Serious Concerns About Skytrak Numbers Calculator/Calculations

[dagratest816]

Hey All, I had to reach out after me using my skytrak today. Everytime ive used my driver i just feel like the numbers just dont come back correct. After todays session i literally went to Rick Shiels youtube page (pretty big golf youtuber) he reviews all kind of equipment and shows his numbers from the quad GC2. Biggest things i look for is ball speed and launch angle and spin as those are most accurate on the skytrak and arent being calculated like club speed is. Today I had a few shots that just didnt make any sense with the output that i had. Just for comparitive purposes i went back to an old post i seen from somebody here in the forums just so i know the skytrak does actually go up to those type of numbers. With all that being said there is a series that Rick Shiels does that he has a mid handicapper test out equipment as well, his ball speeds arent as high as Rick's are and the numbers show it whenever he does a video with him. FOr instance Rick is usually around 158-160 ball speed and carries usually around 275-280 The mid handicapper ball speeds are usually around 130 and his carries are usually around 220-225. I will link videos below of proof that shows what im referring to, but will list out the numbers for the sake of this post.

So on to what i was getting today, These numbers are straight from my session today from the export through Skytrak.

SHOT # 21
BALL MPH 153
CLUB MPH 103
LAUNCH DEG 10.2
SIDE DEG 6.3
BACK RPM 1814
SIDE RPM -1025
FLIGHT SEC 4.9 sec
DESCENT DEG 22
HEIGHT YD 16.1
PTI SCORE 1.48
OFFLINE YD -13
CARRY YD 228 (how is this possible)
ROLL YD 27 (conditions are firm)
TOTAL YD 255 (seems drastically low!!)

Now for comparison first off i want to tie back to a user that posted a pic on these forums of a shot that he had. - https://golfsimulatorforum.com/forum...ips-and-tricks Page 1 #13 post he posts a screen grab of one of his shots, shoutouts to NVONEPUTT for the screen grab, great shot he had by the way, as you can see on his shot the stats are below if you dont care to click the link and check it out

Launch Angle - 13 Deg
Back Spin - 2022 rpm
Ball Speed - 150 mph
Club Speed - 101 mph
Carry Yards - 267
Total Yards - 299

Now this seems like a big drastic contrast. How do i lose 44 yards of total yards and 41 of carry with a faster ball speed granted 3 degree lower launch. Doesnt seem possible. Even More research that i did, i dont know if anybody here knows about the trajectory opitimizer link that Flightscope has that you can put in information of a shot and it gives you what the trajectory should be. So i put in the information above (as close as it would let me it deals with a few more degrees than solid numbers) See Screenshot of what the numbers above show that i shouldve been getting.

So i check that out and im concerned for my unit, but like i mentioned in the beginning i go to Rick shiels just so i can get some more information about simulators and numbers to confirm im not crazy. So also attached you will see the mid handicappers numbers in a picture straight from a youtube video, and also Attached you will see

Again for the people that may not click on the photos (i know this post is getting rather lengthy my apologies) but

Rick Shiels numbers - Lowest comparative

Launch Angle - 11.6 Deg
Back Spin - 2539 rpm
Side Spin - 288 Right
Ball Speed - 159.3 mph
Offline - 3.9 Yards Right
Carry Yards - 272
Total Yards - 292

Mid Handicappers Numbers - Highest Comparative -

Launch Angle - 15.3 Deg
Back Spin - 1923 rpm
Side Spin - 63 Right
Ball Speed - 133.8 mph
Offline - 3 Yards Right
Carry Yards - 229
Total Yards - 249

Now as I've said already this is a rather lengthy post and i greatly appreciate it if you've made it this far, but i would love to hear from either SkyTrak_Seth or any of the skytrak members specifically or any of the community that can make some sense of these numbers to me because they are really making me question my unit and im wondering should i be thinking about exchanging my unit for a different one that might be more calibrated properly, while im still under the warranty and everything for my current unit. Any answers, statements, fun jokes or anything would be greatly appreciative! Thanks.

