Opinion-Launch Monitor Algorithms and How they Dupe People

[RCGA]

25 minutes ago, clevited said:

 

This!  I must have glossed over this comment earlier.  Would you happen to have a link to the video(s) where these observations were talked about?  This would corroborate some of my findings.

 

Here's one example. 

 

118 SS, 1800 RPM, "high on the heel", 325 yards.

 

He spends the entire video hitting 300y+ carry, 325y+ total drives all within 20y dispersion cone left/right. He'd be the best driver on tour if this was realistic.

 

 

[clevited]

1 hour ago, RCGA said:

 

Here's one example. 

 

118 SS, 1800 RPM, "high on the heel", 325 yards.

 

He spends the entire video hitting 300y+ carry, 325y+ total drives all within 20y dispersion cone left/right. He'd be the best driver on tour if this was realistic.

 

 

 

Thanks for the video.  Did he ever mention his observations of its playability on the course (in other words, did he admit it wasn't playable?) or no?

 

Edit: Added a picture from one of my favorite videos they did that exemplifies what I am talking about.  

 

Here is the video link too for anyone interested.

 

Edited September 20, 2021 by clevited

[RCGA]

2 minutes ago, clevited said:

 

Thanks for the video.  Did he ever mention his observations of its playability on the course (in other words, did he admit it wasn't playable?) or no?

 

I'm not sure they ever mention it. 

 

But to be honest, I find these reviews to be incredibly boring. It's tough to watch someone hitting into a net for 20 minutes with numbers that don't match reality.

[clevited]

2 minutes ago, RCGA said:

 

I'm not sure they ever mention it. 

 

But to be honest, I find these reviews to be incredibly boring. It's tough to watch someone hitting into a net for 20 minutes with numbers that don't match reality.

 

I find it kind fun to watch people try and get one out there as far as possible lol.  Their videos are examples of how people can get duped though (although I don't believe that is their intention at all, I think they are just as ignorant and overly trusting of their machine as many others are, plus they may be sponsored by FS for all I know so they likely can't say anything bad).  No doubt a lot of people that watched that think autoflex got Matt to hit 390 with driver.  It sold a lot of people on that shaft.  You have no idea how many people I know that bought that and sold it not too long after.  To me that is an example of getting duped by wildly inaccurate launch monitor data which to me is especially bad coming from one of the big 3 manufacturers of them. FS need to fix their algo badly imo. 

[Kmagnuss]

1 hour ago, RCGA said:

 

Here's one example. 

 

118 SS, 1800 RPM, "high on the heel", 325 yards.

 

He spends the entire video hitting 300y+ carry, 325y+ total drives all within 20y dispersion cone left/right. He'd be the best driver on tour if this was realistic.

 

 

They have a disclaimer on their newer videos stating that they don't count all the shots and only keep the good ones.  You can see the "shot #" on the top right corner go out of order most times.  It will go 4,5,8,12,15, etc... (for example)

 

-Mag

[mgoblue83]

2 hours ago, clevited said:

 

This!  I must have glossed over this comment earlier.  Would you happen to have a link to the video(s) where these observations were talked about?  This would corroborate some of my findings.

 

It's the 2020 driver bracket and then later that summer they did a course vlog where the driver was an absolute mess. 

[Daniel Eason]

The only way to solve this is to have a measuring device to back the data up in the ball on the other end.

 

I wonder if TM/Foresight have thought about this?

 

 

[clevited]

3 hours ago, Daniel Eason said:

The only way to solve this is to have a measuring device to back the data up in the ball on the other end.

 

I wonder if TM/Foresight have thought about this?

 

 

 

That would be great, I would also settle for some independent, thorough physical testing of the accuracy of launch monitors.  This is something I may end up doing myself one day and posting on youtube.

[amace04]

I'd agree mostly.

 

I've only used a foresight product twice, but I was at golftown once and they have a GCHawk.  I wanted to test a few different shafts to get my spin down. I'm a high launch driver and I know my ball flight.

The GCHawk had my drive at about 900rpm on what I'd think are pretty good strikes and the ball falling out of the sky at about 230.  I unfortunately don't have accurate spin measurements for my typical drive, but I know it can be prone to spinning too much and ballooning up.  No way I'm hitting 900.  If I really focused on flattening my attack angle I could get it up to about 1300 and get good carry.  I could only imagine someone who hits their driver "normally" and is wanting to try a new SIM 2 or something and will magically see the ideal spin and launch conditions even though their swing in all likelihood is nowhere near ideal.

