gps-denied-onboard/_standalone/UAV_frame_material/01_solution/solution_draft03.md

Solution Draft (Rev 03) — 8+ Hour Endurance

Assessment Findings

Old Component Solution	Weak Point	New Solution
Single 6S 33Ah battery (1001 Wh)	Only 3.5-4.7h endurance — insufficient for 8h target	4× 6S 33Ah 350 Wh/kg packs (2930 Wh) or 2× 12S 33Ah (2930 Wh)
10 kg MTOW	Cannot carry enough battery for 8h at current energy densities	Increase to 18 kg MTOW
3.0m wingspan	L/D ≈ 15 at AR≈10; higher wing loading increases cruise power	Scale to 3.8-4.0m wingspan (AR≈14, L/D≈17)
S2 FG airframe (3m)	Good but limited battery capacity due to MTOW constraint	S2 FG airframe scaled to 4m; same material, radio transparency preserved
Motor + ESC (500W class)	Undersized for 18 kg platform	Scale to 700-800W motor + 60-80A ESC
ADTI 20L V1 nav camera (20MP APS-C)	34 cm/px GSD at 2 km — too coarse for feature matching	ADTI 26S V1 (26MP APS-C, mech. shutter) + 35mm lens → 21.6 cm/px at 2 km
Viewpro A40 Pro AI camera (1080p, 40×)	1080p limits FoV to 65×37m at max zoom from 2 km	Viewpro Z40K (4K, 20×) → 2.7 cm/px GSD, 103×58m FoV, 479g lighter

Product Solution Description

A scaled-up modular, radio-transparent electric fixed-wing reconnaissance UAV built with S2 fiberglass/foam-core sandwich construction and internal carbon fiber spar reinforcement. Wingspan increased to 3.8-4.0m for better aerodynamic efficiency (L/D ≈ 17). MTOW raised to 18 kg to accommodate 4× semi-solid battery packs totaling ~2930 Wh. Disassembles into modular sections for pickup truck transport; 2 complete aircraft fit in a standard 6.5ft bed.

Target performance: 8-9 hours practical flight endurance, 18 kg MTOW, 3.8-4.0m wingspan. Camera payload: ADTI 26S V1 (26MP, mech. shutter, 21.6 cm/px at 2 km) for GPS-denied navigation + Viewpro Z40K (4K, 20× zoom, 2.7 cm/px at 2 km) for AI reconnaissance. Total payload 892g — 578g lighter than Draft 02.

┌──────────────────────────────────────────────────────────────────┐
│              SCALED-UP MODULAR AIRFRAME LAYOUT                   │
│                                                                  │
│  LEFT WING PANEL       FUSELAGE           RIGHT WING PANEL       │
│  (~1.9m span)         (~1.1m)             (~1.9m span)          │
│  ┌──────────────┐   ┌──────────────────┐   ┌──────────────┐     │
│  │ S2 FG skin   │   │ S2 FG skin       │   │ S2 FG skin   │     │
│  │ PVC foam core│◄─►│ Battery bay ×4   │◄─►│ PVC foam core│     │
│  │ CF spar cap  │   │ Payload bay      │   │ CF spar cap  │     │
│  │ (internal)   │   │ Motor (700W)     │   │ (internal)   │     │
│  └──────────────┘   └──────────────────┘   └──────────────┘     │
│                                                                  │
│  Wing-fuselage joint: aluminum spar joiner + 2 pin locks         │
│  Assembly time target: < 10 minutes                              │
│  Material: S2 fiberglass = RF transparent (GPS/telemetry OK)     │
│  Internal CF spar: minimal RF impact (narrow linear element)      │
│                                                                  │
│  BATTERY BAY (4 packs, 2S2P wiring for 12S 66Ah):               │
│  ┌──────┐ ┌──────┐                                              │
│  │ 6S   │ │ 6S   │  Series pair A → 12S 33Ah                    │
│  │ 33Ah │ │ 33Ah │                                              │
│  └──────┘ └──────┘                                              │
│  ┌──────┐ ┌──────┐                                              │
│  │ 6S   │ │ 6S   │  Series pair B → 12S 33Ah                    │
│  │ 33Ah │ │ 33Ah │  Pairs A+B in parallel → 12S 66Ah            │
│  └──────┘ └──────┘                                              │
│  Total: 44.4V × 66Ah = 2930 Wh                                  │
└──────────────────────────────────────────────────────────────────┘

