High Speed System Examples NASA X-43 flight vehicle (Credit: NASA) - - PowerPoint PPT Presentation

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High Speed Systems & Responsive Space Access: Propulsion Technologies for Next Generation Missions

Alexander Ziegeler, Andrew Hart, Matt McKinna & Paul Smith Missile and Space Propulsion STC Weapons and Combat Systems Division Air Power Development Centre 23 September 2019

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High Speed System Examples

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NASA X-43 flight vehicle (Credit: NASA) B-52 launch of booster + X-43 (Credit: NASA) Booster + X-51A on B-52 wing (Credit: Boeing) Booster + X-51A (Credit: Boeing)

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Space Access: Commercial and ADF Reliance

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Credit: US Air Force tests anti-satellite missile 1985 (bottom middle), Satellite surveillance (top right, Wired), other various open source artists

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Space Access: Traditional vs Responsive

Traditional

• >12 mth lead time
• Heavy payloads > 1 tonne
• High cost > $1 bn
• Significant, fixed ground launch

infrastructure Responsive

• <12 mth lead time
• Payloads of 10’s to 100’s kg’s
• Highly tailored orbits: Mobile launch; air

launch… UNCLASSIFIED

Responsive (Credit: VirginOrbit, PlanetLabs, RocketLab) Traditional (Credit: NASA, ULA)

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Chemical Propulsion - Taxonomy

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SM2 launch (credit: RAN) Artillery launch (credit: Australian Army)

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Military Propulsion System Comparison

Solid Rocket Liquid Rocket Hybrid Rocket Air-breathing

High Performance Missile System

++ High volumetric efficiency ++ Density-Impulse ~480 kg.s/L ++ Long storage life ++ Able to provide very high thrust ++ Mechanically simple

• - Propellant manufacture hazardous

and requires industrial footprint & investment

• - Typically short burn duration limits

time of powered flight ++ Improved specific impulse (vs solid) ++ Density-Impulse ~300 kg.s/L ++ Wide thrust range ++ Throttlable and controllable for multi-missions

• - Liquid propellant often hazardous

to handle

• - Volumetrically inefficient
• - Increased mechanical complexity
• - Pre-fuelling (cryo) reuqires

platform infrastructure ++ Specific impulse between solid and liquid ++ Density-Impulse ~310 kg.s/L ++ Able to be throttled/controlled

• - Solid fuels structurally

weak to loads

• - Low thrust capability

(typically)

• - Partial draw-backs of both

solid and liquid systems ++ highest specific impulse (>1000 s) can maximise payload to target ++ Enables long duration cruise, long burn times ++ Typically controllable thrust for advanced flight dynamics

• - Mechanical complexity

(turbines) or complex flow phenomena (scramjet/ramjet)

• - Low acceleration & thrust

Responsive Space Access

++ Long storage life – stored and used when required ++ Mechanically simple (failure modes) ++ Volumetric efficiency improves platform compatibility (mobile launcher, air-launch etc)

• - Typically unable to throttle or

control thrust for safety or precise orbit insertion

• - Lower Isp increases mass required

for given thrust

• - Burn duration limitation due to

diameter and grain geometry ++ High Isp improves mass efficiency allowing large payload fractions ++ Controllable thrust for safety & precision trajectory ++ Burn duration (powered flight) decoupled from geometry

• - Launch infrastructure

(fuelling/storage) impacts time to launch

• - Complexity and cost often not

suited to small payloads ++ Controllable thrust for safety & precision trajectory ++ Lower cost manufacture & infrastructure due to less hazardous fuel &

• xidiser

++ Lower peak thrust capability impact minimised with rise of micro/nano payloads

• - Fuel grains susceptible to

launch loads

• - Likely upper size limitation

due to lower thrust ++ Offers potential for single- stage to orbit & reusable space access flight vehicles

• - Requires flight through

atmosphere to maximise Isp (inefficient trajectory)

• - Typically have low

acceleration (increased accumulated drag offsets Isp gains)

• - Requires rocket stage for

exo-atmospheric flight anyway

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Missile Propulsion: S&T Areas for Exploitation

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Propulsion Element Key Attributes

Novel Classes of Propulsion Further, faster, higher  operational flexibility Design Optimisation Methodologies Trade-off studies ; synergistic performance gains. Propulsion Materials: Energetic Maximum energy density; robust ; S3 Propulsion Materials: Inert components Maximum strength-weight ratio; robust thermomechanical prop’s; operationally suitable Manufacturing Technologies Exploitation of advanced material properties  new concepts; reduced footprint; maximum efficiency; reduced cost.

