How to test your SkyTrak numbers against GC2 numbers for the exact same shot

[Mickey]

Some of you have seen the Par2Pro video wherein Cory compares carry, ball speed, spin and launch per ST against the same numbers from GC2 for the same shot. He has the two devices side-by-side. The issue - to keep the ST from blocking the cameras on the GC2, the ball must be placed well behind ST's red dot.

I went to GolfTown this weekend to test my ST distances (driver and 6 iron only) against the GC2 using the Par2Pro method. I could never get a single shot to register on both devices until a sales associate changed the configuration (see attached image). He moved the GC2 to a few paces off my left foot and changed it to read left-handed. You'll see in the image that the green light on the GC is on and the ball is on SkyTrak's red dot.

I then hit about 30 drivers and 40 or so 6 irons. Every single shot registered on both devices perfectly. I was only interested in carry, spin, launch and ball speed. I'm pleased to report that after hitting 70 shots, a grand total of one had SkyTrak come in more than 5 yards short of GC2. In fact in virtually all cases ST distances were within +/- 5 yards of GC2 with no bias either way. This was true for driver and 6 iron. What's more, the launch, spin and ball speed were also crazy close to each other.

Bottom line: ST is not "a good launch monitor for the money" - its a "good launch monitor" - full stop.

It would take a special type of incompetence to screw this up, but it appears that SkyGolf is making a go at it.

[TorchRedRob]

Score another win for ST. Good to see!
My opinion is that the lighting is likely not the culprit, and please let us know what you figure out.

[Scyukon]

I will do. It was fun to see my drives simulating realty again!

[goatbarn]

I'm betting it's another one to chalk up under the "swinging differrently indoors" category. To new sim'ers, it's amazing how much that mental aspect effects you even though you know of it and are actively trying to opposite.

[wbond]

Glad to see another confirm their skytrak is working properly. I doubt its lighting as well, but who knows.

[Scyukon]

That's the beauty of this forum. If I do make a breakthrough I will be happy to share it with others to save them the frustration I have been through.

[Scyukon]

So the other thing that Cory and I speculated about was that the protective case raises the unit above the level of the ball. For giggles just now I went down and took the unit out out of the protective case for the first time, and hits three drives.

Yardage: 249, 248, 258!

Needless to say I am pretty stoked!

P.s. Had every light on in the basement. Going to see if can replicate feat without as much light to see if it was height of unit or lights or both or neither.

All I know is my days of 3 woods into par 4s are done!

[happybob]

I was actually thinking about buying the protective case from Skytrak also. Are you saying that it will raise the unit and make the distance inaccurate? I put the Skytrak on the same hitting surface as the ball since I use one of the large hitting mat from NetReturn.

[Scyukon]

Not 100% sure, as I need to do some more testing with less light to see if can still get the 250 distances. But by modifying those two variables I got an instant increase of about 25 yards, which I had not seen since day 1 back on December 22.

Or maybe it was a space issue, namely the 6 inches between my ears! Maybe knowing that I could actually register 250+ on the unit freed me up?

But I do seem to notice more hang time now, which could be related indeed to how high the unit was sitting. I think I may be tinkering around with my protective case and a dremel soon to see if I can make the bottom disappear.

[keithpbz]

I think the cameras are infrared and you could actually hit in a dark room. Lighting shouldn't affect them. But you never know sometimes.

[reider69]

I have a new skytrak with protective case and have it perfectly aligned per the level on the top. I took it to my golf lesson to compare to my instructors flightscope. The flightscope sits behind the ball so there were no issues that would interfere with the readings. The spin readings on the ST were 4000 rpms higher and the distance was 25 yards short.........consistently. I hit my 7 iron on the course 190-200. I can barely hit it 160 on my ST. The spin numbers on ST for a 7 iron were over 8000. Flightscope they were 4000ish. I was using precept range balls. I thought my low distances on ST were due to hitting inside my garage on a mat. I now know that the ST isn't accurate. Very disappointing.

[reider69]

I was using white balls. My golf coach was reading results side by side for over 10 balls. His conclusion was that the spin numbers and therefore the distances were off. I had unit used on ground before case. Same results. I think the flight path and launch angle are accurate but measures 25 yards short on every club. Not a deal breaker for me as I am working on swing plane and hitting I side out but accurate distance measurement would be nice as I start to practice wedges.

[ForeLeft]

I had done similar test comparing to flightscope setup by my son's coach. We all hit shots and the numbers between my skytrak and his flightscope were within 2 yards of each other. We did have an issue where flightscope would pickup only 1 out of 3 shots, which we think was due to it being setup inside and not enough light.