TRANSPORT CONFIGURATION (standard pickup truck, 6.5ft bed):
┌───────────────────────────────────────────────┐
│  Truck bed: 198cm × 130cm (between wells)      │
│  ┌────────────────────┐ ┌──────────────────┐  │
│  │ Plane 1 wings      │ │ Plane 2 wings    │  │
│  │ (2 × 190cm long)   │ │ (2 × 190cm)      │  │
│  │ stacked ~25cm      │ │ stacked ~25cm    │  │
│  ├────────────────────┤ ├──────────────────┤  │
│  │ Plane 1 fuselage   │ │ Plane 2 fuse.    │  │
│  │ (~110cm)           │ │ (~110cm)         │  │
│  └────────────────────┘ └──────────────────┘  │
│  Width per plane: ~35cm × 2 = 70cm            │
│  Total width: 70cm × 2 = 140cm > 130cm ⚠️     │
│  → Stack all 4 wings in one pile + 2 fuselages │
│    alongside: 190cm × 70cm + 110cm × 40cm     │
│    Total width: ~110cm < 130cm ✓               │
│  Total length: 190cm < 198cm ✓                 │
└───────────────────────────────────────────────┘

Existing/Competitor Solutions Analysis

Platform	MTOW	Endurance	Battery	Wingspan	Material	RF Transparent	Transport	Price
DeltaQuad Evo (standard)	10 kg	4h32m	2× 22Ah semi-solid	2.69m	CF+Kevlar+FG	Partial	Wing removable	$25,000+
DeltaQuad Evo (record)	~9 kg	8h55m	2× Tulip Tech 450 Wh/kg	2.69m	CF+Kevlar+FG	Partial	Wing removable	N/A (prototype batteries)
YUAV Y37	17-20 kg	8.5h (1 kg payload)	12S 60Ah semi-solid (~2700 Wh)	3.7m	Full carbon	❌ No	138×55×45 cm	~$15,000+ est.
NOCTUA (H2)	20-25 kg	10h	Hydrogen fuel cell	5.10m	CFRP	❌ No	Field-portable	Academic
CW-80E (JOUAV)	>25 kg	10-11h	Large electric	>4m	Composite	Unknown	Vehicle-mounted	$50,000+
Albatross	10 kg	4h	LiPo	3.0m	FG+CF	Partial	Removable wings	$4,800 RTF
Our Draft 03	18 kg	8-9h target	4× 6S 33Ah 330+ Wh/kg	3.8-4.0m	S2 FG	✅ Yes	2 in pickup	$5,500-7,500

Key insight: YUAV Y37 proves that 8.5h at 17-20 kg MTOW with 3.7m wingspan and semi-solid batteries is achievable in production. Our design targets similar performance with S2 FG (heavier but radio transparent) offset by slightly longer wingspan for better L/D.

Architecture

Component: Frame Material

Solution	Advantages	Limitations	Cost (per unit)	Fit
S2 fiberglass skin + PVC foam core + internal CF spar (recommended)	RF transparent, good impact tolerance, field repairable, proven at 3m scale	~25-30% heavier than carbon at 4m scale; requires careful weight management	$600-1,200 materials	✅ Only option that preserves RF transparency
Full carbon fiber (YUAV Y37 approach)	Lightest possible (~4-5 kg bare at 4m), best L/D	Blocks RF — GPS/telemetry degraded	$1,500-3,000	❌ Fails radio transparency
Carbon-Kevlar hybrid	Good crash survivability, lighter than FG	Partially blocks RF, expensive, hard to machine	$1,200-2,500	❌ RF compromise
S2 FG with Dyneema (UHMWPE) reinforcement	RF transparent, excellent impact resistance	Dyneema has poor compression strength, complex bonding	$800-1,500	⚠️ Complex but possible

Component: Wingspan & Aerodynamics

Solution	L/D	Platform Weight	Endurance Impact	Transport	Fit
3.8m wingspan (recommended for 2-in-pickup)	~17	6.5-7.5 kg	Baseline	190cm half-wings fit 198cm bed ✓	✅ Best balance
4.0m wingspan	~17.5	7.0-8.0 kg	+3-5%	200cm > 198cm; needs 3-section wing	⚠️ Good but transport harder
4.5m wingspan (single UAV transport)	~18.5	8.0-9.5 kg	+8-12%	225cm half-wings; 1 UAV per pickup	⚠️ Maximum endurance, 1 plane only
3.0m wingspan (Draft 02)	~15	5.3 kg	Reference (3.5-4.7h)	150cm easily fits	❌ Insufficient for 8h

Recommendation: 3.8m wingspan as primary design. Half-wings at 190cm fit within 198cm pickup bed length. AR ≈ 13.6, L/D ≈ 17. Optional detachable wingtips (+20cm per side = 4.2m total) for maximum endurance missions where single-UAV transport is acceptable.

