Multi-Axis Rotary-Wing Integrated Design (MARID) Drone

 PATENT PENDING (CAD shown is PROVISIONAL)


https://github.com/MChalak1/MARID_UAV



STEP 1 — CAPABILITY GAP STATEMENT

Document Type: Capability Gap / Operational Need Statement
Focus: Identifying what current systems cannot do and why MARID’s architecture matters.

1. Operational Problem

U.S. and allied forces increasingly require persistent, low-signature airborne ISR in contested or denied environments where:

  • Traditional HALE platforms (Global Hawk) are too large, visible, or expensive

  • Small electric UAVs lack endurance (<8 hours)

  • Propeller-driven platforms have high acoustic and thermal signatures

  • Tactical hydrogen UAVs exist but do not integrate hydrogen into the structural load path or thermal/RCS suppression

  • Morphing-wing systems exist, but none provide full-axis wing rotation for multi-regime aerodynamic control without exposed surfaces

Current assets cannot sustain multi-day surveillance or persistent coverage over maritime zones, mountain regions, or border environments while maintaining:

  • Low radar cross section

  • Low infrared and acoustic signature

  • Small logistics footprint

  • Survivability and redundancy without heavy control-surface mechanisms

The gap is widening as near-peer adversaries improve passive RF detection, electro-optical tracking, and acoustic sensing systems.

2. Capability Gap 

There is no existing small-UAS platform that simultaneously provides:

A. >48-hour endurance in a Group 2/3 UAV footprint

Current electric UAVs: 1–8 hours
Fuel-based UAVs: 12–24 hours
Hydrogen UAVs: 4–12 hours with external tanks

No system integrates thermally regulated micro-channel spars to extend hydrogen endurance beyond 48 hours.

B. Low-RCS, low-acoustic, low-thermal signature platform

Propeller + piston engines have:

  • High thermal emissions

  • Detectable harmonic signatures

  • Hot exhaust plumes

  • Mechanical noise from control surfaces

No fielded platform combines fuel-cell electric propulsion with stealth shaping and minimal moving surfaces.

C. Multi-regime aerodynamic control without conventional control surfaces

Current UAVs rely on:

  • Ailerons

  • Elevators

  • Flaps

  • Rudders

These expose hinge lines, radar retro-reflections, and add mechanical failure points.

No operational system uses independently rotating wings as the primary control mechanism.

D. Integrated structural + thermal + storage architecture

Hydrogen UAVs currently use:

  • Discrete tanks

  • Discrete cooling systems

  • Discrete loads paths

  • Discrete RCS shaping strategies

None combine:

  • Cryogenic micro-channel piping

  • Wing-carrying spars with embedded GH₂ heating

  • Structural load + propulsive thermal management

  • Stealth-edge alignment blended with thermal routing

This multifunctional approach does not exist in any current small-UAS platform.

3. Mission Profiles Directly Impacted by This Gap

A. ISR / Surveillance

  • Maritime domain awareness

  • Border patrol

  • Pipeline / infrastructure monitoring

  • Counter-insurgency overwatch

  • Search-and-rescue (SAR) with silent loiter

B. Signals intelligence (SIGINT) and comms relay

  • Persistent, high-altitude relay nodes

  • Low-power SIGINT arrays requiring stable multi-day hold

C. Special operations

  • Low-acoustic infiltration support

  • Low-signature overwatch for long-duration missions

D. Environmental / scientific

  • Fire monitoring

  • Atmospheric sampling

  • Ecological mapping

4. Operational Impact if Unaddressed

Without a platform like MARID, operators face:

  • Gaps in persistent ISR in contested zones

  • High operational cost from short-endurance drones

  • Increased detection probability against near-peer sensors

  • Heavy logistics burden (batteries, fuel, replacement units)

  • Inability to maintain long-duration coverage in surveillance corridors

  • Limitations in altitude/loiter profiles due to reliance on conventional control surfaces

The inability to field long-endurance, low-signature autonomous systems directly reduces the effectiveness of ISR networks and increases risk to both personnel and assets.

