Piper PA-28 Cherokee — the Hershey-bar wingvsSurf / pump foil — 900 mm reference front wing
root section naca652415 → a18 · dihedral 7.00° → -1.50° · area 14868144 mm² → 111865 mm² · tip chord 1626 mm → 76 mm · mac 1626 mm → 128 mm · te thickness 3 mm → 0 mm
units
These analyses are not directly comparable
- different fluids (air vs water-salt) — density and viscosity both differ, so the drag numbers are not on the same footing
- different trim loads (9565 N vs 932 N) — each wing is carrying a different weight
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Piper PA-28 Cherokee — the Hershey-bar wing
- Surf / pump foil — 900 mm reference front wing
What changed
| Property | Piper PA-28 Cherokee | Surf / pump foil | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 9144 mm | 900 mm | -8244 mm | -90.2% |
| Root chord | 1626 mm | 150 mm | -1476 mm | -90.8% |
| Tip chord | 1626 mm | 76 mm | -1550 mm | -95.3% |
| Sweep parameter | 0.000 | 8.553 | +8.553 | — |
| Dihedral | 7.00° | -1.50° | -8.50° | -121.4% |
| Tip twist | 0.00° | -2.00° | -2.00° | — |
| TE thickness | 3 mm | 0 mm | -3 mm | -91.7% |
| Sections | 40 | 30 | -10 | -25.0% |
| Tip cap peak (chord fraction) | 0.500 | 0.450 | -0.050 | -10.0% |
| Tip cap reach | 0.300 | 0.350 | +0.050 | +16.7% |
| Derived | ||||
| Aspect ratio | 5.624 | 7.241 | +1.617 | +28.8% |
| Area | 14868144 mm² | 111865 mm² | -14756279 mm² | -99.2% |
| Taper | 1.000 | 0.507 | -0.493 | -49.3% |
| MAC | 1626 mm | 128 mm | -1498 mm | -92.1% |
| Sections | ||||
| Root section | naca652415 | a18 | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 1550 mm | |||
| Chord deviation (RMS) | 1502 mm | |||
| Twist deviation (max) | 2.00° | |||
| Dihedral deviation (max) | 573 mm | |||
| Tip cap deviation (max) | 4477 mm | |||
Performance
CoefficientsDimensionless — how good the shape is, independent of size and speed.
Spanwise
withheld — “Piper PA-28 Cherokee” integrates to CL 0.007 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.271 (0.03×); “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×). 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 (air, water (sea))
data
| CD | Piper PA-28 Cherokee | Surf / pump foil |
|---|---|---|
| 0.011 | 0.303 | 0.254 |
| 0.011 | 0.315 | 0.271 |
| 0.011 | 0.323 | 0.284 |
| 0.013 | 0.346 | 0.320 |
| 0.014 | 0.371 | 0.356 |
| 0.014 | 0.375 | 0.363 |
| 0.016 | 0.410 | 0.416 |
| 0.018 | 0.443 | 0.460 |
| 0.019 | 0.455 | 0.481 |
| 0.023 | 0.515 | 0.563 |
| 0.025 | 0.537 | 0.587 |
| 0.030 | 0.597 | 0.667 |
| 0.037 | 0.666 | 0.741 |
| 0.042 | 0.707 | 0.803 |
| 0.060 | 0.848 | 0.953 |
| 0.064 | 0.873 | 0.985 |
| 0.101 | 1.12 | 1.20 |