Component: Battery Configuration

Solution	Total Energy	Weight	Wiring	Cost	Endurance (18 kg)	Fit
4× Tattu 6S 33Ah 350 Wh/kg (recommended)	2930 Wh	8.86 kg	2S2P → 12S 66Ah	~$2,930	8-8.5h	✅ Best modularity, off-the-shelf
2× Tattu 12S 33Ah 350 Wh/kg	2930 Wh	8.89 kg	2P → 12S 66Ah	~$3,800	8-8.5h	✅ Simpler wiring, same endurance
1× Tattu 12S 76Ah 330 Wh/kg	3374 Wh	10.88 kg	Direct 12S	~$4,300	8.5-9h (needs 20 kg MTOW)	⚠️ Best energy but requires 20 kg MTOW
4× Xingto 6S 30Ah 370 Wh/kg	~3280 Wh (est.)	~8.9 kg (est.)	2S2P → 12S 60Ah	~$3,000-4,000	9-9.5h	⚠️ Higher density but less verified
Future: 4× 450 Wh/kg packs	~4000 Wh	~8.9 kg	2S2P → 12S	$5,000-8,000 est.	10-11h	⚠️ Not yet available at volume

4-Battery Configuration Detail (2S2P):

• 2 series pairs: each pair = 2× 6S in series = 12S 33Ah (44.4V, 1465 Wh)
• 2 parallel pairs: both 12S pairs in parallel = 12S 66Ah (44.4V, 2930 Wh)
• Requires: 2× series adapters, 1× parallel bus bar, battery management for each pair
• Advantage: individual pack replacement if one degrades; modular packing for transport
• Disadvantage: more wiring complexity, more connectors (failure points)

2-Battery Configuration (2P):

• 2× 12S 33Ah in parallel = 12S 66Ah (44.4V, 2930 Wh)
• Simpler wiring, fewer connectors
• Each pack heavier individually (4.4 kg) but fewer handling steps

Component: Motor & Propulsion (scaled for 18 kg)

Solution	Power	Weight	Efficiency	Cost	Fit
T-Motor U8 Lite (recommended)	700W max, 200-300W cruise	~250g	η ≈ 0.92 at cruise	~$150	✅ Proven for this MTOW class
Dualsky XM6350EA	800W max	~280g	η ≈ 0.90	~$120	✅ Good budget option
SunnySky V4014	600W max	~210g	η ≈ 0.91	~$90	⚠️ Borderline power margin

Propeller: 16×10 or 17×10 folding (vs 13×8 in Draft 02). Larger prop = higher propulsive efficiency at lower RPM, critical for endurance.

ESC: 60-80A continuous rating (vs 40-60A in Draft 02).

Component: Foam Core

Same as Draft 02 — PVC Divinycell H60 recommended. No change.

Component: Wing-Fuselage Joint

Same aluminum spar joiner + pin lock concept as Draft 02, but scaled for larger wing loads:

• Spar tube: 25mm OD (vs 20mm) to handle higher bending moments
• Joiner: machined 7075-T6 aluminum (stronger than 6061-T6)
• Weight: ~0.35 kg per joint set (vs 0.2-0.3 in Draft 02)

Component: Camera Payload (Upgraded for 2 km Altitude)

GSD = (Sensor Width × Altitude) / (Focal Length × Image Width)

Navigation Camera (GPS-Denied System)

Solution	Sensor	Resolution	Weight (body+lens)	GSD at 2 km	FoV at 2 km	Cost	Fit
ADTI 20L V1 (Draft 02)	APS-C 23.2mm	20MP (5456×3632)	~271g (121g+150g)	34 cm/px (25mm)	1855×1235m	$480+lens	❌ Too coarse at 2 km
ADTI 26S V1 + 35mm (recommended)	APS-C 23.4mm	26MP (6192×4128)	~172g (122g+50g)	21.6 cm/px (35mm)	1337×892m	$1,890	✅ Best value: mech. shutter, light, good GSD
ADTI 61PRO + 50mm	FF 35.7mm	61MP (9504×6336)	~426g (276g+150g)	15 cm/px (50mm)	1426×950m	$2,830	✅ Best GSD but +$940 over 26S
Sony ILX-LR1 + 50mm	FF 35.7mm	61MP (9504×6336)	~393g (243g+150g)	15 cm/px (50mm)	1426×950m	$3,100	⚠️ Lightest 61MP, drone-native, most expensive
ADTI 36S + 50mm	FF 35.9mm	36MP (7360×4912)	~390g (240g+150g)	19.5 cm/px (50mm)	1434×957m	$1,600	❌ No mechanical shutter — rolling shutter distortion

Recommendation: ADTI 26S V1 with 35mm fixed lens. Mechanical shutter eliminates rolling shutter distortion (critical for GPS-denied feature matching at speed). 21.6 cm/pixel GSD at 2 km is sufficient for terrain feature matching, road/building identification, and satellite image correlation. IMX571 back-illuminated sensor delivers excellent dynamic range. Lightest option at 172g. Upgrade to ADTI 61PRO (+$940, 15 cm/px) if finer GSD is needed.

