libdrone — Unified Master Specification

About¶

Complete system specification for libdrone V2.4.6. Covers mission and philosophy, CAD recipes for all printed parts, electronics layout, material strategy, maintenance schedule, software stack summary, and acceptance targets. The authoritative design record for the platform.

The Current State — V2.4.6

• Airframe: Pre-stressed 4-rod box-girder (330 mm wheelbase). Three-layer architecture: sandwich body / platform / backplane.
• Structure: 5-layer sandwich PETG(bottom)/PCCF/PCCF/PCCF/PETG(top). Total height = #SandwichHeight — check the Variables file. Arms connect via PETG tabs with T-profile mechanical lock. No adhesive. No inserts in PCCF.
• Arms: Split into shaft (PETG, printed vertically) + tabs (PETG, printed horizontally). Two tabs per arm. Crash-replaceable shaft only. #ArmShaftLength = 125mm — verify in FreeCAD.
• Rods: 4 × 2.0 mm CF rods, 333mm, pass continuously through all sandwich layers. Spitfire pre-tension logic preserved.
• Platform: Single PETG middle layer, 283mm × 40mm (narrow) / 50mm (electronics zone), mounted on top of X body sandwich. Extends forward (camera/GPS bracket zone) and rearward (electronics zone) beyond X body footprint. Contains battery rails, MIPI channel, wire channels, dual GX12-7 chimneys (A+B), fan slot.
• Layout (nose to tail): Camera+GPS bracket / Battery / ESC+FC+Buck+RX / VTX / Fan / ELRS antenna. All on Platform top surface.
• Navigation: Camera + GPS on removable front bracket. One unit, 2× M3, 60-second removal. VTX is in the electronics zone (NOT on the bracket — V2.4.6 change).
• Battery: Side-slide RIGHT. 78×40×53mm reference. Centred on X body core (+39mm to −39mm from centre). Rails integral to Platform.
• Motor Mount: Fully floating silicone o-ring/sleeve system. PETG-CF passive cover with captured nyloc nuts.
• Backplane: Diamond/hexagonal PETG lattice crash exoskeleton (187×50mm, ~7g, ~65% open). Spans battery front (+39mm) to fan rear (−148mm). Shields battery and electronics on falls. Right side open in battery zone — battery swaps sideways without backplane removal. Payload modules mount on top. Dual GX12-7 boss rings (A at X=−25mm, B at X=+25mm, both Y=−66mm) pass through reinforced lattice rings.
• Sensor Payload: Removable backplane module, SEN66 + ESP32-S3. Independent 1S power. 60-second hot-swap.
• Software: Betaflight 4.5 / AM32 / HDZero / Gyroflow / EdgeTX — see build/LD_-_Software_v246.md.

[0] MISSION & PHILOSOPHY¶

Role: Cinematic Surveillance, High-Intensity Skatepark Chase, Air Quality Mapping. Philosophy: "Spitfire" Aero-Logic. Shell = Skin (damping); 4 Rods = Spar (load). Target: Pre-stressed rigid structure for jello-free 6-inch flight. Acceptance: Dry mass targets — check the Variables file (hw_total_dry_nopayload_target/gate). Sensor config: dry mass with payload — check the Variables file for current targets/gates.

[1] VARIABLE TABLE¶

Single source of truth: All parametric variables are defined exclusively in reference/LD_-_Variables_v246.md. Do not redefine or override values here. Open that file before starting any CAD work.

[2] CAD RECIPES (ONSHAPE)¶

STEP 2.0: DOCUMENT SETUP¶

1. Create FreeCAD document: "libdrone V2.4.6".
2. Run code/LD_V343_Variables.FCMacro to create the Variables spreadsheet — all parameters sourced from reference/LD_-_Variables_v246.md. Units: mm.
3. Create Part files: Arm Shaft, Arm Tab, X Body, GPS-Camera Bracket, Platform, Backplane.
4. Create Assembly: libdrone V2.4.6 Assembly — verify rod threading, sandwich layer clearances, tab T-lock engagement, and motor mount geometry before printing any parts.

