Schempp-Hirth Standard Cirrus — 15 m, two Wortmann sectionsvsPiper J-3 Cub — a rectangular wing that works
root section fxs02196 → usa35b · tip section fx6617a2 → — · tip chord 345 mm → 1545 mm · taper 0.404 → 1.000 · mac 705 mm → 1545 mm · sweep parameter 2.946 → 0.000
units
These analyses are not directly comparable
- different trim loads (3237 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.
- Schempp-Hirth Standard Cirrus — 15 m, two Wortmann sections
- Piper J-3 Cub — a rectangular wing that works
What changed
| Property | Schempp-Hirth Standar… | Piper J-3 Cub | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 15000 mm | 10730 mm | -4270 mm | -28.5% |
| Root chord | 855 mm | 1545 mm | +690 mm | +80.7% |
| Tip chord | 345 mm | 1545 mm | +1200 mm | +347.8% |
| Sweep parameter | 2.946 | 0.000 | -2.946 | -100.0% |
| Dihedral | 2.00° | 1.00° | -1.00° | -50.0% |
| Tip twist | -2.00° | 0.00° | +2.00° | -100.0% |
| TE thickness | 2 mm | 3 mm | +1 mm | +50.0% |
| Tip cap reach | 0.450 | 0.300 | -0.150 | -33.3% |
| Derived | ||||
| Aspect ratio | 22.496 | 6.945 | -15.551 | -69.1% |
| Area | 10001997 mm² | 16577850 mm² | +6575853 mm² | +65.7% |
| Taper | 0.404 | 1.000 | +0.596 | +147.8% |
| MAC | 705 mm | 1545 mm | +840 mm | +119.2% |
| Sections | ||||
| Root section | fxs02196 | usa35b | changed | — |
| Tip section | fx6617a2 | — | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 1200 mm | |||
| Chord deviation (RMS) | 894 mm | |||
| Twist deviation (max) | 2.00° | |||
| Dihedral deviation (max) | 171 mm | |||
| Tip cap deviation (max) | 2333 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 — “Schempp-Hirth Standar…” integrates to CL 0.052 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.541 (0.10×); “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
| V (kt) | Schempp-Hirth Standar… | Piper J-3 Cub |
|---|---|---|
| 39.48 | 33.05 | 12.13 |
| 42.28 | 35.72 | 13.83 |
| 43.74 | 37.11 | 14.74 |
| 47.38 | 39.69 | 17.02 |
| 47.99 | 40.12 | 17.39 |
| 52.24 | 42.14 | 19.95 |
| 52.48 | 42.20 | 20.10 |
| 56.49 | 43.13 | 21.81 |
| 57.59 | 43.17 | 22.28 |
| 60.75 | 43.27 | 23.21 |
| 62.69 | 43.04 | 23.78 |
| 65.00 | 42.76 | 24.36 |
| 67.79 | 42.14 | 25.06 |
| 69.25 | 41.82 | 25.30 |
| 72.89 | 40.79 | 25.88 |
| 73.50 | 40.61 | 25.92 |
| 77.75 | 39.18 | 26.23 |