AI Camera (Reconnaissance — "Nice Shots" from 2 km)

Solution	Sensor	Resolution	Zoom	Weight	GSD at 2 km (max zoom)	FoV at max zoom	Thermal	Cost	Fit
Viewpro A40 Pro (Draft 02)	1/2.8"	1080p (1920×1080)	40× optical	1074g	3.4 cm/px	65×37m	640×512	$2,999	⚠️ Good zoom but 1080p limits FoV
Viewpro Z40K (recommended)	1/2.3"	4K (3840×2160)	20× optical + 25× IA (4K)	595g	2.7 cm/px	103×58m	No	$2,999-4,879	✅ Better GSD, 2.5× wider FoV, 479g lighter
Viewpro Z40TIR	1/2.3"	4K (3840×2160)	20× optical + 40× IA (1080p)	~700g est.	2.7 cm/px (4K)	103×58m	640×480	~$5,000 est.	✅ Best of both: 4K + thermal
Viewpro A40T Pro	1/2.8"	1080p	40× optical	~1200g	3.4 cm/px	65×37m	640×512	$5,999	⚠️ Thermal + zoom but 1080p, heavy

Recommendation: Viewpro Z40K. At 4K resolution with 20× optical zoom, it delivers better GSD (2.7 vs 3.4 cm/px) and 2.5× wider field of view at max zoom than the A40 Pro at 1080p/40×. And it's 479g lighter — weight that can go to battery or margin. If thermal is needed, step up to Z40TIR.

At 2.7 cm/pixel: vehicles clearly identifiable, human figures detectable, building details visible. At 20× wide end (53 cm/px): wide-area situational awareness covering ~2 km × 1.2 km.

Payload Weight Summary (Upgraded)

Component	Draft 02/03	Upgraded	Delta
Navigation camera (body+lens)	ADTI 20L + 25mm = 271g	ADTI 26S + 35mm = 172g	-99g
AI camera + gimbal	Viewpro A40 Pro = 1074g	Viewpro Z40K = 595g	-479g
Jetson Orin Nano Super	60g	60g	—
Pixhawk 6x + GPS	65g	65g	—
Payload total	1470g	892g	-578g

Net effect: 578g saved. This frees ~191 Wh of battery capacity at 331 Wh/kg (~42 min extra endurance) or provides comfortable MTOW margin.

Component: Alternative Power Sources Assessment

Solution	Endurance	System Weight	Cost	Logistics	RF Compat.	Fit
Semi-solid battery (primary)	8-9h	8.9 kg	$2,930-3,800	✅ Charge from any outlet	✅ S2 FG	✅ Recommended
Solid-state 450 Wh/kg (upgrade path)	10-11h	8.9 kg (or lighter)	$5,000-8,000 est.	✅ Same as above	✅ S2 FG	⚠️ Future upgrade
Hydrogen fuel cell	15-17h	9.8 kg (FC + tank)	$25,000-40,000	❌ H2 supply in field	❌ Needs CFRP	❌ Impractical
Solar + battery hybrid	+1h over battery alone	+0.5-1.0 kg panels	+$500-1,500	⚠️ Weather dependent	⚠️ Panels on wing	❌ Marginal gain

Weight Budget (18 kg MTOW, 3.8m Wingspan)

Component	Weight (kg)	Notes
Airframe (S2 FG sandwich + CF spar, 3.8m)	5.5-6.5	Scaled from 3m (3.8-4.5 kg) proportional to area
Wing joints (aluminum 7075)	0.35	Larger joiner for higher loads
Motor (700W) + ESC (80A) + folding prop 16"	0.6	Scaled up from Draft 02
Wiring, connectors, battery bus	0.45	More wiring for 4-battery config
Platform subtotal	6.9-7.9
Payload (ADTI 26S + Z40K + Jetson + Pixhawk + GPS)	0.89	Upgraded cameras — 578g lighter than Draft 02 payload
Battery (4× Tattu 6S 33Ah)	8.86	4 × 2.216 kg
Total	16.7-17.7

Conservative: 7.9 + 0.89 + 8.86 = 17.65 kg (well under 18 kg MTOW ✓). Optimistic: 6.9 + 0.89 + 8.86 = 16.65 kg (1.35 kg margin for accessories or extra battery).