STEP 2.1: ARM SHAFT¶

2.1.1 — Shaft profile: - Sketch on Front Plane: rectangle #ArmWidth × #ArmHeight, centred. → Check the Variables file. - Fillet all corners 3.0 mm. Extrude #ArmShaftLength (~125 mm) from tab junction face.

2.1.2 — Motor head flare: - Sketch on motor-end face: rectangle #MotorHeadWidth × #MotorHeadHeight, centred, 3.0 mm fillets. → Check the Variables file. - Loft from shaft end to head over #MotorHeadTaper. Curvature-continuous. - Verify: no sharp internal edges at loft junction.

2.1.3 — Rod channels: - 2 × Ø#RodDiaChannel circles, both offset to SAME side: Z +5.0 mm and Z +2.0 mm. - Extrude-cut Through All. 0.5×45° chamfers both ends of each channel. - FL/RL arms: normal orientation. FR/RR arms: installed UPSIDE DOWN. - Four rods at four distinct heights in sandwich: +5.0, +2.0, −2.0, −5.0 mm. - One printed part for all four positions. Label "ARM SHAFT" only.

2.1.4 — Pinch slit: - 0.5 mm slot (#PinchSlit), 8 mm deep from SIDE FACE of motor head, 5.0 mm from motor face. - M3 clamp tab: 5×5 mm boss on same side face, Ø3.3 mm through-hole. - Side-face placement: bolt access identical whether arm is normal or inverted.

2.1.5 — Motor mount bores (floating mount): - 4 × Ø6.5 mm at 2507 motor hole pattern (±6 mm from centreline — confirm from motor datasheet). - Extrude-cut Through All (18 mm head height). - Top counterbore: 4 × Ø7.0 mm × 1.5 mm deep. O-ring flush with top surface. - Bottom counterbore: same on bottom face. - O-ring lateral rim: Ø8.0 mm outer × 0.5 mm height around each counterbore, both faces. Prevents o-ring migration under sideways loads. Does not affect axial isolation.

2.1.6 — Cable strain relief port: - Ø5.5 mm through-hole on SIDE FACE of motor head, at arm neutral axis height. - Position: 8–10 mm inboard from motor face. Clear of pinch slit slot. - 1.0×45° entry chamfer both sides. - Wire channel on end face: 4.0 mm wide × 3.0 mm deep, centreline, motor-bore to shaft axis.

2.1.7 — Tab junction face: - Hub end of shaft is flat — tab junction face perpendicular to shaft axis. - 2 × #TabScrewDia through-holes at #TabScrewSpacing centre-to-centre — receive M2 screws through shaft. → Check the Variables file for both values. - Add 0.5×45° entry chamfers.

2.1.8 — Bumper service notch: - 2.0 mm deep recess, full arm width, 1.0 mm radius internal corners. - Cut on BOTH faces of tab junction end (top and bottom) — fits regardless of arm orientation.

2.1.9 — Final checks: - Wall between rod channel and outer surface ≥2.0 mm everywhere. - Wall between motor bore and head outer face ≥6.0 mm. - Chamfers present on all rod channel entries. - Assembly: thread all 4 rods — verify Box-in-Box clearance with sandwich layers.

STEP 2.2: ARM TAB¶

Two tabs per arm. Each tab printed horizontally (layers perpendicular to pull-out load).

2.2.1 — Tab body: - Sketch: rectangle #TabWidth × #TabThick. → Check the Variables file for both values. Extrude #TabLength — engagement depth.

2.2.2 — T-profile lock: - At the inner end (tip inside sandwich), add T-extension: #TabLockWidth wider on each side, #TabLockDepth inboard from tip. → Check the Variables file for both values. - This T-profile engages matching T-slot pocket in PCCF layers — cannot be pulled out axially. - Tab slides in from the side during assembly. Clearance 0.2 mm per side.

