{
  "title": "Approximate digitization and Eq. (2) consistency sensitivity for NASA/TM-2011-217136 Figure 5",
  "status": "Reproducible raster digitization and conditional dimensional check; not source numeric data, author code, an NPSS reproduction, or evidence of a source error.",
  "source": {
    "record": "https://ntrs.nasa.gov/citations/20110015567",
    "pdf": "https://ntrs.nasa.gov/api/citations/20110015567/downloads/20110015567.pdf",
    "pdf_sha256": "73d6f155bffb791bf2a34d0bf65b53f0c28652d02b1bc67ef3551ecde84cf718",
    "locators": "Figure 5: printed p. 8 / PDF p. 12; Eq. (2): printed p. 5 / PDF p. 9; approximate prose: printed p. 9 / PDF p. 13",
    "local_crop": "figure5-crop.png",
    "crop_sha256": "91cab19936d908fb7e547d77421ea0dc4155cc3a91fdbfcf4e67f778596ee63f"
  },
  "digitization": {
    "algorithm": "Threshold red pixels within the plot bounds; sample 5-pixel-wide windows at 0.05 Mach spacing; use median source y-pixel as the curve centerline.",
    "source_axis_calibration_pixels": {
      "mach_min_at_x": [
        3.25,
        188.0
      ],
      "mach_max_at_x": [
        7.0,
        557.0
      ],
      "power_zero_at_y": [
        0.0,
        257.0
      ],
      "power_100_MW_at_y": [
        100.0,
        111.0
      ]
    },
    "calibration_selection": "Plot-frame endpoints selected at the axes/tick intersections and visually inspected on the pinned source crop. A +/-1 px independent vertical endpoint and centerline pick is propagated below.",
    "point_spacing_mach": 0.05,
    "centerline_reading_allowance_MW": 2.0,
    "allowance_meaning": "Project's approximate allowance for raster line thickness and reading; not statistical uncertainty or NASA model uncertainty.",
    "pixel_pick_sensitivity_at_comparison_points": {
      "4.75": {
        "nominal_MW": 69.86,
        "max_abs_shift_MW_for_independent_plus_minus_1_px_y_picks": 1.37,
        "reported_visual_allowance_MW": 2.0
      },
      "5.25": {
        "nominal_MW": 87.67,
        "max_abs_shift_MW_for_independent_plus_minus_1_px_y_picks": 1.37,
        "reported_visual_allowance_MW": 2.0
      },
      "6.0": {
        "nominal_MW": 52.4,
        "max_abs_shift_MW_for_independent_plus_minus_1_px_y_picks": 1.37,
        "reported_visual_allowance_MW": 2.0
      },
      "6.75": {
        "nominal_MW": 75.34,
        "max_abs_shift_MW_for_independent_plus_minus_1_px_y_picks": 1.37,
        "reported_visual_allowance_MW": 2.0
      }
    },
    "unpropagated_reading_factors": [
      "horizontal axis endpoint placement and exact Mach correspondence",
      "color threshold/curve stroke shape",
      "approximate prose input ranges"
    ],
    "csv": "nasa-2011-figure5-digitized.csv",
    "points": 76,
    "redraw_generator": "nasa-2011-figure5-redraw.py"
  },
  "consistency_equation": "P_elec = eta_N(g) * mdot * Cp * T0,12",
  "prose_case_inputs_Mach_4p75_to_5p25": [
    {
      "mach": 4.75,
      "power_MW": 69.86,
      "T0_K": 1180.0,
      "mdot_kg_s_approx": 10.0,
      "eta_approx": 0.5,
      "implied_Cp_kJ_kg_K_using_nominal_prose_values": 11.841,
      "implied_Cp_interval_from_visual_allowance_kJ_kg_K": [
        11.502,
        12.18
      ],
      "implied_mdot_interval_for_Cp_1_to_1p2_kJ_kg_K_kg_s": [
        95.85,
        121.8
      ],
      "prose_value_note": "Approximate ranges, not a pointwise matched NPSS record."