Endurance Estimates

Flight Physics Parameters

• Cruise speed: 17 m/s (optimized for endurance at this wing loading)
• L/D at cruise: 17 (conservative; L/D_max ≈ 19-20 for AR=13.6)
• Overall propulsive efficiency: η = 0.72 (motor 0.92 × prop 0.82 × ESC 0.95)

Cruise Power Calculation

P_cruise = (W × g × V) / (L/D × η) = (18 × 9.81 × 17) / (17 × 0.72) = 3001.9 / 12.24 = 245W P_total = 245 + 30 (payload) = 275W

Endurance by Battery Configuration

Config	Energy (Wh)	Usable 80% (Wh)	Theoretical (h)	Practical (h)	Conservative (h)
4× 6S 33Ah 330 Wh/kg	2930	2344	10.7	8.5	7.5-8.0
2× 12S 33Ah 350 Wh/kg	2930	2344	10.7	8.5	7.5-8.0
4× Xingto 370 Wh/kg (est.)	~3280	~2624	11.9	9.5	8.5-9.0
1× 12S 76Ah 330 Wh/kg (20 kg MTOW)	3374	2699	10.5*	8.4	7.5-8.0
Future 450 Wh/kg (est.)	~4000	~3200	14.5	11.6	10-10.5

*Higher MTOW (20 kg) → higher cruise power (~300W) partially offsets larger battery.

Practical = with 80% DoD. Conservative = with additional 10% real-world margin (wind, maneuvers, non-optimal cruise).

Cross-Validation Against Reference Platforms

Reference	MTOW	Energy	Endurance	Wh/min	Our scaled
DeltaQuad Evo (standard)	10 kg	976 Wh	4.5h	3.62	—
DeltaQuad Evo (record)	~9 kg	~1800 Wh	8.9h	3.37	—
YUAV Y37	~17 kg	2700 Wh	8.5h	5.29	Our 18 kg @ 2930 Wh: extrapolated 8.0-8.7h

The YUAV Y37 cross-check (full carbon, 3.7m) extrapolates to 8.0-8.7h for our S2 FG design at 18 kg with 2930 Wh, accounting for the ~10% aerodynamic penalty of fiberglass vs carbon. This confirms our calculated range.

Comparison to Draft 02

Parameter	Draft 02	Draft 03	Change
MTOW	10 kg	18 kg	+80%
Wingspan	3.0m	3.8m	+27%
Battery weight	3.2 kg	8.86 kg	+177%
Battery energy	1001 Wh	2930 Wh	+193%
Cruise power	~170W	~275W	+62%
Practical endurance	3.5-4.7h	8-8.5h	+80-140%
BOM cost	$2,800-4,500	$5,500-7,500	+67%

BOM Cost Estimate (Per Unit, 8h Config)

Component	Low Est.	High Est.	Notes
S2 fiberglass fabric	$250	$500	~14 m² at $15-30/m² (40% more than 3m)
PVC foam core (Divinycell H60)	$160	$300	Wing + fuselage + tail
Epoxy resin + hardener	$120	$230	~3.5-4 kg resin
CF spar material (tube + UD tape)	$80	$150	Longer spars for 3.8m
Aluminum spar joiners 7075-T6	$50	$100	Larger, machined
Vacuum bagging consumables	$40	$80
Motor (T-Motor U8 Lite or equiv.)	$120	$200	700W class
ESC (60-80A)	$60	$120
Folding propeller (16×10)	$20	$40
Servos (6× for larger surfaces)	$80	$160
Wiring, connectors, battery bus	$80	$150	More complex 4-battery wiring
Batteries (4× Tattu 6S 33Ah 350)	$2,930	$2,930	Retail price
RC receiver	$30	$80
Telemetry radio	$100	$300
Transport case / padded bag	$80	$200	Larger for 190cm wings
Subtotal (airframe + propulsion + battery)	$4,200	$5,540
Nav camera: ADTI 26S V1 + 35mm lens	$1,890	$1,890	26MP APS-C, mech. shutter, 21.6 cm/px at 2 km
AI camera: Viewpro Z40K 4K gimbal	$2,999	$4,879	4K 20× zoom, 2.7 cm/px at 2 km
Pixhawk 6x + GPS	$300	$500
Total BOM (complete unit)	$9,389	$12,809

With 2× 12S 33Ah instead of 4× 6S: battery cost rises to ~$3,800 (+$870). With Xingto 370 Wh/kg: battery cost est. ~$3,000-4,000 but better endurance.

Per-unit cost at batch of 5+: $10,500-14,500 (including cameras, tooling amortization) Per-unit cost first prototype: $13,500-17,000 (includes tooling)

Optional upgrade: swap ADTI 26S → ADTI 61PRO (+$940/unit) for 15 cm/px GSD if finer nav resolution needed.

