1:4 Scale Seastead Drone - Technical Design & Analysis Report

Project: Anguilla Seastead Scale Model (USV) | Date: 2024 | Scale: 1:4 (Froude)

1. Froude Scaling Analysis (1:4 Scale)

Froude scaling preserves the ratio of inertial to gravitational forces (Fr = V / sqrt(gL)). This is critical for wave interaction, resistance, and stability modeling.

Scale Factor: λ = 1/4 = 0.25

Parameter	Full Scale	Scale Factor	Model Scale (1:4)
Length (Triangle Side)	44.0 ft	÷ 4	11.0 ft (132 in)
Leg Length	21.5 ft	÷ 4	5.375 ft (64.5 in)
Leg Chord (Root)	8.5 ft	÷ 4	2.125 ft (25.5 in)
Leg Chord (Tip - truncated)	8.0 ft	÷ 4	2.0 ft (24.0 in)
Living Area Height	7.0 ft	÷ 4	1.75 ft (21 in)
Walkway Width	3.0 ft	÷ 4	0.75 ft (9 in)
Draft (Leg Submerged)	10.75 ft (50%)	÷ 4	2.6875 ft (32.25 in)
Freeboard (Leg Above Water)	10.75 ft	÷ 4	2.6875 ft
Triangle Height (Altitude)	38.1 ft	÷ 4	9.525 ft
Mid-triangle Beam (Structural)	22.0 ft	÷ 4	5.5 ft
Mooring Screw Depth	3.0 ft	÷ 4	0.75 ft

Weight Scaling (Mass ∝ Volume ∝ λ³)

Mass_model = Mass_full × (1/4)³ = Mass_full / 64

Full Scale Displacement	36,000 lbs
Target Model Displacement (Weight)	562.5 lbs

Container Check (Model): The model (11ft x 9.5ft) will NOT fit in a standard container. This is a workshop/launch size. Shipping requires a flatbed truck or disassembly.

2. Seakeeping, Stability & Operational Safety

Righting Moment & Capsize Threshold

Beam (Waterline): ~9.5 ft (Triangle altitude).
KG (Center of Gravity): Estimated low due to batteries in legs. Assume KG ≈ 1.5 ft above waterline (Legs extend 2.7 ft above WL, triangle deck at ~3.5 ft above WL, heavy batteries low in legs).
KB (Center of Buoyancy): ~1.35 ft below WL (Half draft of 2.69 ft).
BM (Metacentric Radius): I/∇. Waterplane area ≈ 3 × (Chord × Draft) ≈ 3 × (2.125 × 2.69) ≈ 17.1 ft². I (transverse) ≈ 2 × (1/12 × 2.69 × 2.125³) × (lever arm)²... Simplified: Wide stance (legs at triangle vertices) gives huge BM. GM >> 5 ft.

Stability Verdict: Extremely high initial stability (GM ~ 6-8 ft). Capsize requires extreme green water loading on the deck triangle or structural failure, not simple heel.

Wave Criteria for Capsize/Damage

Sea State	Sig. Wave Height (H1/3)	Max Wave (Hmax ~ 1.8-2.0 Hsig)	Risk to Model
Sea State 4 (Moderate)	4.0 - 6.0 ft	~10 ft	Green water on deck. Slamming on triangle bottom.
Sea State 5 (Rough)	6.0 - 9.0 ft	~15-18 ft	High Risk: Wave crest impacts solar deck (3.5 ft above WL). Structural loads on legs/connectors peak.
Sea State 6+ (Very Rough)	> 9 ft	> 18 ft	Probable Loss: Leg bending moments exceed yield; deck structure fails.

Practical Avoidance (999/1000 days?)

No. In the Caribbean (Anguilla), avoiding Sea State 5+ "999 days out of 1000" is unrealistic for an unmanned drone.

Winter Swells: North swells regularly generate 8-12 ft seas outside the lee of islands.
Tropical Waves/Storms: June-Nov. Even non-hurricane lows generate 48+ hrs of 10+ ft seas.
Forecast Limits: 5-day forecasts are good; 7-10 day are poor. Drone speed (~3-5 kts) is too slow to outrun a developing system 200nm away.
Sargasso: Heavy weed mats reduce speed to 0.5 kts, trapping drone in building seas.

Recommendation: Design for survivability in Sea State 5 (10-12 ft waves), not avoidance. This means: Submersible electronics, breakaway solar mounts, watertight leg compartments, and automatic "storm mode" (feather stabilizers, drift bow-to-waves).