5. Why MARID Specifically Resolves This Gap

MARID is unique because it integrates four seldom-combined features:

1. Rotating-wing control architecture

  • Eliminates many control surfaces

  • Reduces mechanical & radar signature

  • Enables multi-regime aerodynamic behavior

2. Hybrid hydrogen–electric propulsion

  • Extremely low acoustic & thermal emissions

  • High endurance potential

3. Micro-channel cryogenic “leaf-vein” spars

  • Store hydrogen

  • Pre-heat GH₂

  • Cool fuel cells

  • Serve as structural load paths

  • Double as thermal signature suppressors

4. Stealth-optimized CFRP body with minimal hinges

  • Smooth continuous geometry

  • Reduced RCS from hinge lines, gaps, and metal edges

This combination does not exist in any known U.S. or foreign UAV class.



Fig1. Gazebo MARID simulation with Smoke Emitter Visual


Fig.2 RViz MARID Drone Display

STEP 2 — DARPA “PALS” ABSTRACT

Program Concept: MARID — Multi-Axis Rotary-Wing Integrated Design
Focus: Ultra-long-endurance, low-signature, morphing-geometry hydrogen UAV

P — PROBLEM

Current Group 2/3 UAVs cannot provide persistent (>48 hr), low-signature, and multi-regime flight in contested environments.
Existing systems are limited by:

  • Short endurance due to battery and JP-8 dependence (1–24 hrs)

  • High acoustic and thermal signatures from internal combustion engines

  • Radar-reflective hinge lines and control surfaces

  • Discrete, heavy subsystems (tanks, coolers, spars, load paths) that increase mass and reduce range

  • Inability to morph aerodynamics across loiter, transit, and climb regimes

  • Lack of multifunctional structures integrating propulsion, cooling, and storage

As adversary ISR and sensor networks improve (EO/IR, passive RF, acoustics), conventional UAV architectures are increasingly detectable and unsuited to multi-day missions.

A capability gap exists for a silent, persistent, morphing-geometry UAV capable of bridging the endurance–stealth trade space.

A — APPROACH

MARID introduces a rotary-wing aerostructure integrated with a hybrid hydrogen–electric propulsion system and a cryogenic leaf-vein micro-channel spar network. The approach includes four core technical thrusts:

(1) Full-axis independently rotating wings

  • Replace conventional control surfaces

  • Provide roll/pitch/yaw authority through geometry manipulation

  • Enable transition among high-aspect-ratio loiter, efficient cruise, and compact stowage

  • Reduce RCS by eliminating hinge gaps and discontinuities

  • Limit acoustic signatures by avoiding high-frequency surface deflections

(2) Multifunctional micro-channel spars (“leaf-vein” concept)

  • Embed cryogenic hydrogen micro-pipes into the load-bearing spars

  • Spars simultaneously:

    • Carry primary bending and torsion loads

    • Pre-heat gaseous hydrogen for fuel cell efficiency

    • Cool avionics, motors, and PEM stacks

    • Manage thermal signature by routing cold GH₂ through hotspots

    • Reduce system weight by merging thermal + structural + storage functions

(3) Hybrid LH₂/Fuel-Cell + Battery Electric Propulsion

  • Fuel cell for endurance

  • Lithium battery buffer for transients, takeoff, and maneuvers

  • Near-silent acoustic signature (<30 dB at 100m)

  • Minimal thermal plume (no combustion)

  • High efficiency during long loiter missions

(4) Low-RCS carbon fiber body with edge-aligned geometry

  • Uses aligned edges for backscatter suppression

  • CFRP outer shell with minimal panel lines

  • Embedded antennas and conformal sensor apertures

  • Reduced metallic content at exposed edges

This architecture allows MARID to operate across multiple aerodynamic regimes, with drastically different wing orientations, while maintaining stealth and endurance.

L — LEVEL OF INNOVATION

MARID sits at the high end of DARPA’s innovation envelope. Specific non-incremental innovations include:

• First small-UAS to employ independent full-axis rotating wings

Replacing all major control surfaces with geometry-based control is unprecedented in Group 2/3 UAVs.

• First integrated structural-thermal-cryogenic spar system

No existing UAV merges hydrogen pre-heat, fuel cell cooling, thermal suppression, and primary load-bearing structure into a single micro-channel network.

• Multi-functional hydrogen management

Hydrogen serves simultaneously as:

  • Propellant

  • Heat sink

  • Thermal signature suppressor

  • Structural integration medium

• Morphing RCS profile

Rotating wings allow RCS shaping through geometry rather than fixed contours.

