Launch angle adjustment

[Stonebattle]

I bought a new Skytrak recently and what a nice machine it is.
I have a method of measuring launch angle I have found to be quite accurate in the past and consistent with my Trackman numbers. I find my Skytrak is just a bit low. Not inaccurate but it does make a difference, at least to me.
I have set the unit up as close to the recommended position as I can, but was wondering if there was a way to adjust the unit such that the measured launch angle is impacted?

[brnixon]

Have you checked to make sure your unit is perfectly level? How about even with the stance mat?

[Stonebattle]

Yes to both and I take it from your question some adjustment is possible? If so, what have you found?

[nicklas]

You have adjust it by hand, No built in features but the level indicator.

[Stonebattle]

Yes, I figured that out.
Anyone experiment with manually adjusting for launch angle?

[keithpbz]

How low do you think the launch is?

[Stonebattle]

Ok, let me try to put all of my cards on the table. I do not consider Skytrak inaccurate, in fact I consider it as one fine device.

The launch angle I am observing with my manual method and my trackman are about 1 degree to 1.5 degrees higher then Skytrak reports. Not bad at all, but I would like to get it more spot on with my Trackman numbers.
It does not make much difference with most clubs, but when I get to my lower launching clubs it makes more difference then I would like.

Look guys here's the kind of thing that's bugging me:

With a driver I know I can carry a ball over 230 yards, even 240 yards on occasion. How do I know this? Well, I've done it twice on one try in the last month with no helping wind and fairly flat land. I have used inside simulation for a long time, so I don't think I have an inside swing issue, although Skytrak does show about 1% less ball speed than my outside trackman numbers. The most carry I can get with Skytrak with a swing I would use on a course is about 226 yards. I know my aggressive driver swing speed is 96mph to 102mph, at least that is what it was during my last driver fitting. Last year I ended with a scratch handicap (actually 0.3 but I'm calling that scratch). This year it's more like three, because I can't seem to get it together.

Here's some Skytrak driver shot info a swing I might use for a 230+ yard carry: With the same numbers reported by Skytrak
Trajectory Optimizer Trajectory Optimiser with 1.5 degrees launch angle added
Ball Speed Launch Angle Back Spin Side Spin Side angle Carry Distance Carry Distance Carry Distance
140MPH 11 Degrees 2498 RPM 0 RPM 2 Degrees 226 Yards 229 Yards 232.3 yards

I know, not much difference, but I'm a senior play and need all the help I can get.

For those interested, the manual method I use involves using a high speed camera behind the golfer such that the exact point the ball contacts the screen can be observed.
The height of that point is measured and one can use the center of the ball or the bottom of the ball as a reference point, but one must be consistent. Measure the height the bottom or the center of the ball hits the screen. Subtracted from that height, the height the ball, center or bottom, starts on the tee. The distance from the tee to the screen is measured. Then, one must find the angle who's tangent is that number and that will represent the launch angle. I am not perfect, so if someone sees a problem or improvement to this methods, please advise. Still, I have found this method agrees well with my Trackman or GC2 launch angle number.

[MainStGolf]

If you are using SkyTrak range feature you can adjust your altitude settings to get more accurate "distance" numbers. I know that doesn't help with your launch angle issue, but if distance is the case you at least make that adjustment.

I have found with the SkyTrak that your strike has to be pretty exact to get numbers that are close to real life. Especially with the driver and 3 wood. Irons have more to do with your hitting surface when it comes to real numbers. I know the company has taken a beating regarding distances, but for the money its pretty darn accurate.

[allen2be]

Stonebattle Thanks for the write-up and confirming some of my thoughts. I too drive the ball substantially farther than Skytrak is giving me and would love to get it figured out. It makes TGC par 4s and 5s play way longer than they should (probably not a bad thing for my long iron practice!).

I have calibrated the humidity/temperature/firmness settings in the Skytrak app, but still never get close to my distances in real life. I'm about ~275 yard average, and I haven't came close to this one time with my Skytrak.. I think the farthest few I have hit are about 260 and my average is probably more like 240. My average on TGC is also probably about 240ish.