2.2.3 — Shaft connection: - Outer face of tab (exposed end) has pocket matching shaft tab-junction face profile. - 2 × Ø2.0 mm through-holes at 10 mm spacing — receive M2 screws through shaft. - Pocket depth: 1.0 mm. Ensures flush mating between shaft face and tab face.

2.2.4 — Rod channel continuation: - Rod channels pass through tab at same positions as in shaft: Z +5.0 mm and Z +2.0 mm. - Ø#RodDiaChannel = 2.2 mm. Through All. 0.5×45° chamfers. - Channels must align precisely with shaft channels and PCCF layer channels. Verify in Assembly view before printing.

2.2.5 — Final checks: - T-lock clearance: 0.2 mm per side in PCCF T-slot — slide fit, not press fit. - M2 hole alignment with shaft: zero offset permitted. - Rod channel alignment: check in Assembly cross-section.

STEP 2.3: X BODY (SANDWICH)¶

5-layer sandwich: PETG (bottom) / PCCF / PCCF / PCCF / PETG (top). Total height: #SandwichHeight. → Check the Variables file for current value and layer thicknesses.

X shape — NOT square. Core + four arm extension zones.

2.3.1 — X body plan geometry: - Central core: #XBodyCoreSize × #XBodyCoreSize square, 5 mm corner fillets. → Check the Variables file. - Four arm extensions: #XBodyArmWidth × #XBodyArmLength, centred on each arm axis, extruding from core edges at 45° (True-X geometry). → Check the Variables file. - Total X footprint: approximately 130 × 130 mm diagonal — significantly lighter than 178×178 hub.

2.3.2 — PCCF layer geometry (×3 identical layers): - Thickness: #PCCFLayerThick each. Check the Variables file. Positions: layers 2, 3, 4 (above PETG bottom, below PETG top). - X plan profile as above. - 4 × arm T-slot pockets — one per arm, at 45° on each extension: - Slot width: #TabWidth + 0.2 mm clearance per side. → Check the Variables file. - Slot depth: #TabLength from outer edge of extension inward. → Check the Variables file. - T-profile cross-section: main slot + T-lock pocket matching tab T-extension. - Slot open at outer edge — tab slides in from outside. - 4 × rod channels: #RodDiaChannel at Z offsets defined by #RodOffsetOuter and #RodOffsetInner. → Check the Variables file for all current values. Channels must align across all 5 layers — verify in Assembly. - Stack pattern: 4 × Ø3.3 mm on 30.5 mm pattern, centred. - Sandwich bolt pattern: 4 × Ø3.3 mm M3 through-holes, symmetric, clear of T-slots and rod channels. Suggested positions: ±20 mm from core centre on X and Y axes. - Lightening pockets in non-structural zones (≥3.0 mm wall to any feature).

2.3.3 — NOTE on V2.4.6 layer architecture: In V2.4.6, all five sandwich layers are printed parts (PETG bottom + 3× PCCF + PETG top). The V2.4.6 concept of "arm tabs as layers" no longer applies — tabs occupy T-slots, not a dedicated layer position. The space between PCCF layers is occupied by the tab body. Tab height (#TabThick) must equal #SandwichHeight — check the Variables file. Verify in Assembly: zero gap between tab face and adjacent PCCF layer faces.

2.3.4 — X body top surface (V2.4.6 — clean structural face): - FC/ESC stack pattern: 4 × Ø3.3 mm on #StackPattern, centred on X core. → Check the Variables file. These holes accept M3 standoffs that pass through Platform base and into X body top PETG. - Platform attachment holes: 4× Ø3.3 mm M3 countersunk, symmetric around core, #PlatformAttachSpacing. → Check the Variables file. - V2.4.6: battery rails, MIPI channel, wire channels, GX12 chimney, fan slot are ALL in the Platform — NOT in the X body top layer. The X body top PETG layer is a clean structural surface with only standoff and attachment holes. - Sensor mast boss pads retained on X body top surface if needed as backup — confirm in FreeCAD whether mast moves to Platform or stays on X body.

