Square face, straight path, ball still curves

[slamp]

See photo. If my path is straight and my club face is square why does the ball curve. I see the spin axis is not vertical which may be the reason. Is this due to not hitting the center of the club face?

[Wundej]

See photo. If my path is straight and my club face is square why does the ball curve. I see the spin axis is not vertical which may be the reason. Is this due to not hitting the center of the club face?

How do you know your path is straight and face is square? Skytrak can’t measure those values. Not familiar w/ TGC but maybe they estimate those on screen? Spin axis is what the sims are going to use to calculate what the ball is going to do.

[colinjm18]

Unless your using r motion to track the club path and face angle. I wouldn’t pay any attention to the values that are shown on screen as they are estimated.

[Yrrdead81]

Just as an addition, lets say you have a GCQuad or GC2 w/ HMT. And you have everthing squared up and are still seeing "side spin". There is another parameter that you need to pay attention to. Strike, by that I mean strike location on the face which will also change your spin axis.

Also when they are talking about spin axis that is "side spin", it is the result.

Hopefully I'm making sense to you. If you let us know which LM you are using we can be even more specific.

[pcascio]

Suppose the Skytrak is not in perfect parallel alignment with your aim path? Wouldn't that create a misread?

[slamp]

Well if the path is straight and the face is straight it would produce a straight shot. It may be left or right but it would be a straight flight path. It would not produce a curved flight path.

[andygg1986]

Skytrak only measures the ball, so you can ignore the face and path regardless of how it is aligned. If the Skytrak is not parallel to your aiming line, the ball horizontal launch angle will be off by the equal and opposite number of degrees. Say your ST is aimed 5* right of your target. A straight shot will read as 5* left and with a straight ball flight. A draw that starts 5* right and comes back to the center would read as a draw that starts straight and ends up left of the target.

[jut111]

As has been stated, gear effect from off center strike can cause curvature regardless of face to path. That said, what system is giving you that club data?

[slamp]

I am using a SkyTrak launch monitor.

[Dave Lee]

Hi Slamp,

If you don't have something like R-Motion or Skypro attached to your club, the club data you are seeing is basically estimated (ie. made up). A skytrak unit alone only measures what the ball is doing. Programs can try to guess what the club is doing based on the ball data. But in the end, it's just a guess. Best example is skytrak's club head speed result. There's nothing measuring the club head...it's assuming the most likely combination of club movments that gave your that ball flight to guess what the speed is.

So if you're using a simulation that tells you the club path, without r motion or skypro, it's doing the same type of guessing. If you think about it, there's a whole bunch of combinations that can send the ball off the way it goes (angle of attack, face angle, swing direction, etc) so there's really no exact way of guessing correctly what really happened. Best case is they have a database of millions of swings that they used to guess the most probable combo. But then again, you can be an outlier like me who can hit a really straight shot with a really dumped under plane, through manipulation.

[slamp]

Do you think the club head speed using a Sky Pro is more accurate than the estimated club head speed of the Sky Trak? Also, don't know how Sky Pro would be able to give you data such as where on the club face you struck the ball. Seems like Sky Trak using high speed cameras would be able to determine where the club face struck the ball.

[Dave Lee]

I've actually used skypro at the same time as trackman. it was typically about 1-2 mph of what trackman was spitting out. I was impressed. Angle of attack was the other thing i compared...my unit had a 5 degree bias but it trended in the same direction as trackman. So I know -5 degrees is 0 degree on track man and -8 is really -3 etc.

Honestly, the other major camera type launch monitor, foresight GC type, uses dot stickers on the club data. And their flash system seems a lot more hardcore than what skytrack uses. So if they need dots...i wouldn't hold much hope for skytrak picking much club type data by camera.

[slamp]

When I was using my Skypro for the first time I was killing myself trying to get my attack angle from being too much of a downward angle. I am so happy to hear that the Skypro is off by 5 degrees. Now I know it is not my swing but it is the device!

[slamp]

Thanks Dave Lee this makes much more sense.

[Wundej]

Thanks Dave Lee this makes much more sense.

Any chance you could respond to all the other questions, specifically, were you using anything that could give you that info or was it just the Skytrak?

[slamp]

I was just using the Sky Trak. I do have a Sky Pro but wasn't using it at the time.

[Morini]

1. If a centre strike could be confirmed (via footspray or similar), the Skytrak calculated club data is very accurate.
2.For the driver, each degree of difference between face and path leads to an increase of 6 degrees of spin axis.
3. For driver, each dimple (4 mm) horizontally off centre strike leads to 6 degrees of spin axis.
4. 6 degrees of spin axis curves the ball about 3.5 yards per hundred.

[skytrakali]

FYI Skytrak uses linear combinations of the ball data (spin, speed, direction etc.) to estimate club data. If you have sufficient patience you can fairly easily back the coefficients out. For "normal" shots this gives quite good club data, but nothing about the club is actually being measured - it's essentially a data fit. For "non standard" shots (like short pitches with arms at 7.30, 9 o'clock, 10.30 - something I practice a lot) the estimated club data can be way off and it's possible to get really odd smash factors e.g. less than 1.

[Morini]

Skytrakali,

The formula is something like I described. For example, for driver, 18 degrees spin axis entails roughly 3 degrees face to path (assuming center strike).
For partial wedges, the impact of face-path difference on spin axis should be far far smaller.

[SkyTrak_Seth]

The club data in the screenshots you posted are generated by TGC. I'm not sure how they figure a square club face with those spin axis numbers.....

[slamp]

Thanks for the feedback! I this something you can collaborate with TGC to figure out or is there a TGC expert on this forum you could forward this to?

[Morini]

The screenshots don't make sense. It lists path as 4 degrees in to out, face 1.5 open, but then gives face to path of zero. Also, a smash of 1.45 is not achievable with an 8 iron.Launch angle on the high side for an 8 iron. Not sure what to make of it.

[slamp]

Morini yes, seems like most of my shots register a 1.45 smash factor, I have no idea why. I agree, none of this TGC data make sense to me. Even if it is interpreted data it should still make sense. My concern is not that all the data is correct but that the TGC sim game is not screwing up the ball flight. Otherwise what was the point of spending all that money to play golf on a simulator?

[Jwheels9876]

As numerous people have already told you, the club data should be ignored because skytrak doesn't collect any of it.
TGC ball flight algorithm works just fine, just dont look at any club data that shows in the post shot screen.