{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.fairchild-at-21-gunner","code":"thing-q613549","url":"https://ver.cy/models/thing/q613549/","name":"Fairchild AT-21 Gunner","alternateNames":[],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.OBJ"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"The Fairchild AT-21 Gunner was an American twin-engine military aircraft developed during the Second World War as a specialized crew trainer for bomber gunnery and operated by the United States Army Air Forces.","purpose":"Enable an agent to identify the Fairchild AT-21 Gunner aircraft type, distinguish its documented configurations and assess what evidence is needed to interpret, preserve or evaluate an associated airframe.","scope":{"in":["AT-21 designation, recognition evidence and boundaries with related experimental aircraft","Production configuration and manufacturer-dependent provenance","Twin-engine airframe, laminated plywood structure and installed systems","Aerial-gunnery training equipment, crew stations and documented training roles","Configuration-dependent performance, service limitations and preservation requirements"],"out":["Individual airframes' complete ownership, location and maintenance histories","Fairchild, Bellanca and McDonnell as organisations","General aircraft flight mechanics and pilot-training doctrine","Duramold manufacture and material chemistry beyond aircraft-specific implications","Standalone engine, firearm and turret models","Related prototypes and derivative aircraft as independent types"],"boundaries":[]},"distinguishingFeatures":["Require evidence identifying the aircraft as AT-21 Gunner; manufacturer attribution alone is insufficient because Fairchild, Bellanca and McDonnell built examples. [Museum of Flight](https://archives.museumofflight.org/subjects/1315)","Check the combination of twin engines and laminated plywood construction against type documentation; neither feature alone establishes identity. [Historic American Engineering Record](https://tile.loc.gov/storage-services/master/pnp/habshaer/nc/nc0300/nc0371/data/nc0371data.pdf)","Look for evidence of the advanced aerial-gunner training role rather than identifying the type solely from a bomber-like appearance. [Historic American Engineering Record](https://tile.loc.gov/storage-services/master/pnp/habshaer/nc/nc0300/nc0371/data/nc0371data.pdf)","Cross-check designation, powerplant installation and training-station arrangement when distinguishing an AT-21 from a related prototype, derivative or modified survivor."],"structure":{"bundles":[{"id":"designation-and-production","name":"Designation and production","description":"Establish AT-21 identity independently of captions, manufacturer names and related aircraft.","layers":[{"id":"type-boundary","name":"Type boundary","description":"Define which configurations belong to the registered AT-21 concept.","findings":[{"id":"designation-membership","name":"Designation membership","description":"Require evidence connecting an aircraft or record to AT-21 and describe related designations as relationships rather than assumed synonyms.","questions":[{"text":"Which contemporary designation or acceptance documents establish AT-21 membership?","id":"designation-membership-q01","kind":"definition"},{"text":"Which related experimental designations represent predecessors or derivatives rather than interchangeable AT-21 names?","id":"designation-membership-q02","kind":"boundary"}]}]},{"id":"builder-and-baseline","name":"Builder and baseline","description":"Connect production attribution to the correct configuration evidence.","findings":[{"id":"production-configuration-applicability","name":"Production configuration applicability","description":"Track builder and serial applicability without automatically creating separate types for contract production.","questions":[{"text":"Which records connect Fairchild, Bellanca and McDonnell production to particular AT-21 serial ranges?","id":"production-configuration-applicability-q01","kind":"provenance"},{"text":"Which documented equipment or construction differences require separate configuration baselines within AT-21?","id":"production-configuration-applicability-q02","kind":"boundary"}]}]}]},{"id":"airframe-and-propulsion","name":"Airframe and propulsion","description":"Describe the physical configuration needed to recognise and assess an AT-21.","layers":[{"id":"laminated-airframe","name":"Laminated airframe","description":"Locate materials, structural assemblies and diagnostic geometry.","findings":[{"id":"construction-and-geometry","name":"Construction and geometry","description":"Establish component-level construction and dimensions from applicable drawings rather than extending a general plywood description to every part.","questions":[{"text":"Which AT-21 assemblies use Duramold or other laminated construction, and which use different materials?","id":"construction-and-geometry-q01","kind":"definition"},{"text":"What dimensions and wing, tail and landing-gear geometry are specified for the selected production baseline?","id":"construction-and-geometry-q02","kind":"measurement"}]}]},{"id":"powerplant-installation","name":"Powerplant installation","description":"Identify engines, propellers and their aircraft-level interfaces.","findings":[{"id":"matched-propulsion-baseline","name":"Matched propulsion baseline","description":"Associate engine ratings, propellers, fuel requirements and controls with the same documented AT-21 configuration.","questions":[{"text":"Which engine and propeller designations are supported for production AT-21 aircraft, as distinct from related prototypes?","id":"matched-propulsion-baseline-q01","kind":"provenance"},{"text":"What rated power, fuel