Golf launch monitor glossary

Bilingual definitions of golf delivery, launch, spin and aerodynamic terms, with vendor naming cross-references.

D-Plane (Descriptive Plane)

The three-dimensional geometric plane spanned by the clubhead velocity vector (V_club) and the clubface normal vector (N_face) at the instant of maximum ball compression.

Clubhead Velocity Vector (V_club)

The 3D vector representing the speed and instantaneous direction of the geometric center of the clubhead at impact, determined by Club Path and Attack Angle.

Clubface Normal Vector (N_face)

The 3D unit vector pointing perpendicularly outward (90°) from the clubface at the contact point, determined by Dynamic Loft, Face Angle, and Delivered Lie.

Club Path (θ_path)

The horizontal direction of clubhead motion at impact relative to the target line (+ right / in-to-out for RH; - left / out-to-in for RH).

Attack Angle (γ_AoA)

The vertical direction of the clubhead motion at impact relative to the horizontal ground plane (+ upward strike; - downward strike).

Face Angle (φ_face)

The horizontal orientation in which the clubface points relative to the target line at maximum compression (+ open / right for RH; - closed / left for RH).

Dynamic Loft (δ_loft)

The actual vertical loft angle of the clubface at the moment of maximum compression, resulting from static loft, shaft lean, and delivery dynamics.

Face to Path (ψ_ftp)

The angular difference between Face Angle and Club Path (φ_face - θ_path), which primarily dictates the tilt of the spin axis and curvature.

Spin Loft (3D Angle)

The true 3D spatial angle between the clubhead velocity vector and the face normal vector, driving oblique friction, spin rate, and smash factor efficiency.

Spin Axis (τ_spin)

The tilt angle of the ball’s rotation axis relative to the horizontal horizon, dictating aerodynamic Magnus lateral curve (+ right / slice; - left / draw for RH).

Smash Factor

The ratio of ball speed to clubhead speed, measuring the efficiency of mechanical energy transfer during the collision.

Gear Effect

The rotation of the clubhead around its center of gravity during off-center impacts (Toe/Heel or High/Low), which twists the face and imparts counter-rotational spin onto the ball.

Swing Direction (θ_plane)

The horizontal orientation of the base of the inclined swing plane relative to the target line.

Vertical Swing Plane (β_plane)

The geometric angle of inclination of the swing arc plane measured from the horizontal ground plane.

Delivered Lie Angle (Δλ_lie)

The angle of the clubhead relative to the ground at impact compared to neutral lie, causing toe-up or toe-down orientation and shifting the face normal.

Low Point

The lowest spatial point in the swing arc, located after the ball for irons (hitting down) and before the ball for driver (hitting up).

Launch Direction / Horizontal Launch Angle (HLA)

The initial horizontal angle at which the golf ball departs from the target line immediately after leaving the clubface (governed 60%–85% by Face Angle).

Launch Angle / Vertical Launch Angle (VLA)

The initial vertical takeoff elevation angle of the golf ball above the horizontal ground plane.

Magnus Force

The aerodynamic force generated perpendicular to the ball velocity vector by the spinning golf ball dimples interacting with the surrounding air.

Carry Distance

The distance the golf ball travels through the air from the impact point to the initial touchdown point on the fairway.

Uneven Lie

A terrain condition where the ground slopes uphill, downhill, or sidehill (ball above or below feet), altering stance, swing plane, attack angle, and effective lie.