Airfoil Lift-to-Drag Polar Plotter implementation

Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

Record owner

Guth Instruments

Lifecycle

verified-clean

Evidence ID

t7-101

Effect

Computation or source lookup only

Input and validation requirements

The zero-Cd input produces an undefined L/D result and should be rejected or explicitly flagged. The branch and sign-convention probes also demonstrate outputs that can change materially depending on dataset regime and reporting convention.

Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

{
  "inputs": {
    "alpha_deg": 4,
    "Cl": 0.5,
    "Cd": 0.025,
    "aspect_ratio": 6,
    "Oswald_efficiency": 0.8
  },
  "expected_outputs": {
    "L_over_D": 20,
    "Cdi": 0.01657864094,
    "Cdp": 0.00842135906,
    "max_L_over_D_in_supplied_rows": 20,
    "max_L_over_D_alpha_deg": 4
  },
  "reference_data": {
    "polar_rows": [
      {
        "alpha_deg": 4,
        "Cl": 0.5,
        "Cd": 0.025,
        "source_convention": "widely tabulated standard value (NACA 0012 benchmark polar convention)"
      }
    ],
    "pi": 3.141592653589793,
    "pi_source_convention": "mathematical constant"
  },
  "working": "L/D = Cl/Cd = 0.5 / 0.025 = 20.0. Cl² = 0.5² = 0.25. πeAR = 3.141592653589793 × 0.8 × 6.0 = 15.0796447366. Cdi = 0.25 / 15.0796447366 = 0.01657864094. Cdp = Cd - Cdi = 0.025 - 0.01657864094 = 0.00842135906. With one supplied row, its L/D of 20.0 is the row maximum."
}

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche7/tranche7-results.json