{
  "source": {
    "title": "Experimental investigation of a Mach 6 fixed-geometry inlet featuring a swept external-internal compression flow field",
    "author": "M. G. Torrence",
    "report": "NASA-TN-D-7998 (1975)",
    "record": "https://ntrs.nasa.gov/citations/19750024978",
    "pdf": "https://ntrs.nasa.gov/api/citations/19750024978/downloads/19750024978.pdf",
    "figure": "Figure 12(c), printed p. 57 (PDF p. 58)",
    "local_primary_source_sha256": "8C37ACC003C561749D6E1EC3EB0D559041DC4A562BE2EB7DAC519409D13FD7D0"
  },
  "data_status": "Approximate visual digitization of Figure 12(c); the source presents these four points graphically, not as a numeric table.",
  "test": {
    "freestream_mach": 6.0,
    "test_section_reynolds_number_per_m": 15500000.0,
    "stagnation_pressure_atm": 20,
    "stagnation_temperature_K": 500,
    "angles_of_attack_deg": [
      -5,
      0,
      3,
      5
    ],
    "chosen_data_reduction_limit_eta_D_max": 0.91,
    "data_reduction_limit_note": "A limiting recovery used in the data reduction to correct survey quantities. The report considers 0.91 the most realistic of the limits examined; this is not the measured average recovery.",
    "reported_mean_area_averaged_throat_total_pressure_recovery": 0.78,
    "reported_corresponding_adiabatic_kinetic_energy_efficiency": 0.99,
    "measurements": "Pitot and static pressure surveys in the inlet throat, wall static pressures, and surface temperatures; boundary-layer bleed was used on the centerbody and cowl internal surface.",
    "figure_12c_average_definition": "The report describes an arithmetic average of recovery over the throat area for each angle of attack. It is not the mass-weighted recovery quantity discussed separately elsewhere in the report."
  },
  "digitization": {
    "method": "Four marker centers in Figure 12(c) were read against the printed axes and rounded to 0.01. The connecting line is only a visual guide and does not assert intermediate measurements.",
    "estimated_visual_reading_tolerance": "About +/-0.01 in recovery, estimated from line width, marker size, and scan quality. This is digitization tolerance only, not experimental repeatability, uncertainty in the report's data reduction, or uncertainty in the inlet model.",
    "points": [
      {
        "angle_of_attack_deg": -5,
        "approx_area_averaged_throat_total_pressure_recovery": 0.75
      },
      {
        "angle_of_attack_deg": 0,
        "approx_area_averaged_throat_total_pressure_recovery": 0.74
      },
      {
        "angle_of_attack_deg": 3,
        "approx_area_averaged_throat_total_pressure_recovery": 0.8
      },
      {
        "angle_of_attack_deg": 5,
        "approx_area_averaged_throat_total_pressure_recovery": 0.81
      }
    ]
  },
  "limits": [
    "This is one tested inlet configuration and these specific Mach-6 ground-test conditions, not a universal inlet curve or flight test.",
    "The report states that the 0.91 recovery cap was judged the most realistic for data reduction; other caps were also examined.",
    "The reported 0.78 recovery and 0.99 adiabatic kinetic-energy efficiency are different metrics. Do not interpret either as recovered electrical energy or as whole-engine efficiency.",
    "This plot does not report heat flux from the inlet wall, nor does it show an integrated propulsion-cycle result."
  ]
}