Surf / pump foil — 900 mm reference front wingvsGossamer Condor — 96 ft of wing at 11 mph
root section a18 → l7769 · area 111865 mm² → 66293551 mm² · span 900 mm → 29260 mm · root chord 150 mm → 2862 mm · tip chord 76 mm → 1431 mm · mac 128 mm → 2358 mm
units
These analyses are not directly comparable
- different fluids (water-salt vs air) — density and viscosity both differ, so the drag numbers are not on the same footing
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Surf / pump foil — 900 mm reference front wing
- Gossamer Condor — 96 ft of wing at 11 mph
What changed
| Property | Surf / pump foil | Gossamer Condor | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 900 mm | 29260 mm | +28360 mm | +3151.1% |
| Root chord | 150 mm | 2862 mm | +2712 mm | +1808.0% |
| Tip chord | 76 mm | 1431 mm | +1355 mm | +1782.9% |
| Sweep parameter | 8.553 | 11.711 | +3.158 | +36.9% |
| Dihedral | -1.50° | 3.00° | +4.50° | -300.0% |
| Tip twist | -2.00° | 0.00° | +2.00° | -100.0% |
| TE thickness | 0 mm | 2 mm | +1 mm | +500.0% |
| Sections | 30 | 40 | +10 | +33.3% |
| Tip cap peak (chord fraction) | 0.450 | 0.500 | +0.050 | +11.1% |
| Tip cap reach | 0.350 | 0.200 | -0.150 | -42.9% |
| Derived | ||||
| Aspect ratio | 7.241 | 12.914 | +5.674 | +78.4% |
| Area | 111865 mm² | 66293551 mm² | +66181686 mm² | +59162.3% |
| Taper | 0.507 | 0.500 | -0.007 | -1.3% |
| MAC | 128 mm | 2358 mm | +2230 mm | +1737.2% |
| Sections | ||||
| Root section | a18 | l7769 | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 2712 mm | |||
| Chord deviation (RMS) | 2185 mm | |||
| Twist deviation (max) | 2.00° | |||
| Dihedral deviation (max) | 779 mm | |||
| Tip cap deviation (max) | 14773 mm | |||
Performance
CoefficientsDimensionless — how good the shape is, independent of size and speed.
ForcesNewtons and watts — what each wing actually carries and costs at this condition.
Spanwise
withheld — “Surf / pump foil” integrates to CL 0.022 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.363 (0.06×); “Gossamer Condor” integrates to CL 0.112 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.539 (0.21×). A loading that does not integrate back to its own wing’s CL is not a coarse curve, it is a wrong one.
mixed fluids (water (sea), air)
data
| V (kt) | Surf / pump foil | Gossamer Condor |
|---|---|---|
| 7.74 | 14.72 | 17.21 |
| 7.90 | 15.44 | 18.16 |
| 8.57 | 18.41 | 22.19 |
| 8.75 | 19.18 | 22.79 |
| 9.41 | 21.39 | 25.08 |
| 9.60 | 22.03 | 25.71 |
| 10.24 | 23.65 | 27.83 |
| 10.45 | 24.17 | 28.46 |
| 11.07 | 25.03 | 30.35 |
| 11.30 | 25.35 | 30.86 |
| 11.91 | 25.68 | 32.21 |
| 12.15 | 25.81 | 32.39 |
| 12.74 | 25.85 | 32.83 |
| 13.00 | 25.87 | 32.66 |
| 13.57 | 25.67 | 32.27 |
| 13.85 | 25.57 | 31.85 |
| 14.41 | 25.17 | 31.02 |
| 14.70 | 24.96 | 30.54 |
| 15.24 | 24.44 | 29.65 |