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Simplified Rocket Propulsion Development Cycle

Typical System Design

Propulsion Sub-system

Motor Design parameters

Inert & energetics

Materials Development Material characterisation Sub-system testing Sub-scale testing & integration Article through- life S3 Mission Requirements Trade Space Studies System Performance

TLS not always considered during system design

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System Constraints Mass Volume Length Performance Requirements Thrust Burn duration

Propellant

Density

Specific Impulse

Mechanical Properties Burn Rate

Chamber Pressure Case Thickness Nozzle Throat Grain Shape Grain Stress Grain Web Operating Temp Batch Variation Ageing Properties

• Motor design is a balance of competing

priorities, i.e.

– Grain shape dictates thrust and pressure profile – Burn rate is a function of pressure, influences thrust and pressure via throat diameter – Increased thrust leads to increased peak pressure, requiring thicker (heaver) case and increased thrust requirement to maintain acceleration

• Iterative design procedure to distill

system & motor requirements into actual as designed motor and performance (grain design, inert mass, Pmax, etc)

• As designed performance (T-t & m-t)

combined with chosen trajectory impacts delivered performance

– Fly the motor differently? – Different motor design?

• Problem ripe for optimisation approaches

– not just motor optimisation, but system level optimisation integrating platform performance and constraints

Rocket Design – multi-variable compromise

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Improved rocket design: CGHOST

CMAES with GPOPS for Hypersonic Optimal Solid rocket Trajectories

Source: http://en.wikipedia.org/wiki/CMA-ES

Each motor design has determined its best possible trajectory to fly, in order to meet the specified mission

• Stochastic & derivative free
• “Black box” implementation
• Especially suited to non-linear

problems

“The optimization tool developed under this effort is exceedingly innovative and has significant potential for improving military systems.”

• Excerpt from SRI External Panel Review Summary: S.Walker & P.Erbland (DARPA), G.Frazer

(DST Group), G.Milosz UNCLASSIFIED

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System Optimisation – design paradigm

System

• Synergistic benefits of system level physics based design optimisation as applied to

rocket science

• Alternative metrics include maximising range, payload mass & multi-objective
• ptimisation

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Inert Component Development & Characterisation

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Carbon Fibre Reinforced Plastic (CFRP) case design and burst testing DST rocket motor insulation torch testing

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Inert Component Develop & Characterise

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Vulloy bodies prior to Densification Flame testing setup Graphite post flame testing Vulloy post flame testing CFD analysis of heat flux through the nozzle Validation of thermal models using an instrumented BATES rocket motor

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Propellant Development

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DST solid propellant manufacture, test and characterisation

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Propellant Development

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DST advanced booster technologies development

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Propellant Development

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DST static firing of development rocket motor DST experimental rocket motor design

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Propellant Development

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DST vulnerability assessments of propellants

18 Material Properties

• Stabiliser (HPLC)
• Composition (GC, FTIR)
• Sensitiveness (EHDS)
• Heat evolution (HFC)
• Thermal transitions (DSC,

TGA)

• Energy content (Bomb

calorimeter)

• Burn rate prop’s (LPSB)
• Moisture Content (KF-T)
• Density (x-link and

material)

• Thermo-mechanical

prop’s (Instron; TMA; DMA; conductivity)

Life-Limiting Factors (safe-life/performance)

Sub-scale tests

• Burn rate and thrust (K-

round; BATES)

• Thermal vulnerability

(SSCO)

• Fragment impact (2 stg

light gas gun)

System integration test capabilities

• Non-destructive

diagnostics (X-ray, CT)

• Static testing (GP1, LA5)
• Dynamic flight tests

Propellant Characterisation

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Through-Life Health Assessment

DST Specialist Capabilities: – Propellant mechanical & chemical test laboratories. – Rocket motor structural, thermal and dynamic modelling (FEA). – Accelerated ageing of propellant samples and/or rocket motors.

RMSL Program

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DST health assessment facilities and capabilities, environmental chambers, structural modelling, propellant testing and dissection

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Composite Case Materials

New technologies for high-pressure, low-weight & low-thickness composite rocket motor case designs (high- temperature, chemically stable). Evaluation via modelling & experiments.

Low Erosion Lightweight Nozzle

High-performance, lightweight nozzle designed with thermal management and new throat liner materials.

Optimal Motor & Grain Design

Co-development of new modelling tool that combines optimization of grain design & trajectory to maximise motor performance and minimize volume & weight.

Advanced Tactical Booster Technologies (ATBT)

DST-AFRL S&T Collaboration Progressing Research into Enabling Technology for Future Applications Castable Insulation

Low erosion thermal liner material designed to be cast thus improving performance, weight and cost of manufacture.

High-Performance Robust Propellant

High-performance formulations with good low-temperature mechanical properties compliant with tactical temperature-cycling.

Rigid Thermal Protection

Light weight extreme temperature erosion- resistant material that maintains structural integrity in SRM combustors.