I have it leveled (I still don't understand why everyone is up in arms about this since the Skytrak is supposed to be fine withing 5 degress of tilt forward/back & side/side - regardless, it's leveled)... Since everybody says the leveling is important, I'm starting to think about tilting it forward on purpose, so that the launch angle gets exaggerated (but again, it's supposed to adjust its calculation anyways)

My problem also has to be launch angle. My ball speeds seem pretty fair. I can really try to tilt the spine and stay back on it, but I still rarely clear 6 or 7 degrees of launch.

[Godfather]

allen2be You should do the same triangle (trig) physical measuring method as Stonebattle. Take bottom of ball from screen to mat height divided by distance from ball bottom to screen at same height as mat. Then inverse tangent function in a calculator.

[allen2be]

Good thinking.. I'll give it a shot tonight and see if I come back with my tail tucked

[Godfather]

Ha I don't know about that, but low shots don't seem to get quite the roll in sims vs real-life summer fairways.

[allen2be]

Did the trig. I'm sure I wasn't real accurate, but every time I did it and tried my best to use my 240 fps phone camera to check the spot, my launch angle was always higher by a couple degrees than the skytrak range app reported Idk, maybe I'm a little out of whack or it's the indoor swing still breaking in for the winter, I'm just hoping to get it worked out. The accuracy on everything else seems pretty solid. I also added a little more black hockey tape to the outside egde of my driver and it seemed to drop the random skulls to the left that are hitting the net in the center.

[Stonebattle]

I stood on a driving range today. It was about 60 degrees with right to left wind that may have been slightly aiding. After hitting a few shots with irons the first shot I hit with a driver landed a few feet in front and to the left of a flag and then bounced and rolled about 20 yards beyond the flag. I had measured this flag at a distance of 243 yards with my Bushnell Pro 1600 laser range finder. At this point in time, I have no explanation why I cannot accomplish anywhere near this same thing with Skytrak without unrealistic settings. Interesting you are also seeing higher measured launch angles. It makes me wonder about the method of measurement, although I don't know how it could be that far off. Hopefully others will provide some additional insights.

My 3 hybrid stinger also does not seem to have much roll with Skytrak as well.

I've rejected the idea of a different indoor swing, but hey maybe.

[FaultyClubs]

...The launch angle I am observing with my manual method and my trackman are about 1 degree to 1.5 degrees higher then Skytrak reports. Not bad at all, but I would like to get it more spot on with my Trackman numbers....

....226 Yards 229 Yards 232.3 yards I know, not much difference...

...With a driver I know I can carry a ball over 230 yards, even 240 yards on occasion. How do I know this? Well, I've done it twice on one try in the last month with no helping wind and fairly flat land....

etc.

I don't have anything earth shattering to add but my initial thought is you may be expecting too much.

In your table 1-1.5 degrees adds 3 yards on a 230 yard drive. This is probably well within the range of Skytrak's accuracy specs. Especially combined with different trajectory algorithms (Skytrak, TO, OF etc).

Skytrak claims +/-1 mph on ball speed. And +/- 1 degree on launch angle. +/- 250 rpm, +/- 2 deg Azimuth. Taken together I'm guessing that's more than a 3 yard difference. I also suspect just switching from TO to OF can make that much difference as well.

Then there is the system accuracy these specs imply. Azimuth error affects LA error so 2 deg Azimuth already exceeds 1 deg LA error meaning their LA spec is not a total system spec.

And then one has to consider the real world performance of the Skytrak versus the stated specs.

Overall 3 yards looks pretty darn good to me!

Having said that, some ideas:

- Can you adjust assumed elevation (or other physical parameters in the trajectory model) enough to fine tune the distances? It wouldn't take much to gain 3 or 6 yards.
- Have you verified the Skytrak is pointing at 0 azimuth? It will make a difference in LA (higher or lower depending which way the Skytrak is pointing).
- Can you change the height of the Skytrak? (LA error changes with the relative height of the ball versus the lens boresight)
- Can you change the distance of the Skytrak to the ball? (LA error changes with distance)
- Have you tried changing the tilt of the Skytrak? (LA error could change depending on tilt in almost any direction)
- Does Skytrak have a way to verify the calibration or reset it?
- Are you hitting the same balls?