[RCGA]

Is there a website where I can enter ball speed, spin, temperature, wind, etc. and it tell me how far the ball will go? I'm trying to verify some numbers from my PRGR.

[clevited]

1 hour ago, RCGA said:

Is there a website where I can enter ball speed, spin, temperature, wind, etc. and it tell me how far the ball will go? I'm trying to verify some numbers from my PRGR.

Best out there that will do that, that I am aware of is Optimal Flight.  It is an Excel based program for sale at like 10 bucks per machine you install it on per year.  

[crussogolf]

7 hours ago, RCGA said:

Is there a website where I can enter ball speed, spin, temperature, wind, etc. and it tell me how far the ball will go? I'm trying to verify some numbers from my PRGR.

Flightscope has a trajectory optimizer.  I find it to be pretty decent and representative of my outdoor distances using known launch conditions ( I have an X3).  Honestly, flightscope's algorithm does probably the best job I've seen estimating ballflight and carry distance (the environmental optimizer built into their VX software seems good based on my observation).

 

Foresight really needs to fix the low spin/high ballspeed thing.  The few times I've used a gc2, everything was pretty close outside of those freak ball low spinners off the Dstick. 🙂 

 

 

https://flightscope.com/products/trajectory-optimizer/

Edited September 25, 2021 by crussogolf

[RCGA]

15 hours ago, clevited said:

Best out there that will do that, that I am aware of is Optimal Flight.  It is an Excel based program for sale at like 10 bucks per machine you install it on per year.  

 

9 hours ago, crussogolf said:

Flightscope has a trajectory optimizer.  I find it to be pretty decent and representative of my outdoor distances using known launch conditions ( I have an X3).  Honestly, flightscope's algorithm does probably the best job I've seen estimating ballflight and carry distance (the environmental optimizer built into their VX software seems good based on my observation).

 

Foresight really needs to fix the low spin/high ballspeed thing.  The few times I've used a gc2, everything was pretty close outside of those freak ball low spinners off the Dstick. 🙂 

 

 

https://flightscope.com/products/trajectory-optimizer/

 

Thanks for these. It confirms my thinking, the PRGR is dead accurate on ball speed and the rest of the numbers don't really matter outside a club fitting. 

 

Assuming it's a "normal" ball flight, I can cross reference the numbers from the Trackman stats off the PGA Tour (https://blog.trackmangolf.com/trackman-average-tour-stats/) and get distances within 0-3 yards of reality. 

 

Then using the FlightScope optimizer, I can then see how a +/- change in ball speed impacts distance.

[Blaiser]

To me, when it comes to carry distances I really only care about wedges and irons. I find them to be pretty accurate on the high level launch monitors.

 

With driver, I really only care about the ball speed. Driver is the one club you are trying to maximize distance, and I can deduce all I need from the ball speed.

 

The spin, launch angle, spin axis....etc are never going to be perfect on every reading. And even if they were, I'm certain I don't have the skill level to stand on the tee with my driver and say "ok, this one I'm going to launch 2.7 degrees lower than normal and also lower my average spin by 650rpm."

 

At my home course, I can have up to 50 yard deltas on where my drive ends up on shots I felt like I flushed with the driver. Weather, course conditions...etc can do that. To me, I just chalk it up to "golf"

 

However, I rarely have huge deltas with my wedges and mid irons. I find that using a launch monitor to dial in wedge/iron distances is very helpful. And I'm more likely to control spin/launch angle with those clubs too.

 

So in the end, the only things I'm looking for with driver data on a launch monitor is ball speed, and also knowing if I'm hitting duck hooks or not. Which I do more than I'd like to admit.

[hammersia]

I spent some time hitting on GC2 indoors at the weekend, I found the driver calculations... silly to be honest. It wasn't my GC2 and I suspect the software hadn't been updated for a while, but with a ball speed of 154mph I got a carry of.... 271 yards. 0 elevation as far as I could see on the settings. New ProV1.

 

It's possible there was a bit of indoor swing syndrome, because on a couple of other monitors my ball speed is close to 160, but my real world  carry is 235-240. 

 

(Iron distances looked a bit far with too little spin as well so I'm not convinced the monitor was perfectly setup tbh, but it's the distance algorithm off whatever numbers are captured that looks very strange)

 

 

 

[Stuart_G]

2 hours ago, hammersia said:

I spent some time hitting on GC2 indoors at the weekend, I found the driver calculations... silly to be honest. It wasn't my GC2 and I suspect the software hadn't been updated for a while, but with a ball speed of 154mph I got a carry of.... 271 yards. 0 elevation as far as I could see on the settings. New ProV1.