2.3.5 — Assembly sequence: 1. Insert all 8 arm tabs (2 per arm) into T-slots in bottom PCCF layer. Slide from outside. Verify T-locks fully engaged — no lateral play. 2. Place middle PCCF layer. Align rod channels and sandwich bolt holes. 3. Place top PCCF layer. Align all features. 4. Thread 4 CF rods through entire sandwich — all 5 layers simultaneously. This aligns all layers as a single operation. 5. Install sandwich M3 bolts. Torque to 0.3 N·m — firm but not crushing PCCF. 6. Connect arm shafts to tabs via 2× M2 screws per tab (4 screws per arm, 16 total).

STEP 2.4: GPS / CAMERA BRACKET¶

Single PETG bracket at front of Platform. Carries GPS antenna (top) and camera (middle) ONLY. VTX is in the electronics zone of the Platform — NOT on this bracket (V2.4.6 change).

2.4.1 — Bracket body: - Width: #BracketWidth (26 mm). Height: ~60 mm. Wall 2.0 mm. - Camera tilt: field-adjustable arc-slot mechanism, 0°–30° (#BracketCamTiltMin to #BracketCamTiltMax). Default #BracketCamTiltDefault = 15°. Two M3 bolts (pivot + slot). 2.5mm hex key, ~15 s to adjust. See Variables §[11]. - GPS pocket: top of bracket, horizontal. Matek M10Q-5883 footprint — verify dimensions. GPS patch antenna faces up. Clear of all obstructions above. - No VTX pocket — VTX mounts in electronics zone at #VTXZoneFront to #VTXZoneRear. → Check the Variables file.

2.4.2 — MIPI cable routing: - MIPI cable exits camera body, routes rearward through Platform MIPI channel (centreline, 16mm wide × 1.5mm deep). - Cable never disconnected in service — bracket removes as one unit; MIPI cable has enough service loop to allow bracket removal without disconnecting VTX. - Cable length: 225mm. Camera-to-VTX distance: ~198mm. Service loop: ~26mm. ✓ - Channel entry at bracket base: 4mm wide × 2mm deep, covered by clip or retainer.

2.4.3 — Mounting to Platform: - 2 × #BracketMountDia (M3) clearance holes at #BracketMountSpacing (20 mm) spacing. - Bracket mounts to Platform nose zone at #BracketZoneRear (+50mm from body centre). - M3 socket head + washer. Removable in field in <60 s.

STEP 2.5: PLATFORM¶

Single PETG part. 283mm × 40mm (nose/battery) / 50mm (electronics zone) × 3mm base plate plus integral features. Sits on top of X body sandwich. Extends fore and aft beyond X body footprint. Contains all cable management, battery rails, electronics mounting, GX12 chimney, fan slot.

2.5.1 — Base plate: - Dimensions: #PlatformLength × #PlatformWidthNarrow (battery/nose zone) stepping to #PlatformWidthElec (electronics zone from #PlatformStepY) × #PlatformThick. → Check Variables §[13]. - Attachment to X body: 4× M3 countersunk screws through Platform base into X body top PETG. Positions at ±20mm from body centre on each axis. - Material: PETG. Print orientation: flat (largest face on bed). 4 perimeters minimum.

2.5.2 — Battery zone (+39mm to −39mm): - Integral battery rails: see Variables [8b] for all rail geometry. - LEFT rail taller — includes Connector A GX12-7 chimney at #GX12A_PositionX, #GX12_PositionY. → Check the Variables file. - RIGHT rail: open right end (battery exit). Closed left end (endstop wall). - Strap slots: #BattStrapSlotWidth × #BattStrapSlotDepth, through rail top faces. - Battery lead relief notch: #BattLeadNotchWidth × #BattLeadNotchDepth at rear face of battery zone.

2.5.3 — MIPI channel (centreline, full Platform length): - #MIPIChannelWidth × #MIPIChannelDepth, centreline, nose-to-tail. → Check the Variables file. - Runs from bracket base (+50mm) to VTX zone (−133mm). Cover plate or snap retainer.

