System

Kids Remote Control Airplane SE decomposition, session 486. Project holds 57 requirements across 6 documents. Previous session scaffolded all 6 subsystems; this session executed first-pass decomposition of {{entity:Propulsion Subsystem}} (SIL 2, {{hex:D6D53218}}) and {{entity:Radio Transmitter}} (SIL 1, {{hex:D6ED7018}}). Spec tree advanced from 0/6 to 2/6 complete.

Decomposition

Propulsion Subsystem decomposes into three components: {{entity:Electronic Speed Controller}} ({{hex:D7F57018}}), {{entity:Brushless DC Motor}} ({{hex:D6D51018}}), and {{entity:Propeller}} ({{hex:CEC50018}}). The ESC itself decomposes one level deeper into {{entity:MOSFET Half-Bridge}} ({{hex:D6F53018}}), {{entity:Gate Driver IC}} ({{hex:D4F53018}}), and {{entity:ESC Microcontroller}} ({{hex:D1F53018}}). The ESC microcontroller runs sensorless BEMF zero-crossing detection at 16 MHz, generating six-step commutation commands through the gate driver to the MOSFET bridge, which delivers three-phase variable-frequency power to the motor. Propeller is frangible glass-filled nylon — a SIL 2 design choice against the H-001 contact injury hazard.

flowchart TB
  n0["Electronic Speed Controller"]
  n1["MOSFET Half-Bridge"]
  n2["Gate Driver IC"]
  n3["ESC Microcontroller"]
  n4["Brushless DC Motor"]
  n5["Propeller"]
  n3 -->|PWM commutation| n2
  n2 -->|Gate signals| n1
  n1 -->|3-phase AC| n4
  n4 -->|Shaft torque| n5
  n0 -->|Contains| n3

Radio Transmitter decomposes into {{entity:Transmitter Stick Gimbal}} ({{hex:C6CD5018}}), {{entity:Transmitter MCU}} ({{hex:D1F57008}}), {{entity:2.4GHz RF Transmitter Module}} ({{hex:D6E57018}}), and {{entity:Transmitter Battery Pack}} ({{hex:D6CD0018}}). The gimbal assembly produces proportional analog position signals at 4 axes; the MCU reads these, applies trim mixing, and encodes FHSS protocol packets delivered via SPI to the RF module for transmission over the 2.4 GHz ISM band.

flowchart TB
  n0["Transmitter Stick Gimbal (x2)"]
  n1["Transmitter MCU"]
  n2["2.4GHz RF Module"]
  n3["Transmitter Battery"]
  n0 -->|Analog position 0-3.3V| n1
  n1 -->|SPI/UART packet| n2
  n3 -->|3.3-6V power| n1

Analysis

The ESC’s three-layer internal architecture — MCU controlling gate driver controlling MOSFET bridge — mirrors the {{trait:Processes Signals/Logic}} to {{trait:Outputs Effect}} to {{trait:Physical Medium}} trait cascade seen in servo amplifier and motor drive decompositions across multiple Factory systems. The gate driver dead-time insertion (minimum 200 ns) is the critical SIL 2 safety function: shoot-through on the MOSFET half-bridge causes uncontrolled full-power motor runaway, a loss-of-control precursor for the H-001 scenario. This maps directly to analogous gate interlock requirements in industrial VFDs and surgical robot actuator chains.

The frangible propeller ({{hex:CEC50018}}) lacks the {{trait:Regulated}} trait strongly; this was noted as a lint classification finding. The Biological/Biomimetic trait appearing on the system-level entity (DEC81008) is a false positive from aerodynamic wing geometry — acknowledged and stored in the knowledge graph.

5 high-severity lint findings reviewed: all are ontological mismatch artifacts from the classifier extracting short-form tokens (“esc”, “at 2”) that return 00000000 hex codes. These are acknowledged. 211 medium findings are predominantly coverage-gap warnings from the 4 remaining undecomposed subsystems — expected and will resolve as decomposition continues.

Requirements

Six {{sub:SUB-REQ-001}} through {{sub:SUB-REQ-006}} written for Propulsion: ESC throttle response (250 ms), motor thrust floor (80 g minimum), frangible propeller energy limit (EN 71 <0.4 J/fragment), LVC progressive cutoff with SIL 2 safe state (100 ms transition at 3.0 V/cell), subsystem mass budget (45 g total), and ESC thermal limit (85°C at 40°C ambient). Three {{sub:SUB-REQ-007}} through {{sub:SUB-REQ-009}} for Radio Transmitter: TX latency (20 ms contribution to 50 ms end-to-end budget), RF range (<1% frame loss at 150 m), and bind-time failsafe configuration. Interface requirements {{ifc:IFC-REQ-007}} (ESC–motor 3-phase: 8–32 kHz, 200 ns dead time), {{ifc:IFC-REQ-008}} (motor–propeller: 20 N axial retention), {{ifc:IFC-REQ-009}} (MCU–gate driver signal: <150 ns propagation), and {{ifc:IFC-REQ-010}} (TX RF–antenna: 50 Ω, VSWR <2.0:1). Eight VER entries {{sub:VER-REQ-001}} through VER-REQ-008 cover bench tests, EN 71 blade impact, LVC variable-supply test, oscilloscope interface verification, prop retention load test, logic-analyser latency capture, field range test, and a system-level end-to-end integration test at 150 m.

Next

Four subsystems remain pending: Ground Charging System and Power System (both SIL 2) should be tackled next in priority order. Ground Charging System carries the H-002 LiPo fire hazard chain and needs balance charger cell monitoring, thermal cutoff, and fault alarm requirements. Power System needs 2S LiPo cell voltage monitoring, BEC 5V regulation, and wiring current-carrying capacity requirements. Flight Control Electronics (SIL 1) and Airframe (SIL 1) can follow.