{
  "physical_measurements": 0,
  "status": "RIG_DESIGN_AND_BLANK_RECORDS_ONLY",
  "scope": "Stationary pressure-footprint, leakage and installed power measurements. Full-scale road and cryogenic tests are separate work packages.",
  "heads": [
    {
      "name": "earlier",
      "outer_length_m": 0.25,
      "outer_width_m": 0.12,
      "effective_area_m2": 0.028899,
      "effective_perimeter_m": 0.74,
      "pressure_force_at_600Pa_N": 17.3394
    },
    {
      "name": "broad",
      "outer_length_m": 0.196,
      "outer_width_m": 0.19,
      "effective_area_m2": 0.036091,
      "effective_perimeter_m": 0.772,
      "pressure_force_at_600Pa_N": 21.6546
    }
  ],
  "expected_equal_pressure_comparison": {
    "nominal_pressure_Pa": 600.0,
    "predicted_pressure_force_ratio_at_equal_pressure": 1.2488667427938682,
    "equal_pressure_extra_force_N": 4.315199999999998,
    "evidence": "Area-pressure identity. Actual net load, leakage and electrical power have not been measured."
  },
  "operating_envelope": {
    "normal_vacuum_target_Pa": 600.0,
    "pressure_limit_Pa": 650.0,
    "force_abort_N": 30.0,
    "gap_settings_m": [
      0.00015,
      0.0003,
      0.00045,
      0.0006
    ],
    "road_speed_ms": 0.0
  },
  "instrument_requirements": {
    "force_balance": {
      "range_N": [
        0,
        50
      ],
      "resolution_target_N": 0.02,
      "uncertainty_target_N": 0.1
    },
    "four_cavity_pressure_channels": {
      "range_Pa": [
        0,
        1000
      ],
      "uncertainty_target_Pa": 5.0
    },
    "gap_measurement": {
      "uncertainty_target_m": 2e-05,
      "points": 4
    },
    "electrical_power": {
      "measure": "Synchronous blower-terminal voltage and current; account for controller input separately.",
      "relative_uncertainty_target": 0.01
    },
    "flow": {
      "measure": "Calibrated common outlet mass or volume flow",
      "relative_uncertainty_target": 0.03
    }
  },
  "load_path": [
    "A rigid crosshead carries the pressure head through the calibrated force balance.",
    "The road plate is attached to the independent base, not to the measured head.",
    "Gap-setting shims are removed before the run; they cannot bypass the measured load path.",
    "Symmetric flexible hose loops and a separate hose-force tare bound connection forces."
  ],
  "test_matrix": [
    {
      "comparison": "Equal cavity pressure",
      "pressure_targets_Pa": [
        200.0,
        400.0,
        600.0
      ],
      "gaps_m": [
        0.00015,
        0.0003,
        0.00045,
        0.0006
      ],
      "repetitions": 5,
      "purpose": "Check measured force against the integral of all four cavity pressures times their measured areas."
    },
    {
      "comparison": "Equal blower-terminal electrical power",
      "power_points": "Choose three shared stable power points after measuring the actual blower curve; do not assume a model power.",
      "gaps_m": [
        0.00015,
        0.0003,
        0.00045,
        0.0006
      ],
      "repetitions": 5,
      "purpose": "Test whether the broader head improves net force after its additional leakage and installed losses are paid."
    }
  ],
  "measurement_rules": [
    "Record calibration, ambient pressure/temperature, measured head dimensions, gap at all four corners, pressure in every cell, net force, flow and electrical power.",
    "Randomize head order and repeat the initial head at the end to check drift.",
    "Keep source and tare files unchanged. Mark excluded runs with a written reason.",
    "Estimate uncertainty before checking whether a measured difference supports a gain.",
    "The equal-pressure area gain is not an equal-power or full-scale vehicle gain."
  ],
  "acceptance_gates": [
    "Force balance agrees with sum(delta_pressure_i * measured_area_i) within the combined declared uncertainty.",
    "The lower 95% confidence bound for the paired equal-power net-force gain is above zero before claiming an installed efficiency benefit.",
    "All pressure, force and clearance limits remain satisfied during recorded samples."
  ],
  "scaling_limit": "One-tenth dimensions do not preserve Reynolds number, seal compliance, rotor maps, road forcing or thermal behaviour. Results qualify this bench geometry only."
}