Battery Upgrade Roadmap

Timeline	Battery Technology	Energy Density (pack)	Endurance (18 kg platform)	Availability
Now (2025-2026)	Tattu/Grepow semi-solid 350 Wh/kg	~331 Wh/kg	8-8.5h	✅ Off-the-shelf
Now (2025-2026)	Xingto semi-solid 370 Wh/kg	~350 Wh/kg	9-9.5h	✅ Available (limited)
Near-term (2026-2027)	Tulip Tech Ampera solid-state	~430 Wh/kg	10-11h	⚠️ Shipping to select partners
Near-term (2026-2027)	Amprius SA102 silicon-nanowire	~430 Wh/kg	10-11h	⚠️ Pilot production
Future (2027-2028)	Tulip Tech Enerza / Amprius 500	~475 Wh/kg	11-12h	❓ Announced, not volume

Solid-State 450 Wh/kg Cost Impact

Solid-state batteries (Tulip Tech, Amprius) are not yet priced publicly — both sell on custom quotes to defense/aerospace customers. Industry estimates for 2025-2026 production cost: $800-1,000/kWh. With small-volume aerospace/defense retail markup (1.5-3×), estimated retail: $1,500-2,500/kWh.

Battery	Pack Wh/kg	Total Energy	Endurance	Battery Cost	Total UAV BOM	Delta vs Baseline
Tattu semi-solid (baseline)	~331	2930 Wh	8-8.5h	$2,930	~$6,500	—
Solid-state 450 (low est.)	~430	3810 Wh	10-11h	$5,700	~$9,300	+$2,800 (+43%)
Solid-state 450 (mid est.)	~430	3810 Wh	10-11h	$7,600	~$11,200	+$4,700 (+72%)
Solid-state 450 (defense premium)	~430	3810 Wh	10-11h	$9,500	~$13,100	+$6,600 (+100%)

Prices should converge toward production cost ($800-1,000/kWh → low estimate above) as Amprius scales 1.8 GWh contract manufacturing capacity and Tulip Tech ramps with Dutch MoD backing through 2026-2027.

Design for upgradability: The battery bay should accommodate the same physical volume regardless of chemistry. Start with Tattu semi-solid at 8-8.5h for $2,930. When solid-state packs become available in compatible form factor, drop them in for 10-11h — no airframe changes needed, just a battery swap.

Modular Transport Specifications

Dimension	Value (3.8m)	Value (4.0m, 3-section)
Wing panel length	190 cm (half-span)	170 cm outer + 60 cm center
Wing panel chord	28-30 cm	28-30 cm
Wing panel thickness	4-5 cm	4-5 cm
Fuselage length	110 cm	110 cm
Fuselage width/height	18-22 cm	18-22 cm
Assembly time	< 12 minutes	< 15 minutes
Disassembly time	< 7 minutes	< 10 minutes

Pickup truck (2 planes, 3.8m design): All wing panels stack in one pile (190×30×20 cm = 4 panels × 5cm). Fuselages alongside (110×22 cm × 2). Total footprint: 190×110 cm < 198×130 cm. ✅

Car trunk (1 plane, 3.8m): Tight but possible in larger sedans/SUVs. Two wing panels (190cm) require fold-down rear seats or diagonal placement. Fuselage fits easily. ⚠️ Borderline for sedans; SUV or wagon preferred.

Hydrogen Fuel Cell — Assessment (Not Recommended)

Investigated as requested. While hydrogen offers dramatically higher endurance (15-17h), it is not recommended for this application:

Factor	Assessment
Endurance	✅ 15-17h theoretical with IE-SOAR 2.4 + 10.8L tank
System weight	⚠️ ~9.8 kg (FC 4.8 + tank 4.2 + regulator 0.3 + buffer 0.5) — similar to 4-battery pack but higher complexity
Cost	❌ $25,000-40,000 per unit (FC module alone est. $15-25k)
H2 logistics	❌ Compressed hydrogen (350 bar) supply chain in eastern Ukraine = extremely difficult. Requires specialized transport, hazmat protocols, compressor equipment
Radio transparency	❌ H2 platforms (NOCTUA, Doosan) use CFRP to save weight, conflicting with RF requirement
Reliability	⚠️ Fuel cells have 1000h life but are sensitive to contaminants and temperature extremes
Practical recommendation	Revisit only if (1) hydrogen infrastructure develops in theater, (2) RF transparency requirement is relaxed, or (3) endurance requirement exceeds 12h

Solar Augmentation — Assessment (Not Recommended)

