System

{{entity:Kids Remote Control Airplane}} ({{hex:DEEC5058}}) is the new decomposition target — a battery-powered fixed-wing model aircraft for children aged 8–14, controlled via 2.4GHz radio transmitter at up to 300m range. The system sits at the intersection of recreational consumer electronics and small UAS regulation. This session establishes the project scaffold: five subsystems classified, 8 stakeholder requirements, 8 system requirements, and 3 Radio Control Link subsystem requirements, with trace links connecting the primary stakeholder needs to quantified system requirements.

Stakeholder Requirements

Three stakeholder classes drive the requirements. The {{entity:Child Pilot}} ({{hex:00080A51}}) sets the control latency and endurance floor: 150ms total stick-to-surface response, 10-minute minimum powered flight at 70% throttle, and a low-battery alert at 20% remaining capacity. The {{entity:Parent Guardian}} ({{hex:010908A1}}) adds constraints on battery charging safety — LiPo cell voltage capped at 4.25V and thermal cutoff at 45°C to prevent domestic fire risk — and on structural behaviour at crash (no loose high-energy fragments at stall speed). The {{entity:Regulatory Authority}} ({{hex:008578FD}}) imposes CAA/FAA compliance including VLOS, 120m AGL ceiling, and sub-500g mass for registration-free operation.

Key stakeholder requirements: {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-001}} (attitude control), {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-002}} (failsafe), {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-004}} (low-battery warning), {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-008}} (LiPo charging safety).

System Requirements

System requirements allocate the stakeholder budgets to subsystem interfaces. The 150ms control response ({{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-001}}) is decomposed as: 20ms for RC link decode and forward ({{sys:REQ-SEKIDSREMOTECONTROLAIRPLANE-009}}), leaving 130ms for servo mechanical travel at 180ms/60° — within budget for typical ±30° aileron throw. The failsafe chain ({{sys:REQ-SEKIDSREMOTECONTROLAIRPLANE-010}}) allocates 100ms for link-loss declaration at −85 dBm RSSI and 100ms for failsafe actuation to meet the 200ms total in {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-002}}.

The Power System requirement {{sys:REQ-SEKIDSREMOTECONTROLAIRPLANE-012}} covers both low-voltage cutoff (9.0V, 3.0V/cell) and the warning threshold (9.9V) that implements {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-004}}. The ESC current-limiting and thermal cutback in {{sys:REQ-SEKIDSREMOTECONTROLAIRPLANE-015}} is derived from the crash-fragment hazard in {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-007}}: gradual power reduction gives warning before complete thrust loss, reducing the frequency of unexpected high-energy impacts. The airframe longitudinal stability requirement ({{sys:REQ-SEKIDSREMOTECONTROLAIRPLANE-014}}) specifies Cm_alpha < 0 across 18–60 km/h without active stabilisation — this is the aerodynamic safety foundation for a self-recovering trainer.

Functional Analysis

Five functional groupings emerged from the ConOps scenarios:

1. Control link — RF propagation from pilot to aircraft; cross-domain analog: {{entity:Radio Control}} from the corpus (AN/ARC-5 radio family); shares {{trait:Processes Signals/Logic}}, {{trait:System-integrated}}, {{trait:Signalling}}.
2. Flight control — channel mixing and servo actuation; analog: {{entity:Flight Controller Processor}}; shares {{trait:Processes Signals/Logic}}, {{trait:Outputs Effect}}.
3. Propulsion — energy conversion to thrust; analog: {{entity:safety controller}} for thermal cutback logic.
4. Power — energy storage and distribution; LiPo management is the only subsystem with {{trait:State-Transforming}} potential (thermal runaway is an irreversible state transition).
5. Airframe — structural envelope and aerodynamic surfaces; {{trait:Structural}}, {{trait:Physical Object}}, {{trait:Observable}}.

Decomposition

flowchart TB
  PILOT[Child Pilot] -->|2.4GHz TX| RCL
  RCL[Radio Control Link hex:54E57018] -->|PWM channels| FCS
  RCL -->|throttle PWM| PROP
  FCS[Flight Control System hex:50E53018] -->|servo signals| AFS
  PROP[Propulsion System hex:55F53018] -->|thrust| AFS
  PWR[Power System hex:D6D53018] -->|11.1V / BEC 5V| RCL
  PWR -->|11.1V| PROP
  PWR -->|BEC 5V| FCS
  AFS[Airframe Structure hex:CE811008]

Radio Control Link ({{hex:54E57018}}) is the highest-priority subsystem for next-session decomposition: it contains the failsafe logic (most safety-critical function), the binding protocol (cross-control hazard mitigation), and the RSSI-based link quality monitoring. The {{trait:Signalling}} and {{trait:Processes Signals/Logic}} trait pattern matches closely with the autonomous underwater vehicle sonar processing chain from the corpus — both are safety-critical signal pipelines with hard latency budgets and explicit degraded-mode behaviour.

Next

Radio Control Link and Propulsion System decomposition remain. RCL should be tackled first: classify transmitter module, receiver module, FHSS hopping engine, and failsafe controller; create IFC requirements for the TX-RX interface; add VER entries for {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-001}} (bench latency test procedure) and {{stk:REQ-SEKIDSREMOTECONTROLAIRPLANE-002}} (failsafe range test at 300m with deliberate jamming). Propulsion decomposition should classify ESC (MOSFET bridge, gate driver, microcontroller), motor, and propeller as distinct components with their own hex codes and thermal/structural failure modes.