• Potential for ultra-long endurance (>48–72 hrs)

If successful, MARID would exceed the performance of comparable electric or JP-8 UAVs by a significant margin.

This is high-risk, high-reward, with several TRL 2–3 elements, matching DARPA’s disruptive program profile.

S — SIGNIFICANCE

If successful, MARID would:

• Create a new class of low-signature, persistent ISR UAVs

Providing multi-day surveillance in contested zones with negligible acoustic/thermal detectability.

• Reduce logistics footprint

Hydrogen + multifunctional structures reduce fuel mass, battery swaps, and maintenance.

• Enable multi-regime operations with a single aircraft

The wing rotation concept allows:

  • Efficient cruise

  • Ultra-slow silent loiter

  • Compact stow/deployment

  • Precision maneuvering in complex environments

• Provide an ISR platform that can survive in future sensor-rich battlefields

By eliminating obvious control surfaces, thermal plumes, and acoustic engines.

• Lay groundwork for next-decade DARPA and AFRL initiatives

In:

  • Morphing aerostructures

  • Hydrogen-powered tactical platforms

  • AI-based nonlinear control laws

  • Multifunctional materials

MARID would represent a disruptive advance in long-endurance UAV design, with significant implications for defense, border security, maritime surveillance, and autonomous sensing networks.


Fig. 3 Top View

Fig. 4 Side View

STEP 3 — TECHNICAL FEASIBILITY BRIEF

Concept: MARID – Multi-Axis Rotary-Wing Integrated Design
Objective: Assess feasibility and identify key enabling technologies and risks.

1. Aerodynamic Feasibility

1.1 Rotating-Wing Control Concept

MARID’s most distinctive aerodynamic feature is its independently rotating wings, acting as multi-axis effectors. This enables:

  • Pitch control via symmetric rotation

  • Roll control via differential rotation

  • Yaw damping via asymmetric drag from offset rotations

  • Regime switching (cruise ↔ loiter ↔ climb) without discrete surfaces

1.2 Aerodynamic Advantages

  • Eliminates ailerons/elevators/flaps → reduced hinge-line drag + RCS

  • Smooth continuous lifting surfaces

  • Allows variable effective dihedral/anhedral

  • Enables “feathered” orientation in high-wind or high-altitude operations

1.3 Aerodynamic Risks

  • Wing-root joint must transmit lift, bending, and torsion while rotating → high structural demand

  • Rotation induces strong cross-coupling across axes → requires nonlinear control

  • Potential transient loads during rotation, especially if rotating under aerodynamic load

  • Unknown aeroelastic modes introduced by partially rotated wings

1.4 Mitigation

  • CFD exploration of rotating-wing states (steady + transient)

  • Subscale wind-tunnel test with instrumented rotating spar

  • Add rotation-rate limiters to prevent aerodynamic stall during deflection

Aerodynamically feasible, but demands significant simulation and control-law sophistication.

2. Structural Feasibility

2.1 Wing-root Load Path

The rotating wing requires a high-strength rotational joint capable of:

  • Transmitting full bending moment

  • Controlling torsional rigidity

  • Supporting asymmetric loads

  • Maintaining positional accuracy

Candidate architectures:

  • Splined titanium shaft with integrated bearing race

  • Cross-roller bearing assembly for high moment loads

  • Hybrid carbon/titanium root section to prevent delamination under torsion

2.2 Micro-Channel Spar (“Leaf-Vein”)

This is uniquely challenging and innovative:

  • Spar contains 145+ cryogenic micro-channels

  • Channels route hydrogen as a heat sink / preheater

  • Spar must carry primary wing loads while functioning as thermal architecture

  • Requires:

    • Metal (Al/Ti) microchannel insert

    • CFRP overwrap for stiffness

    • Bondline isolation to prevent galvanic issues

2.3 Structural Risks

  • Differential thermal expansion: cryogenic GH₂ in metal → composite skin mismatch

  • Microchannel fatigue from cyclic temperature gradients

  • Hydrogen embrittlement for certain alloys

  • Stress concentrations at channel intersections (“leaf-vein” branching)

2.4 Mitigation

  • Use Ti-6Al-4V or 316L stainless for microchannels

  • CFRP layup with quasi-isotropic root + tailored orthotropic distal spars

  • Add 1–2 layers GFRP as a galvanic insulator between metal + carbon

Structurally feasible, but high TRL development is required for multifunctional spars.