2.5.4 — Wire channels: - LEFT channel (signal, −20mm from centreline): #WireChannelWidth × #WireChannelDepth. Carries: GPS cable, RP2 receiver signal, GX12 loom. - RIGHT channel (power, +20mm from centreline): same dimensions. Carries: battery lead, ESC phase wire exits, buck input. - Channels run full electronics zone length (−44mm to −148mm).

2.5.5 — Electronics zone (−44mm to −148mm): - FC/ESC stack standoff holes: 4× Ø3.3mm on #StackPattern at zone centre. - Dowel pin holes: 2× Ø2.0mm at two diagonally opposite standoff positions, offset 3mm radially. - Buck converter mounts RIGHT of FC/ESC stack (power zone, +20mm side). - RP2 receiver mounts LEFT of FC/ESC stack (signal zone, −20mm side). - VTX (HDZero Freestyle V2) mounts at #VTXZoneFront to #VTXZoneRear on Platform base. → Check the Variables file. 4× M2 screws or adhesive mount.

2.5.6 — Fan slot (−138mm to −148mm): - #FanSlotWidth × #FanSlotHeight slot in Platform rear shroud face. → Check the Variables file. - Fan (Gdstime 3010) inserts from rear, secured with M2 screws or snap fit. - Fan exhausts rearward. Always-on, hardwired to FC 5V pad.

2.5.7 — Backplane interface (top surface): - Dual GX12-7 male connector bosses (panel mount, pins face upward): Connector A at #GX12A_PositionX = −25mm, #GX12_PositionY = −66mm (LEFT). Connector B at #GX12B_PositionX = +25mm, #GX12_PositionY = −66mm (RIGHT). → Check the Variables file for all chimney geometry. - 2× M3 heat-set insert boss pads for backplane mechanical retention, 20mm spacing, rear centreline of electronics zone. - Top surface of Platform is flat between battery rails and electronics zone — backplane modules seat here.

2.5.8 — Final checks: - Verify Platform clears all arm tabs and rod channels in FreeCAD cross-section. - Verify battery slides freely right-side out with arms in position. - Verify MIPI channel cover does not foul bracket removal. - Verify both GX12-7 chimneys (A+B) clear FC/ESC standoffs below.

STEP 2.6: BACKPLANE (crash exoskeleton + payload interface)¶

Diamond/hexagonal PETG lattice. 187mm × 50mm × 1.5mm beam thickness. ~65% open area — excellent airflow, fan exhausts freely through rear open zone. Shields battery and electronics stack against falls and side impacts. Payload modules mount on top of backplane. Backplane is the interface layer.

2.6.1 — Lattice structure: - Two longitudinal spine beams: left and right edges, full length. - Transverse ribs: #BackplaneRibSpacing spacing, 10 ribs total. → Check the Variables file. - Diagonal cross-members at 45° in alternating bays — racking resistance. - Beam width: #BackplaneBeamWidth. Beam thickness: #BackplaneBeamThick. → Check the Variables file. - Estimated mass: ~7 g. Material: PETG Natural.

2.6.2 — Zone-specific geometry: - Battery zone (Y = +39 to −39 mm): RIGHT SIDE FULLY OPEN — no beam on right edge. Battery slides out RIGHT under open lattice without removing backplane. Left edge: standard spine beam retained. - Fan exhaust zone (Y = −138 to −148 mm): NO lattice material — fully open. Tail beam at Y = −148 mm only. - GX12 zone (Y = −66 mm): TWO reinforced boss rings. Connector A boss at X = −25 mm, Connector B boss at X = +25 mm. Both #BackplaneGX12BossOD. Payload GX12-7 females (cable mount) connect from above. → Check the Variables file.