Factor	Assessment
Available wing area	~0.7 m² usable upper surface
Solar power at altitude	~35-40W average (Ukrainian latitude, 22% efficient flexible panels)
Endurance gain	+1.0-1.5h theoretical, but -0.5h from panel weight → net +0.5-1.0h
Cost	+$500-1,500 per unit for flexible panels
Complexity	Adds MPPT controller, fragile surface, weather dependency
Recommendation	Not worth the cost/complexity for ~1h marginal gain

Testing Strategy

Integration / Functional Tests

• Static wing load test: 3× max flight load at spar joiner (verify no failure at 3g with 18 kg MTOW)
• Wing joint cycling: 100× assembly/disassembly, verify no wear (critical at higher loads)
• RF transparency test: measure GPS signal through airframe skin (target: < 3 dB attenuation)
• Assembly time test: verify < 12 minutes from transport case to flight-ready
• Battery wiring test: verify 2S2P balancing, measure voltage sag under load, test fail-safe (single pack disconnect)
• Range/endurance test: fly at cruise until 20% reserve, measure actual vs predicted
• Payload integration: electronics function under vibration at 18 kg flight loads

Non-Functional Tests

• Transport test: load 2 planes in pickup, drive 100 km on mixed roads, verify no damage
• Hard landing test: belly landing at 2.5 m/s descent (higher than Draft 02 due to heavier aircraft)
• Field repair test: wing skin puncture → FG patch + epoxy → airworthy in < 30 minutes
• Temperature test: battery + avionics at -10°C and +45°C
• Battery endurance test: 50 charge/discharge cycles on 4-battery 2S2P config, verify balanced degradation
• CG test: verify stable CG across all battery configurations (4-battery, 3-battery partial, 2-battery emergency)
• Emergency flight test: verify aircraft can fly safely on 2 batteries (reduced endurance) if 1 series pair fails

Production BOM: 5 UAVs From Scratch (8h Config)

A. One-Time Equipment & Tooling

Same as Draft 02 base equipment: $3,335. Add:

Item	Qty	Unit Price	Total	Notes
Larger mold materials (4m wing + fuselage)	1 set	$900	$900	MDF plugs + tooling epoxy for 3.8m molds
Aluminum spar joiner machining (7075, 12 sets)	1	$600	$600	Larger joiners, CNC outsourced
Battery parallel bus bar / wiring jig	1	$100	$100	For consistent 2S2P assembly
Equipment & Tooling TOTAL			$4,935

B. Raw Materials (5 UAVs + 20% waste)

Item	Qty (5 UAVs + margin)	Unit Price	Total
S2 fiberglass fabric 6oz	100 yards	$12.50/yard	$1,250
PVC foam Divinycell H60 10mm	24 sheets	$40/sheet	$960
Laminating epoxy resin	6 gallons	$125/gal	$750
Epoxy hardener	3 gallons	$80/gal	$240
Carbon fiber tube (spar, 25mm OD, 2.0m)	12	$35 each	$420
Carbon fiber UD tape 25mm	50 m	$5/m	$250
Vacuum bagging consumables	—	—	$400
Misc hardware	—	—	$250
Materials TOTAL (5 UAVs)			$4,520
Per UAV materials			~$904

C. Electronics & Propulsion (per UAV × 5)

Item	Per UAV	×5 Total
Motor (T-Motor U8 Lite or equiv.)	$150	$750
ESC (80A)	$80	$400
Folding propeller 16×10 (2 per UAV)	$40	$200
Servos (6× digital metal gear)	$150	$750
Nav camera: ADTI 26S V1 + 35mm lens	$1,890	$9,450
AI camera: Viewpro Z40K 4K gimbal	$3,500	$17,500
Pixhawk 6X Mini + GPS	$380	$1,900
RC receiver (TBS Crossfire)	$60	$300
RFD900x telemetry	$170 air × 5 + $350 GCS	$1,200
Power distribution + BEC	$30	$150
Wiring, connectors, battery bus	$80	$400
Batteries: 4× Tattu 6S 33Ah 350 (per UAV)	$2,930	$14,650
Electronics TOTAL (5 UAVs)		$47,650
Per UAV electronics		~$9,530

D. Summary

Category	Total	Per UAV
A. Equipment & Tooling	$4,935	$987
B. Raw Materials	$4,520	$904
C. Electronics & Propulsion	$47,650	$9,530
D. Consumables & Misc	$1,200	$240
E. Labor (est. same structure as Draft 02, +20%)	$19,176	$3,835
GRAND TOTAL (5 UAVs)	$77,481
Per UAV (all-in, with labor)		$15,496
Per UAV (materials + electronics, no labor)		$11,661

The cost increase vs Draft 02 ($6,502/unit) is driven by cameras (+$2,391/unit: ADTI 26S replaces ADTI 20L, Z40K replaces A40 Pro), batteries (+$2,200/unit), and larger airframe (+$250/unit). Optional: swap to ADTI 61PRO (+$940/unit) for 15 cm/px nav GSD.