 

 

Foresight is well known for over estimating distance on low spin driver shots.  That is an algorithm issue and not something they've ever addressed to my knowledge (so updates would not likely help).

 

Also, if the tee height is not exactly the same as what you are used to on the course, it can effect the delivery and (especially) face impact location - both of which can significantly effect the launch and spin.

 

 

2 hours ago, hammersia said:

(Iron distances looked a bit far with too little spin as well so I'm not convinced the monitor was perfectly setup tbh, but it's the distance algorithm off whatever numbers are captured that looks very strange)

 

That's not a setup issue or the algorithms.   It's very common when hitting off mats for the spin with irons to be quite low - which can greatly effect the distances.

 

Edited November 1, 2021 by Stuart_G

[hammersia]

6 minutes ago, Stuart_G said:

 

 

Foresight is well known for over estimating distance on low spin driver shots.  That is an algorithm issue and not something they've ever addressed to my knowledge (so updates would not likely help).

 

Also, if the tee height is not exactly the same as what you are used to on the course, it can effect the delivery and (especially) face impact location - both of which can significantly effect the launch and spin.

 

 

 

That's not a setup issue or the algorithms.   It's very common when hitting off mats for the spin with irons to be quite low - which can greatly effect the distances.

 

Yep, I was familiar with those issues, but didn’t realise until spending more time on gc2 how pronounced they were. Unless you’re shooting for sensible 2800rpm driver spin targets then driver fitting seems pointless. 
 

I have my own CCE mat setup so knew a bit about reduced iron spin, this mat was more like a Fiberbilt and the fliers were more pronounced. 

The good bit - the worthwhile bit - was shot shape, which ‘felt right’.

 

[Stuart_G]

3 minutes ago, hammersia said:

Yep, I was familiar with those issues, but didn’t realise until spending more time on gc2 how pronounced they were. Unless you’re shooting for sensible 2800rpm driver spin targets then driver fitting seems pointless. 
 

 

Not really, a bit inconvenient maybe but far from pointless.  Ball speed, launch angle and actual spin numbers are accurate and can be used for the fitting to judge relative performance of different options.  Distance is only a small part of the driver fitting anyways.

 

[hammersia]

52 minutes ago, Stuart_G said:

 

Not really, a bit inconvenient maybe but far from pointless.  Ball speed, launch angle and actual spin numbers are accurate and can be used for the fitting to judge relative performance of different options.  Distance is only a small part of the driver fitting anyways.

 

 

I'm sure you'll agree that depends on the fitter. Big box stores? Perceived distance is everything. 

[Stuart_G]

Just now, hammersia said:

 

I'm sure you'll agree that depends on the fitter. Big box stores? Perceived distance is everything. 

 

I wouldn't call anyone in a big box store a fitter - or anything done there a fitting.  😆

[mgoblue83]

3 hours ago, hammersia said:

I spent some time hitting on GC2 indoors at the weekend, I found the driver calculations... silly to be honest. It wasn't my GC2 and I suspect the software hadn't been updated for a while, but with a ball speed of 154mph I got a carry of.... 271 yards. 0 elevation as far as I could see on the settings. New ProV1.

 

It's possible there was a bit of indoor swing syndrome, because on a couple of other monitors my ball speed is close to 160, but my real world  carry is 235-240. 

 

(Iron distances looked a bit far with too little spin as well so I'm not convinced the monitor was perfectly setup tbh, but it's the distance algorithm off whatever numbers are captured that looks very strange)

 

 

 

 

The bigger problem is Foresight makes that shot out to look like a nice draw but I guarantee if you hit that shot outdoors it's a borderline duck hook. 1700 spin with that much tilt just won't stay in the air. 

[hammersia]

51 minutes ago, mgoblue83 said:

 

The bigger problem is Foresight makes that shot out to look like a nice draw but I guarantee if you hit that shot outdoors it's a borderline duck hook. 1700 spin with that much tilt just won't stay in the air. 

 I think I agree, but I can't see much discussion of real world side spin numbers - in other words if you hit a driver with 2800rpm of backspin, 155mph ballspeed, 12 degree launch, how many rpm of side spin is required for a 15 yard draw? Etc. etc.

[mgoblue83]

2 hours ago, hammersia said:

 I think I agree, but I can't see much discussion of real world side spin numbers - in other words if you hit a driver with 2800rpm of backspin, 155mph ballspeed, 12 degree launch, how many rpm of side spin is required for a 15 yard draw? Etc. etc.

