Ball flight & delivery
Start Direction vs Curvature: What the Ball Flight Can and Cannot Tell You
Where a shot starts and how it curves are different observations. Read them separately, then connect them to face angle, club path, and impact location before deciding what to change.
By FORJ
Source-backed educational guide. Fitting suggestions are editorial guidance.
“The ball went right” is not yet a complete description.
Did it start right and stay there? Start near the target and curve right? Or start left before finishing right?
Those flights can finish in a similar place while presenting different questions to the fitter.
Separate three parts of the shot
| Observation | What it describes |
|---|---|
| Start direction | The ball’s initial horizontal direction relative to the target line |
| Curvature | How its flight bends away from its initial direction |
| Finishing position | Where it lands or comes to rest relative to the target |
If needed, scroll this table horizontally. Keyboard users can focus the table region and use the arrow keys.
Trackman calls the first measurement launch direction. It distinguishes that from carry side, the lateral position where the flight returns to launch elevation.
A shot can start away from the target and curve toward it, or start toward the target and curve away. The final position alone does not tell you which happened.
Face angle and club path are different references
Face angle describes where the clubface points horizontally at impact. Club path describes the clubhead’s horizontal direction of movement.
Face orientation is a major influence on start direction, but path also contributes. Avoid treating the ball’s starting line as a perfect measurement of the face.
The difference between those two club measurements is face-to-path:
Face-to-path = face angle − club path
Crucially, face-to-path describes the face relative to the path, not relative to the target.
An illustrative example (not a fitting result)
Suppose the face points 2° right of target and the path travels 4° right.
The face-to-path difference is −2°. The face points right of the target, but left of the path.
Under the centred-contact relationship described by Trackman, that combination supports a right-starting shot with leftward curvature. It does not establish how much the ball curves or whether it finishes on target.
“Open to the target” and “closed to the path” can both describe the same face orientation.
Strike location can change the explanation
Trackman’s face-to-path guidance explicitly qualifies its curvature relationship with centred contact.
Off-centre impact can influence the ball’s spin axis through gear effect, particularly with a driver. Driver-face curvature also means the local face orientation at the contact point can differ from that at the centre.
If the observed flight does not match a simple face-to-path explanation, examine strike location rather than forcing the shot into the expected pattern.
Wind and the quality of the measurement also belong in the interpretation.
What this means for fitting
A directional miss does not automatically prescribe a softer shaft, a different grip, or a particular head setting.
First establish the recurring pattern:
- Where do shots start?
- Which way do they curve?
- Where do they finish?
- Where is contact?
- Do the measured delivery and flight agree?
Then compare whether an equipment change produces a more useful pattern for the player. Describe the improvement without claiming that ball flight alone identifies its cause.
The next test
Review launch direction, face angle, path, face-to-path, spin axis, and strike location together where available.
If a measurement is missing, acknowledge the uncertainty rather than replacing it with a diagnosis.
Start direction tells you where the flight began. Curvature tells you what happened next. Neither, alone, tells you which club to prescribe.
Sources and editorial note
Source-backed educational guide. The numerical example illustrates angular relationships, not a predicted trajectory or FORJ fitting result.