    },
    {
      "mach": 5.25,
      "power_MW": 87.67,
      "T0_K": 1380.0,
      "mdot_kg_s_approx": 10.0,
      "eta_approx": 0.5,
      "implied_Cp_kJ_kg_K_using_nominal_prose_values": 12.706,
      "implied_Cp_interval_from_visual_allowance_kJ_kg_K": [
        12.416,
        12.996
      ],
      "implied_mdot_interval_for_Cp_1_to_1p2_kJ_kg_K_kg_s": [
        103.47,
        129.96
      ],
      "prose_value_note": "Approximate ranges, not a pointwise matched NPSS record."
    }
  ],
  "prose_case_inputs_Mach_6_to_6p75": [
    {
      "mach": 6.0,
      "power_MW": 52.4,
      "T0_K": 1720.0,
      "mdot_kg_s_approx": 4.0,
      "eta_approx": 0.6,
      "implied_Cp_kJ_kg_K_using_nominal_prose_values": 12.694,
      "implied_Cp_interval_from_visual_allowance_kJ_kg_K": [
        12.209,
        13.178
      ],
      "prose_value_note": "Approximate endpoint trend values, assumed paired for this diagnostic; not pointwise NPSS inputs."
    },
    {
      "mach": 6.75,
      "power_MW": 75.34,
      "T0_K": 2089.0,
      "mdot_kg_s_approx": 5.0,
      "eta_approx": 0.6,
      "implied_Cp_kJ_kg_K_using_nominal_prose_values": 12.022,
      "implied_Cp_interval_from_visual_allowance_kJ_kg_K": [
        11.703,
        12.341
      ],
      "prose_value_note": "Approximate endpoint trend values, assumed paired for this diagnostic; not pointwise NPSS inputs."
    }
  ],
  "cross_range_implied_Cp_summary": {
    "nominal_implied_values_kJ_kg_K": [
      11.841,
      12.706,
      12.694,
      12.022
    ],
    "minimum": 11.841,
    "maximum": 12.706,
    "mean": 12.316,
    "range_width": 0.865,
    "interpretation": "All four approximate prose/plot endpoint pairings imply values near 12 kJ/(kg K). The clustering is compatible with a shared scale factor or convention, but the approximate range pairings can produce a similar cluster. It does not establish a common NASA Cp or convention, nor exact matched operating points; exact Cp and pointwise inputs remain unavailable in the inspected record."
  },
  "sensitivity_assumptions": {
    "Cp_kJ_kg_K": [
      1.0,
      1.2
    ],
    "status": "Exploratory interval selected by this project; not stated as the NASA NPSS setting.",
    "eta_and_mdot": "Use the report's approximate nominal prose values (0.50 and 10 kg/s) for Mach 4.75–5.25; no numeric uncertainty range is supplied in the prose.",
    "T0": "Use the report's stated approximate endpoint values, not inferred pointwise station data."
  },
  "interpretation": "Under the explicitly chosen Cp interval 1.0–1.2 kJ/(kg K), Mach 4.75 and 5.25 prose values imply about 5.9–8.3 MW, below the Figure 5 readings. However, pairing the report's approximate endpoint descriptions over both Mach 4.75–5.25 and Mach 6.00–6.75 with the digitized curve yields four implied effective Cp values near 12 kJ/(kg K). The clustering is compatible with a shared scale factor or convention, but approximate range pairings can produce a similar cluster. It does not establish a common NASA Cp, convention, or matched operating points. The report alone does not expose enough exact inputs for reproduction; this is not a confirmed NASA error or novelty.",
  "limitations": [
    "Figure 5 has no source pointwise numerical table; values are approximate raster readings.",
    "No NPSS input deck, pointwise flow file, exact Cp, or matched operating-point output was exposed in the inspected NTRS record.",
    "The visual allowance is not a statistical interval and does not include all axis/calibration uncertainty.",
    "The report's prose values are approximate ranges and not necessarily matched point-by-point to the digitized curve."
  ]
}