPrimero]

@ DirkDiggIr: Very interesting thread! Concerning the balls: I use Pro V1s and I use them till the surface is quite bad and the spin drops. I never had a crack! I swing a maximum of 105 mph.

[DirkDigglr]

I am going to switch to Pro V1s for this year. Hopefully they will be more durable!

[sinkingputts]

I swing at 117-119 mph and i noticed the balls are toast after about 250 driver swings. That’s with both PRO-V’s and TP5.

[DirkDigglr]

Just to close the loop on this, Foresight Sports reviewed the data and provided this response:

In almost every case he highlighted in which the sign of the face-to-path measurement differed from the sign of the spin axis, and the magnitude of both were quite small.

That is, a face-to-path magnitude less than 2 (often less than 1) and a spin axis magnitude less than 3, resulting in side spin of less than 200RPM.

When the face-to-path angle was substantial, the sign of the spin axis agreed in almost all cases.

There are many factors that affect spin axis. While face-to-path is the dominant factor given a center of the face strike, the other factors can add up when the face-to-path angle is small.

This device is working as intended, and the data is representative of its proper operation.