3. Hydrogen & Thermal Management Feasibility

3.1 Hybrid LH₂ / GH₂ / Fuel Cell System

MARID’s endurance relies on effective hydrogen thermal management:

  • LH₂ or high-pressure GH₂ stored internally

  • Hydrogen passes through microchannel spars → preheat to 70–85°C

  • Heated GH₂ enters PEM fuel cell for peak efficiency

  • Waste heat from PEM + avionics + motors is cooled by routing GH₂

3.2 Thermal Benefits

  • Thermal signature reduction: cold GH₂ absorbs heat from motors and PEM stacks

  • Suppresses IR hotspots

  • Eliminates need for large heat sinks or radiators

  • Enables multi-hour loiter without thermal buildup

3.3 Thermal Risks

  • Condensation and icing around microchannels during startup

  • Managing both cryogenic (–253°C) and high-temperature (+80°C) zones

  • Potential hydrogen leakage within composite structure

3.4 Mitigation

  • Use vacuum-jacketed microchannel feed sections

  • Perform thermal FEA (steady + transient)

  • Redundant hydrogen sensors within wing cavities

  • Resin system designed for cryogenic cycling

Thermally feasible, but design must be extremely rigorous.

4. Control & Avionics Feasibility

4.1 Control Authority from Wing Rotation

Replacing conventional control surfaces requires:

  • Precision wing-angle encoders

  • High-torque brushless actuators or harmonic drives

  • Nonlinear, cross-coupled control laws

  • Real-time estimators (EKF/MKF) for state reconstruction

4.2 Control Challenges

  • Cross coupling between rotational axes

  • Actuator saturation in high-wind conditions

  • Need to prevent wing rotation during high dynamic pressure

  • Ensuring fail-safe “neutral” wing orientation if actuator fails

4.3 Control Mitigation

  • Use gain-scheduled nonlinear controllers

  • Model predictive control (MPC) for high-speed maneuvers

  • Implement mechanical detents for neutral orientation

  • Redundant IMUs on each wing for differential sensing

  • ROS2-based simulation stack for early testing (Gazebo → PX4 → HIL)

Control feasibility is medium–high, but requires strong algorithmic development (which aligns well with your robotics background).

5. Material Feasibility

5.1 Outer Body (CFRP)

  • High specific stiffness

  • Good for stealth shaping

  • Strong for composite shells

  • Sensitive to cryogenic thermal cycling → needs special resin

5.2 Internal Structure

Aluminum is attractive for:

  • Machinability

  • Integration of brackets/mounts

  • Thermal conduction

  • Low cost

But Al next to CFRP demands isolation layers.

5.3 Recommended Material Map

  • Wing Spar Microchannels: Ti-6Al-4V or 316L stainless

  • Spar Overwrap: High-modulus CFRP

  • Fuselage Skins: Low-CTE aerospace-grade CFRP

  • Fuselage Frames: 7075-T6 or 6061-T6 Al with GFRP interface

  • V-tail surfaces: CFRP with foam core

  • Hardpoints: Titanium inserts

Materials are feasible but must be chosen with thermal + galvanic constraints in mind.

6. Manufacturing Feasibility

6.1 Complexity Drivers

  • Multi-channel spars require precision additive manufacturing (AM)

  • CFRP overwrap must avoid microchannel collapse

  • Rotating wing joint needs near-zero internal backlash

6.2 Candidate Manufacturing Methods

  • Additive manufacturing (SLM for Ti / DMLS for 316L)

  • Out-of-autoclave CFRP for large skins

  • RTM (Resin Transfer Molding) for thin-walled shells

  • CNC aluminum frames for internal supports

6.3 Feasibility Conclusion

Manufacturing is feasible at prototype level using modern AM + composites.