Risk Assessment

Risk	Impact	Probability	Mitigation
S2 FG airframe heavier than estimated → MTOW exceeded	Reduced endurance	Medium	Build weight tracking into construction; accept 18.5 kg MTOW if needed
4-battery wiring complexity → connector failure	Loss of power pair	Low	Redundant connectors; test fail-safe on 2 batteries; parallel bus bar design
Semi-solid battery supply disruption	Cannot build	Low	Multiple suppliers (Tattu, Grepow, Xingto)
L/D lower than 17 in practice	Endurance drops to 7-7.5h	Medium	Use Xingto 370 Wh/kg for margin; optimize airfoil selection (SD7037 or AG series)
Wing flutter at 3.8m span	Structural failure	Low	Ground vibration test; CF spar sized for 1.5× flutter speed margin
CG shift with 4 battery packs	Controllability	Low	Fixed battery bay positions; CG calculated for all configurations

References

1-34: See Draft 01 and Draft 02 references (all still applicable)

Additional sources: 35. DeltaQuad Evo 8h55m record: https://uasweekly.com/2025/06/27/deltaquad-evo-sets-record-with-8-hour-flight-endurance-for-electric-vtol-uas-milestone/ 36. Tulip Tech batteries: https://tulip.tech/batteries/ 37. DeltaQuad Evo specs: https://docs.deltaquad.com/tac/vehicle-specifications 38. DeltaQuad Evo performance calculator: https://evo.deltaquad.com/calc/ 39. YUAV Y37 specs: https://www.airmobi.com/yuav-y37-a-new-standard-in-long-endurance-vtol-fixed-wing-uavs/ 40. YUAV Y37 product page: https://www.airmobi.com/product/yuav-y37-3700mm-vtol-fixed-wing-uav-pnp/ 41. Tattu 350 Wh/kg 6S 33Ah: https://tattuworld.com/semi-solid-state-battery/semi-solid-350wh-kg-33000mah-22-2v-10c-6s-battery.html 42. Tattu 350 Wh/kg 12S 33Ah: https://tattuworld.com/semi-solid-state-battery/semi-solid-350wh-kg-33000mah-44-4v-10c-12s-battery.html 43. Tattu 330 Wh/kg 12S 76Ah: https://tattuworld.com/semi-solid-state-battery/semi-solid-330wh-kg-76000mah-44-4v-10c-12s-battery.html 44. Xingto 370 Wh/kg battery: https://www.xtbattery.com/370wh/kg-42v-high-energy-density-6s-12s-14s-18s-30ah-semi-solid-state-drone-battery/ 45. Amprius SA102 450 Wh/kg: https://amprius.com/the-all-new-amprius-500-wh-kg-battery-platform-is-here/ 46. Amprius UAV selection: https://amprius.com/amprius-high-power-silicon-batteries-selected-by-esaero-to-power-next-generation-uavs/ 47. NOCTUA hydrogen UAV: https://noctua.ethz.ch/technology 48. IE-SOAR 2.4 fuel cell: https://www.intelligent-energy.com/our-products/ie-soar-fuel-cells-for-uavs/ie-soar-2-4/ 49. IE-SOAR specs (retail): https://shop.thebioniceye.co.uk/products/ie-soar-2-4kw-hydrogen-fuel-cell 50. Doosan DS30W specs: https://www.doosanmobility.com/en/products/drone-ds30 51. Cellen hydrogen refueling: https://cellenh2.com/reinventing-hydrogen-refueling-for-drones/ 52. Tattu battery catalog (pricing): https://rcdrone.top/collections/tattu-semi-solid-state-battery 53. Tattu 76Ah pricing (FlexRC): https://flexrc.com/product/tattu-semi-solid-state-330wh-kg-76000mah-10c-44-4v-12s1p-lipo-battery-pack-with-qs12-s-plug/ 54. JOUAV CW-80E: https://www.jouav.com/products/cw-80e.html 55. Discus 2b 4m glider: https://icare-rc.com/discus2b_4m.htm 56. Pickup bed dimensions: https://kevinsautos.com/faq/what-are-the-dimensions-of-a-65-foot-truck-bed.html 57. Tulip Tech Dutch MoD partnership: https://www.tulip.tech/news/

Related Artifacts

• Previous drafts: solution_draft01.md (CFRP), solution_draft02.md (S2 FG, 3m, 10 kg)
• Research artifacts: _standalone/UAV_frame_material/00_research/UAV_frame_material/