I also note you are comparing 230 or 240 yard drives on occasion with no wind and fairly flat land. What is your average drive on confirmed flat land and no wind? I'm not sure your peak drive is a good indication of anything. Also "no helping wind" is hard to judge since there may be none where you are standing but plenty over the ball flight. And what does fairly flat land mean? It would only take a few yards of total slope to change your distance by 3 yards. I guess my point is to make sure you have a good test. I can easily see the differences you are talking about being due to other factors (indoor swing, better data, paying more attention to data, more controlled environment etc) not strictly due to the Skytrak.

And a comment on your LA measurement approach. I did the same thing when I first got my GC2. Do you have markers on your screen? I needed to add those to get sufficient accuracy because it was otherwise too hard to see exactly where the ball hits. Even then at 240 fps it was still difficult to get under 1 degree of accuracy.

[Stonebattle]

Wow, thanks guys for some great comments and insights.

MainStGolf:
I have only changed the altitude to match that of my locality.
I have not changed it because my L wedge to 5 iron are accurate but already slightly long for carry distance and I don't want to make that worse. set the temperature to 78 degrees F.
For some reason I can't change the humidity, but 50% seems about right.

You're right the strike makes a big difference, although it seems golfing on a course is harder due to different lies.

Allen2be:
I have adjusted the level, by a half inch, or so and tilt of the unit, about 2 to 3 degrees, without much difference in launch angle.
By the way, I am not saying I'm right about all of this. What I am saying is there are some differences I can't explain.

FaultyClubs:
Great observations
Let me start with your last comment. Actually 240 fps is what I am using. With that one can observe just where the ball strikes the screen. In Skytrak's driving range there are a series of rectangular objects in the center of the screen that look like lines in the center of a road. Fortunately most of my drives hit near the center which makes it easy to measure the height where the ball strikes the screen.

As far as your bullet item list:
I have not found a reasonable way to adjust launch angle
I have tried to lower and raise the height of the unit to a small degree, half inch, without any noticeable impact.
I have not experimented with ball distance to the Skytrak sensor
I have tried to change the tilt of the unit, but not beyond about 3 degrees because I don't want to change other parameters and other club distances.
Skytrak does not have a calibration verification that I know of
I use new balls of the same type I use on courses

It's not about 3 yards to 6 yards and I am not saying I am right and Skytrak is wrong. What I am trying to point out is differences I have observed with the hope others will provide more information on what they may be seeing.

Here's the rub for me, it's not about the specific numbers, it's about the scoring opportunity. There's a course I play that has a par 5 that I can hardly wait to get to. It's about 500 yards to the green with a culvert that crosses the fairway. It requires about a 240 yard carry to clear. If one can do that, the ball hits a down slop and bounces and roles like crazy. I can only make that happen about 40% of the time, but I always try because if I do I have a chance for eagle. In the Skytrak simulation as it sits right now, I would have no chance.

[FaultyClubs]

The launch angle I am observing with my manual method and my trackman are about 1 degree to 1.5 degrees higher then Skytrak reports.

If you have access to a trackman the best approach would be to measure the same shot simultaneously with both and compare all the numbers. It will remove all the guessing plus tell you how the other parameters compare.

I only know of a couple people who have done it.

Skytrak published one comparison at http://www.skytrakgolf.com/en-CA/abo...uct-comparison You'll notice similar LA errors you are seeing but in the opposite direction.

davray666 had another test here. http://golfsimulatorforum.com/forum/...0030#post40030. His data also showed a bias skytrak to read high (opposite of your results and similar to Skytrak's). His data showed bigger variances as one gets to the wedges.

[Stonebattle]

FaultyClubs
Thanks for the info, I saw and read all of the posts you show above before I bought a Skytrak. So, I guess I had some high expectations. I have played sim golf inside for a long time, so I did not think this could be the result of anything I was doing, but it's starting to look like it might be me. I suppose I could get a trackman session, but I played inside with Protee and GC2 in the recent past with results that seemed reasonable.

This thread got a long way from my original question. That was, if anyone knows of a way to adjust launch angle with Skytrak. I wanted to at least attempt to eliminate all the variable I could, but it looks like the answer is no.

Do folks here find that Flightscope's Trajectory Optimizer accurate?