grade, usable fuel capacity and lubricant requirements apply to that installation?","id":"matched-propulsion-baseline-q02","kind":"measurement"},{"text":"Which cockpit controls and indicators govern each engine and propeller installation?","id":"matched-propulsion-baseline-q03","kind":"definition"}]}]}]},{"id":"gunner-training-arrangement","name":"Gunner training arrangement","description":"Connect crew accommodation and installed equipment to the AT-21's training purpose.","layers":[{"id":"crew-and-instruction","name":"Crew and instruction","description":"Determine who occupied each station and what instruction the aircraft supported.","findings":[{"id":"station-role-allocation","name":"Station role allocation","description":"Separate nominal seating capacity from pilot, instructor and trainee duties in documented training arrangements.","questions":[{"text":"How many occupants were provided for, and which stations belonged to pilots, instructors and gunner trainees?","id":"station-role-allocation-q01","kind":"definition"},{"text":"Which AT-21 training tasks are demonstrated by contemporary manuals or unit records, including any bombardier instruction?","id":"station-role-allocation-q02","kind":"provenance"}]}]},{"id":"training-equipment","name":"Training equipment","description":"Identify mounts, sights, communications and equipment states relevant to instruction.","findings":[{"id":"equipment-fit-and-safeguards","name":"Equipment fit and safeguards","description":"Distinguish installed, removed, simulated and inert equipment, recording safeguards only when supported by applicable documentation.","questions":[{"text":"Which gun positions, mounts, sights and instructor communications were fitted in each documented AT-21 configuration?","id":"equipment-fit-and-safeguards-q01","kind":"definition"},{"text":"What evidence distinguishes operational training equipment from display substitutes or later additions?","id":"equipment-fit-and-safeguards-q02","kind":"provenance"},{"text":"Which documented isolation procedures or interlocks constrain inspection and demonstration of retained equipment?","id":"equipment-fit-and-safeguards-q03","kind":"action"}]}]}]},{"id":"performance-and-service-suitability","name":"Performance and service suitability","description":"Relate published performance and historical training suitability to their actual evidence.","layers":[{"id":"loading-and-flight-envelope","name":"Loading and flight envelope","description":"Bind performance figures to loading, equipment and test conditions.","findings":[{"id":"conditional-performance","name":"Conditional performance","description":"Keep nominal specifications, measured performance and operating limitations distinct.","questions":[{"text":"What empty and loaded masses, centre-of-gravity limits and crew-equipment assumptions accompany AT-21 performance figures?","id":"conditional-performance-q01","kind":"measurement"},{"text":"Which speed, climb, range and asymmetric-flight claims are supported by tests, and under what conditions?","id":"conditional-performance-q02","kind":"measurement"}]}]},{"id":"training-service-evidence","name":"Training service evidence","description":"Assess reported shortcomings and changes in employment without assuming a single cause.","findings":[{"id":"service-outcome-attribution","name":"Service outcome attribution","description":"Separate documented technical deficiencies from changes in training policy, equipment availability or later historical interpretation.","questions":[{"text":"Which contemporary evaluations substantiate reported AT-21 handling, vibration or training-effectiveness problems?","id":"service-outcome-attribution-q01","kind":"provenance"},{"text":"What records establish when and why training employment changed, and whether the explanation applies to all aircraft?","id":"service-outcome-attribution-q02","kind":"boundary"}]}]}]},{"id":"surviving-material-and-permitted-use","name":"Surviving material and permitted use","description":"Define AT-21-specific evidence needed to assess surviving assemblies, reconstructions and proposed uses.","layers":[{"id":"structural-condition-and-repair","name":"Structural condition and repair","description":"Connect condition evidence and repair history to original AT-21 construction.","findings":[{"id":"bond-and-repair-evidence","name":"Bond and repair evidence","description":"Treat moisture damage, biological deterioration and bond separation as assessment subjects, without presuming their presence or an undocumented repair method.","questions":[{"text":"Which inspection methods and acceptance criteria are documented for the AT-21's laminated assemblies and bonded joints?","id":"bond-and-repair-evidence-q01","kind":"provenance"},{"text":"What observations and repair records distinguish retained original structure from replacement or reconstructed material?","id":"bond-and-repair-evidence-q02","kind":"measurement"},{"text":"Which AT-21 technical orders specify acceptable repair materials, processes and inspection intervals?","id":"bond-and-repair-evidence-q03","kind":"action"}]}]},{"id":"authenticity-and-use-evidence","name":"Authenticity and use evidence","description":"Determine what an identified airframe or assembly can substantiate and what proposed use requires.","findings":[{"id":"use-specific-assessment","name":"Use-specific assessment","description":"Require separate evidence for historical attribution, static display, movement, equipment demonstration and flight.","questions":[{"text":"Which serial evidence, component records and restoration documents support an asserted AT-21 identity?","id":"use-specific-assessment-q01","kind":"provenance"},{"text":"What structural, systems and equipment assessments