Downwind glide foil — high aspect reference front wingvsGossamer Condor — 96 ft of wing at 11 mph
root section e818 → l7769 · area 121109 mm² → 66293551 mm² · tip chord 48 mm → 1431 mm · span 1240 mm → 29260 mm · mac 104 mm → 2358 mm · root chord 130 mm → 2862 mm
units
These analyses are not directly comparable
- different fluids (water-salt vs air) — density and viscosity both differ, so the drag numbers are not on the same footing
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Downwind glide foil — high aspect reference front wing
- Gossamer Condor — 96 ft of wing at 11 mph
What changed
| Property | Downwind glide foil | Gossamer Condor | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 1240 mm | 29260 mm | +28020 mm | +2259.7% |
| Root chord | 130 mm | 2862 mm | +2732 mm | +2101.5% |
| Tip chord | 48 mm | 1431 mm | +1383 mm | +2881.3% |
| Sweep parameter | 9.717 | 11.711 | +1.994 | +20.5% |
| Dihedral | -2.50° | 3.00° | +5.50° | -220.0% |
| Tip twist | -2.50° | 0.00° | +2.50° | -100.0% |
| TE thickness | 0 mm | 2 mm | +1 mm | +650.0% |
| Sections | 30 | 40 | +10 | +33.3% |
| Tip cap reach | 0.400 | 0.200 | -0.200 | -50.0% |
| Derived | ||||
| Aspect ratio | 12.696 | 12.914 | +0.219 | +1.7% |
| Area | 121109 mm² | 66293551 mm² | +66172442 mm² | +54638.5% |
| Taper | 0.369 | 0.500 | +0.131 | +35.4% |
| MAC | 104 mm | 2358 mm | +2254 mm | +2164.1% |
| Sections | ||||
| Root section | e818 | l7769 | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 2732 mm | |||
| Chord deviation (RMS) | 2210 mm | |||
| Twist deviation (max) | 2.50° | |||
| Dihedral deviation (max) | 794 mm | |||
| Tip cap deviation (max) | 14607 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 — “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×); “Gossamer Condor” integrates to CL 0.112 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.539 (0.21×). 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 (water (sea), air)
data
| V (kt) | Downwind glide foil | Gossamer Condor |
|---|---|---|
| 8.55 | 22.02 | 22.07 |
| 8.57 | 22.15 | 22.19 |
| 9.41 | 27.74 | 25.08 |
| 9.91 | 31.15 | 26.75 |
| 10.24 | 31.77 | 27.83 |
| 11.07 | 33.35 | 30.35 |
| 11.27 | 33.73 | 30.80 |
| 11.91 | 33.58 | 32.21 |
| 12.64 | 33.40 | 32.76 |
| 12.74 | 33.28 | 32.83 |
| 13.57 | 32.34 | 32.27 |
| 14.00 | 31.87 | 31.64 |
| 14.41 | 31.20 | 31.02 |
| 15.24 | 29.84 | 29.65 |