{
  "base_envelope_mm": [
    650,
    450,
    12
  ],
  "nominal_internal_volume_each_L": 0.5,
  "equivalent_bore_diameter_mm": 70,
  "equivalent_internal_length_mm": 129.9224025239962,
  "cad_scope": "Commercial-component space claim only, not pressure-vessel walls, joints, certified hardware or fabrication instructions.",
  "prototype_materials": [
    "New traceable 6061 base and non-pressure brackets",
    "New C10100/Cu-OFE thermal inserts; effective heat capacity measured",
    "Supplier-qualified vacuum/pressure-rated chambers and seals",
    "PEEK thermal breaks where supplier temperature/creep limits permit"
  ],
  "initial_thermal_stage": "Independent metered 0 C and 40 C loops; separate hardware temperature trip at 45 C. These temperatures do not constitute a cryogenic test.",
  "instruments": [
    "Absolute and differential pressure on both chambers",
    "Gas, wall and source temperatures",
    "Signed inlet/outlet mass flow",
    "Independent hot/cold heat-flow measurements",
    "Shaft work or calibrated pneumatic load",
    "DC source/output power and cold-store state"
  ],
  "integration": "External cartridge for WP2/WP8 proof-of-mechanism. Later duct/body packaging is a separate WP1 gate."
}