TRACKMAN Ball Flight Laws

1
TRACKMAN
Ball Flight Laws - part 1
of 25
Fredrik Tuxen, CTO, TrackMan A/S

of 25
Common Comments
• “The Ball Flight Laws are wrong!”
• “Ball starts to the PATH…”
• “If you’re on PLANE, you’re on PATH.”
• “A divot should go straight to the target.”
• “If FACE is closed to PATH, the ball can’t fade!”
• “D-Plane?!”
• “Hitting Down on the ball creates more spin.”
2

of 25
Questions
1. What’s more important in determining a ball’s Starting
Direction – Club Path or Face Angle?
2. True or False: Swing (Plane) Direction should be
the same for all clubs in the bag.
3. (Assume no wind) True or False: If path and face are
square, the ball will always go straight.
4. (No wind) True or False: If face is closed relative to
path, the ball will always curve left.
5. True or False: Ball flight never lies.
3

Shot Pattern Interpretations?
• Shot Shape is determined by Launch Conditions
1. Launch Direction: Push (+) or Pull (-)
2. Spin Axis Tilt: Fade (+) or Draw (-)
• Other Factors (Wind, Aerodynamics)
4
of 25

Spin Axis 0°
of 25
lift
gravity
Spin Axis
gravity
Rule of thumb:
A spin axis of 10° will take the ball 7% to the side – Meaning a 200 yards
carry with a +10° spin axis will curve 14 yards to the right
5
Axis of rotation
Spin Axis -20° (hook)
lift
Spin axis angle

The curvature of a
shot is directly related
to the tilt of the spin
axis. There is
physically no such
thing as “side spin” –
the golf ball rotates
around one single
spin axis.
6
Spin Axis
of 25
-5° spin
axis 7
yards left
-5° Spin axis
3.5 yds left
+10° spin
axis 7 yards
right

Club/Ball Collision
• Contact time 1/2000 of a second
– At 120 mph club speed, club and ball have contact
over less than 1 inch (21mm) !!!
– Collision can be threated as if it is instantaenous
• For a -5 deg Attack Angle (hitting down), the club head moves
less than 2 mm downwards during impact!
7
of 25
First
contact
Full
compression
20 mm
Ball
separation
2 mm

of 25
Ball Launch Direction
ONLY two things influence the
Launch Direction:
• Face Angle
The orientation of the club face
where the ball impacts
• Club Path
The direction of the club head
during collision with the ball
8
Target line

9
of 25
Impact seen from above

10
of 25
Keep watching!
Face angle ~0 deg

11
Launch direction following club
of 25
path?
Face angle ~0 deg
Club path ~10 deg
Launch Direction ~2 deg

Launch Direction
In general, Face Angle has four times greater impact than
Club Path in determining the ball’s starting direction.
12
of 25
DRIVER: 85% Face / 15% Path
IRONS: 75% Face / 25% Path

13
of 25
LD dictated by FA or CP?

of 25
Launch Angle
ONLY two things influence the Launch
Angle:
• Dynamic Loft
The orientation of the club face
where the ball impacts
(similar to face angle just vertically)
• Attack Angle
The direction of the club head during
collision with the ball
(similar to club path just vertically)
14
Horizon

Launch Angle
In general, Dynamic Loft has four times greater impact than
Attack Angle in determining the ball’s starting direction.
15
of 25
DRIVER: 85% Loft / 15% Attack
IRONS: 75% Loft / 25% Attack

16
of 25
LA dictated by DL or AA?

of 25
The D Plane (Theodore P. Jorgensen, 1994)
Representation of perfect contact
between the clubface and the ball
• Clubhead direction:
The path which the clubhead is
moving at impact
• Clubhead orientation:
The normal to the clubface at
impact
• When the ball hits the angled
clubface, the ball rolls up the
clubface due to friction
– Spin Axis 90 deg relative to D plane
(center impact)
– Lift force 90 deg up relative ball
direction
(center impact)
17
horizon

18
of 25
Clubface orientation
Ball direction
Target line Clubhead direction
D-Plane
CP
AA
FA
DL
HLA
VLA
SL
VLA: Launch Angle
HLA: Launch Direction
AA: Attack Angle
CP: Club Path
DL: Dynamic Loft
FA: Face Angle
SL: Spin Loft
SA: Spin Axis
SA

Club Path
Face Angle
19
Neg.
1
of 25
The 9 Ball Flights
Negative Neutral Positive
Neu.
2
Pos.
Shot Type Path Face
1 Pull Neg. Neg.
2 Fade Neg. 0
3 Quick slice Neg. Pos.
3
Neg.
4
Neu.
5
Shot Type Path Face
4 Hook 0 Neg.
5 Straight 0 0
6 Slice 0 Pos.
Pos. Neg.
Outside-in Inside-out
6
7
Neu.
8
Pos.
Shot Type Path Face
7 Quick hook Pos. Neg.
8 Draw Pos. 0
9 Push Pos. Pos.
9

of 25
Spin Axis from D plane
Club Path Face Angle Spin Loft Spin Axis Shot Bend
20
0 deg 1 deg 10 deg (Drv-3W) 5.7 deg 4%
0 deg 1 deg 20 deg (3i-6i) 2.9 deg 2%
0 deg 1 deg 30 deg (6i-9i) 2.0 deg 1.3%
0 deg 1 deg 40 deg (9i-Wdg) 1.5 deg 0.9%
Center impact assumed

Off-center impact: Gear effect
When impact is off-center (CG), the club
head will twist slightly, forcing the ball to
counteract.
TOE impact Creates a DRAW spin axis
HEEL impact Creates a FADE spin axis
Driver: ½” = 20⁰ spin axis tilt
Driver: 0.14” = 6⁰ spin axis tilt
6-Iron: ½” = 7⁰ spin axis tilt
21
of 25
From www.tutelman.com

of 25
D-Plane
Total Spin Axis
Total SpinAxis (Heel)
Added Side Spin (Heel)
• Amount of added ”Side Spin” depends on MOI and off-center
distance
• Impact on Spin Axis depends on magnitude of added ”Side Spin”
relative to total spin rate.
22

of 25
Ball Curvature - Spin Axis
ONLY two things influence the Spin
Axis:
• Face-to-Path
The difference between Face
Angle and Club Path
– Less loft more tilting of Spin Axis
• Impact Location
Impact location relative to centerof-gravity
of club head
23
– Small influence on irons
– Major influence on Driver
Face-to-Path
Target line

of 25
Straight Shots
There are multiple ways to launch the ball such
that it travels in a straight line to the target…
Method 1
(“Classic”)
Club Path 0 degrees
Face Angle 0 degrees
Centeredness CENTER
24
Method 2
Positive
(inside-out)
Negative
(closed)
HEEL
Method 3
Negative
(outside-in)
Positive (open)
TOE

Horizontal Ball Flight -Summary
• Can be described by two parameters
– Launch Direction
– Spin Axis
• But there are three causes
– Club Path
– Face Angle
– Impact location
• You can NOT derive club path and face angle from
the ball flight
25
– The ball flight does NOT tell the reason for the ball flight
of 25