7. Systems Integration Feasibility

Integration Strengths

  • Hydrogen doubles as coolant + propellant → system consolidation

  • Rotating wings simplify external actuators

  • CFRP shaping integrates naturally with RCS optimization

Integration Risks

  • Complexity rises inside the rotating joint (power/signal routing)

  • Microchannel-integrated wings require strict leak-proofing

  • Hydrogen safety protocols must be embedded at design level

Integration Mitigation

  • Rotary electrical feed-throughs with slip rings

  • Hydrogen sensors within spars

  • Redundant O-ring + metal-sealed joints

  • Modular wing-root assembly to allow safe maintenance

8. Feasibility Summary

MARID is technically feasible as a high-risk concept with several unproven, but achievable, subsystems.
Nothing violates physical laws or exceeds the capability of current materials/manufacturing.
Key challenges lie in:

  • Control complexity

  • Rotating wing load transmission

  • Microchannel cryogenic-thermal integration

  • Hydrogen safety

  • High-fidelity simulation and testing

This places MARID at TRL 2–3 with a clear development path to TRL 6 if subscale demonstrations validate the rotating wing and cryogenic spar concepts.

Fig. 5 Front View


Fig. 6 General View

STEP 4 — MARID TRL ROADMAP (TRL 2 → TRL 6)

Objective: Mature the MARID UAV architecture from conceptual analysis to a flight-tested prototype suitable for early operational evaluation.

Assumed timeline: ~36 months (aggressive but plausible for a lean DARPA/contractor-style effort)

TRL 2 — Technology Concept & Application Formulated

STATUS: Completed / In progress (MARID is currently at TRL 2)

Goal:

Define and validate the fundamental scientific concept behind the system.

Tasks to Complete TRL 2:

  • Finalize rotating-wing control concept

  • Define cryogenic micro-channel spar architecture

  • Establish preliminary aerodynamic regimes (cruise / loiter / feathered)

  • Develop preliminary hydrogen–thermal management loop

  • Compare configurations (single rotating axis vs. dual-axis)

  • Review materials candidates for cryogenic + structural integration

  • Conduct initial RCS sensitivity analysis for hinge-less geometry

Deliverables:

  • System Concept Document

  • Preliminary CAD geometry

  • Functional block diagram for power/thermal/control

  • Initial mass budget & endurance estimate

Decision Gate to TRL 3:
Concept shows theoretical feasibility with no physical impossibility.
→ PASS: MARID qualifies.

TRL 3 — Analytical & Experimental Proof of Concept

EXPECTED DURATION: 4–6 months

Goal:

Demonstrate viability of the critical subsystems through simulation and early lab-level testing.

Critical Subsystem Demonstrations at TRL 3

1. Rotating Wing Aerodynamics (CFD)

  • Quasi-steady CFD on rotated configurations (0°, ±30°, ±60°, ±90°)

  • Transient CFD for rotation-under-load events

  • Determine drag penalty, stall onset, cross-coupling moments

2. Micro-channel Spar Thermal Model

  • 1D + 3D thermal FEA of:

    • Hydrogen preheat

    • Avionics cooling

    • Temperature cycling

  • Evaluate local stress concentrations around channels

3. Hydrogen Pathway Modeling

  • Preheat timing

  • Pump/compressor requirements

  • Pressure drop along microchannels

4. Control Simulation (MATLAB/Simulink + ROS2)

  • Nonlinear 6-DoF simulation

  • Wing-angle → moment mapping

  • Gain scheduling exploration

  • EKF/MKF estimator integration

5. Structural Load Transmission Model

  • FEM analysis of the wing root with rotating bearing

  • Evaluate bending load transfer under wing rotation

TRL 3 Success Criteria

  • No catastrophic failure predicted in FEA CFD

  • Rotating wings provide sufficient control authority

  • Microchannel thermal model achieves 70–85°C GH₂ preheat

  • Control simulation stable across ±60° wing rotations

  • Structural loads manageable with Ti/CFRP hybrid root

Decision Gate to TRL 4:
Subsystems show feasibility with modeled data.
→ Expected Outcome: PASS

TRL 4 — Component and Breadboard Validation in Lab Environment

EXPECTED DURATION: 6–8 months

Goal:

Physically validate core components in a controlled environment.