2.6.3 — Attachment posts: - 3 post pairs, integral to Platform, at Y = +39 mm, −39 mm, −148 mm. - Post height #BackplanePostHeight = 54 mm (1 mm clearance above battery top). → Check the Variables file. - Backplane seats on post tops. M3 screw through lattice boss into post. - Battery swap: backplane remains in place. Battery exits RIGHT under open lattice edge.

2.6.4 — Payload modules (examples): - Air quality: SEN66 + ESP32-S3 logger (independent 1S power) — hot-swap in 60 s. - Mapping: additional camera or LiDAR. - Blank plate: when no payload fitted — snaps onto backplane top, no GX12 needed.

STEP 2.7: PRINTED PARTS (bumpers, covers)¶

Sensor payload (backplane module): SEN66 + ESP32-S3. Now a hot-swap backplane module — see payloads/LD_-_Payload_SDK_v246.md Appendix A.

Arm Cover Active (PETG): cable protection, dovetail groove, 2× M2 screw retention.

Arm Cover Passive (PETG-CF): structural cover, o-ring bosses, captured nyloc nut pockets. FFP3 respirator mandatory during printing and post-processing. See PRUSA guide.

Bumpers (ASA Natural): geometry-compensated, hollow, length = motor tip + 3 mm extension. Update geometry for 125mm arm shaft — verify in FreeCAD.

[3] FLOATING MOTOR MOUNT SYSTEM (UNCHANGED FROM V2.14)¶

Per motor: 2 × silicone o-rings (ID 4.0 / OD 7.0 / CS 1.5 mm, 40–50A), 4 × silicone sleeves (OD 6.0 / ID 3.5 / L 11.5 mm, 30–40A). Motor screws: M3 × 20 mm stainless. Nyloc nuts captured in Passive Cover. Torque: 0.4–0.5 N·m. Replace every 20–30 flight hours. Silicone retains full flexibility to −60°C.

[4] ELECTRONICS LAYOUT (V2.4.6 — PLATFORM NOSE-TO-TAIL)¶

Three-layer architecture. All electronics on the Platform middle layer.

Nose-to-tail map (positions from body centre):¶

  +110 | GPS patch antenna (top)
       | Camera - adjustable tilt
   +50 | -- Camera/GPS bracket base / Platform nose
   +39 | BATTERY front edge
       |   Tattu 150C-1800mAh-6S-XT60  78x40x53mm
     0 | -- X body centre (arms at +/-117mm diagonal)
   -39 | BATTERY rear edge
   -44 | ESC front (5mm gap)
       |   ESC Pilotix 75A AM32  44.5x40.5mm
       |   FC H7A3-SLIM 36x36mm on standoffs above ESC
       |   Buck XL4015  alongside RIGHT (power zone)
       |   RP2 ELRS receiver  alongside LEFT (signal zone)
   -99 | Buck rear edge
  -104 | VTX front (5mm gap after buck)
       |   HDZero Freestyle V2  29x30x14mm
  -133 | VTX rear
  -138 | Fan front (5mm gap)
       |   Gdstime 3010  30x30x10mm -- always on, rearward exhaust
  -148 | Fan rear / exhaust
  -153 | ELRS antenna (RP2)
  -173 | -- Platform tail end

Prop clearance (330mm wheelbase, 6-inch props, 15mm minimum):¶

Camera bracket: 12.7mm/side @ 40mm | Battery: 48.9mm/side @ 40mm | ESC: 20.9mm/side @ 50mm | VTX: 17.4mm/side @ 50mm | Fan: 22.4mm/side @ 50mm — all clear. ⚠ Tightest: 15.7mm/side at motor Y (−116.7mm) — verify in FreeCAD before printing.

Stack height: ESC ~8mm + standoffs 7mm + FC 5mm = 20mm vs battery 53mm -- 33mm clearance. All electronics below battery top surface.¶

MR30 connectors:¶

• All 4 motor wires: MR30 gold-plated pairs, 30A continuous.
• Label M1-M4 on heatshrink. Pigtail motor side: 40-50 mm. ESC side: 60-80 mm.

