libdrone — Declaration of Design and Performance
About¶
This Declaration of Design and Performance (DDP) is the authoritative summary of what libdrone is, who is responsible for the design, what it is designed to do, and what its verified performance limits are. It is intended for institutional buyers, regulatory review, insurance assessment, and any party requiring a formal design declaration before procurement or deployment.
This document does not supersede the full technical documentation stack — it summarises and points to it. All numeric values are sourced from LD-REF-001 (Variables) and LD-REF-002 (Hardware). All operational limits are sourced from LD-OPS-002 (DSRA) and LD-OPS-003 (Regulatory).
1. Platform Identification¶
| Field | Value |
|---|---|
| Platform name | libdrone Pro |
| Designation | libdrone V2.4.6 |
| Platform type | Unmanned Aerial System (UAS) — multirotor quadcopter |
| Frame class | 6-inch True-X, 330mm wheelbase |
| Architecture | Three-layer: X sandwich / Platform / Backplane |
| Payload interface | Dual GX12-7 A/B — see LD-PAY-002 (ICD) |
| Design origin | Czech Republic, European Union |
| Designer | Jakub Safar, Telč, Czech Republic |
| Design date | 2026-03 |
| Hardware licence | CERN OHL-S v2 (open hardware, strong copyleft) |
| Documentation licence | CC BY-SA 4.0 |
2. Design Intent and Mission Profile¶
libdrone Pro is designed as an open-architecture aerial payload platform — a modular, repairable, fully documented UAS that enables third-party payload integration through a documented electrical interface standard.
Primary missions: - Air quality mapping (particulate matter, CO₂, VOC, temperature/humidity) - Cinematic and FPV aerial photography - Sensor data collection with GPS-tagged, timestamped logs - Platform research and payload development - Civilian resilience operations — flood reconnaissance, chemical plume assessment, thermal person search, radiation zone survey, and supply delivery to isolated persons (see LD-COM-001 / LD-COM-002 for documented use cases)
Design philosophy: The airframe structure follows Spitfire aero-logic — the printed shell is a damping skin, the four carbon fibre rods are the structural spar. Crash-sacrificial arm shafts are the only element expected to fail on impact. All other structural elements are designed to survive the arm shaft fracture load.
3. Performance Declaration¶
All values are design targets verified by calculation or test unless marked (C). Values marked (C) are calculated from component specifications; flight-test verification is in progress at the time of this declaration.
3.1 Mass Budget¶
| Configuration | Mass | EASA Category |
|---|---|---|
| Dry (no battery, no payload) | < 607g target / < 617g gate | — |
| Bare AUW (+ 210g battery) | ~807g target | Open A1 ✓ |
| With 80g payload | ~887g | Open A2 ✓ (13g headroom) |
| With 150g payload | ~957g | Exceeds A2 limit ❌ |
| Hard payload limit (A2) | < 93g | Open A2 boundary |
3.2 Propulsion Performance¶
| Parameter | Value | Notes |
|---|---|---|
| Motors | 4× BrotherHobby Avenger V2 2507 1750KV | |
| Battery | 6S LiPo, 1800mAh, 150C | Tattu R-Line V5 or equivalent |
| Propellers | HQProp 6×3×3 or 6×2.5×3 tri-blade | |
| Peak thrust per motor | ~2400–2600g @ 40–55A | Manufacturer spec (C) |
| Total peak thrust (4 motors) | ~10,000g | |
| Hover throttle (bare AUW) | ~28% | Calculated (C) |
| TWR at bare AUW | ~12.4:1 | |
| TWR with 80g payload | ~11.3:1 | |
| Estimated endurance | 8–12 min | Depends on payload and throttle |
3.3 Structural Limits¶
| Parameter | Value |
|---|---|
| Minimum prop clearance | 15mm design minimum — tightest: 15.7mm at motor Y position |
| Arm shaft | Crash-sacrificial PETG — designed to fracture before tabs or rods |
| Rod architecture | 4× 2.0mm CF, pre-stressed box-girder, 333mm |
| Tab T-lock | Mechanical lock in PCCF — no adhesive required |
| Operating temperature | PETG arms: not recommended below 0°C |
| Motor mount isolation | Floating silicone o-ring/sleeve system |
3.4 Payload Interface¶
| Parameter | Value |
|---|---|
| Interface standard | GX12-7 dual A/B — ICD: LD-PAY-002 v1.0.0 |
| Available payload power | 5V @ 2A continuous (FC BEC) |
| Communication channels | UART4, UART5, I2C (400kHz), AUX GPIO ×2, GPS tap (read-only) |
| Payload mass limit (A2) | < 93g hard limit for EASA Open A2 compliance |
| Payload mass limit (physical) | < 150g (CG and structural limit — breaks A2) |
| Hot-swap time | ~60 seconds without tools |
4. Regulatory Declaration¶
| Requirement | Status |
|---|---|
| EASA Open A1 (bare AUW < 900g) | ✓ Compliant at ~807g bare AUW |
| EASA Open A2 (with payload ≤ 93g) | ✓ Compliant with payload mass discipline |
| EASA Open A2 (low-speed mode ≤ 4.8 m/s) | ✓ Implemented in Betaflight profile 2 |
| Czech Republic registration | Required — drone >250g must be registered with CAA CZ |
| Remote pilot competency | A2 certificate of competency required for A2 operations |
| CE marking | Not applicable — custom-built UAS, EASA Open Category rules apply |
Regulatory reference: LD-OPS-003. Regulatory status current as of 2026-03. Always verify current rules at caa.cz and easa.europa.eu before each operating season.
5. Open Hardware and Reproducibility Declaration¶
libdrone is fully open hardware under CERN OHL-S v2. This means:
- All CAD files, firmware configurations, and documentation are publicly available
- Any party may reproduce, modify, and distribute the design under the same licence
- The designer makes no warranty of fitness for any particular purpose
- Third parties building from these files are responsible for their own compliance verification
Full documentation stack: [github.com/libdrone — TBD when published]
6. Responsible Person¶
| Field | Value |
|---|---|
| Name | Jakub Safar |
| Role | Designer and responsible person |
| Location | Telč, Czech Republic |
| Contact | [TBD] |
| Declaration date | 2026-03-27 |
| Declaration status | Draft — pending maiden flight verification |
This declaration will be updated to released status following successful maiden flight and verification of calculated performance values against measured data.
Revision History¶
| Version | Date | Author | Summary |
|---|---|---|---|
| 1.1.0 | 2026-04-01 | JS | Civilian resilience added to primary missions. References LD-COM-001/002. |
| 1.0.0 | 2026-03-27 | JS | Initial draft. Awaiting maiden flight verification before release. |