Oh yea P.S. For those that may not click on the flightscope trajectory optimizer pic those numbers are posted below - (for comparison of what they say the shot should look like (and it did look like this picture by the way just the numbers were way shorter)

Launch Angle - 10.2 Deg (Vertical)
Back Spin - 1816.8 rpm
Side Spin - 1053.2 Left (negative)
Ball Speed - 153 mph
Launch Angle - +6.3 Deg (Horizontal)
Altitude - 4400 ft (did this to match what shots are like in UK where Rick and mid handicapper are from and play, assumed they had same setting, regularly play it at 910ft which is what it is here her missouri - didnt notice a major difference though - more reason as to why i think my unit is miscalculating shots)
Surface Type - Hard (same setting for skytrak - firm - with colder weather in the midwest its set to this right now)
Height - 67.6 ft
Flight time - 5.6 Seconds
Carry Yards - 250.7 yards
Total Yards - 295.2 Yards

Thanks again if you are able to help in my concern!

[Brutaly]

I am a custom fitter and at first glance those numbers you get from the SkyTrak seems reasonable. I havent run them thru my software but i can tell by just looking on them that the spin numbers are low and that in combinationwith the low launch angle will mean less distance. There is also a lot of side spin which means less distance.

The optimal launch angle for you should be around 15-17 degrees for max distance and about 20 degrees for max carry. Soft tipping your shaft a bit would increase spin (to little spin can result in loss of lift and distance) some what and also increase launch angle which would increase feel, distance and in combination with about 3 degrees more loft also generate more fariway hits. Those numbers are a sign of the tip being to stiff in combination with a mid release, not late.

Are you sure that you set the altitude to the same in both the skytrak and the Flightscope software. The reason i ask is that i own both devices and they are very similar in results in my comparisons.

I notice 4400 feet in the flightscope software and the skytrak is 500 default. Set them to the same and i am sure you will find that the numbers do add up. At last they do that for me.

I know why you set them the way you did but you need all variables if you want to compare like that.:
What ball
Temperatur
Etc

4400 feet (1341 meters)is at the summit of Ben Nevis and cant be the regular altitude you guys play at.

If you are interested in checking out the skytrak just compare numbers between the flightscope software and the outcome from the skytrak. Dont involve obscure testing from sponsored videos.

EDIT: Just your rather high sidespin and vertical launch angle steals like 20 yards of distance. So dont compare your shots with some one elses shots if not all variables are the same.

[dagratest816]

Yeah I'm sure both altitudes are set the same. I literally just Google what it is and input that number in to my skytrak. And I input 4400 just to compare the numbers with Rick and the mid handicapper. I just compare for numbers purposes of my "research" if you will. I have the sky caddie app that came with skytrak that I track shots with and hit a dive 282 (don't know carry distance and I know things like wind and all that affect outdoors) but for my driver on my skytrak I literally have no idea what my numbers are for that club. My biggest concern was when I fed the numbers into the trajectory optimizer for flightscope and didn't get anywhere close but the shot shape was 100% accurate. Altitude was the same because I have it at either 910 (what Google says it is for me here in Missouri, but I changed it last night again like I said... For "research" lol) is there any explanation how flightscope got more yards but skytrak didn't? Even taking out comparing Rick and the mid handicapper shots that seems weird right?

[Clevited]

I know you might not want to hear this, but your Skytrak is operating just fine. Rick for one, likely doesn't set his GCQ up for 4444 ft. His carry numbers would be 10-15 yards higher if he did. Also, you have an incredible 30 degree spin axis, and relatively high spin. That is a snap hook in my opinion. That loses quite a lot of carry right there. If you straightened that out, it would carry 250 at sea level easily. Skytrak is quite good with its carry calculations, it does however error on the low side more often than it does on the high side. I can stick some of my numbers into Traj Opt and have a 15 yard carry difference at times, but often those are the high spinners I sometimes get and at much higher ball speeds and higher launches which could be what causes that problem.

If you work on straightening those shots out you will see your carry distance come up to what you should expect. Also, I suggest not paying attention to the roll out. That is not something to rely on, on the course, or in a simulator. It can differ a ton from course to course, and sim to sim. Carry is more important and in your control anyways.