Backplane (crash exoskeleton + payload interface):¶

• Diamond/hexagonal PETG lattice, 187×50mm, ~7g. Spans battery front to fan rear.
• Sits on 3 post pairs (integral to Platform) at Y=+39mm, -39mm, -148mm. Posts height 54mm -- 1mm clearance above battery top. Backplane does not rest on battery.
• RIGHT SIDE OPEN in battery zone: battery slides out RIGHT under lattice without removing backplane.
• Fan exhaust zone fully open: no lattice material at -138 to -148mm.
• TWO GX12-7 boss rings: Connector A at Y=−66mm, X=−25mm / Connector B at Y=−66mm, X=+25mm.
• Payload modules (air quality, mapping) mount on top of backplane.

Electronics service procedure:¶

1. Remove battery. Disarm. Remove props.
2. If backplane module fitted: unplug Connector A and Connector B (both GX12-7), remove 2x M3 screws, lift clear.
3. Remove Camera/GPS bracket: 2x M3 screws, lift clear (MIPI service loop allows this).
4. Disconnect MR30 motor connectors (4x). Check labels M1-M4.
5. Disconnect buck input and VTX power wire.
6. Unscrew FC/ESC stack standoff top nuts. Lift FC and ESC as unit.
7. VTX accessible after FC/ESC removal -- 4x M2 or adhesive mount.
8. Service as required. Reseat on dowel pins. Torque standoffs.
9. Reconnect all wiring. Refit bracket. Boot -- verify all motors and GPS lock.

[5] MATERIAL STRATEGY (V2.4.6)¶

Post-process all structural PETG and PCCF: heat-gun 250°C / 15 s + laminating epoxy wipe + full cure.

[6] MAINTENANCE SCHEDULE¶

Tab crash behaviour:¶

Shaft designed as the sacrificial element — praskne na shaft, ne na tabu. Tabs remain in sandwich after shaft fracture. Replace shaft only (~125 mm PETG shaft). Inspect tab T-lock seating after any hard crash. Replace tab if T-lock shows cracking. Spare shafts and tabs must be in field bag at all times.

Epoxy mass logging:¶

Weigh every printed part before and after epoxy. Log delta per part. - Target epoxy delta: ≤1.0 g per shaft, ≤0.5 g per tab, ≤1.5 g per PCCF layer. - Total structural delta must not push dry mass above the acceptance gate — check the Variables file. Use kitchen scale, 0.1 g resolution.

[7] SOFTWARE STACK SUMMARY¶

Full configuration in build/LD_-_Software_v246.md.

Note V2.4.6: Longer arms (125mm) and larger wheelbase (330mm) increase moment of inertia vs V2.4.6. PID retuning required at maiden — expect slightly slower roll/pitch response vs V2.4.6 starting values. Raise D-term cautiously if prop wash present. Expect faster roll/pitch response. Reduce D-term first, then P. Start conservative.

Dual Betaflight profiles (unchanged):¶

[8] ACCEPTANCE TARGETS (V2.4.6)¶

• Dry mass (no payload): → Check the Variables file for current targets and gates (hw_total_dry_nopayload_*)
• Dry mass (with payload): → Check the Variables file for current targets and gates (hw_total_dry_withpayload_*)
• Rod joints: zero play by hand feel (primary criterion)
• Tab T-lock: fully seated; zero lateral play in sandwich
• Acoustic guard: 2.2–2.6 kHz; above 2.6 kHz before zero play = stop
• Motor mount: zero lateral play; passive cover contacts ONLY o-ring bosses
• GPS: ≥8 satellites before arming
• Low-speed mode: calibrated ≤4.8 m/s; verified in flight
• Bracket removal: GPS/camera bracket removable in <60 s
• Conformal coating: applied to FC, ESC, VTX pads before first flight
• Crash readiness: 2 spare shaft sets + 2 spare tab sets + o-ring spares in field bag

[9] FINAL ELECTRONICS BOM (EST. ~36,550 CZK)¶

Revision History¶