# Fact Cards — Material Comparison

## Fact #1
- **Statement**: Ukrspecsystems PD-2 (predecessor to Shark M) has a "fully composite airframe" with "absence of large metal parts" providing "low radar visibility." This means the composite is non-conductive (i.e., fiberglass/GFRP), because carbon fiber is conductive and would reflect radar.
- **Source**: Source #2 (PD-2 Datasheet)
- **Phase**: Assessment
- **Target Audience**: 10-20 kg reconnaissance UAV class
- **Confidence**: ⚠️ Medium — material type is inferred from "low radar visibility" + "fully composite" + "no large metal parts." Not explicitly stated as fiberglass.
- **Related Dimension**: Material identification

## Fact #2
- **Statement**: SHARK-M uses catapult launch + parachute landing, identical recovery method to user's Variant B. 14.5 kg MTOW, 3.4m wingspan, 7h endurance. Max wind for landing: 7 m/s.
- **Source**: Source #1 (Ukrspecsystems official page)
- **Phase**: Assessment
- **Target Audience**: 10-20 kg reconnaissance UAV class
- **Confidence**: ✅ High
- **Related Dimension**: Platform comparison baseline

## Fact #3
- **Statement**: Carbon fiber composite provides electromagnetic shielding effectiveness of 30-52 dB across UHF to X-band frequencies (up to 12.4 GHz). It is "pretty much opaque to 2.4 GHz radio waves" and acts as a Faraday cage.
- **Source**: Source #4 (KSZYTec), Source #8 (IEEE), Source #5 (StackExchange)
- **Phase**: Assessment
- **Target Audience**: All UAVs with internal antennas
- **Confidence**: ✅ High — confirmed by multiple independent sources
- **Related Dimension**: Radio transparency

## Fact #4
- **Statement**: S-Glass (S2) fiberglass composites are radio-transparent and are the standard material for aerospace radomes, antenna windows, and communication antenna protective coverings. E-glass/epoxy has dielectric constant 4.4 and loss tangent 0.016 at 8.5 GHz — low enough for reasonable RF transmission.
- **Source**: Source #6 (Springer), Source #7 (Tencom), Source #15 (Radome EM Theory)
- **Phase**: Assessment
- **Target Audience**: All UAVs with internal/embedded antennas
- **Confidence**: ✅ High
- **Related Dimension**: Radio transparency

## Fact #5
- **Statement**: GFRP is inherently dielectric and transparent to both radio-frequency communications AND radar waves. Carbon fiber reflects/absorbs radar. A fully GFRP airframe achieves low radar cross section by being transparent to radar rather than reflecting it.
- **Source**: Source #7 (Tencom), Source #2 (PD-2 datasheet context)
- **Phase**: Assessment
- **Target Audience**: Military reconnaissance UAVs
- **Confidence**: ✅ High
- **Related Dimension**: Radio transparency, stealth

## Fact #6
- **Statement**: User confirms from operational experience that SHARK-M has no issues with radio transparency — "it is still alive." This is consistent with GFRP fuselage and inconsistent with carbon fiber fuselage.
- **Source**: User direct experience
- **Phase**: Assessment
- **Target Audience**: This specific UAV project
- **Confidence**: ✅ High (direct field evidence)
- **Related Dimension**: Radio transparency

## Fact #7
- **Statement**: Carbon fiber composites fail in a brittle manner with sudden delamination and fiber fracture under impact. Low-velocity impacts can cause barely visible internal damage (BVID) that substantially reduces structural integrity without external signs.
- **Source**: Source #12 (Preprints.org), Source #9 (Ganglong)
- **Phase**: Assessment
- **Target Audience**: UAV impact/crash scenarios
- **Confidence**: ✅ High
- **Related Dimension**: Parachute landing survivability

## Fact #8
- **Statement**: Fiberglass composites are more flexible and absorb shock better than carbon fiber. Under impact, fiberglass bends/deforms rather than cracking or shattering. E-glass composites are a viable, cost-effective, and tougher alternative to CF for impact-resistant UAV structures.
- **Source**: Source #12 (Preprints.org), Source #9 (Ganglong)
- **Phase**: Assessment
- **Target Audience**: UAV impact/crash scenarios
- **Confidence**: ✅ High
- **Related Dimension**: Parachute landing survivability

## Fact #9
- **Statement**: S2-glass has >5% elongation at break (vs 4.7% for E-glass), 30-40% higher tensile strength than E-glass (4600 MPa vs 3400 MPa), and 10× fatigue resistance. S2/FM94 cross-ply laminates absorb impact energy with no penetration in tested configurations.
- **Source**: Source #10 (SMI Composites), Source #11 (MDPI Polymers)
- **Phase**: Assessment
- **Target Audience**: UAV structural design
- **Confidence**: ✅ High
- **Related Dimension**: Parachute landing survivability

