Glossary

Foilbench glossary: short, citable definitions of key pump-foil and simulation terms. InfoTip keys in parentheses match the app translations.

A

Angle of attack (α) — Angle between inflow and wing chord. Controls lift and drag. In the pump cycle the effective angle swings (panel B, red in panel C).

Aspect ratio (AR) — Span² / area. Higher → less induced drag, sharper angle-of-attack sensitivity (hints.aspectRatio).

B

Best glide — Speed with best whole-rig L/D (metricBestGlide).

E

Efficiency | Speed (goal) — Goal mode for analysis marker and trade-off: Efficiency → best glide; Speed → Vmax and High-speed focus (pumpfoil.intent.v1, Advanced/Pro+).

G

Lift-to-drag (L/D) — Lift ÷ total drag. Higher = more efficient. Panel C: front wing only. Panel D: whole rig. In Foilbench this is the main efficiency comparison between setups.

H

Heave — Vertical foil motion in the pump cycle (panel B, panel A).

K

Knoller-Betz effect — Thrust from oblique inflow on the downstroke — same mechanism as fish fins.

M

Metabolic power — Rough factor on mechanical pump power (muscle efficiency below 100 %). Use for comparing operating points, not as ergometer watts.

Mast and fuselage drag — Drag from the non-lifting parts (mast, fuselage, spray, etc.). Dominates at high speed; counterpart to induced drag on the wing (hints.chartSpeed, panel E).

P

Polar — Curve of lift/drag or L/D vs angle of attack (panel C).

Pump cycle — One full up/down stroke at the set frequency.

R

Reduced frequency (k) — Dimensionless pump rhythm relative to wing depth and speed (metricReducedFrequency).

Reynolds number — Flow scale; affects friction and stall (metricReynoldsFront).

Ride height — Distance from board underside to water surface.

S

Shim — Angle wedge between wing and fuselage (front/rear, ±3°).

Stall — Flow separation — lift collapses.

T

Take-off — Minimum flying speed (metricTakeoff). In Foilbench the metric for when the rig flies — ideal for comparing larger vs. smaller front wings.

t/c — Relative profile thickness — derived from catalog volume (hints.thicknessRatio).

Theodorsen / Garrick — Unsteady aerodynamic corrections in the pump model.

V

Vmax — Highest useful steady ride speed: still trimmable and L/D ≥ 40 % of peak (metricMaxSpeed). Not GPS top speed. Foilbench reports Vmax as a model high-speed trim limit, not a session peak.

W

Drag shares — Split into front wing, mast, interference, rear wing, fuselage, spray (panel E).

→ Metrics · Panels A–E