System

{{entity:Kids Remote Control Airplane}} — scaffold session transforming concept-phase data into a requirements baseline and physical decomposition. The concept session established the mission (safe RC airplane for children 8-14), 5 ConOps scenarios, 6 stakeholders, 7 hazards (H-001 through H-007), 6 operating modes, and 3 external interfaces. This session derived 36 requirements (14 STK, 10 SYS, 6 IFC, 6 ARC), identified 7 system functions, grouped them into 6 subsystems, created 9 STK-to-SYS trace links, and built the decomposition diagram. Baseline SCAFFOLD-2026-03-23 captures the full state.

Stakeholder Requirements

14 {{stk:STK-REQ-001}} through {{stk:STK-REQ-014}} requirements derived from ConOps scenarios, covering all 6 stakeholders plus environment-as-stakeholder. Child Pilot requirements (STK-REQ-001, -002) anchor to the Weekend Park Flight scenario — 25-minute session budget, novice-accessible controls. Parent/Guardian requirements (STK-REQ-003, -004) derive from the Charging Fire Emergency and post-crash inspection scenarios. Bystander requirements (STK-REQ-005, -006) address kinetic energy limits (<12 J) and failsafe descent, grounded in H-003 and H-004. Regulator requirements (STK-REQ-009, -010) mandate EN 71/ASTM F963 compliance and the critical sub-250g mass threshold for UAS registration exemption. Retailer requirements (STK-REQ-011, -012) cover IATA DGR packaging and age-rating labelling.

System Requirements

10 {{sys:SYS-REQ-001}} through {{sys:SYS-REQ-010}} requirements with quantified acceptance criteria. The flight envelope (SYS-REQ-001: 5-15 m/s, <250g) is the most constrained — jointly driven by regulatory mass limit, kinetic energy safety, and stall speed physics. Safety-critical requirements carry SIL tags: SYS-REQ-004 (failsafe descent, SIL 1 from H-003), SYS-REQ-005 (charge safety, SIL 2 from H-002), SYS-REQ-006 (frangible propeller, SIL 2 from H-001). All 7 hazards from the concept phase are addressed by at least one SYS requirement.

Functional Analysis

Seven system functions identified and classified in UHT: Flight Control {{hex:D4F57018}}, Propulsion {{hex:D6D53218}}, Power Management {{hex:D6D53018}}, Radio Control Link, Stability Augmentation, Structural Integrity {{hex:CE851008}}, and Charging Safety {{hex:D6F41018}}. Functions grouped by trait similarity, failure independence, and physical co-location. Flight Control and Stability Augmentation cluster on a single board (shared MCU, same PID loop). Propulsion groups motor, ESC, and propeller (single thrust chain with shared failure modes). Charging Safety isolates as a ground-based unit — the 50g charger cannot fly on a 250g aircraft.

Decomposition

Six subsystems with explicit function-to-subsystem mapping:

flowchart TB
  n0["Kids Remote Control Airplane"]
  n1["Airframe Subsystem"]
  n2["Propulsion Subsystem"]
  n3["Flight Control Electronics"]
  n4["Radio Transmitter"]
  n5["Power System"]
  n6["Ground Charging System"]
  n7["USB Power Supply"]
  n8["Atmosphere"]
  n9["2.4 GHz ISM Band"]
  n10(["Child Pilot"])
  n0 -->|contains| n1
  n0 -->|contains| n2
  n0 -->|contains| n3
  n0 -->|contains| n4
  n0 -->|contains| n5
  n0 -->|contains| n6
  n5 -->|7.4V power| n2
  n5 -->|5V BEC| n3
  n3 -->|PWM throttle| n2
  n4 -->|2.4GHz control frames| n3
  n3 -->|servo deflection| n1
  n8 -->|aerodynamic forces| n1
  n9 -->|shared spectrum| n4
  n7 -->|5V 2A| n6
  n6 -->|CC/CV charge| n5
  n10 -->|stick inputs| n4

Cross-domain analog discovery: {{entity:Flight Control Electronics}} matched Factory’s {{entity:Flight Controller Processor}} at Jaccard 0.737, confirming the integrated receiver-gyro-MCU architecture is a well-established pattern. {{entity:Ground Charging System}} matched {{entity:Battery Management System}} at 0.524 — lower similarity reflects the charger’s simplified topology (no state-of-charge estimation, no cell balancing during discharge). Six architecture decisions (ARC-REQ-001 through ARC-REQ-006) document key trade-offs: integrated FCE board, ESC-integrated BEC, ground-based charger, EPP foam construction, dedicated transmitter, and 2S LiPo chemistry.

Next

{{entity:Propulsion Subsystem}} should be decomposed first — it carries SIL 2 (H-001 propeller strike), has the most inter-subsystem interfaces (power input, PWM control input, aerodynamic output), and its mass/thrust trade-off most tightly constrains the system. Classify ESC components (MOSFET bridge, gate driver, microcontroller), create SUB requirements for motor, ESC, and propeller, and define the IFC for the ESC-to-motor 3-phase interface. Then decompose {{entity:Flight Control Electronics}} as the second priority — it implements 3 of the 7 system functions and all failsafe logic.