{
  "revision": "P2.2-A first scientific demonstration / design specification",
  "evidence": "UNBUILT_EXPERIMENT_SPECIFICATION_NO_RECORDED_MEASUREMENTS",
  "purpose": "Demonstrate cooling-induced pressure deficit and an installed suction force, then optionally measure a small displacement work. Keep the vehicle and high-pressure freezing stages as later experiments.",
  "core_layout": [
    "Two approximately 0.5 L commercial vessels rated for the intended external-pressure/vacuum and temperature range; weigh and measure their actual internal and thermal capacities.",
    "Thermal interfaces connect the gas vessels to a finite 0 C ice/water cold store. Record actual ice/water mass, vessel temperatures and any circulation/heater electricity.",
    "A separate ambient-temperature contact pan or four annular shoes connect by compliant gas hoses. Measure total hose, valve and pan dead volume.",
    "A calibrated tensile load cell, rigid crosshead and metal links connect mechanically to the pan/shoe housings. The gas hoses do not serve as the force load path.",
    "An independent stage and fixed ambient contact plate set normal displacement and seal preload. Record stage position and seal contact condition; pressure force and pull-off force are separate observations.",
    "Optional calibrated bellows/piston connects to a low-force load and displacement encoder. Meter integral F dx; record spring/stiction and reset work."
  ],
  "instrument_targets_not_purchased": [
    {
      "item": "Differential pressure",
      "target": "0-10 kPa range; standard uncertainty <=20 Pa after calibration"
    },
    {
      "item": "Absolute/ambient pressure",
      "target": "Record both core and ambient pressure; absolute scale traceable"
    },
    {
      "item": "Force",
      "target": "500 N tension/compression channel; standard uncertainty <=0.25 N after fixture calibration"
    },
    {
      "item": "Bellows work force",
      "target": "Separate low-range channel or calibrated deadweight; target uncertainty <=0.01 N around 2 N"
    },
    {
      "item": "Temperature",
      "target": "Gas at multiple positions, both vessel walls, bath and contact plate; target standard uncertainty <=0.1 K"
    },
    {
      "item": "Displacement/time",
      "target": "<=10 micrometre displacement uncertainty for the optional 10 mm stroke; synchronized logging >=10 Hz for this slow test"
    },
    {
      "item": "Cold and electrical energy",
      "target": "Weighed ice/water and bath calorimetry; meter every pump, heater, fan, controller and reset input"
    }
  ],
  "tests": [
    {
      "id": "T0",
      "test": "Fixture and sensor calibration",
      "method": "Calibrate pressure, load, displacement and temperature independently. Apply known pressure deficits with a separate calibration source and measure effective force area, seal preload and hose-force offsets. Isolate that source for cold-only trials."
    },
    {
      "id": "T1",
      "test": "Warm/null cycles",
      "method": "Begin with all gas volumes at ambient pressure and temperature. Run the valve/timing/fixture sequence with no temperature difference. Repeat with a vent open while applying the cold treatment to expose thermal drift or freezing-adhesion artefacts."
    },
    {
      "id": "T2",
      "test": "Sealed cooling mechanism",
      "method": "Reset to ambient, close the vent, apply the cold interface, and log pressure, temperatures and force for 600 s. Use at least five independent cold cycles interleaved in randomized order with five null cycles."
    },
    {
      "id": "T3",
      "test": "Leak and surface sensitivity",
      "method": "At stable gas temperature measure pressure relaxation separately. Repeat cold trials with characterized leak restrictions and defined dry/wet/rough contact coupons. Equivalent uniform gaps are a model parameter, not a measurement of a real seal."
    },
    {
      "id": "T4",
      "test": "Moving-load work",
      "method": "Use the calibrated low-force load module. Integrate measured force over measured stroke, subtract its independently measured spring/friction baseline, and meter the complete reset. Static holding force alone is not work."
    },
    {
      "id": "T5",
      "test": "Powered suction comparison",
      "method": "With the thermal circuit isolated, characterize a rated external blower and the same complete shoe/pan on a load cell. Record installed net force, pressure, flow and electrical power over seal gaps and surface coupons."
    },
    {
      "id": "T6",
      "test": "Unpowered wheel kinematics",
      "method": "Use a stationary supported rig, stopped wheels and a rated slow actuator. Verify support loads, docking clearance, pre-lift, continuous sweep, locks and sensor interlocks before adding any rotating impeller."
    },
    {
      "id": "T7",
      "test": "Later vehicle evidence",
      "method": "Only after measured fan, leakage, tyre/pad and actuator maps exist, replace the assumed maps and compare matched stopping and trajectory tests. No road demonstration is claimed by this package."
    }
  ],
  "predeclared_questions": [
    "Does the cold treatment create a pressure deficit exceeding three combined standard uncertainties relative to paired null trials?",
    "Does force versus pressure agree with the independently calibrated effective area after seal-preload/hose corrections, within the stated uncertainty?",
    "Does any moving-load work exceed three combined standard uncertainties, with the complete energy/reset ledger reported?",
    "Can mass and energy discrepancies be explained by measured leakage, heat leaks, thermal mass and instrument uncertainty without adding an unknown energy term?"
  ],
  "uncertainty_example": {
    "area_m2": 0.03,
    "area_relative_standard_uncertainty_assumed": 0.01,
    "pressure_standard_uncertainty_Pa_assumed": 20,
    "force_sensor_standard_uncertainty_N_assumed": 0.25,
    "combined_force_standard_uncertainty_N_near_6kPa": 1.9137659209004638,
    "scope": "Illustrative instrument budget. Seal/contact modelling errors and fixture bias must be characterized separately; this is not a measured confidence interval."
  },
  "bill_of_materials_candidates": [
    {
      "item": "Rated gas vessels/fittings",
      "material_or_specification": "New traceable 316L stainless commercial vacuum-compatible components; supplier temperature and external-pressure rating govern"
    },
    {
      "item": "Thermal inserts",
      "material_or_specification": "New oxygen-free copper interfaces with documented mass and thermal contact; mechanically removable from the gas envelope"
    },
    {
      "item": "Pan/tray and brackets",
      "material_or_specification": "New traceable 6061-T6/T651 or functionally equivalent machinable aluminium, with inspection of the actual sealing face"
    },
    {
      "item": "Thermal breaks",
      "material_or_specification": "PEEK or G10 candidates in moderate-temperature mounts; grade and creep/contact load verified before purchase"
    },
    {
      "item": "Replaceable seals/contact coupons",
      "material_or_specification": "Fresh documented elastomer grades selected for the measured surface, water, temperature and wear conditions. Price is not assigned a friction gain."
    },
    {
      "item": "Later cryogenic loop",
      "material_or_specification": "Separate supplier-qualified cryogenic seals, pressure equipment and compatible materials. Moderate-temperature elastomers receive no assumed liquid-N2 qualification."
    }
  ],
  "measurements_available": false,
  "purchases_made": false,
  "fabrication_completed": false
}