Major TRL 4 Builds

1. Wing-Root Rotation Mechanism (Benchtop Prototype)

  • High-torque BLDC + harmonic reducer

  • Absolute magnetic encoder

  • Cross-roller bearings

  • Test:

    • Rotational stiffness

    • Backlash

    • Load-holding capability

    • Thermal flow during operation

2. Micro-channel Spar Subsection (20–40 cm Demonstrator)

  • AM Ti-6Al-4V or 316L microchannel lattice

  • CFRP overwrap section

  • Test:

    • Cryogenic cycling (–150°C ↔ +80°C)

    • Leak rate monitoring

    • Bending fatigue

    • Thermal flow uniformity

3. Fuel Cell Stack Bench Test

  • PEM stack connected to GH₂ preheat loop

  • Measure electrical output, waste heat, system response

4. Software-in-the-loop (SIL) Control Stack

  • ROS2 / PX4-based virtual avionics stack

  • Nonlinear controllers

  • Fault-injection testing

  • Sensor dropout/IMU drift scenarios

TRL 4 Validation Tests

  • Static load testing of wing-root assembly

  • Hydrogen leak detection under cycling

  • Actuator stall torque + failure mode testing

  • Thermal performance of microchannel section

  • Control law validation in simulation

TRL 4 Success Criteria

  • Wing-root assembly operates under load without failure

  • Microchannel section withstands cryogenic cycling

  • Fuel cell + preheater reaches stable output

  • Control laws converge and remain stable during test scenarios

Decision Gate to TRL 5:
Subsystems validated physically, integrated architecture no longer purely theoretical.
→ Expected Outcome: PASS

TRL 5 — Subsystem Validation in Relevant Environment

EXPECTED DURATION: 8–10 months

Goal:

Test integrated subsystems in an environment representative of real flight conditions.

TRL 5 Demonstrators

1. Full Wing Prototype (Non-Flying Structural Article)

  • 1:1 scale rotating wing with microchannel spars

  • Test under simulated aerodynamic loads

  • Wing rotation under dynamic pressure simulated by rig

2. Hydrogen–Thermal Integration Loop

  • GH₂ storage

  • Microchannel preheat

  • PEM stack

  • Electric motor + power distribution

  • Thermal rejection through microchannels

3. Avionics Integration Unit

  • Flight computer

  • Wing-angle encoders

  • Redundant IMUs

  • Power bus

  • Hydrogen safety sensors

  • Nonlinear controller firmware

4. Subscale Flying Testbed (Very Important)

A ~1–2 meter wingspan RC-scale aircraft with:

  • Simplified rotating wings

  • Electric only (no hydrogen yet)

  • Testing:

    • Control architecture

    • Stability

    • Cross-coupling

    • Fault modes

This de-risks the control system and geometry before investing in a full-scale flight.

TRL 5 Validation Tests

  • Rotating wings under load cycling >100k cycles

  • Microchannel system under prolonged thermal stress

  • Control architecture in subscale testbed

  • Hydrogen leak-safety pass

  • EMI testing for avionics

  • Vibration testing of wing-root assembly

TRL 5 Success Criteria

  • All subsystems operate reliably in integrated bench tests

  • Subscale aircraft achieves stable, controlled flight

  • Microchannel + FC powertrain maintains thermal stability

Decision Gate to TRL 6:
System ready for full-scale prototype construction.
→ PASS contingent on stable subscale flight

TRL 6 — Prototype Demonstration in Relevant Environment

EXPECTED DURATION: 8–12 months

Goal:

Fly a full-scale MARID UAV with integrated hydrogen system and rotating-wing architecture.

TRL 6 Prototype Build

1. Full-Scale Airframe

  • CFRP fuselage

  • Dual rotating wings

  • Composite V-tail

  • Embedded antennas

  • Stealth-aligned edges

2. Full Hydrogen Powertrain

  • Compressed GH₂ or LH₂ tank

  • Microchannel spars

  • PEM fuel cell stack

  • Battery buffer

  • Power distribution

3. Full Flight Avionics

  • Dual IMUs

  • GPS + INS fusion

  • Wing-root torque sensors

  • Hydrogen safety controller

  • ROS2 or PX4 flight stack

4. Ground Tests

  • Engine run

  • Thermal soak test

  • Hydrogen leak + venting tests

  • Load tests on wing-root

  • Software-Hardware integration

5. Flight Program

  • Tethered hover / rotation tests

  • Free flight low-speed tests

  • High-speed cruise tests

  • Multi-regime wing-position transitions

  • Endurance runs (12–24 hr)