 

Good question and I don't know the answer but almost nobody should be trying to get less than 2000 spin. Spin less than 2000 just won't stay in the air unless your ball speed is 170-180mph and if you do tilt the ball it's going to curve like crazy and dive out of the air.

 

For your average single digit player with ball speeds of 150-160mph you really want spin around 2500 to stabilize the flight (reduce curve) and keep the ball in the air. Remember backspin makes the ball curve less similar to how a bicycle at speed stays upright.

 

 

This is the major issue with Foresight software:

Sub 2000 spin stays in the air when it really shouldn't and gives super inflated carry numbers vs. reality. 

Edited November 1, 2021 by mgoblue83

[HiTrajLoSpin]

5 hours ago, hammersia said:

 in other words if you hit a driver with 2800rpm of backspin, 155mph ballspeed, 12 degree launch, how many rpm of side spin is required for a 15 yard draw? Etc. etc.

 

Here's an example using the Flightscope Trajectory Optimizer (FTO); I used your inputs for backspin, ball speed, launch angle, and then assumed the spin axis was tilted 15° left (to produce a draw). Note that the FTO assumed the 2800 rpm was total spin (i.e., 2705 backspin + 725 sidespin). It's hard to tell the exact amount of shot curvature (because the drawing doesn't show distance scales), but if you use your imagination you miiight see about a 15 yard draw 😉.

 

 

 

Edited November 1, 2021 by HiTrajLoSpin

[HiTrajLoSpin]

On 11/1/2021 at 2:33 PM, mgoblue83 said:

For your average single digit player with ball speeds of 150-160mph you really want spin around 2500 to stabilize the flight (reduce curve) and keep the ball in the air. Remember backspin makes the ball curve less similar to how a bicycle at speed stays upright.

 

I don't know how this notion of backspin stabilizing flight and making the ball curve less has been perpetuated, but it's just untrue.

 

After a golf ball is struck, its trajectory is only determined by 3 forces: gravity, aerodynamic drag, and aerodynamic lift due to spin (Magnus effect). Gravity and drag forces have no effect on horizontal curvature of its trajectory, only the forces due to spin.

 

If the ball's initial spin axis tilt is zero with respect to the horizontal, the amount of backspin is irrelevant with respect to trajectory curvature (what you term as stability). Certainly, the amount of lift force increases with added backspin, but that's only in the vertical direction and therefore, doesn't affect trajectory curvature, it only increases the time the ball is in the air.

 

However, if the ball's initial spin axis tilt is non-zero, then the lift force has horizontal, as well as vertical, components, which result in trajectory curvature (instability); and increased spin produces more horizontal force and more curvature.

 

 

[whumber]

8 hours ago, HiTrajLoSpin said:

However, if the ball's initial spin axis tilt is non-zero, then the lift force has horizontal, as well as vertical, components, which result in trajectory curvature (instability); and increased spin produces more horizontal force and more curvature.

The idea is that by adding more backspin you diminish the effect of whatever sidespin is added from face-to-path angle or gear effect and promote a more neutral spin axis at launch, not that the backspin changes the spin axis mid-flight.

[Stuart_G]

17 hours ago, HiTrajLoSpin said:

 

I don't know how this notion of backspin stabilizing flight and making the ball curve less has been perpetuated, but it's just untrue.

 

It's a misinterpretation of the concept/recommendation that more loft can help reduce offline tendencies.    The recommendation is valid (but only if the increase in loft is big enough) but the interpretation of why it actually helps is not understood correctly and frequently misrepresented in these types of posts.

 

8 hours ago, whumber said:

The idea is that by adding more backspin you diminish the effect of whatever sidespin is added from face-to-path angle or gear effect and promote a more neutral spin axis at launch, not that the backspin changes the spin axis mid-flight.

 

No, that's not correct either.   Well, your interpretation of the idea is correct, it's the idea itself that's just wrong and has no actual basis so support it. 

 

As @HiTrajLoSpin tried to explain, lateral curvature of the ball comes from side spin alone, not the tilt axis.   Adding more backspin does not mean less lateral curvature.   Instead, the backspin influences the hang time and distance.

 

The recommendation that more loft (not just more spin) helps with offline tendencies comes down to distance.  Higher launch/spin means shorter carry distance and that also means less distance offline.   So only a significant (~5*+) change in loft will really help in practice.   It's as simple as that yet people continually try to make it more complex then it has to be, read more into it then there really is, or mistakenly think smaller changes can provide a noticeable amount of help.

