SkyTrak vs Mevo+ First Comparison

[a98cr125]

https://youtu.be/ougUXPuBVyU

So here is my first comparison. Many more to come, also using the same software. But I think this is really good to show the ST software and what it does. From what everyone is saying the ST range does not have spin decay. That would make send on how the ball on longer irons and driver is getting huge curve vs Mevo+ etc. Thoughts? Let me know in the YouTube comments. Thanks for watching and be sure to subscribe because there is a lot more coming!

[a98cr125]

[skytrakali]

Thanks - great study!

My understanding is that the ST flight algorithm does not include spin decay. There's not been a huge amount of work done on this, but lots of people use a spin decay of 4% per second of ball flight (see for example Aerodynamics of Golf Balls in Still Air, Bin Lyu, Jeff Kensrud, Lloyd Smith and Taylor Tosaya - open access on the web). Probably though it would not be that hard to write down a differential equation for spin decay by balancing friction and drag for a dimpled ball.

For a 6 second flight that means the spin drops by about 1/4 but it's hard to see that this could make the ball flight difference that's observed in your comparison.

[Morini]

I did not watch the whole video, but no, for most shots the effect is not large. Duck hooks, yes, it is huge. The easiest way is if we compare the ball data side by side. If we want a second opinion, we can then use flightscope trajectory optimizer to check.

[pwade3]

I play my Skytak and Mevo+ together all the time and have the same results. Driver toe shot will be a big draw with ST and a slice with Mevo+. I think you had the same issue with the 5 iron shot. The big draw is wrong for me but the slice seems wrong to. They both feel wrong to me, but the big draw more so. My driver toe shots usually hold the line (right of target) and once in a while will have a slight draw but they don’t usually slice either. I’m not convinced of either at the moment. Feel the Mevo+ is more accurate overall though.
Good video though, showing the shot shapes makes for good viewing of both units. Thanks again.

[StodgyBarley]

That's interesting pwade3. I just got my Mevo and am playing it beside my Skytrak. The horizontal launch seems almost identical between the 2 units but the spin seems reversed somewhat. I just figured there was some interference from some metal in my garage. I know this post of yours is from before some firmware updates.. just wondering if you got the two units presenting the same data or not? I'm kind of frustrated at the moment.

[pwade3]

StodgyBarley. I sold both units. I was a little frustrated with the Mevo+ data and the ST did not have enough data. The issue I had with HLA Of the ST was the ball would hit dead center on the screen where alignment had been validated and it would show 3 degrees one time and 0 the next.

[skytrakali]

What I got from the video was that both ST and Mevo+ are very consistent in their measurements. Essentially all they do is provide a set of initial conditions for some coupled ODEs which are then solved numerically by the associated software. The units are both measuring everything just fine - it's the equations that are a bit different.

BTW if you want to see what Trackman does then you can view it directly at

https://www.lens.org/lens/patent/195-900-135-229-626

https://www.lens.org/images/patent/US/20090075744/A1/US_2009_0075744_A1.pdf

(Actually some of the equations are missing a cos (wt) but probably this doesn't matter very much in the scheme of things)