Master Specification

Summary¶

The Master Specification is the single authoritative reference for the libdrone Pro V2.4.6/V2.4.7 platform: what it is, what it must do, what it must weigh, what must pass before maiden flight, and what the IFF architecture commits to at the platform level. All specific values that are not hard design decisions live in the Variables file — the Master Spec states the principles and acceptance criteria; the atoms provide the depth.

Concept¶

Mission and philosophy¶

libdrone Pro serves three concurrent roles: cinematic surveillance (1080p60 digital FPV, pilot-controlled), high-intensity skatepark chase (low-speed A2 compliance mode), and air quality mapping (SEN66 payload, GPS-tagged data). These are not three separate builds — they are the same platform reconfigured by payload swap and profile selection.

The underlying philosophy is "Spitfire aero-logic": shell as skin (PETG/PCCF sandwich absorbs and distributes crash energy), four rods as spar (pre-tensioned CF rods carry structural load through all five layers). → sandwich-structure and → cf-rod-architecture explain the engineering. → failure-hierarchy explains the crash energy management sequence.

The design target is jello-free 6-inch flight. → vibration-isolation-theory and → floating-motor-mounts are the primary mechanisms. → imu-gyroscope explains what the IMU needs from the frame. → rpm-filter explains what the firmware does with what the frame provides.

Single source of truth: the Variables file¶

All parametric dimensions, mass targets, and performance thresholds are defined in the Variables file (→ variable-table-values). The Master Specification does not restate them. Any question of the form "what is the target mass?" or "what is the rod diameter?" has one answer: the Variables file. Everything else is a copy that may be wrong.

CAD architecture¶

The FreeCAD parametric model generates all geometry from the Variables spreadsheet. → freecad-document-setup covers the setup procedure. → parametric-modelling-philosophy explains why parametric design is the correct approach for a community build platform. → variable-table-structure explains the organisation of the variable namespace.

Acceptance targets¶

The platform is accepted for maiden flight when all of the following pass:

Mass: bare dry mass (no payload, no battery) within the target/gate in the Variables file. With battery: within EASA A2 limit (< 900g total).

Structural: rod joints show zero play by hand feel (primary criterion). T-lock tabs fully seated, zero lateral play in sandwich. Acoustic test: all four rods ring at 2.2–2.6 kHz. Above 2.6 kHz before zero play: stop and investigate. Motor mount passive covers contact arm head only at O-ring bosses.

Electronics: GPS ≥ 8 satellites outdoors within 90 seconds (cold start). All motors spin correct direction in Betaflight Motors tab. OSD visible with correct telemetry fields. Conformal coating applied and cured on FC, ESC, and GPS module.

Compliance: low-speed mode calibrated ≤ 4.8 m/s in flight. Operator e-ID label on frame. Crash readiness: 2 spare arm shaft sets + O-ring spares in field bag.

IFF readiness (for operational deployments): IR strobe mounted and operational. Remote ID module broadcasting. If CoT output is configured: blue icon confirmed on ATAK tablet before deployment.

Material strategy¶

→ material-selection-philosophy covers the full rationale for each material choice. The summary: PCCF for stiffness and structural layers, PETG for arms and accessories (controlled ductile fracture in crashes), ASA for bumpers (UV stability), TPU for motor mount pads (vibration isolation), silicone O-rings for floating mount isolation. All materials are available from Prusa.shop or standard filament suppliers. No exotic or single-source materials.

Maintenance schedule¶

→ scheduled-maintenance contains the full interval table. The Master Specification states only the philosophy: libdrone is a machine under continuous maintenance. Airworthiness is maintained by scheduled inspection and interval-based replacement, not by "it worked last time." The O-ring replacement interval (every 20–30 flight hours) is the most important — functional degradation precedes visible failure.

Software stack¶

→ sk-electronics-deep-dive and → sk-complete-build-guide cover the full software stack narrative. The platform-level commitments:

Betaflight 4.5 on MATEKH743 target. AM32 ESC firmware. ELRS 250 Hz LBT. HDZero digital FPV. EdgeTX on TX16S MKII. All firmware is open source. Configuration is applied via CLI diff to a known-clean base flash — no manual GUI configuration that cannot be reproduced from the diff. All configuration backed up to repository before maiden.

IFF architecture¶

→ iff-architecture covers the full five-layer implementation. The platform-level commitments:

The ESP32-S3 is optional but prepared on all platforms: dedicated mount point, pre-wired UART stub to FC, 5V power tap. Deploying an ESP32-S3 is a field- installable operation requiring no airframe modification.

The platform does not implement any nation-specific IFF protocol at hardware level. The GX12-7 Connector B GPIO reservation and ESP32-S3 firmware architecture accommodate any national defence IFF requirement through a module and firmware update — no airframe change.

For contested environments: the ESP32-S3 firmware implements a hardware kill switch that simultaneously disables WiFi, Remote ID, and CoT output while leaving flight operations unaffected. → operational-security for the full EMCON protocol.

Reference¶

Acceptance checklist summary¶

Procedure¶

Using the Master Specification¶

The Master Specification is a reference and decision record, not a build guide. Use → sk-complete-build-guide for the step-by-step build sequence. Use this document when: making a design decision that affects acceptance criteria, understanding the platform-level IFF commitments, or verifying that a proposed change is consistent with the platform philosophy.

Rationale¶

The V2.4.6 Master Specification (612 lines) combined acceptance criteria, variable table references, CAD recipes, and IFF architecture in a single document that was difficult to update consistently. The 3.0.0 skeleton delegates everything with a single source of truth (Variables, atoms, IFF doc) and retains only the platform-level commitments and acceptance gates that belong in a specification document.

Connections¶

requires: [] related: - sk-complete-build-guide - sk-electronics-deep-dive - sk-security-operations-guide leads_to: - sk-complete-build-guide