3. Active Stabilizer / Hydrofoil Potential

Geometry & Forces

Stabilizer Area (est.): 3 wings × (Span 4ft × Chord 1ft) = 12 ft² total.
Lift Coeff (Cl): ~1.0 (max with flaps/tail).
Lift Force: L = 0.5 * ρ * V² * S * Cl. (ρ=1.99 slugs/ft³).

Speed (kts)	Speed (ft/s)	Total Lift (lbs) @ Cl=1.0	% Weight (562 lbs)
3.0	5.06	~305 lbs	54%
4.0	6.75	~540 lbs	96%
5.0	8.44	~845 lbs	150%

Foiling Takeoff Speed: ~3.8 - 4.0 knots. Below this, stabilizers act as heave/damping plates. Above this, they can unload the legs significantly.

Foiling Range & Speed Analysis

Drag Reduction: Legs (3 × NACA 0035 @ 2.7ft draft, 2.1ft chord) have significant drag. Foiling lifts hull/legs clear.

Leg Drag (Displacement @ 4 kts): ~35-50 lbs total.
Foil Drag (Induced + Profile @ 4 kts lifting 562 lbs): ~25-35 lbs total.
Net Savings: ~15-20 lbs thrust.

Thruster Position for Foiling

Do NOT put thrusters below stabilizer wings.

Prop wash over foil increases drag/turbulence.
Ventilation risk: Thrusters suck air down when foil breaches.
Structural complexity.

Keep thrusters on Legs (aft end). Push configuration is fine. Foil angle of attack controlled by tail flap.

Foiling Endurance Estimate (LiFePO4 @ 30% Disp = 168 lbs batts ≈ 3.5 kWh usable)

Mode	Speed	Power (Mech)	Duration	Range
Displacement (Night)	2.5 kts	~120 W	~29 hrs	~72 nm
Displacement (Day Solar)	3.5 kts	~250 W	∞ (Solar > Load)	∞
Foiling (Burst)	5.0 kts	~500 W	~7 hrs	~35 nm

Foiling is viable for tactical sprints (intercept, escape weather, station keeping in current), not continuous transit. Battery energy density is the limiter.

4. Solar Panel Recommendations & Wattage

Recommended Technology: "Shingled" or "Half-Cut" Monocrystalline PERC with Polymer Frontsheet (ETFE/TPT)

Why not Glass? Weight (3-4 lbs/ft² vs 0.5-1 lb/ft²), shattering risk on impact/slamming.
Why Shingled/Half-cut? Shade tolerance (rigging, mast, antennas), no busbar micro-cracking from flex/vibration.
Encapsulation: ETFE front sheet (self-cleaning, high transmittance, impact resistant) + High peel-strength EPO.
Vendors: SunPower Maxeon (shingled, premium), Solbian (marine flexible, rugged), Custom laminates from China (e.g., Sungold, Wanhos) for 1/3 cost.

Triangle Area Calculation

Side = 11.0 ft. Altitude = 11.0 * sin(60°) = 9.526 ft.
Area = 0.5 * 11.0 * 9.526 = 52.4 ft² (4.87 m²)

Usable Area (minus legs, hatches, camera mast, walkway brackets): ~42 ft² (3.9 m²).

Panel Type	Efficiency	W/ft²	Total Watts (42 ft²)	Weight (lbs)
Rigid Glass (Std)	21%	19.5	~820 W	~150 lbs (Too Heavy)
Flexible ETFE (Marine)	23% (SunPower)	21.5	~900 W	~15 lbs
Custom Shingled (China)	22%	20.5	~860 W	~12 lbs

Target: ~850-900 Wp @ ~13-15 lbs. Fits weight budget easily. MPPT Controllers: 3x Victron SmartSolar 100/20 (one per leg battery bank).

5. Propulsion: Blue Robotics M200 vs Alternatives

Blue Robotics M200 Specs

Max Thrust: 11.2 lbf (5 kgf) @ 16V, 32A (512 W) each.
Efficiency Peak: ~3-4 g/W (grams thrust per Watt) ~ 0.0066 lbf/W.
Cable: 4mm thick, ROV tether style (good for oil-filled pressure compensation).

MTBF / Reliability Estimate

Blue Robotics does not publish MTBF. Community data (ROV forums, ArduSub users):

Infant Mortality: ~2-5% DOA or fail < 10 hrs (seal leakage, bearing grit).
Useful Life (Continuous): 500 - 1,500 hours before bearing wear/seal weep requires rebuild.
Catastrophic Failure (Locked rotor/flood): ~1,000 - 2,000 hrs.
Sargasso Weed: M200 open prop handles weed better than T200 (no shroud to clog), but weed wraps on motor can = high current -> ESC thermal shutdown.

