Distance is inaccurate with the woods

[Willymakit]

Just wanted to see if anybody else went to the range and actually tested it with the woods and how accurate it was. And what results they came up with. Well this weekend I did and I can confirm that the woods are definitely short on Skytrak.

Here's my setup on how I did it. Was on the 18th tee box and was a slow day so I tested all the woods. I had a friend stand out by the landing zone and would hit the balls and he would stand where the ball landed. Then I would lazer it from tee box to where he was standing and then lazer again on where it finished. I wrote down all the numbers from the driver , 3wood and 5 wood. And recorded what was shown on Skytrak. I can confirm its at least 20 plus yards out. From what I can tell , for example. If Skytrak would say it landed at 240 yards and rolled 20 yards for a total of 260. But The lazer would say 265 on where it landed and would roll out 20 yards to end up being 285 yards. I did this on all the woods and it seems where the end result of where the ball rolled out on Skytrak would be the distance it would land shot by the lazer on the course So in the end result I sure hope that SkyTrak_Seth reads this and can figure out real quick on a solution to this problem or I'm just going to lose interest and hopefully be able to return it for something more reliable when playing simulator.

So Skytrak I hope you get this rectified ASAP or you will lose a customer.

[ryanoneill1]

Anyone who is reporting issues with distance have you hit outdoors and did you notice the same issues? I dont have distance issues, but have reported massive spin issues. I found out the issues to be with my simulator setup and not the demo skytrack unit. We should be comparing to the ball flights outside.

[Willymakit]

To answer your first question, I have one screen shot that shows center/center, and the ball was 11 yds left of centerline at 275 yds total distance. It started a little left, and it also curved a little left.

To answer your second question- if you know that you are 10-20 mph lower on ball speed that you are on trackman, using the same type balls, same driver, etc. Then, it is possible that your Skytrak is not right. BUT, first I would make darn sure that it is level and that you tee the ball up about 1 inch behind the red dot. If you tee the ball really high, then perhaps raise the Skytrak up an inch or so above the teeing ground, while keeping the ball the same distance away from the unit. If it still reads low, then there you go. Also, do you have a friend that knows their numbers? If so, ask them to warm up and hit a few balls. If they experience the same reduction in ball speed, then there you go.

More thoughts in general regarding "Center":
when v1.7 came out, this was one of the features:
"-- Added a "Center" reading for side angle and side spin when it's under certain parameters"
We just need to know what "Certain parameters" means. Perhaps "center" is 1 degree or something when it should be more like 0.5 degree to better fit most peoples definition of "center." It's all relative.

But just for the heck of it, let's look at the math:
If you hit a straight push/pull (no side spin), then for every 1 degree that you push or pull it, you'll be 3.5 yds from the centerline at 200 yds downrange. Add in some overestimated curvature, and sure, you'd be offline by some amount.

So what's your numbers that your getting 275 yards. Because the longest I can hit it is 259 yards. That's with 107 club head speed and 154 ball speed with 5200 rpm on back spin.


Now I tried last night with the tee 1/2" and 1" back of red light and it goes 30 yards offline and maybe 230 yards. Now I know I don't hit it that far off line.

[hks8888]

To answer your second question- if you know that you are 10-20 mph lower on ball speed that you are on trackman, using the same type balls, same driver, etc. Then, it is possible that your Skytrak is not right. BUT, first I would make darn sure that it is level and that you tee the ball up about 1 inch behind the red dot. If you tee the ball really high, then perhaps raise the Skytrak up an inch or so above the teeing ground, while keeping the ball the same distance away from the unit. If it still reads low, then there you go. Also, do you have a friend that knows their numbers? If so, ask them to warm up and hit a few balls. If they experience the same reduction in ball speed, then there you go.

I was typing an answer to the second question, but TorchRedRob was faster than me. My additional 2 cent is that you try to use a different type of driver if possible. I am not sure, but I remember that there was a report about driver head's colors making differences.
The point is that we try to catch something that might hinder Skytrak from capturing proper ball images. From my experience, I don't have any problem with my driver because of lower ball speeds than yours. But, I occasionally get an extremely high rpm on my mid-iron shots. More than 10,000 rpm that kills my distances by 20 yards or more. I bet this is due to something on the ball at that particular moment. I can bear with it, but your case is different, though.

Look at the photo below from the last PGA show. This guy is a professional long drive player. Look at how the set-up is adjusted for him.

[TorchRedRob]

So what's your numbers that your getting 275 yards. Because the longest I can hit it is 259 yards. That's with 107 club head speed and 154 ball speed with 5200 rpm on back spin.


Now I tried last night with the tee 1/2" and 1" back of red light and it goes 30 yards offline and maybe 230 yards. Now I know I don't hit it that far off line.

The particular shot I referenced is one of the ones I posted earlier:

148mph,18 VLA, 'CTR' HLA, 2024 spin, 'CTR' side, 257 carry, 275 total (11 yds offline left)

With 5200 rpm, it's killing the distance that skytrak is reporting to you. My shot above, but with 5200rpm instead of 2000, becomes 227 yds of carry in the flightscope optimizer. I'm sure OF would show something similar.

[wbond]

As stated before ctr, does not mean zero. You can view this on the skygolf website and see what your actual SS reading is. It would be nice to know though, at how many rpm's or degree's does it go from ctr to left or right?

