Piper J-3 Cub — a rectangular wing that worksvsGossamer Albatross II — same span, two-thirds the area
root section usa35b → l7769 · dihedral 1.00° → 3.60° · area 16577850 mm² → 45296522 mm² · span 10730 mm → 29260 mm · aspect ratio 6.945 → 18.901 · te thickness 3 mm → 2 mm
units
These analyses are not directly comparable
- different trim loads (5396 N vs 991 N) — each wing is carrying a different weight
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Piper J-3 Cub — a rectangular wing that works
- Gossamer Albatross II — same span, two-thirds the area
What changed
| Property | Piper J-3 Cub | Gossamer Albatross II | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 10730 mm | 29260 mm | +18530 mm | +172.7% |
| Root chord | 1545 mm | 1651 mm | +106 mm | +6.9% |
| Tip chord | 1545 mm | 1404 mm | -141 mm | -9.1% |
| Sweep parameter | 0.000 | 7.476 | +7.476 | — |
| Dihedral | 1.00° | 3.60° | +2.60° | +260.0% |
| TE thickness | 3 mm | 2 mm | -2 mm | -50.0% |
| Tip cap reach | 0.300 | 0.200 | -0.100 | -33.3% |
| Derived | ||||
| Aspect ratio | 6.945 | 18.901 | +11.956 | +172.2% |
| Area | 16577850 mm² | 45296522 mm² | +28718672 mm² | +173.2% |
| Taper | 1.000 | 0.850 | -0.150 | -15.0% |
| MAC | 1545 mm | 1552 mm | +7 mm | +0.5% |
| Sections | ||||
| Root section | usa35b | l7769 | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 141 mm | |||
| Chord deviation (RMS) | 80 mm | |||
| Twist deviation (max) | 0.00° | |||
| Dihedral deviation (max) | 827 mm | |||
| Tip cap deviation (max) | 9449 mm | |||
Performance
CoefficientsDimensionless — how good the shape is, independent of size and speed.
Spanwise
withheld — “Piper J-3 Cub” integrates to CL 0.002 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.330 (0.01×); “Gossamer Albatross II” integrates to CL 0.118 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.613 (0.19×). A loading that does not integrate back to its own wing’s CL is not a coarse curve, it is a wrong one.
air, ρ = 1.225 kg/m³
data
| CD | Piper J-3 Cub | Gossamer Albatross II |
|---|---|---|
| 0.012 | 0.313 | 0.374 |
| 0.013 | 0.328 | 0.419 |
| 0.013 | 0.330 | 0.423 |
| 0.013 | 0.347 | 0.472 |
| 0.015 | 0.376 | 0.535 |
| 0.015 | 0.378 | 0.539 |
| 0.017 | 0.419 | 0.613 |
| 0.017 | 0.437 | 0.637 |
| 0.020 | 0.483 | 0.709 |
| 0.021 | 0.511 | 0.746 |
| 0.025 | 0.568 | 0.829 |
| 0.027 | 0.605 | 0.876 |
| 0.032 | 0.673 | 0.982 |
| 0.036 | 0.729 | 1.06 |
| 0.043 | 0.796 | 1.18 |
| 0.053 | 0.894 | 1.30 |
| 0.065 | 0.992 | 1.45 |