Question about launch angle

[mgranato]

Is it possible, from Trackman launch data, to determine the amount of forward shaft lean? For example, my 7i (34*) has a launch angle of 16* with a -2* angle of attack. Is it as simple as subtracting the launch angle and angle of attack from the club loft to determine 16* of forward lean - can that be correct?

 

[Kevin Shields]

Trackman gives you dynamic loft which is totally separate from shaft lean. Its weird. I deliver about 20 degrees of loft with my 6 iron but theres no way I HAVE 10/11 degrees of lean.

 

[mjstrong]

Doesn't the 85/15 rule apply vertically as well as horizontally?

If so, you could calculate delivered (dynamic?) loft by accounting for the vertical face and vertical path as such:

Launch Angle = 16*
Vertical Path = -2*
Vertical Face = ?

.85(?) + .15(-2*) = 16*
Vertical Face = 18.5*

So, by this theory (no idea if it's correct or not), you would have 15.5* of forward lean. That does sound like a lot, but who knows?

If it isn't correct, where did my theory go wrong?

 

[Matt Bryda]

when you enter the club your hitting into the set up data into trackman before you hit a shot with that club what loft does the 6iron preset button represent to trackman??

 

[mgranato]

16 or 15.5 does sound like alot, but that "extra" loft has to be accounted for by something, right? Forward lean/delofting sounds like the most logical explanation - but I'm just guessing. There has to be math to explain why the launch angle is so low compared to loft if it isn't due to that much forward lean/delofting.

16* degrees sound like a ton, basically 4 clubs worth of delofting. However, thinking about it as a "clock", it doesn't seem as bad. Each minute mark on a clock represents 6*. If a vertical shaft (34* in this example) is at 12:00, then a forward lean of 16* would be less than 12:03.

 

[mjstrong]

I suppose COG would come into play as well, but probably at only a fraction of the effect of forward lean...

 

[Kevin Shields]

when you enter the club your hitting into the set up data into trackman before you hit a shot with that club what loft does the 6iron preset button represent to trackman??

Nothing. It doesnt subtract anything. The preset club stuff is just for your printouts and records to know which club u were using.

 

[Kevin Shields]

Clubface roll at impact is responsible for more deloft than forward lean.

 

[mgranato]

Can you explain that?

 

[Matt Bryda]

Clubface roll at impact is responsible for more deloft than forward lean.

What do you mean by this Kevin?

bulge, roll on an iron?

 

[ggsjpc]

I think what Kevin is saying and please correct me if I'm wrong. The dynamic loft on Trackman is calculated and not measured. Trackman is using the launch angle of the ball to help estimate what the face angle was both loft and direction(open or closed). The reason the dynamic loft is so low is because when the club face and ball collide, the shaft will deflect back thus delofting the face. It's for this reason that delivered loft is a phrase better replaced by dynamic loft.

watch the face at .54 in this vid and you'll see why.

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Can't calculate shaft lean with trackman.

 

[mgranato]

I think I understand what you're saying, but I don't think that same "impact bending" happens with an iron. If the launch angle is measured, what do you think might account for the 18* of loft difference if it's not delofting/shaft lean?

 

[westy]

A shaft that is bent/stressed/lagging has some degree of curvature along the surface of the plane (as well as droop) which must account for some of it...
Lets define the exact answer here, because apparently nobody knows exactly.
A distilled description of this kind of stuff is so key in my opinion.

 

[mgranato]

Okay...

Shafts can (if the release is late enough) flex forward at impact. This amount of forward flex has a limit. It's limitted by how far the CofG of the head is behind the CofG of the shaft. Meaning, the shaft will only flex forward to the point were the two CofG line up. For a driver shafted with a graphite shaft, this potential amount is basically limitted to 1.5-2.5 degrees of added loft. With an iron the potential is even smaller. Because steel iron shafts have much firmer bending profiles, and because the CofG of an iron head is so close to the face - the amount of potential added loft from a forward flexing iron shaft is very small.

In either case, the shaft can only add to the loft of the clubhead by way of the CofG lining up at impact. A 34* lofted head cannot have it's loft decreased by the shaft's bend, it can only be increased. The shaft does deflect into a backwards bend as it digs into the ground during a divot, but the ball has left the face before that delofting occurs.

With a shaft's bend potentially adding loft (or at the least, staying straight), the only way I can a 34* iron launching at 16* is to have the hands leaning the shaft forward by the difference. That just seems like a lot of forward delofting. I've always been told that 5-6 degrees of forward lean is what "good" swings have - I wonder now if the amount isn't 2 to 3 times that.