Edit: I noticed in your trajectory optimizer screen shot, you are missing your total backspin. It is backspin plus the side spin. So you are nearer to 2800 rpm. I usually make my Skytrack show me total spin and spin axis rather than side spin. That is meaningless to me.

[dagratest816]

Thanks for the info, you are probably right about elevation I was literally playing with it because before I did I had it set at my location elevation and wanted to see the changes. I keep it at 910 feet. I do have a couple questions about your comment though you said high spin. Are you referring to high side spin after mentioning the side spin of the 30 degree spin axis? I thought 1800 back spin was low spin, pretty good for a driver I thought? Also yeah I don't pay much attention to roll or total yards either I just mentioned it for the sake of the "research" to match the firm setting of the skytrak to the surface type of hard for the flightscope trajectory optimizer. I'm more concerned about the carry miscalculation. Or what seems to be a miscalculation. Also you said I'm missing backspin in my screenshot and you out it in for 2800 I see back and side spin in my screen shot matching (very close) to what skytrak had so im not sure I follow your edit comment. Thanks.

[Clevited]

I believe you need to add side spin to your backspin number for Skytrak. I added your 1800 rpm to your ~1k rpm. I could be wrong but I eliminate that issue by changing the settings of what is displayed. I only care about total spin and spin axis. If you do that, the numbers make more sense when put into TO, but you are still be short changed a little carry distance. I tend to see 10-15 yards of difference on higher spin shots, especially if they are big curvers like the one you posted.

[Clevited]

I actually think you are indeed seeing some of the Skytrak "low carry" calculation though too. I find Trajectory Optimizer to be very accurate to what I see on a Trackman for instance. Here is what you should see with your numbers at sea level. Would be a little better at 910ft where you are at.

[dagratest816]

Yeah see from my comment above the back and side spin are different than what skytrak calc'd and also what was in my screenshot above pretty sure that would cause some differences. Right?

[Clevited]

Trajectory Optimizer takes your total spin and divides it up into side spin and backspin. Notice how they add up to 2800 though. That is why I added the side and backspin for yours and got 2800. Trajectory Optimizer just does it a little differently, they all calculate ball flight just a little differently.

I really think Skytrak short changes us on carry sometimes due to how it handles spin decay. There is a thread or two about that if you search for it and want to read about it. I do think if you are in doubt of something on Skytrak, plug it into TO like you are, but make sure you put all the numbers in correctly. Spin axis and total spin make a huge different in carry. It should show you what shots ST is a little low on.

EDIT: I can't add, they don't add up to 2800 on TO, not sure what they do there and perhaps I am incorrect regarding the adding them together thing. But as I said, I just turn the settings so Skytrak only shows me spin axis and total spin, then I put that in TO for direct comparisons.

[jut111]

1st off, forget total distance. No Launch monitor is going to be accurate with that, and frankly real world conditions make rollout pretty unpredicatable - i.e. landing on a downslope, vs upslope, hard patch etc.

2nd, forget your comparisons to Rick and Rob's numbers. Your launch conditions are quite different, you cant just look at ball speeds that are close and do an apples to apples comparison.

Frankly you're hitting what I'd class as a low push snap hook. Your launching the ball 7 degrees right and finishing left of target. That's a ton of curvature and is what is robbing you of carry distance along with a low launch angle. While I agree that due to skytraks lack of spin decay modeling you're being robbed of a few carry yards, its not nearly as significant as you think.

[dagratest816]