One time where I saw lower distance in skytrak was in the range in bright sunlight. I had to move to a location with shade and then it was back to giving accurate readings.

[Lefty13]

Interesting Reider69. My 7 iron flies between 180 and 190 but I have a tough time getting it to register anything past 155 to 160. So I'm seeing a drop of 20-25 yards for my mid to longer clubs. Hybrids are the same. My short irons and wedges are short about 10-15 yards. My pitches with my wedges are pretty normal though (75 yards and under). My garage has 10 foot ceilings so I'm not worried about hitting it with any club.

I'm wondering if there is some sort of algorithm limitation against longer hitters? I know this isn't a distance issue thread but I've paid attention to this idea on other threads and we aren't the only ones. My buddy who don't hit the ball as long and has played on my ST don't find there's much of an issue (although he's not quite as in tune with his distances). I've hit on another simulator (an older commercial one ) and those distances were about what I expected from real life.

Apologies if this comes up twice... lost my comment the first time.

[bradski]

It is more common to hit a 7 iron with 8k spin than 4k?

[luv2golf]

Is that a question or a statement?

[goatbarn]

Depends on swing speed, but yes. Usually it's the number on the iron x 1000 rpm. So 5 iron should be around 5000 rpm...etc

[TorchRedRob]

So I decided to see what I could do to get my spin down to 4000rpm with enough ball speed to fly a 7-iron 190 on the ST range. Interesting results. Gonna try to get some to spin 8000rpm later today, too. As soon as I get those results, I'll post up some photos of the data.

Teaser: the only way I got close to 4000rpm was with an e6 ball, an inside to out swing path, and intentionally launching it a few degrees higher than my norm.

[goatbarn]

Not trying to be a dick, but why?

[TorchRedRob]

1) Curiosity / fun / learning based on above posts
2) Figured if I was gonna make big statements and call someone out, I'd better back it up with some data.

[goatbarn]

Makes sense, just curious

[goatbarn]

Easiest way would be to hit the cheapest ball you can find.

1 piece, non urethane cover balls spin the least in comparison to other types.

[TorchRedRob]

E6 is closest I have to that at the house

[bradski]

Range ball. Lol.

[TorchRedRob]

Since the forum is a little bored (pinball, etc.) and sparked by the previous ST / FS comparison above, I thought it might be fun (although I guess goat doesn't see any fun in it... ) to see if I could even get a 7-iron shot to spin as low as 4000 rpm. Then I'd see if I could get one to spin 8000.

My thinking here is that you would need significant ball speed to get a 7-iron to fly 190-200 yds, and at that ball speed, there's no way the ball is only spinning 4000 rpm. I realize that swings are different, shafts, balls, and clubheads are different, etc. But I'm thinking if you can fly a 7-iron that far, then you already have pretty good swing mechanics. My idea is that with those good swing mechanics and hitting a reasonably straight ball, you'd be hard pressed to get a ball to only spin 4000rpm off a 7-iron at that ball speed.

I also wondered if it was possible to spin a 7-iron at 8000 or more. Never seen anything that high with anyone, so I thought I'd try.

So, on with the pointless endeavor:

Firstly, my ball speed is higher than average, but I'm certainly not flying a 7-iron 190. I tried to get as close as I could though. This leads me to my first conclusion:

Conclusion 1:
With a urethane tour ball, you have to have one helluva ball speed off a 7-iron to get out to 190+ yds. Best I could manage was 188 carry with 129 mph ball speed.
With an e6 or other non-urethane ball, you still have to have one helluva ball speed to get there. I recorded a 125 mph e6 with fairly high launch and fairly low spin that still only got to 185 in the air.

Conclusion 2:
Good luck getting down to 4000 rpm spin with enough ball speed to fly it 190+. Perhaps the FS is incorrect in its spin measurement in the comparison a few posts above.
The e6 almost got me down to 4000 rpm. Best I could do was an average of about 4700 rpm with the e6 ball. As expected, the e6 ball launches higher than a urethane ball, and I tried to launch it even higher to get the spin down, but still couldn't get down close to 4000, though.

Conclusion 3:
I was not able to get to 8000 rpm with a somewhat normal shot, either. I got to mid-7000's with a urethane tour ball and a cut shot. So, maybe the ST is incorrect in the situation a few posts ago. I think 8000+ might be really hard to get to. Note- I was able to get over 8000 rpm with the 7-iron, but it was more like a trick shot, and certainly not with any significant ball speed.