  • Post-flight structural inspection

TRL 6 Success Criteria

  • First stable, controlled flight with rotating wings

  • Hydrogen–thermal architecture performs nominally

  • System-level endurance test successful

  • No structural anomalies in spars or rotating joints

  • Avionics and safety systems operate reliably

  • Demonstrated multi-regime aerodynamic control

Achieving TRL 6 means MARID has a fully proven prototype, ready for:

  • DARPA demonstrator program

  • Contractor IRAD expansion

  • Small-batch military evaluation

  • Academic partnership scaling


Fig. 7 Back View

STEP 5 — RISK–REWARD ANALYSIS 

Program Concept: MARID — Multi-Axis Rotary-Wing Integrated Design
Goal: Evaluate major risks vs. potential payoff to inform funding and prioritization.

1. Risk Overview

We’ll treat risk along five axes:

  1. Technical risk

  2. Schedule risk

  3. Cost / manufacturability risk

  4. Operational / safety risk

  5. Programmatic / adoption risk

Use a mental scale of Low / Medium / High for both Likelihood (L) and Impact (I).

2. Technical Risks

2.1 Rotating Wing Architecture

  • Risk: Complexity and reliability of wing-root rotational joint; aero/control coupling.

  • L: Medium–High

  • I: High (loss of control if it fails or behaves unpredictably)

Drivers:

  • Joint must carry full bending + torsion + shear while rotating.

  • Any backlash or jamming impacts stability.

  • Aero moments will be strongly nonlinear vs. wing angle.

Mitigations:

  • Use conservative mechanical architecture: cross-roller bearings, Ti shaft, harmonic drive.

  • Hard mechanical stops, detents for “neutral” mode.

  • Redundant position sensing (encoder + resolver).

  • Extensive subscale flying testbed to validate control laws before full-scale.

2.2 Micro-Channel “Leaf-Vein” Spar

  • Risk: Structural integrity + leakage + thermal cycling in multifunctional spar.

  • L: Medium

  • I: High (spar failure = catastrophic; leak = safety + performance hit)

Drivers:

  • AM metal channels bonded to CFRP overwrap.

  • Cryogenic → hot cycling introduces thermal mismatch.

  • Hydrogen embrittlement and microcracking.

Mitigations:

  • 20–40 cm subsections for early structural + thermal + leak testing.

  • Choice of Ti-6Al-4V or 316L stainless with proven cryogenic behavior.

  • GFRP isolation plies between metal and CFRP.

  • Conservative safety margins on composite layups (quasi-isotropic around joints).

2.3 Hydrogen System Integration

  • Risk: Handling cryogenic / high-pressure hydrogen safely at small-UAV scale.

  • L: Medium

  • I: High (safety-critical)

Drivers:

  • Small fuselage volume → tight routing, dense packing.

  • Multi-use hydrogen (propulsion + cooling) increases complexity.

  • Leak detection and venting in confined wing structure.

Mitigations:

  • Start with compressed GH₂, not LH₂, for early prototypes.

  • Use external ground tanks for early TRL 4/5 tests.

  • Triple containment on wing-root and fuselage pass-throughs.

  • Multiple hydrogen sensors and automatic safe shutdown modes.

2.4 Nonlinear Control & Autonomy

  • Risk: Developing robust control architecture for full-axis rotating wings.

  • L: Medium

  • I: Medium–High (flight stability)

Drivers:

  • Highly coupled roll–pitch–yaw due to wing rotation.

  • Need for gain scheduling / MPC / nonlinear control.

  • Interaction with gusts and turbulence.

Mitigations:

  • Aggressive use of simulation (6-DoF nonlinear model, ROS2/Gazebo).

  • Subscale flying demonstrator with scaled geometry and rotating wings.

  • Incremental flight test envelope expansion (small rotations → larger).

  • Conservative actuator rate limits to reduce dynamic overshoots.

3. Schedule Risks

3.1 Multi-Disciplinary Dependencies

  • Risk: Structural, thermal, hydrogen, and controls must advance in sync.

  • L: Medium

  • I: Medium

Drivers:

  • If one subsystem lags (e.g., microchannel manufacturing), it stalls integration.

  • Nonlinear dependencies: control law tuning depends on real aero data.

Mitigations:

  • Parallel-path development:

    • Path A: Controls + subscale electric-only testbed.