Redundancy Math (6 Thrusters, 2 per Leg)

Requirement: 2 Working thrusters on different legs (Port/Stbd) for differential steer.

State: 6 Thrusters. Failure Rate λ ≈ 1/1000 hr (optimistic continuous).
Mission Time Target: 72 hrs (3 days).
Probability of >4 failures (leaving <2 functional): Negligible.
Probability of losing one entire leg (both thrusters fail): P ≈ (1 - e^(-λt))² ≈ (0.07)² ≈ 0.5% per 72hr mission.
Expected Operational Life (Continuous): ~60-90 days before probability of losing differential steer exceeds 10%.

Better Alternative: Torqeedo / ePropulsion / Custom Rim-Drive?

Option	Pros	Cons	Verdict
Blue Robotics M200 (x6)	Cheap ($200), 16V direct to 4S/6S LiPo, ArduSub native, replaceable.	Low efficiency, short bearing life, weed wrap risk.	BEST for Prototype. Low risk capital.
Torqeedo Travel 1103C (x3)	Integrated GPS/Comm, efficient, 1000W, reliable.	$2,500 each. 29V system (needs boost/buck). Heavy. Hard to integrate 6x.	Too expensive for "drone swarm".
ePropulsion Navy 3.0 (x3)	Direct drive, quiet, hydro-generatable.	$3,000+. Large diameter (leg chord limit?).	No.
Custom Rim Drive (3D Print + Magnets)	No seals, fits leg chord perfectly, weed proof.	R&D heavy. Low torque density at 16V. Requires custom ESC/FOC.	Future V2. Not V1.

Decision: Stick with 6x Blue Robotics M200. Buy 8 (2 spares). Budget $1,600. Accept 500-1000 hr rebuild cycle. Implement "Weed Shedding" routine in firmware (Reverse pulse every 10 mins).

6. Control System, Stabilizer Mechanism & Compute

Flight Controller: Blue Robotics Navigator + Raspberry Pi CM4

Navigator: 16 PWM (6 ESC + 3 Stabilizer Servos + 3 Spare), IMU, Baro, Compass, 2x CAN, 2x I2C, 1x UART (GPS), 1x UART (Telem/Starlink). Perfect fit.
OS: Raspberry Pi OS Lite (64-bit) + ArduRover (firmware on Navigator) + MAVLink router.
Compute: CM4 4GB eMMC (32GB). No SD Card. eMMC is soldered = vibration proof.

Potting Strategy (Sylgard 184 / Ecoflex / MG Chemicals 832TC)

Yes, potting is excellent for this.

Use Thermally Conductive potting (k > 0.8 W/m·K). Standard Sylgard 184 is ~0.2 W/m·K (too insulating for Pi CPU).
Recommended: MG Chemicals 832TC (1.5 W/m·K, 2-part silicone) or Henkel Loctite ECCOBOND 2850FT.
Pot the CM4 Carrier Board + Navigator + ESC BECs inside a Aluminum Box (wall of leg). Box acts as heatsink.
CPU Heatsink: Tall finned block (30mm) epoxied to CPU, protruding INTO potting compound, base of box is outer wall of leg (water cooled).
Connectors: SubConn (Bulkhead) or potted cable glands for Starlink, GPS, Thruster leads.

Stabilizer Actuation & Locking Mechanism

Requirement: Rotate foil ±15° for active control. Lock at 0° (heave plate mode) or ±Feather (storm). Spring-loaded pin.

Actuator Selection

Option	Torque	Speed	Cost	Notes
High-Torque Servo (DS3225 / Savox 2290)	25-30 kg·cm	0.15s/60°	$40	Winner. PWM direct from Navigator. Metal gears. 6V/7.4V.
Linear Actuator (12V, 500N)	High	Slow	$60	Needs H-bridge/relay board. Overkill.
Stepper + Gearbox	High	Precise	$80	Needs driver board. Holding current = heat.

