Surf / pump foil — 900 mm reference front wingvsDrela SuperGee II — a 1.5 m discus-launch glider, drawn to the plan
root section a18 → ag455ct02r · tip section — → ag47ct02r · dihedral -1.50° → 4.00° · tip twist -2.00° → 0.00° · area 111865 mm² → 218576 mm² · span 900 mm → 1498 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
- different trim loads (932 N vs 2 N) — each wing is carrying a different weight
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Surf / pump foil — 900 mm reference front wing
- Drela SuperGee II — a 1.5 m discus-launch glider, drawn to the plan
What changed
| Property | Surf / pump foil | Drela SuperGee II | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 900 mm | 1498 mm | +598 mm | +66.4% |
| Root chord | 150 mm | 183 mm | +33 mm | +22.0% |
| Tip chord | 76 mm | 94 mm | +18 mm | +23.7% |
| Sweep parameter | 8.553 | 3.400 | -5.153 | -60.2% |
| Dihedral | -1.50° | 4.00° | +5.50° | -366.7% |
| Tip twist | -2.00° | 0.00° | +2.00° | -100.0% |
| TE thickness | 0 mm | 0 mm | +0 mm | +20.0% |
| Tip cap peak (chord fraction) | 0.450 | 0.500 | +0.050 | +11.1% |
| Tip cap reach | 0.350 | 0.400 | +0.050 | +14.3% |
| Derived | ||||
| Aspect ratio | 7.241 | 10.266 | +3.026 | +41.8% |
| Area | 111865 mm² | 218576 mm² | +106711 mm² | +95.4% |
| Taper | 0.507 | 0.514 | +0.007 | +1.4% |
| MAC | 128 mm | 151 mm | +23 mm | +18.0% |
| Sections | ||||
| Root section | a18 | ag455ct02r | changed | — |
| Tip section | — | ag47ct02r | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 33 mm | |||
| Chord deviation (RMS) | 23 mm | |||
| Twist deviation (max) | 2.00° | |||
| Dihedral deviation (max) | 64 mm | |||
| Tip cap deviation (max) | 306 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×); “Drela SuperGee II” integrates to CL 0.056 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.371 (0.15×). 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 | Drela SuperGee II |
|---|---|---|
| 8.75 | 19.18 | 13.28 |
| 9.60 | 22.03 | 16.67 |
| 10.45 | 24.17 | 18.11 |
| 11.30 | 25.35 | 18.91 |
| 12.15 | 25.81 | 19.30 |
| 13.00 | 25.87 | 19.35 |
| 13.85 | 25.57 | 19.11 |
| 14.70 | 24.96 | 18.62 |
| 15.55 | 24.15 | 17.97 |