## Fact #10
- **Statement**: Carbon fiber is approximately 40% lighter than aluminum and density ~1.5-1.6 g/cm³ vs fiberglass at 2.46-2.58 g/cm³. Carbon fiber is roughly 5× stiffer than fiberglass by specific modulus.
- **Source**: Source #9 (Ganglong), Source #10 (SMI Composites)
- **Phase**: Assessment
- **Target Audience**: UAV airframe design
- **Confidence**: ✅ High
- **Related Dimension**: Weight/stiffness

## Fact #11
- **Statement**: Carbon fiber material costs 5-10× more than fiberglass. Basic fiberglass cloth ~$20-50/m² vs standard carbon fiber (T300) ~$200-500/m².
- **Source**: Source #9 (Ganglong)
- **Phase**: Assessment
- **Target Audience**: UAV production cost
- **Confidence**: ✅ High
- **Related Dimension**: Cost

## Fact #12
- **Statement**: Field repair of fiberglass/epoxy structures can be done by personnel with average manual skills without specialized training or vacuum equipment. Pre-cured composite patches bonded with adhesive enable rapid field repairs.
- **Source**: Source #13 (MATEC Conference)
- **Phase**: Assessment
- **Target Audience**: UAV field operations
- **Confidence**: ✅ High
- **Related Dimension**: Field repairability

## Fact #13
- **Statement**: Carbon fiber repair requires specialized equipment (autoclave, vacuum bagging) and trained technicians. Scarf-repaired CFRP laminates remain sensitive to subsequent impacts. Internal damage (BVID) requires non-destructive testing to detect.
- **Source**: Source #12 (Preprints.org), research on CFRP repair
- **Phase**: Assessment
- **Target Audience**: UAV maintenance
- **Confidence**: ✅ High
- **Related Dimension**: Field repairability

## Fact #14
- **Statement**: In a hybrid FG+CF design (like S2 FG skin + carbon stiffeners), carbon stiffeners create localized RF shadow zones. The ACASIAS project demonstrated that CFRP ribs in a GFRP panel create electromagnetic interactions that must be designed around. Antennas must be placed in GFRP-only zones away from CF structural elements.
- **Source**: Source #14 (ACASIAS/NLR)
- **Phase**: Assessment
- **Target Audience**: Hybrid composite UAV designers
- **Confidence**: ✅ High
- **Related Dimension**: Radio transparency of hybrid design

## Fact #15
- **Statement**: Hybrid composites (FG skin + CF stiffeners) achieve similar deformation characteristics to pure CFRP while offering cost savings and higher damping factors than either pure aluminum or pure CFRP.
- **Source**: Source #17 (IJVSS), Source #18 (Frontiers)
- **Phase**: Assessment
- **Target Audience**: UAV structural design
- **Confidence**: ✅ High
- **Related Dimension**: Weight/stiffness

## Fact #16
- **Statement**: Stiffener optimization with reinforced rib designs can achieve 60.9% stress reduction and 5.2% mass reduction compared to unstiffened designs.
- **Source**: Source #18 (Frontiers)
- **Phase**: Assessment
- **Target Audience**: UAV structural design
- **Confidence**: ✅ High
- **Related Dimension**: Weight/stiffness

## Fact #17
- **Statement**: SHARK-M has 50,000+ operational hours on the battlefield (per Ukrspecsystems marketing). The system is designed for 1,200 flight hours without additional service maintenance.
- **Source**: Source #1 (Ukrspecsystems official)
- **Phase**: Assessment
- **Target Audience**: Military reconnaissance UAVs
- **Confidence**: ⚠️ Medium — marketing claim, but backed by extensive combat use
- **Related Dimension**: Proven reliability

## Fact #18
- **Statement**: A pure fiberglass (no carbon stiffeners) airframe for a 14.5 kg MTOW UAV (Shark M class) can achieve 7h endurance. This suggests that pure GFRP without carbon stiffeners is structurally adequate for this weight class, though it may require thicker skins or more material.
- **Source**: Source #1 (Ukrspecsystems official), Source #2 (PD-2 datasheet)
- **Phase**: Assessment
- **Target Audience**: 10-20 kg reconnaissance UAV class
- **Confidence**: ⚠️ Medium — material type inferred, not explicitly confirmed
- **Related Dimension**: Weight/structural adequacy