Conclusion 4:
I haven't hit balls very much lately, and I really should have worn some tape on my right index finger.

I'd love to see if anyone can hit a 7-iron with high ball speed and 4000 rpm or 8000 rpm. Is it even in the realm of possibility, or are both ST and FS giving BS numbers to the OP?

[Alienator]

hit some jacked loft SGI irons it makes a huge difference. The ping gmax are like 31degree 7 irons and have very low spin. SGI irons lose 2k spin over forged irons from the getgo.

[TorchRedRob]

Interesting. Had not even considered that fact. I guess low-loft SGI's can maintain normal launch angle with their lower CG, but I can see where the lower loft could kill spin. Or maybe the trampoline effect kills spin. Haven't stopped to think about the physics of it- just guessing.

[TorchRedRob]

Here are pictures of some shots with similar ball speeds, e6 first group, Callaway SR3 next, then the SR3 8000 rpm attempts are the ones in the separate session.

(And this is what I do when there is no sim available...)

[AndyF]

I'd love to see if anyone can hit a 7-iron with high ball speed and 4000 rpm or 8000 rpm. Is it even in the realm of possibility, or are both ST and FS giving BS numbers to the OP?

I've got some figures from my range sessions with crappy Srixon range balls.
2 shots from the same session using my 7 iron with different balls gave the following

ball speeds: 129, 123
VLA: 18.6, 15.8
spin: 4047, 6678
Carry: 198, 170
Total: 204, 174

The max spin I've had with my 7-iron on normal swings is 7294rpm with a ball speed of 121, VLA of 18.8 and a carry of 164

Andy

[coz]

Since the forum is a little bored (pinball, etc.) and sparked by the previous ST / FS comparison above, I thought it might be fun (although I guess goat doesn't see any fun in it... ) to see if I could even get a 7-iron shot to spin as low as 4000 rpm. Then I'd see if I could get one to spin 8000.

My thinking here is that you would need significant ball speed to get a 7-iron to fly 190-200 yds, and at that ball speed, there's no way the ball is only spinning 4000 rpm. I realize that swings are different, shafts, balls, and clubheads are different, etc. But I'm thinking if you can fly a 7-iron that far, then you already have pretty good swing mechanics. My idea is that with those good swing mechanics and hitting a reasonably straight ball, you'd be hard pressed to get a ball to only spin 4000rpm off a 7-iron at that ball speed.

I also wondered if it was possible to spin a 7-iron at 8000 or more. Never seen anything that high with anyone, so I thought I'd try.

So, on with the pointless endeavor:

Firstly, my ball speed is higher than average, but I'm certainly not flying a 7-iron 190. I tried to get as close as I could though. This leads me to my first conclusion:

Conclusion 1:
With a urethane tour ball, you have to have one helluva ball speed off a 7-iron to get out to 190+ yds. Best I could manage was 188 carry with 129 mph ball speed.
With an e6 or other non-urethane ball, you still have to have one helluva ball speed to get there. I recorded a 125 mph e6 with fairly high launch and fairly low spin that still only got to 185 in the air.

Conclusion 2:
Good luck getting down to 4000 rpm spin with enough ball speed to fly it 190+. Perhaps the FS is incorrect in its spin measurement in the comparison a few posts above.
The e6 almost got me down to 4000 rpm. Best I could do was an average of about 4700 rpm with the e6 ball. As expected, the e6 ball launches higher than a urethane ball, and I tried to launch it even higher to get the spin down, but still couldn't get down close to 4000, though.

Conclusion 3:
I was not able to get to 8000 rpm with a somewhat normal shot, either. I got to mid-7000's with a urethane tour ball and a cut shot. So, maybe the ST is incorrect in the situation a few posts ago. I think 8000+ might be really hard to get to. Note- I was able to get over 8000 rpm with the 7-iron, but it was more like a trick shot, and certainly not with any significant ball speed.

Conclusion 4:
I haven't hit balls very much lately, and I really should have worn some tape on my right index finger.

I'd love to see if anyone can hit a 7-iron with high ball speed and 4000 rpm or 8000 rpm. Is it even in the realm of possibility, or are both ST and FS giving BS numbers to the OP?

i normally hit 7 iron 155 and if i give it a bit more i can control up to 170 carry. Over swinging my max carry was 188. Ball speeds scattered throughout the 120s. Most spin rates were in the low 7k range some high 6k range. My most spin registered was 7982. Urethane covered golf balls. I never attempted 4k range. I would trust ST spin rate over FS. 4k C'Mon man! Maybe FS needed a few more metal stickers placed on the ball? ?

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