 

So the recommendation is really about a suggestion to use a 3wd off of tight tees instead of the driver when offline misses would be overly penalizing.   It has no place in fitting the equipment to the player.

 

 

Edited November 3, 2021 by Stuart_G

[mgoblue83]

2 hours ago, Stuart_G said:

 

It's a misinterpretation of the concept/recommendation that more loft can help reduce offline tendencies.    The recommendation is valid (but only if the increase in loft is big enough) but the interpretation of why it actually helps is not understood correctly and frequently misrepresented in these types of posts.

 

 

No, that's not correct either.   Well, your interpretation of the idea is correct, it's the idea itself that's just wrong and has no actual basis so support it. 

 

As @HiTrajLoSpin tried to explain, lateral curvature of the ball comes from side spin alone, not the tilt axis.   Adding more backspin does not mean less lateral curvature.   Instead, the backspin influences the hang time and distance.

 

The recommendation that more loft (not just more spin) helps with offline tendencies comes down to distance.  Higher launch/spin means shorter carry distance and that also means less distance offline.   So only a significant (~5*+) change in loft will really help in practice.   It's as simple as that yet people continually try to make it more complex then it has to be, read more into it then there really is, or mistakenly think smaller changes can provide a noticeable amount of help.

 

So the recommendation is really about a suggestion to use a 3wd off of tight tees instead of the driver when offline misses would be overly penalizing.   It has no place in fitting the equipment to the player.

 

 

 

 

A knuckle ball pitcher in baseball would disagree. 

[Stuart_G]

8 minutes ago, mgoblue83 said:

 

 

A knuckle ball pitcher in baseball would disagree. 

 

Then I guess it's a good thing this is a golf discussion forum/topic and not a baseball one.  Besides, I've never met a pitcher that when pitching, had to worry about water hazards, OB, and lost balls. 😆

 

It's rotation in general that provides stability in flight.  And by 'stability' I mean consistent, predictable motion, not the lack of curvature.    The previous uses of "stability" are really have nothing to do with actual stability of the flight.  The real instability we need to deal with here is instability of the golf swing itself, not of the ball in flight.

 

Edited November 3, 2021 by Stuart_G

[Krt22]

1 hour ago, Stuart_G said:

 

It's a misinterpretation of the concept/recommendation that more loft can help reduce offline tendencies.    The recommendation is valid (but only if the increase in loft is big enough) but the interpretation of why it actually helps is not understood correctly and frequently misrepresented in these types of posts.

 

 

No, that's not correct either.   Well, your interpretation of the idea is correct, it's the idea itself that's just wrong and has no actual basis so support it. 

 

As @HiTrajLoSpin tried to explain, lateral curvature of the ball comes from side spin alone, not the tilt axis.   Adding more backspin does not mean less lateral curvature.   Instead, the backspin influences the hang time and distance.

 

The recommendation that more loft (not just more spin) helps with offline tendencies comes down to distance.  Higher launch/spin means shorter carry distance and that also means less distance offline.   So only a significant (~5*+) change in loft will really help in practice.   It's as simple as that yet people continually try to make it more complex then it has to be, read more into it then there really is, or mistakenly think smaller changes can provide a noticeable amount of help.

 

So the recommendation is really about a suggestion to use a 3wd off of tight tees instead of the driver when offline misses would be overly penalizing.   It has no place in fitting the equipment to the player.

 

 

This is getting a bit into the weeds, but aren't side spin and spin axis directly linked via mathematical formula? Same goes for backspin and axis tilt, the only way to get more back spin is to delivery more dynamic loft. The more dynamic loft you deliver, the lower the spin axis for the same face/path ratio.  But as total spin goes up, so does side spin for the same given spin axis. I am not certain if there are any inflection points in there. Assumptions here are  100mph CHS, 0 AoA, -4 club to path ratio. Shot 1 has 14.5* of dynamic loft, shot 2 has 11.5* of dynamic loft. Playing with trackmans calculators I get the following, with the key caveat being they likely hold total spin constant in their offline calculator where you can play with spin axis.

 

From the spin axis/total spin calculators based off Club, path, dynamic loft, AoA.

Shot 1-14.6 spin axis, 2751 total spin, 693 side spin (based on formula)

 

Shot 2-17.9 spin axis, 2182 total spin, 670 side spin

 

From the offline calculator for spin axis.

 

Shot 1-14.6 spin axis 238 carry,  ~77 ft offline

 

Shot 2-17.9 spin axis, 236 carry, 95ft offline.