# Question Decomposition — Material Comparison: S2 FG + Carbon Stiffeners vs Shark M

## Original Question
Compare the researched and selected material (S2 fiberglass with carbon stiffeners) with the Shark M fuselage material. Pros and cons of each approach considering parachute landing survivability and radio transparency.

## Active Mode
Mode B: Solution Assessment — assessing existing solution_draft05 material selection.

## Problem Context Summary
- The project is building a reconnaissance UAV maximizing flight duration
- Previous drafts selected S2 fiberglass (S2 FG) fuselage with carbon fiber stiffeners
- Catapult launch + parachute landing is a key variant (Variant B)
- Shark M by Ukrspecsystems is a combat-proven reference platform with similar mission profile
- User confirms Shark M has no radio transparency issues from experience

## Question Type
**Concept Comparison** + **Decision Support**
Comparing two material approaches across multiple engineering dimensions with a decision outcome.

## Research Subject Boundary
| Dimension | Boundary |
|-----------|----------|
| Population | Fixed-wing reconnaissance UAVs, 10-20 kg MTOW class |
| Geography | Global, with emphasis on combat-proven systems |
| Timeframe | Current (2024-2026), materials science is Low novelty sensitivity |
| Level | Airframe structural material for fuselage |

## Timeliness Sensitivity Assessment
- **Research Topic**: Composite material comparison for UAV airframes
- **Sensitivity Level**: Low
- **Rationale**: Composite material properties (fiberglass, carbon fiber) are well-established engineering fundamentals. S2 glass and carbon fiber properties have been stable for decades.
- **Source Time Window**: No limit
- **Priority official sources**: Material datasheets, aerospace research papers, UAV manufacturer specifications

## Decomposed Sub-questions

### SQ1: What material does the Shark M actually use?
- "Shark M UAV fuselage material specifications"
- "Ukrspecsystems Shark composite airframe construction"
- "Ukrspecsystems PD-2 PD-1 fuselage material composite"
- "SHARK-M БПЛА матеріал корпус" (Ukrainian language)
- "Ukrspecsystems composite low radar cross section material"

### SQ2: How does each material behave under parachute landing impact?
- "fiberglass composite impact resistance parachute landing UAV"
- "carbon fiber composite impact damage brittleness crash landing"
- "S2 glass fiber impact energy absorption composite"
- "carbon fiber vs fiberglass UAV crash landing repair"
- "belly landing UAV composite damage modes"

### SQ3: What are the RF transparency properties of each material?
- "carbon fiber electromagnetic shielding effectiveness dB UAV antenna"
- "fiberglass radome RF transparent dielectric constant"
- "S2 fiberglass radio frequency transparency composite"
- "carbon fiber stiffener fiberglass skin RF shadow antenna"
- "GFRP radar transparent stealth composite UAV"

### SQ4: What are the weight/stiffness trade-offs?
- "fiberglass vs carbon fiber UAV airframe weight comparison"
- "S-glass vs E-glass impact strength toughness"
- "carbon fiber stiffener fiberglass hybrid composite advantages"

### SQ5: What are the cost and field repairability differences?
- "fiberglass UAV field repair epoxy patch battlefield"
- "carbon fiber repair cost UAV composite"
- "fiberglass vs carbon fiber material cost comparison"

## Chosen Perspectives
1. **Practitioner / Field operator**: What works in real battlefield conditions? Shark M has 50,000+ operational hours.
2. **Implementer / Engineer**: What are the structural engineering trade-offs between pure FG and hybrid FG+CF?
3. **Contrarian / Devil's advocate**: What could go wrong with each approach? Hidden failure modes?
4. **Domain expert / Aerospace**: What do composite material scientists say about impact, RF, and hybrid designs?
