Facts re Impact II

[burners]

Mandrin's recent post on this subject had some very good (interesting) data as it related to impact conditions. I haven't seen any data recently (if ever) on what the length (in distance) of impact is...so I thought I'd do the nums.

Intuitively, I thought because of the very short time interval, that this length would be on the order of a couple millimeters (or less). Not so!

Using the case were the impact dwell time intersects the .0004 line (approx 57m/sec or about 127 mph), I get 22.8 mm (.9 inch).

Feel free to check my work, but if this is about correct, can the true clubface angle change more than a couple of tenths of a degree during the impact interval?

 

[Brian Manzella]

Mandrin's recent post on this subject had some very good (interesting) data as it related to impact conditions. I haven't seen any data recently (if ever) on what the length (in distance) of impact is...so I thought I'd do the nums.

Intuitively, I thought because of the very short time interval, that this length would be on the order of a couple millimeters (or less). Not so!

Using the case were the impact dwell time intersects the .0004 line (approx 57m/sec or about 127 mph), I get 22.8 mm (.9 inch).

Feel free to check my work, but if this is about correct, can the true clubface angle change more than a couple of tenths of a degree during the impact interval?

I have been studying impact for a long time and I have NEVER heard of anything as long as 9/10th of an inch.

I'll make a couple of calls for some up-to-date info, but the last I heard was .25 to .75 max.

 

[savydan]

When you see a close up SwingVision of impact, can't you make a good approximation knowing the diameter of the ball for scale purposes?

Just for kicks, I assume the ball stays on the face 3/4 of an inch and we are swinging 100 mph.

Rate x Time = Distance

Time = Distance/Rate

Distance = 0.75 inch = 0.0625 feet

Rate = 100 miles per hour = 528,000 feet per hour = 147 feet per second

0.0625 feet/147 feet per second = 0.0004 sec that the ball stays on the face. At least a decent approximation.

 

[hcw]

Guesstamite

When you see a close up SwingVision of impact, can't you make a good approximation knowing the diameter of the ball for scale purposes?....

it always looks to me on those that the ball is gone by the time the club has moved midway thru where the ball is...so equal to or less than half the diameter of a golf ball?

 

[savydan]

it always looks to me on those that the ball is gone by the time the club has moved midway thru where the ball is...so equal to or less than half the diameter of a golf ball?

That's what I see too: so maybe 3/4 inch?

 

[burners]

Another data point

I did the calculation for a point on the graph that corresponds with a much slower swing speed to get a feel for how sensitive the variables are. At approx .000525 sec dwell time and a 28m/s (63 mph) velocity the distance is .579 inch.

An assumption in the calculations is constant velocity (it's a wall), so if one accounted for some impact deceleration of a clubhead, maybe the .898 inch (at 127mph) goes down a little, but not as much as .579 inch--63 mph is pretty slow. (But then again, 127 mph is pretty fast!)

Guess my point is the answer is probably somewhere in between, but this still seems a bit long.

Does this matter? Seems like a rapidly-rotating clubface could close a few degrees between initial touch and separation.

 

[savydan]

Ah...no

I did the calculation for a point on the graph that corresponds with a much slower swing speed to get a feel for how sensitive the variables are. At approx .000525 sec dwell time and a 28m/s (63 mph) velocity the distance is .579 inch.

An assumption in the calculations is constant velocity (it's a wall), so if one accounted for some impact deceleration of a clubhead, maybe the .898 inch (at 127mph) goes down a little, but not as much as .579 inch--63 mph is pretty slow. (But then again, 127 mph is pretty fast!)

Guess my point is the answer is probably somewhere in between, but this still seems a bit long.

Does this matter? Seems like a rapidly-rotating clubface could close a few degrees between initial touch and separation.

I'm not mandrin, but I do like "back of the envelope" calculations just to put some perspective on things.

Guys......4 ten-thousandths of a sec is a VERY short time!!!!!!!!

If you could rotate a clubface 3 degrees in 0.0004 sec that means you could rotate it 7,500 degrees in 1 second. As Brian would say, got it?

Since there are 360 degrees in a full revolution, that means you could spin the club face in your hands 21 times in a second. Does anyone play golf this way??? Maybe "fooseball" or whatever they call that table soccer game.

Now we are going to multiply 21 x 60 and get 1,260 RPM.

Does anyone put 1,260 RPM of clubface closure or openness on a swing? No.

Not much of anything happens in 0.0004 second.

 

[burners]

I'm not mandrin, but I do like "back of the envelope" calculations just to put some perspective on things.

Guys......4 ten-thousandths of a sec is a VERY short time!!!!!!!!

If you could rotate a clubface 3 degrees in 0.0004 sec that means you could rotate it 7,500 degrees in 1 second. As Brian would say, got it?

Since there are 360 degrees in a full revolution, that means you could spin the club face in your hands 21 times in a second. Does anyone play golf this way??? Maybe "fooseball" or whatever they call that table soccer game.

Now we are going to multiply 21 x 60 and get 1,260 RPM.