At about :48 watch how the shaft is released and flexing forward (lofting the head) and then deflects backward as it digs.

 

[mjstrong]

Granato,

That's all correct information, but doesn't get us any closer to why shots seem to launch lower than what we'd expect from using face angle and attack angle.

List of all factors to launch angle: (Please add)

Face Angle (Vertical Clubface)
Attack Angle (Vertical Clubpath)
COG
Shaft Flex
Shaft Lean
Clubhead Speed? (It would seem that initially, this shouldn't matter to launch angle, but would faster clubhead speed result in higher launch?)

 

[savydan]

Well, some quick math.

If the club is 3 feet long and the shaft is leaning 5* forward, the butt end of the club is 3 inches forward of perpendicular.

Is that in the ballpark?

 

[Kevin Shields]

I think what Kevin is saying and please correct me if I'm wrong. The dynamic loft on Trackman is calculated and not measured. Trackman is using the launch angle of the ball to help estimate what the face angle was both loft and direction(open or closed). The reason the dynamic loft is so low is because when the club face and ball collide, the shaft will deflect back thus delofting the face. It's for this reason that delivered loft is a phrase better replaced by dynamic loft.

watch the face at .54 in this vid and you'll see why.

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Can't calculate shaft lean with trackman.

Exactly, vertical gear effect. Sure, more shaft lean will deloft the club even more all things being equal, but you get alot of deloft by vertical gear effect. I''l have to review these exact launch angle numbers club by club.

 

[Kevin Shields]

Okay...

Shafts can (if the release is late enough) flex forward at impact. This amount of forward flex has a limit. It's limitted by how far the CofG of the head is behind the CofG of the shaft. Meaning, the shaft will only flex forward to the point were the two CofG line up. For a driver shafted with a graphite shaft, this potential amount is basically limitted to 1.5-2.5 degrees of added loft. With an iron the potential is even smaller. Because steel iron shafts have much firmer bending profiles, and because the CofG of an iron head is so close to the face - the amount of potential added loft from a forward flexing iron shaft is very small.

In either case, the shaft can only add to the loft of the clubhead by way of the CofG lining up at impact. A 34* lofted head cannot have it's loft decreased by the shaft's bend, it can only be increased. The shaft does deflect into a backwards bend as it digs into the ground during a divot, but the ball has left the face before that delofting occurs.

With a shaft's bend potentially adding loft (or at the least, staying straight), the only way I can a 34* iron launching at 16* is to have the hands leaning the shaft forward by the difference. That just seems like a lot of forward delofting. I've always been told that 5-6 degrees of forward lean is what "good" swings have - I wonder now if the amount isn't 2 to 3 times that.

At about :48 watch how the shaft is released and flexing forward (lofting the head) and then deflects backward as it digs.

You can have a 34* club launch at 16* with only 11 degress of deloft. A 23* delivered clubface due to DPlane application will start a ball only 70-85% to the true clubface. So if you have a high friction contact it will start roughly 70% or so to the face, which is 16* launch.

 

[mgranato]

You can have a 34* club launch at 16* with only 11 degress of deloft. A 23* delivered clubface due to DPlane application will start a ball only 70-85% to the true clubface. So if you have a high friction contact it will start roughly 70% or so to the face, which is 16* launch.

This makes a ton of sense. So the old "hands ahead by 5*" or "he turned that 7iron into a 6iron" does not nearly account for the amount of forward lean in middle to high lofted irons?

What's interesting is that the tour average launch angle for irons is roughly just 50% of the static loft of the club being hit. Yet with driver through PW, the max height of a shot only varies by 13' - with the highest shot coming from 7 irons. Just find that incredible that their window of trajectory is that consistent through the bag.

 

[ggsjpc]

This makes a ton of sense. So the old "hands ahead by 5*" or "he turned that 7iron into a 6iron" does not nearly account for the amount of forward lean in middle to high lofted irons?

What's interesting is that the tour average launch angle for irons is roughly just 50% of the static loft of the club being hit. Yet with driver through PW, the max height of a shot only varies by 13' - with the highest shot coming from 7 irons. Just find that incredible that their window of trajectory is that consistent through the bag.

This is a signature of properly fitted clubs. All the clubs should max out at the same height. When they reach that height changes our perception of it. Lofted clubs earlier looks higher.