Gossamer Albatross II — same span, two-thirds the areavsPiper J-3 Cub — a rectangular wing that works
root section l7769 → usa35b · sweep parameter 7.476 → 0.000 · te thickness 2 mm → 3 mm · dihedral 3.60° → 1.00° · area 45296522 mm² → 16577850 mm² · span 29260 mm → 10730 mm
units
These analyses are not directly comparable
- different trim loads (991 N vs 5396 N) — each wing is carrying a different weight
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Gossamer Albatross II — same span, two-thirds the area
- Piper J-3 Cub — a rectangular wing that works
What changed
| Property | Gossamer Albatross II | Piper J-3 Cub | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 29260 mm | 10730 mm | -18530 mm | -63.3% |
| Root chord | 1651 mm | 1545 mm | -106 mm | -6.4% |
| Tip chord | 1404 mm | 1545 mm | +141 mm | +10.0% |
| Sweep parameter | 7.476 | 0.000 | -7.476 | -100.0% |
| Dihedral | 3.60° | 1.00° | -2.60° | -72.2% |
| TE thickness | 2 mm | 3 mm | +2 mm | +100.0% |
| Tip cap reach | 0.200 | 0.300 | +0.100 | +50.0% |
| Derived | ||||
| Aspect ratio | 18.901 | 6.945 | -11.956 | -63.3% |
| Area | 45296522 mm² | 16577850 mm² | -28718672 mm² | -63.4% |
| Taper | 0.850 | 1.000 | +0.150 | +17.6% |
| MAC | 1552 mm | 1545 mm | -7 mm | -0.5% |
| Sections | ||||
| Root section | l7769 | usa35b | 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 — “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×); “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×). 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 | Gossamer Albatross II | Piper J-3 Cub |
|---|---|---|
| 0.012 | 0.374 | 0.313 |
| 0.013 | 0.419 | 0.328 |
| 0.013 | 0.423 | 0.330 |
| 0.013 | 0.472 | 0.347 |
| 0.015 | 0.535 | 0.376 |
| 0.015 | 0.539 | 0.378 |
| 0.017 | 0.613 | 0.419 |
| 0.017 | 0.637 | 0.437 |
| 0.020 | 0.709 | 0.483 |
| 0.021 | 0.746 | 0.511 |
| 0.025 | 0.829 | 0.568 |
| 0.027 | 0.876 | 0.605 |
| 0.032 | 0.982 | 0.673 |
| 0.036 | 1.06 | 0.729 |
| 0.043 | 1.18 | 0.796 |
| 0.053 | 1.30 | 0.894 |
| 0.065 | 1.45 | 0.992 |