Downwind glide foil — high aspect reference front wingvsDrela SuperGee II — a 1.5 m discus-launch glider, drawn to the plan
root section e818 → ag455ct02r · tip section — → ag47ct02r · dihedral -2.50° → 4.00° · tip twist -2.50° → 0.00° · tip chord 48 mm → 94 mm · area 121109 mm² → 218576 mm²
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
- different trim loads (932 N vs 2 N) — each wing is carrying a different weight
The geometry comparison below is unaffected — it is a comparison of shapes, not of runs.
- Downwind glide foil — high aspect reference front wing
- Drela SuperGee II — a 1.5 m discus-launch glider, drawn to the plan
What changed
| Property | Downwind glide foil | Drela SuperGee II | Change | % |
|---|---|---|---|---|
| Geometry | ||||
| Span | 1240 mm | 1498 mm | +258 mm | +20.8% |
| Root chord | 130 mm | 183 mm | +53 mm | +40.8% |
| Tip chord | 48 mm | 94 mm | +46 mm | +95.8% |
| Sweep parameter | 9.717 | 3.400 | -6.317 | -65.0% |
| Dihedral | -2.50° | 4.00° | +6.50° | -260.0% |
| Tip twist | -2.50° | 0.00° | +2.50° | -100.0% |
| TE thickness | 0 mm | 0 mm | +0 mm | +50.0% |
| Derived | ||||
| Aspect ratio | 12.696 | 10.266 | -2.429 | -19.1% |
| Area | 121109 mm² | 218576 mm² | +97466 mm² | +80.5% |
| Taper | 0.369 | 0.514 | +0.144 | +39.1% |
| MAC | 104 mm | 151 mm | +47 mm | +45.4% |
| Sections | ||||
| Root section | e818 | ag455ct02r | changed | — |
| Tip section | — | ag47ct02r | changed | — |
| Shapedeviation at matched span fractions, 64 samples | ||||
| Chord deviation (max) | 53 mm | |||
| Chord deviation (RMS) | 48 mm | |||
| Twist deviation (max) | 2.50° | |||
| Dihedral deviation (max) | 79 mm | |||
| Tip cap deviation (max) | 147 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×); “Drela SuperGee II” integrates to CL 0.056 against the polar’s CL at the same α (this analysis predates the loading reporting its own) 0.371 (0.15×). 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 | Drela SuperGee II |
|---|---|---|
| 8.75 | 23.32 | 13.28 |
| 9.60 | 29.03 | 16.67 |
| 9.91 | 31.15 | 17.20 |
| 10.45 | 32.16 | 18.11 |
| 11.27 | 33.73 | 18.89 |
| 11.30 | 33.73 | 18.91 |
| 12.15 | 33.52 | 19.30 |
| 12.64 | 33.40 | 19.33 |
| 13.00 | 32.99 | 19.35 |
| 13.85 | 32.03 | 19.11 |
| 14.00 | 31.87 | 19.03 |
| 14.70 | 30.72 | 18.62 |
| 15.36 | 29.65 | 18.12 |
| 15.55 | 29.28 | 17.97 |