[FaultyClubs]

How are you guys accounting for the basic inaccuracies of Skytrak measurements? It's specs are +/- 2 degress HLA for example (+/- 1 deg VLA, +/- 250rpm spin, +/- 1pmh ball speed).

With 4 degrees of horizontal uncertainty, 2 degrees of vertical, 2 mph on ball speed and 500 rpm on back and side spin the errors on a 250 yard carry can be MANY yards. The specs don't provide any information on the error statistics but I'm sure there are shots falling outside those boundaries too.

Add in calibration, leveling, atmospheric, ball variation, club factors, algorithmic and software errors plus who knows what else....and it might not be possible for the results to be as accurate as people would like.

It might be a useful exercise to draw the landing spot's error circle based on the stated hardware specs alone.

[TorchRedRob]

How are you guys accounting for the basic inaccuracies of Skytrak measurements? It's specs are +/- 2 degress HLA for example (+/- 1 deg VLA, +/- 250rpm spin, +/- 1pmh ball speed).

With 4 degrees of horizontal uncertainty, 2 degrees of vertical, 2 mph on ball speed and 500 rpm on back and side spin the errors on a 250 yard carry can be MANY yards. The specs don't provide any information on the error statistics but I'm sure there are shots falling outside those boundaries too.

Add in calibration, leveling, atmospheric, ball variation, club factors, algorithmic and software errors plus who knows what else....and it might not be possible for the results to be as accurate as people would like.

It might be a useful exercise to draw the landing spot's error circle based on the stated hardware specs alone.

At 250 yds, it is +/- 8.7 yds left to right, and +/- 6 yds carry.

This is for a nominal shot of 150 mph, 2250 rpm, 15 VLA, 0 HLA, 0 axis, and does not include any effects of side axis. L/R results based on trigonometry and carry distance based on FTO.

FYI- GC2 for the same shot, with their stated accuracy:

At 250 yds, it is +/- 4.4 yds left to right, and about + 4 yds, - 1 yds carry.

This is, of course, specific to this one particular shot.

These are much larger differences than the GC2, but still small compared to the OP's original concern of being 30+ yds left or right and 20+ yds short. I also wouldn't be surprised if the hardware is actually more capable than Skytrak publishes...

[longhornlove]

I believe ST is pretty accurate for irons, however I also think they are coming up short on woods. The longest drive I have ever hit on ST was 283 with 113 mph club head speed. I had a buddy of mine over who smashes it. He squared one up with 127 mph club head speed and hit it 327. This guy routinely hits and carries his 3 wood 300 yards.

[FaultyClubs]

At 250 yds, it is +/- 8.7 yds left to right, and +/- 6 yds carry.

This is for a nominal shot of 150 mph, 2250 rpm, 15 VLA, 0 HLA, 0 axis, and does not include any effects of side axis. L/R results based on trigonometry and carry distance based on FTO.

Side spin errors are important. If we assume the shot actually was dead on center with zero side spin, the ST could be off by 250 rpm either way plus the azimuth 2 deg error. This is almost 20 yards offline each way depending on what errors are occurring with the other parameters (ie 40 yards total dispersion). Allowing some reasonable room for other error sources mentioned and who knows what might be considered acceptable for ST (ie not defective). All this for a dead straight driver shot which is probably unlikely in real life.

[TorchRedRob]

Side spin errors are important. If we assume the shot actually was dead on center with zero side spin, the ST could be off by 250 rpm either way plus the azimuth 2 deg error. This is almost 20 yards offline each way depending on what errors are occurring with the other parameters (ie 40 yards total dispersion). Allowing some reasonable room for other error sources mentioned and who knows what might be considered acceptable for ST (ie not defective). All this for a dead straight driver shot which is probably unlikely in real life.

I'm not sure that the +/- 250 applies to spin axis/"side spin". This would be good to know, though. A 250 rpm error would translate to a spin axis error of +/- 6.4 degrees in the case of 2250 rpm total spin. I just can't see the spin axis varying that much because of measurement or calculation error. For comparison, at 6000 rpm total spin, the error would decrease to +/- 2.4 deg, but still that seems high.

[FaultyClubs]

ST spec is in terms of backspin and side spin separately and is +/- 250rpm on each component. I agree that's roughly 6.4 degree spin axis error in our example so apparently it does vary that much.

[TorchRedRob]

ST spec is in terms of backspin and side spin separately and is +/- 250rpm on each component. I agree that's roughly 6.4 degree spin axis error in our example so apparently it does vary that much.

Wow. You are correct. It's right there on the website. That is significant. Optimal Flight says that translates to +/- 12 yds with a 166 mph ball and 14 VLA. Add 2 deg of HLA error and that gives you 22 yds of maximum one sided error for this shot at 300 yds downrange. Not cool for a shot that was actually dead straight. I hope that the stated tolerance is some gross CYA exaggeration on their part.

[Willymakit]

How many guys adjust the sea level adjustment much higher then where your geographically are. For example I'm at 2000ft above sea level. That's where I find my woods are much shorter then irl. Last night I was adjusting the sea level all over the place from 0 to 99,999. Now I found at 10,000 my drives were going around the 260-280 range where it's irl. Now with the irons they are 20 yards farther then what I normally would hit them. So question is. How many guys set the sea level much higher then where you are geographically?

[wbond]

I don't change anything. All seems very close for my inconsistent swing.

[keithpbz]

I put elevation to 600' which is what it is where I live and adjust temp to 80* and 70% humidity. That's what it generally is in the Midwest where I'm at.