Spring-Loaded Locking Pin Design (The "Deadbolt")

Pin: 316 SS Ø6mm rod, chamfered tip.
Spring: Compression spring (Lee Spring LC-045E-6 or similar), Force ~5-10 lbs at full compression. Keeps pin OUT (Locked) by default (Fail-Safe).
Solenoid (Unlock): Tubular Push/Pull Solenoid (e.g., Geeplus VMN3025 or D-frame 12V/24V, 20mm stroke, ~$15). Energize to PULL pin IN (Unlock).
Receiver Hole: Machined in stabilizer horn / bracket. Tapered entry for wave-alignment capture.
Position Feedback: Hall Effect Sensor (A3144) + Magnet on pin flank -> Navigator GPIO. Confirms Locked/Unlocked.

Sequence:
1. Boot: Pin OUT (Locked) by Spring. Hall = HIGH.
2. Stabilize Mode: Energize Solenoid (12V) -> Pin IN. Hall = LOW. Servo moves foil.
3. Storm/Heave Mode: Cut Solenoid Power -> Spring SLAMS Pin OUT. Servo centers foil (0°).
4. Power Loss: Failsafe -> Locked Heave Plate.

Cost per Stabilizer: Servo ($40) + Solenoid ($15) + Spring/Pin/Hardware ($10) + Bracket ($10) = ~$75 ea ($225 total).

7. Recovery Strategy Analysis

1. Upwind Self-Rescue (Sail Mode)

Viable. Legs = Daggerboards (Aspect Ratio ~2.5). Drift angle ~30-40° off wind. Control: Differential thrust (1 motor) OR Stabilizer differential lift (if foiling) OR Stern "Water Brake" (see below). Risk: Leeway. Needs GPS waypoint "Home" logic. Works if 1 motor + compute alive.

2. Passive "Water Brake" (Drogue/Sea Anchor Deploy)

BEST SINGLE UPGRADE. Do not rely on a hinged flap (fouling, corrosion, complexity).

Carry a 12-18 inch Para-Drogue (Seabrake GP24L or similar) in a stern tube.
Deployment: Burn-wire (Nichrome) or Servo-released pin. No power = Deployed.
Effect: Aligns bow to waves (weathercock), reduces drift 5-10x, prevents broaching.
Recovery: Winch on rescue drone (see below).

3. Drone-to-Drone Rescue (The "Hook & Tow")

Component	Spec
Target (Disabled)	4ft Red Dyneema (SK78) + 3" Orange Float (A0 Polyform). Stowed in Bow "Launch Tube".
Catcher (Rescuer)	Stern "V-Funnel" (Aluminum/HDPE) 24" wide -> 2" throat. U-capture hook at throat. Underwater camera (BlueRobotics LowLight) looking aft/up.
Process	Rescuer approaches disabled bow @ 0.5 kts. Vision servoing (OpenCV on Pi) centers rope in funnel. Hook captures. Winch (small 12V trailer winch, 500lb) takes load.
Upside Down?	If disabled turtle: Legs are symmetric. Hook catches rope floating from bottom. Towing upside-down is stable (legs up = keels). Righting moment at dock.

Cost/Drone: Rope/Float ($15) + Funnel ($30 printed/alum) + Winch ($80) + Camera ($60) = ~$185. Worth it.

8. Weight Budget (Target: 562.5 lbs)

Component	Qty	Unit Wt (lbs)	Total (lbs)	Notes
Legs (Aluminum NACA 0035, 64.5" x 25.5" x 0.125" skin + ribs)	3	45.0	135.0	Welded 5086/6061. Foam filled (2lb) for reserve buoyancy.
Triangle Frame (2"x2"x0.25" Al Angle, 33ft total + cross beams)	1	65.0	65.0	Bolted corners. Deck beams included.
Walkway/Railing (Al Grating + Pipe Rail, 3 sides)	1	40.0	40.0	Modular bolt-on.
Stabilizers (3 Foils + Shafts + Housings)	3	18.0	54.0	Carbon/Al hybrid.
Stabilizer Actuation (Servo, Solenoid, Bracket)	3	3.5	10.5
Thrusters M200 + Mounts	6	1.8	10.8
Batteries (LiFePO4 3.5 kWh Usable / ~168 lbs)	3 Banks	56.0	168.0	30% Disp Target Met. 12.8V 140Ah x 3 per leg.
Solar Panels (ETFE 900W)	1 Set	15.0	15.0
Electronics (Pi CM4, Navigator, ESCs, MPPTs, Starlink, Cams, Wiring)	1	25.0	25.0	Potted in Leg 1.
Recovery Gear (Drogue, Winch, Hook, Lines)	1	10.0	10.0
Ballast / Lead (Trim)	-	-	29.2	To hit 562.5 target & lower KG.
TOTAL			562.5

Budget Balanced. 30% Battery fraction achieved. KG very low (Batteries in bottom of legs). Reserve buoyancy (Foam in legs) > 200 lbs positive.