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ATBT Innovations Summary

Technology Components ATBT Innovations

Rocket Motor Design

Trajectory-Coupled Boost Motor Design Optimisation

Unique enabling S&T capability for optimal booster design linking sub-system components (grain, nozzle, materials) performance to mission requirements (payload, trajectory) and mission constraints (platform, flight conditions).

Robust Solid Propellant

High Performance Robust Solid Propellant

Jointly developed over several years. Designed to withstand severe environmental thermo-mechanical gradients and loads unique to very high-performance missions.

Composite Case

High Temperature Composite Motor Case

Unique enabling technology based upon wound carbon fibres and high temperature

• resins. Enables propellant mass fractions >0.90 for very high-performance missions.

Thermal Insulation

Castable Thermal Insulation

Unique low erosion thermal liner material designed to be cast thus reducing cost of manufacture and weight, and increasing propellant mass fraction. DST Patent.

Rigid Thermal Protection

“Zero” Erosion Rigid Thermal Protection

Unique light weight extreme temperature erosion-resistant material that maintains structural integrity in rocket motor combustion environments. DST Patent pending.

Nozzle Design & Materials

Metal Matrix Composite

Light weight, low erosion nozzle liner material developed by an Australian company.

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Transformative Energetics Research

Enabling advanced weapons systems that offer disruptive performance gains and increasing the safety, agility and efficiency of munitions manufacture.

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DST & various open source

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• Disruptive technology  Step-change in EM performance

– Previously unrealisable charge geometries with complex, multi- component structures = Tailored energy release

3D Printing of Energetic Materials

Performance Benefits: Propulsion

• Enhanced operational flexibility
• Thrust – time profile tailorability
• Greater range/velocity from existing guns
• Improved precision
• Reduced ammunition size
• Cheaper and lighter barrels with reduced wear
• Soft-launch (sensor/electronic preservation)

Performance Benefits: Explosives

• Improved detonation performance with

enhanced safety

• Tuneable initiation (eg. dial-a-yield)
• Combined effect explosives

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Top: Spiral Hybrid Operation (Credit: Fuller, Joint Propulsion Conference) Left: DST 3D printing of energetics

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3D Printing of Energetic Materials

Forecast Strategic Benefits

• Provides security of warstock by enabling

Australia to manufacture advanced natures

• Dramatically lowers the cost of entry for the

munition manufacturing industry base – diversification of supply

• Print energetics on-demand and in-theatre,

easing logistics and avoiding capability gaps

UV Paste extrusion technology DLP printer: UV intensity spatial mapping Photosensitive polymer characterisation

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Nano-energetics

Enhanced performance & safety – effective energy utilisation in volume constrained, extreme environments

Nano Energetics

Performance Sensitivity

Traditional Materials

• Higher surface area
• Increased chemical reactivity
• Enhanced mechanical

properties

• Higher solubility
• Altered optical properties
• Smaller defect dimensions

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RDX/CAB: d50=5 mm RDX: d50=200 mm

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Resonant Acoustic Mixing (RAM)

• RAM is a new processing technique that utilises low

frequency high-intensity acoustic energy to blend materials

– Fast – Increased safety – Versatile – Environmental benefits – Currently used for research, development and production of energetic materials globally

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Video: Resodyn Credit: Resodyn Credit: Resodyn

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Rotating Detonation Engines - Background

• RDEs use detonation of propellant to

generate thrust

– More energy available for work – More efficient by combusting at higher pressures

• Operation

– F/O pre-mixed in plenum – Dynamic DP forces mix through micro-nozzles – Igniter detonates mixture – Rotating detonation wave established

• Self-regulating and self-sustaining

– Combustion products expanded through nozzle

• Two propulsion system configurations

– ‘rocket-mode’ carrying oxidiser – ‘Air-breathing mode’ capturing atmospheric air

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RDE Modelling (Credit: Naval Research Laboratory) RDE Research at AFRL (Credit: Journal of Propulsion & Pwr) Temperature & entropy thermodynamic cycle comparison, Tangirala & Dean 2007

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RDE’s: Benefits, Challenges and Opportunities

• Many benefits over conventional engines:

– Greater system performance (Isp/Thrust) – Greater range over existing systems – Higher speeds for same mass (survivability) – Larger payloads for same mass (lethality) – Compactness for same performance

• Many Challenges:

– Thermal Management – Combustion stability & mixing – Fuel Operability – Experimental and numerical validity

• Key Opportunities:

– High speed/compact weapons – Space access – Decoys/Targets – Energy generation (turbines)

NASA RDE Detonation Wave Modelling RDE Static Testing at Nagoya University Japan

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High Speed Systems & Responsive Space Access: Propulsion Technologies for Next Generation Missions

Alex Ziegeler, Andrew Hart, Matt McKinna & Paul Smith alexander.ziegeler@dst.defence.gov.au Missile and Space Propulsion STC Weapons and Combat Systems Division

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