Piper PA-28 Cherokee — the Hershey-bar wingvsDownwind glide foil — high aspect reference front wing
root section naca652415 → e818 · dihedral 7.00° → -2.50° · aspect ratio 5.624 → 12.696 · area 14868144 mm² → 121109 mm² · tip chord 1626 mm → 48 mm · mac 1626 mm → 104 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
- Downwind glide foil — high aspect reference front wing
What changed
| Property | Piper PA-28 Cherokee | Downwind glide foil | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 9144 mm | 1240 mm | -7904 mm | -86.4% |
| Root chord | 1626 mm | 130 mm | -1496 mm | -92.0% |
| Tip chord | 1626 mm | 48 mm | -1578 mm | -97.0% |
| Sweep parameter | 0.000 | 9.717 | +9.717 | — |
| Dihedral | 7.00° | -2.50° | -9.50° | -135.7% |
| Tip twist | 0.00° | -2.50° | -2.50° | — |
| TE thickness | 3 mm | 0 mm | -3 mm | -93.3% |
| Sections | 40 | 30 | -10 | -25.0% |
| Tip cap reach | 0.300 | 0.400 | +0.100 | +33.3% |
| Derived | ||||
| Aspect ratio | 5.624 | 12.696 | +7.072 | +125.8% |
| Area | 14868144 mm² | 121109 mm² | -14747035 mm² | -99.2% |
| Taper | 1.000 | 0.369 | -0.631 | -63.1% |
| MAC | 1626 mm | 104 mm | -1522 mm | -93.6% |
| Sections | ||||
| Root section | naca652415 | e818 | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 1578 mm | |||
| Chord deviation (RMS) | 1529 mm | |||
| Twist deviation (max) | 2.50° | |||
| Dihedral deviation (max) | 588 mm | |||
| Tip cap deviation (max) | 4313 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×); “Downwind glide foil” integrates to CL 0.061 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.446 (0.14×). 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 | Downwind glide foil |
|---|---|---|
| 0.006 | 0.164 | 0.092 |
| 0.007 | 0.167 | 0.102 |
| 0.007 | 0.173 | 0.115 |
| 0.007 | 0.178 | 0.131 |
| 0.007 | 0.183 | 0.141 |
| 0.007 | 0.187 | 0.150 |
| 0.007 | 0.198 | 0.173 |
| 0.007 | 0.207 | 0.187 |
| 0.008 | 0.215 | 0.203 |
| 0.008 | 0.236 | 0.236 |
| 0.008 | 0.238 | 0.240 |
| 0.009 | 0.268 | 0.289 |
| 0.009 | 0.271 | 0.294 |
| 0.011 | 0.306 | 0.355 |
| 0.011 | 0.315 | 0.368 |
| 0.013 | 0.360 | 0.446 |
| 0.014 | 0.371 | 0.460 |
| 0.018 | 0.443 | 0.565 |
| 0.019 | 0.449 | 0.577 |
| 0.025 | 0.537 | 0.653 |
| 0.035 | 0.651 | 0.775 |