9. Power Budget & Speed Predictions

Hotel Load (Continuous)

Device	Current (A) @ 12V	Power (W)	Duty	Avg (W)
Raspberry Pi CM4 + Navigator	0.8	9.6	100%	9.6
Starlink Mini (DC PoE)	2.5	30.0	100%	30.0
Cameras (x3 IP / USB)	0.5	6.0	100%	6.0
AIS Transponder (Receive + TX)	0.2	2.5	100%	2.5
Nav Lights (LED)	0.1	1.2	50% (Night)	0.6
Stabilizer Servos (Hold/Hunt)	0.5	6.0	50%	3.0
MPPT/ESC Quiescent	0.3	3.6	100%	3.6
TOTAL HOTEL				~55 W (Day) / 56 W (Night)

Available Motor Power

Solar Avg (Caribbean, 42ft², 23% eff, 5.5 PSH): 900W * 0.75 (temp/angle) * 5.5h / 24h = ~155 W Avg Continuous.
Day (6 hrs peak): 600W available. Hotel 55W. Motor Budget = 545 W.
Night (18 hrs): 0W Solar. Battery Only. Reserve 20% SOC. Usable 2.8 kWh / 18h = 155 W Avg. Hotel 56W. Motor Budget = 99 W.

Speed Predictions (Displacement Mode)

Drag Model: Legs (3x NACA 0035, Submerged 32") + Triangle Deck Windage + Stabilizers (Locked).

Condition	Thrust Power	Predicted Speed (Calm)	Into Wind/Seas (15kt/3ft)	Downwind
Day (545 W)	545 W	4.2 kts	2.8 kts	4.5 kts
Night (99 W)	99 W	2.2 kts	1.0 kts	2.5 kts
Foiling Sprint (500W)	500 W	5.5 kts	N/A (Unstable)	6.0 kts

Note: Windage on triangle deck is significant. "Into Wind" assumes 15kt apparent wind + 3ft chop. Legs act as keels, reducing leeway to < 15°.

10. Salt Spray, Sargasso & Camera Protection

Salt Spray Mitigation

Starlink Mini: Mount on 4ft mast (center pipe). It has IP56 rating. Add Hydrophobic Nano-coating (NeverWet / Rain-X) on dish face. Tilt slightly forward (15°) to shed water.
Cameras: Use M12 Lens "Bullet" Cameras (IP67) behind Acrylic Domes (3-4mm) with Hydrophobic Coating. Add Compressed Air "Puffer" Nozzles (12V solenoid valve + small CO2 cartridge or diaphragm pump) triggered by timer/image blur detection. Best low-cost solution.
Solar Panels: ETFE surface is naturally hydrophobic. Mount at 10-15° angle (triangle roof slope) for self-cleaning. Heat-shrink all MC4/junctions + Self-amalgamating tape (Tommy Tape). Conformal coat junction box PCBs.

Sargasso Avoidance (Night)

IR Camera NOT required. Sargasso reflects NIR (Night Vision) poorly; it looks dark like water.

Day: RGB Camera + Simple CNN (MobileNetV3) on Pi CM4. Detects brown mats vs blue water. 30 FPS easy.
Night: Polarized IR Illuminators (850nm/940nm) + Mono Camera. Sargasso dampens capillary waves -> "Glass calm" patches in IR. Detect absence of wave texture (speckle contrast) rather than color. Cheaper than Thermal (FLIR Lepton).
Backup: Current sensor on thrusters. Sudden current rise + speed drop = Weed. Auto-reverse pulse.

11. Market Analysis & Competitor Comparison

Target Markets

EEZ Patrol (Anguilla/Caribbean Govs): IUU Fishing monitoring. Low cost per boat-day.
Marine Research (Universities/NGOs): Persistent sensor platform (Acoustics, CTD, eDNA). "Launch from dock" capability.
Offshore Wind/Oil Survey: Pre-lay surveys, metocean buoys replacement.
Defense (ISR): Chokepoint monitoring, mine countermeasures (towing sonar).

Market Size: Global USV Market ~$1.0B (2024), growing 12% CAGR. Long-endurance Solar niche ~$150M. 50-100 units/yr addressable for < $50k class.

