"Smash Factor" - PTI Rating calculation - clubhead speed...

[acn684]

How does that even work on Skytrak? Since smash is basically (ball speed)/(club head speed), this figure is only useful if you can measure clubhead speed. From my understanding, skytrak can't measure club head speed. So is the way club head speed is presented via (ball speed)/(potential smash) factor of the club? That would be a little silly no? It's like backsolving a number using a fixed variable...which would not give PTI results and clubhead speed results any value. I'm just wondering what that's even a figure that is presented in the charts.

[Wyzyguy]

I have found PTI usefel for spin rates with wedges.. The lower the PTI the more spin I have found. On pured wedges I get figures below .70. I am not to concerned with swingspeed... ball speed to me is a better indicator of speed and strike that club speed. I could swing a 120 and have a ball speed of 150... the 150 is the number that matters to me.

[acn684]

I have found PTI usefel for spin rates with wedges.. The lower the PTI the more spin I have found. On pured wedges I get figures below .70. I am not to concerned with swingspeed... ball speed to me is a better indicator of speed and strike that club speed. I could swing a 120 and have a ball speed of 150... the 150 is the number that matters to me.

But is that PTI number real? You can't measure smash unless you know club head speed (from what i understand). Smash measures efficiency of energy transfer. So a 150 ball speed with a 100 mph club head speed is a 1.5 smash - this only occurs when the person swinging it hits it on the center of the clubface and with a proper face angle to path relationship. An amateur with a 100 mph club head speed might hit closer to the heel of the face with a cut/slice club face pattern an only get 140 mph ball speed so a 1.4 smash. In a sense you can measure the quality of strike given two same swing speeds.

It seems like Skytrak does this calculation backwards. Given the above scenario where two people swing the same speed but have different qualities of strike. They assume a 1.5 smash factor and if they see a ball speed of 150mph, then the clubhead speed is 100. If they see a ball speed of 140mph, then they calculate the clubhead speed to be 93 MPH. This would be completely nonsensical.

If skytrak doesn't measure club head speed, how is the smash factor (pti) even being calculated? If it only measures ball speed and then uses a certain "factor" to calculate clubhead speed (i'm guessing the factor is determined by what club you have set the club to - lets say its 1.5 when you select driver), then using this calculated "club-head speed" to measure PTI (smash-factor) is just a loop. So what is the point of displaying PTI?

[Wyzyguy]

That is a question for SkyTrak_Seth .. I know that PTI is not a fixed # because the value changes. Before there was the PTI is was doing the calculations in excel myself. Same equation. It is probably some type of algo. As mentioned I am more concerned with ball speed, LA, Spin Rates than SF or PTI.. I find PTI to be useful for quality of strike & launch with wedges. Anything near 1.0 is like throwing a ball... Where the ball and your clubhead are very close MPH & makes judging the carry and rollout a little more predictable than a PTI of say .70 where the ball with come off slower than the clubhead because of spin loft, dynamic loft and backspin.. Going up with spin.

I actually have not paid much attention to PTI on driver because driver parameters for my needs are all ball speed, LA, Back Spin and HA... Matching LA with spin in a way that I can repeat it. It I could hit a driver @ 15* & 1700 spin over and over I would be doing that because it would work great with my ball speed. I have better luck repeating 13* @ 2000 without hooking it off the planet.

[TorchRedRob]

I believe they use launch angle and spin to factor into the calculation. granted, still approximate, but better.

[SkyTrak_Seth]

It's a good question. We currently calculate club speed based on all measured parameters and if you hit a shot in the center of the club face, the swing speed is extremely accurate. But you are correct, at the end of the day, our PTI is only as good as our club speed calculation.

[moadhia]

Last night, I was hitting pitching wedge on my Skytrak with SkyPro attached to my PW. The club head speed displayed on the SkyTrak is quite off. SkyTrak consistently showed my PW club speed of 83-86 mph, meanwhile SkyPro showed 77-78 Mph. I trust SkyPro and PGA tour avg PW speed is 83 mph, so SkyTrak club head speed number is quite off, rendering the PTI number useless in my opinion.

[GungHoGolf]

I agree that club speed and PTI numbers are way off... see the PW data I posted tonight at http://golfsimulatorforum.com/forum/...han-ball-speed

Wrong/misleading numbers are worse than no numbers... I really hope SkyTrak gets this resolved. Should just be a software tweak. My guess is the algos are lowering PTI too much for given spin numbers and launch angles.

And to the poster above who had a PW PTI of 0.70 and liked it... I don't think that's even possible in real life, except for a bunker shot where the club head sometimes passes the ball. PGA and LPGA smash factors with PW are around 1.28.

[acn684]

I agree that club speed and PTI numbers are way off... see the PW data I posted tonight at http://golfsimulatorforum.com/forum/...han-ball-speed

Wrong/misleading numbers are worse than no numbers... I really hope SkyTrak gets this resolved. Should just be a software tweak. My guess is the algos are lowering PTI too much for given spin numbers and launch angles.

And to the poster above who had a PW PTI of 0.70 and liked it... I don't think that's even possible in real life, except for a bunker shot where the club head sometimes passes the ball. PGA and LPGA smash factors with PW are around 1.28.

I had a 1.45 6 iron...lol. Id rather they actually use max smash factors for specific clubs to estimate pti.


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[jut111]

are you telling it what club your hitting? I haven't played with it much as I just chose to ignore PTI and clubhead speed. But I'm wondering if it assumes a different PTI (smash) with different clubs.

[GungHoGolf]

I had a 1.45 6 iron...lol. Id rather they actually use max smash factors for specific clubs to estimate pti.

I think you mean to use max smash factors (PTI) to estimate club head speed, and if so, I agree with you.


SkyTrak_Seth, whaddya think about just fixing the PTI numbers at something reasonable for each club (LMGA avg numbers would be fine), then calculating club head speed based on that and ball speed? Worst case, it would show our CH speed as lower than actual, cause most of us don't reach the PTI numbers that the pros do, even the ladies. But at least it wouldn't produce wildly wrong data, as is the case now.

[SkyTrak_Seth]

It's very hard to accurately calculate swing speed (and PTI) without knowing the club and ball you are using. That said, we will have some exciting new features/integrations that I think you'll be happy to see coming in late Q1.