forgive me for within my original post, i probably spent too much time referencing total distance and also rick and robs numbers, the total distances im not worried about at all i know that varies between real life conditions. the addition of rob and ricks numbers were literally just something to wrap my head around to try and understand and have a gauge of what i should be looking for in between i know its not a straight solid comparison but i did assume i could probably get some type of "gauge" if you will just understanding their numbers versus mines. The biggest concern to me was the flight scope trajectory optimizer link and its figures versus what skytrak gave me. A few carry yards to me is maybe 3-7 but 21 yards seems excessive, no? If it isnt then i can just shut up about the thing and keep it pushing lol but to me it seems like thats a bit off. And thats the carry difference not total. Thats my biggest concern, and after the other user below posted his screenshots of shots starting left of target and going right just like the flightscope optimizer showed i didnt have a super huge hook or a slice to the left after it started right, so im not quite sure what you mean when you say "ton of curvature" definitely was some curve but (not to compare apples to apples with someone hitting a ball speed of 171+ mph) but he had curve as well similar with just very higher launch. But if anything i would expect that to alter numbers on both applications not just the skytrak, if i go in and change the flightscope trajectory optimizer to a launch of 14 or 15 degrees instead of the 10 i put in because thats what my shot was, not only would the skytrak read differently but flightscope would calculate it differently as well...but would that make them still both different at a difference of 21 yards? hopefully that makes sense what i just explained. Thats my biggest concern here.

[drewtaylor21]

OP, the info above from jut111 and Brutaly is correct. The primary issue here is that you are hitting a low-launching, low-spinning hook. 30 degrees of spin axis is huge, regardless of what the image looks like on the trajectory optimizer. Get that number down in the single digits and you'll see more carry for sure (higher launch will help as well).

Have you ever used foot-spray to see where on the face you are making contact? My guess would be that the shot in question was hit towards the toe end of the face, if anything. I would encourage you to experiment with this, as contact location has a huge influence on shot patterns. Buy a $3 can of athlete's foot spray at Walmart, spray it on the face of your driver and hit some shots. Look at the data and how it changes drastically depending on contact location. I am guessing that is part of the issue here as well. Good luck!

[dagratest816]

naw i havent ever used the foot spray, i will get some of that on the way home and start checking it out though. I hope you're right for ball speeds that im hitting this closer to the toe of the club than the face bwahahahah lol. I've used contact tape before on woods and irons but that was long ago actually before i ever even got my skytrak, so i will definitely start trying the athletes foot spray trick and start checking ball contact on the club. I do really wish i could see path and club face angles but i wont even go down that road.

[Clevited]

Here are a couple examples of when Skytrak calculates carry short compared to Ttraj Opt (I suspect is mostly due to spin decay), and one where it is a little too kind to me.

[dagratest816]

I thought all i needed to do was grib down on the club? the skypro attaches to the club and measures swing speed so i assumed i would just attach it and then grip down and swing away then start doing my measurements and calculations.

[Clevited]

Club length is assumed by the Skypro if I remember correctly (sold mine a while ago). If you use apple app, there should be a club edit area where you can change club length, and it did change my swing speed value considerably when I had one.

[dagratest816]

maybe an update came out or the android version doesnt have such a thing, but i have never put in any information about club length, i just calibrate it by sitting the phone on the club, and then its ready to go from there. I'll try it and if the numbers dont look right then well I'll go from there i guess in finding my local golf store somewhere lol

[Morini]

I did not read the thread in its entirety so my apologies if I missed something.

Q1: is this particular unit defective?

AFAIK all the skytrak does is send two pictures to the PC/iPad which is then processed. If the "measured" variables (ball speed, vla, hla, spin) look reasonable, the unit itself is likely not defective.

Q2 a: Is the ball flight algorithm used by skytrak different than that of the flightscope optimizer?

Clearly yes, at least for this particular shot.

Q2 b: which algorithm is more accurate?

Don't know, obviously both have been extensively tested, but since fs is more mature so probably the safer bet.

I could be missing something, but that has how I see it.

[James James]

I questioned this myself but I knew my skytrak carry distances matched measurements from trackman. I therefore investigated and concluded the gc2/quad is quite generous with its carry calculation compared to ST:

https://exploringimpact.blogspot.co.uk/2017/03/efficiency-spin-axis.html?m=1

[James James]

And as others said tilting the spin axis reduces carry as well.

[SkyTrak_Seth]

dagratest816 , thanks for the detailed post! As others have mentioned, I would tend to agree that those distance numbers look fairly accurate when dealing with a low spin/low launch hook. There's actually quite a bit of difference between 10 and 13 degrees of launch with your ball speed - and straightening out that hook spin will get your distances up to where you think they should be.