    • Path B: Hydrogen + microchannel test articles.

  • Integrate hydrogen only once aero/control concept is validated at subscale.

3.2 Novel Manufacturing Learning Curve

  • Risk: Time lost refining AM parameters, CFRP overwrap techniques, sealing methods.

  • L: Medium

  • I: Medium

Mitigations:

  • Use off-the-shelf AM partners early (bureau with aerospace experience).

  • Start with simplified channel networks before full leaf-vein complexity.

  • Freeze one spar design for a phase, even if suboptimal, to enable system testing.

4. Cost / Manufacturability Risks

4.1 High Unit Cost for Early Prototypes

  • Risk: Expensive AM metal parts + composite layups + specialized testing.

  • L: High (for early units)

  • I: Medium (affects scalability and internal support)

Mitigations:

  • Design modular spar segments for re-use across test campaigns.

  • Avoid bespoke hardware where COTS substitutes exist (motors, fuel cell stacks, electronics).

  • Use simple prismatic fuselage/wing geometries at first, refine stealth later.

4.2 Scalability to Production

  • Risk: Microchannel complexity may hinder production scaling.

  • L: Medium

  • I: Medium

Mitigations:

  • Evaluate variant with “regional microchannels” (fewer, larger channels) for production.

  • Identify simplified “Block 1” version with reduced functionality but easier to build.

5. Operational / Safety Risks

5.1 Hydrogen Handling in Field Conditions

  • Risk: Ground crew mishandling, leaks, ignition sources, poor training.

  • L: Medium

  • I: High

Mitigations:

  • Clearly defined CONOPS: fueling procedures, venting, emergency response.

  • Standardized quick-disconnect fittings with intrinsic safety features.

  • Conservative pressure and tank sizing for early systems.

5.2 Failure Modes of Rotating Wing

  • Risk: Jammed wing, runaway rotation, encoder failure.

  • L: Medium

  • I: High

Mitigations:

  • Mechanical failsafe that forces wing to a near-neutral pitch in power loss.

  • Dual encoders and detection of inconsistency.

  • Hard stops to prevent extreme attitudes.

  • Flight controller default modes that maintain or slowly reduce angle on sensor uncertainty.

6. Programmatic / Adoption Risks

6.1 Conservatism of End-Users

  • Risk: Military users and acquisition offices may view the architecture as too exotic.

  • L: Medium

  • I: Medium

Mitigations:

  • Emphasize continuity with existing tech: fuel cells, CFRP, AM structures—all familiar individually.

  • Start with non-stealth, non-weaponized ISR demonstrations (less political friction).

  • Offer MARID as a technology demonstrator platform, not an immediate program-of-record.

6.2 Competing Solutions

  • Risk: Incremental improvements to existing small UAVs may look “good enough” to acquisition.

  • L: Medium

  • I: Medium

Mitigations:

  • Highlight clear differentiators: multi-day endurance + stealth + low acoustic + multifunctional structures.

  • Quantify advantages in a data-driven way (e.g., cost per hour on station, detectability curves, logistics footprint).

7. Reward Analysis

Now, the upside.

7.1 Technical Rewards

If MARID works even at 70–80% of its theoretical promise:

  • Demonstrates world-first small-UAV with:

    • Rotating wings as primary control modality

    • Integrated structural/thermal/hydrogen microchannel spar

    • Multi-day endurance with fuel-cell propulsion

This yields:

  • New architectures for morphing UAVs.

  • A practical validation of multifunctional structures (huge research interest).

  • A scalable knowledge base for future hydrogen and stealth platforms.

7.2 Operational Rewards

  • Persistent ISR: 48+ hours on-station with small footprint.

  • Low detectability: Low acoustic + thermal + RCS = deep penetration / standoff ISR capability.

  • Flexible deployment: Smaller ground crew, fewer refuels, reduced logistics burden.

7.3 Strategic / Business Rewards 

  • First-mover advantage in hydrogen-long-endurance stealth UAVs.

  • IP around:

    • Microchannel spar designs

    • Control laws for rotating wings

    • Integrated hydrogen thermal management

  • Strong alignment with:

    • Future DARPA calls on morphing aircraft / alternative propulsion

    • AFRL interests in attritable long-endurance systems

    • Commercial / civil ISR (border, maritime, wildfire, environmental)




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