Competitor Comparison (Top 3 Long-Endurance Solar/Wave USVs)

Platform	Type	Speed (kts)	Endurance	Payload	Weight	Cost (Est.)	Open Architecture?	Self-Righting
Saildrone Explorer	Wind (Wing)	2-3 (Avg)	12+ Months	50 kg	~1,500 lbs	$500k - $1M/yr (Lease)	No (Black Box API)	Yes (Wing ballast)
Liquid Robotics Wave Glider	Wave + Solar	1.3 (Avg)	12+ Months	50 kg	~250 lbs (Float) + Sub	$300k - $500k	Sensor integration only	Yes (Passive)
AutoNaut	Wave + Solar	2-4	6-9 Months	100 kg	~500 lbs	$200k - $400k	ROS / MOOS supported	Yes
Ours (1:4 Model)	Solar/Electric	2.2 - 4.2	30-60 Days (Battery limited)	50 kg	562 lbs	$15k - $25k (Parts x5)	Full Root / ArduPilot	NO

Why the Price Difference?

Business Model: Competitors sell Data-as-a-Service (DaaS). Price includes satellite comms, mission control, insurance, shore crew, recovery, data pipeline, regulatory compliance. You are buying Hardware Only.
Reliability Engineering: 12-month MTBF requires aerospace-grade parts, redundancy (triple MRU, dual comms), burn-in testing. Your model: Hobby/Industrial grade, 500hr MTBF thrusters.
Self-Righting: Adds 30-50% structural weight/cost. You omitted this.
Warranty: They warranty "Mission Success". You get "Parts Work on Arrival".

Competitiveness at 2x Parts Cost (~$40k/unit)

HIGHLY COMPETITIVE for specific niches.

Coastal/EEZ Patrol (1-30 days): 10x cheaper than leasing Saildrone. Speed advantage over Wave Glider.
Research: Full code access (ArduPilot/Python) is a massive win for scientists needing custom sensor triggers.
Gap: Cannot do "Months at sea" without self-righting and higher reliability. Position as "Tactical/Coastal Endurance", not "Ocean Crossing".

12. Summary & Critical Path

Design Verdict: FEASIBLE & HIGH VALUE

Weight: 562.5 lbs target met with 30% Battery Fraction.
Performance: 2.2-4.2 kts sustained. Foiling sprint to 5.5 kts.
Power: 900W Solar / 3.5 kWh Battery. Positive energy balance in Caribbean sun.
Control: Navigator + CM4 (Potted) is robust, standard, open source.
Stabilizers: Servo + Spring-Lock Pin is elegant, fail-safe, cheap.
Recovery: Passive Drogue + Drone-to-Drone Hook is viable.

Critical Risks & Mitigations

Risk	Likelihood	Impact	Mitigation
No Self-Righting -> Total Loss in Storm	High	Critical	Operate only in forecast < 20kt winds. Auto-deploy Drogue on comms loss / low batt / high pitch.
M200 Thruster Failure / Weed	High	Medium	Carry 2 spares. Auto-reverse firmware. Design leg fairing to shed weed.
Starlink Dropout (Rain fade / Obstruction)	Medium	High (Loss of Control)	ArduPilot "Lost Link" -> Return to Home (RTL) / Loiter / Deploy Drogue. MUST work autonomously.
Salt Ingress (Potting failure)	Low	Critical	Pressure test potted boxes to 15 psi (30 ft). Conformal coat PCBs BEFORE potting.
Structural Fatigue (Aluminum Welds)	Medium	High	Post-weld heat treat (if 6061-T6) or use 5083/5086 (non-heat treatable). FEA on leg-root/triangle joint.

Recommended Next Steps (China Manufacturing)

CAD Freeze: Leg Foil (NACA 0035 trunc), Triangle Extrusion Profile, Stabilizer Foil.
RFQ Packets:
- Aluminum Extrusion (Triangle angles, Leg skins/ribs) -> 5 Sets.
- CNC Machined Parts (Stabilizer hubs, Motor mounts, Lock pin receivers).
- Carbon Fiber Stabilizer Wings (or Al welded).
- Custom ETFE Solar Laminates (900W, Triangle shapes).
Procure COTS: M200 x30, Navigator x5, CM4 4GB/32GB x5, Servos x15, Solenoids x15, LiFePO4 Cells (Headway 38120S or EVE 280Ah for leg packs), Victron MPPTs, Starlink Minis.
Software Sprint: ArduRover "Skid Steer" + Custom Stabilizer Mixer + "Weed Detect/Reverse" Lua Script + "Drogue Deploy" Failsafe.
Tank Test (1/10 scale printed): Validate stabilizer lock/unlock, foil lift, self-righting attempt (confirm it fails).