Does anyone put 1,260 RPM of clubface closure or openness on a swing? No.

Not much of anything happens in 0.0004 second.

Please explain how it's possible for the face to be laying on the plane a couple feet from impact and rotate all the way to square and beyond.

That means it's going to rotate 90 degrees in say, 2 feet (for the sake of argument) and continue to rotate through impact at this rate (3.75 degrees of rotation per inch).

 

[savydan]

I see where you're coming from.

Brian had stated between the time of our posts that it's like 0.25 degree of rotation through impact interval. I'm sure that's coming from actual measurements rather than back-of-the-bar-napkin calcs.

The justification between your calcs and mine may have to do with with the majority of the rotation coming around the waist high positions rather than that super short time of impact interval.

If someone has additional insights or data, I'd like to hear it.

 

[puttmad]

Please explain how it's possible for the face to be laying on the plane a couple feet from impact and rotate all the way to square and beyond.

That means it's going to rotate 90 degrees in say, 2 feet (for the sake of argument) and continue to rotate through impact at this rate (3.75 degrees of rotation per inch).

Burners,

Very possible, in fact it's done every day (watch Ernie in slow motion)..
Try this, Hold your left hand out in hitch-hiking fashion..now move to where it is level with your right shoulder, with the back of the hand facing skyward and the thumb pointing to the right..
Move the hand to the left, and as it passes the center of your chest, flip the hand over so the palm is facing skyward..
If you do it quickly enough you will find you cannot see the thumb at all. It moves so fast in an anti-clockwise direction it is more or less invisible....

Now add to your golf swing...

 

[burners]

Getting Back to The Initial Question

Burners,

Very possible, in fact it's done every day (watch Ernie in slow motion)..
Try this, Hold your left hand out in hitch-hiking fashion..now move to where it is level with your right shoulder, with the back of the hand facing skyward and the thumb pointing to the right..
Move the hand to the left, and as it passes the center of your chest, flip the hand over so the palm is facing skyward..
If you do it quickly enough you will find you cannot see the thumb at all. It moves so fast in an anti-clockwise direction it is more or less invisible....

Now add to your golf swing...

Yes! Exactly the point I was trying to make (Ernie is a nice example).

When I asked for an "explanation", I just wanted others to understand this concept. Sorry for the confusion.

So, if Ernie's (or yours, or mine) club is rotating at some rate, what does this mean if the ball is stuck on the face for 3/4 inch (or whatever the length of impact is)?

 

[Burner]

Yes! Exactly the point I was trying to make (Ernie is a nice example).

When I asked for an "explanation", I just wanted others to understand this concept. Sorry for the confusion.

So, if Ernie's (or yours, or mine) club is rotating at some rate, what does this mean if the ball is stuck on the face for 3/4 inch (or whatever the length of impact is)?

It means that from the top of your backswing (not the end, necessarily) to the top of your follow through (not the end, necessarily) your club face will rotate through 180*.

Hopefully, it will have reached the 90* point at impact separation.

 

[Brian Manzella]

Some of you guys can't handle the truth

Wake up and smell the coffee!!!!!!!

Damn.

 

[Tom Bartlett]

Some of you guts can't handle the truth. Wake up and smell the coffee!!!!!!!

Damn.

Kopi Luwak?

 

[Brian Manzella]

Reading this thread ruined my day.

I go out and research my rear end off, and I have guys like Zick and Mandrin to fact check me, and I have to listen to this DRIVEL about how the clubface closes a few degrees during impact!!!!!!!!!!!!!!!!!!

It doesn't!

Got it?

Geez.

(But, Brian, the toe is up and then it is up again, so that's 90°....)

Blah, blah, blah.

 

[BurnItUp]

I go out and research my rear end off, and I have guys like Zick and Mandrin to fact check me, and I have to listen to this DRIVEL about how the clubface closes a few degrees during impact!!!!!!!!!!!!!!!!!!

It doesn't!

Got it?

Geez.

(But, Brian, the toe is up and then it is up again, so that's 90°....)

Blah, blah, blah.

It wasn't that long ago when you were preaching the exact same drivel.

3 degrees open club face at impact.

Remember?

 

[Brian Manzella]

Are you serious?

Yup.

I was wrong.

If THE GOFLING MACHINE would have been correct on impact, then I would have been correct.

I knew that the only way the ball could go straight, assuming a straight path, was for the club to be "square at separation."

If you have a mid-iron, and Horizontal Hinge action, the math and geometry says that with a normal plane angle, the face would be about 3° open at impact.

The math and geometry said nothing about separation, but the book did.

The book was WAY OFF, and because of it, I was too.

So, just like I do a few times a year, I admit I was wrong when I learn better science.

The KEY word here is science, not someone's opinion of "science" written in a non-scientifically sound book.

The book was also wrong about path line vs. Path....so I was wrong about that too.

I'll be wrong a lot less nowadays, because my research is better than the book, and my fact finding missions, always include TrackMan, 6° 3D, and real physics guys.

Who else do you know ever does research, 1, and 2, ever admits they are wrong.

Don't hurt yourself.