are required for the particular proposed use?","id":"use-specific-assessment-q02","kind":"action"},{"text":"Which issuing body and applicable document establish historical acceptance requirements or present authorisation for that use?","id":"use-specific-assessment-q03","kind":"provenance"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of Fairchild AT-21 Gunner this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-identifiers","name":"Identifiers and schemes","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these identifiers and schemes hold for the sense of Fairchild AT-21 Gunner this model covers, and on what evidence?","id":"evidence-identifiers-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of Fairchild AT-21 Gunner this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of Fairchild AT-21 Gunner this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of Fairchild AT-21 Gunner this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Describe the aircraft's role in training bomber gunners during the Second World War.","Support historians and museums in cataloguing records."],"mustNot":["Present uncertain production or service details as established fact.","Confuse it with other types sharing a similar designation.","Glorify violence when describing training for war."],"requiresHuman":["Publishing interpretations where sources disagree."]},"ethics":{"considerations":["Training aircraft histories record the young crews prepared for dangerous missions."],"affectedParties":["Veterans and their families","Historians"]},"owners":{"steward":"Nobody owns the design history; archives and museums hold the surviving records.","roles":[],"masterSystems":[]},"relations":[{"target":"Q68057922","type":"parent","note":"registry parent class"},{"target":"Q68073115","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.fairchild-at-21-gunner","Wikidata: Q613549 (https://www.wikidata.org/wiki/Q613549)"]},"properties":{"applicability":"required","items":["Designation evidence: Designation linked to identification plate, acceptance record, drawing or dated photograph","Production attribution: Builder, factory, serial range and supporting production record","Configuration baseline: Documented production configuration; service modification; restoration configuration; unresolved","Structural material distribution: Material and construction method by fuselage, wing, empennage and control surface","Installed propulsion: Engine and propeller designations by position, with configuration applicability","Engine rating: kW or hp per engine, with rating duration, rpm and altitude","Airframe dimensions: Wingspan, length and height in m, with configuration and source","Mass and balance envelope: kg and centre-of-gravity position relative to a stated datum","Training station configuration: Station roles, occupancy, installed training equipment and operational status","Documented performance: Speed in km/h, climb in m/s, altitude and range in m or km, with test conditions","Structural assessment state: Unassessed; inspected with recorded limitations; repair required; assessed for a specified use"]},"recognition":{"applicability":"required","items":["A twin-engine aircraft with a twin tail and a compact fuselage.","Gun positions for training gunners in the nose and fuselage."]},"capabilities":{"applicability":"required","items":["Classify an aircraft record or photograph as confirmed, probable or unresolved AT-21 identification.","Compare a represented configuration with dated AT-21 drawings and equipment records.","Map crew stations and installed equipment to documented training capabilities.","Identify missing evidence before interpreting performance or historical serviceability.","Prepare an aircraft-specific conservation or restoration research brief.","Flag proposed handling or operation that lacks applicable structural, equipment or authorisation evidence."]},"hazards":{"applicability":"required","items":["Records are scarce, so errors about the type can spread easily."]},"interfaces":{"applicability":"required","items":["The United States Army Air Forces classified the AT-21 in its advanced trainer aircraft designation series."]},"context":{"applicability":"required","items":["The AT-21 was developed during the Second World War to train bomber crews in aerial gunnery.","It is now principally encountered in aviation archives, historical photographs and research into military training aircraft."]}},"sources":[{"title":"Wikidata item Q613549: Fairchild AT-21 Gunner","url":"https://www.wikidata.org/wiki/Q613549","note":"identity and sense of the item"},{"title":"Wikipedia: Fairchild AT-21 Gunner","url":"https://en.wikipedia.org/wiki/Fairchild_AT-21_Gunner","note":"general description of the item"}],"openQuestions":["Which original AT-21 specifications, flight manuals and technical orders establish production dimensions, powerplant variants, ratings and operating limitations?","What exact crew complement, gun-station arrangement and training-equipment fit applied across builders and modifications?","How should the boundaries with XAT-13, XAT-14, XAT-14A and XBQ-3 be documented without treating related designs as synonyms?","Which contemporary records establish the causes and timing of reduced or discontinued AT-21 training employment?","What authenticated AT-21 material survives, and what documented criteria govern assessment and repair of its laminated structure?"],"resources":{"spec":"/models/things/publications/thing-q613549/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q613549/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T09:37:45Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:32+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}