UNCLASSIFIED 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 1
UNCLASSIFIED High Speed System Examples NASA X-43 flight vehicle (Credit: NASA) Booster + X-51A (Credit: Boeing) Booster + X-51A on B-52 wing (Credit: Boeing) B-52 launch of booster + X-43 (Credit: NASA) 2
UNCLASSIFIED Space Access: Commercial and ADF Reliance Credit: US Air Force tests anti-satellite missile 1985 (bottom middle), Satellite surveillance (top right, Wired), other various open source artists 3
UNCLASSIFIED Space Access: Traditional vs Responsive Traditional (Credit: NASA, ULA) Responsive (Credit: VirginOrbit, PlanetLabs, RocketLab) Traditional Responsive • • >12 mth lead time <12 mth lead time • • Payloads of 10’s to 100’s kg’s Heavy payloads > 1 tonne • • High cost > $1 bn Highly tailored orbits: Mobile launch; air • launch… Significant, fixed ground launch infrastructure 4
UNCLASSIFIED Chemical Propulsion - Taxonomy SM2 launch (credit: RAN) Artillery launch (credit: Australian Army) 5
UNCLASSIFIED Military Propulsion System Comparison Solid Rocket Liquid Rocket Hybrid Rocket Air-breathing ++ High volumetric efficiency ++ Improved specific impulse (vs ++ Specific impulse between ++ highest specific impulse ++ Density-Impulse ~480 kg.s/L solid) solid and liquid (>1000 s) can maximise ++ Long storage life ++ Density-Impulse ~300 kg.s/L ++ Density-Impulse ~310 payload to target ++ Able to provide very high thrust ++ Wide thrust range kg.s/L ++ Enables long duration High ++ Mechanically simple ++ Throttlable and controllable for ++ Able to be cruise, long burn times multi-missions throttled/controlled ++ Typically controllable thrust Performance -- Propellant manufacture hazardous for advanced flight and requires industrial footprint & -- Liquid propellant often hazardous -- Solid fuels structurally dynamics Missile investment to handle weak to loads System -- Typically short burn duration limits -- Volumetrically inefficient -- Low thrust capability -- Mechanical complexity time of powered flight -- Increased mechanical complexity (typically) (turbines) or complex flow -- Pre-fuelling (cryo) reuqires -- Partial draw-backs of both phenomena platform infrastructure solid and liquid systems (scramjet/ramjet) -- Low acceleration & thrust ++ Long storage life – stored and ++ High Isp improves mass efficiency ++ Controllable thrust for ++ Offers potential for single- used when required allowing large payload fractions safety & precision stage to orbit & reusable ++ Mechanically simple (failure ++ Controllable thrust for safety & trajectory space access flight vehicles modes) precision trajectory ++ Lower cost manufacture ++ Volumetric efficiency improves ++ Burn duration (powered flight) & infrastructure due to -- Requires flight through platform compatibility (mobile decoupled from geometry less hazardous fuel & atmosphere to maximise Responsive launcher, air-launch etc) oxidiser Isp (inefficient trajectory) Space -- Launch infrastructure ++ Lower peak thrust -- Typically have low -- Typically unable to throttle or (fuelling/storage) impacts time capability impact acceleration (increased Access control thrust for safety or to launch minimised with rise of accumulated drag offsets precise orbit insertion -- Complexity and cost often not micro/nano payloads Isp gains) -- Lower Isp increases mass required suited to small payloads -- Requires rocket stage for for given thrust -- Fuel grains susceptible to exo-atmospheric flight -- Burn duration limitation due to launch loads anyway diameter and grain geometry -- Likely upper size limitation due to lower thrust 6
UNCLASSIFIED Missile Propulsion: S&T Areas for Exploitation Propulsion Element Key Attributes Further, faster, higher operational flexibility Novel Classes of Propulsion 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. 7
UNCLASSIFIED Simplified Rocket Propulsion Development Cycle Typical System Design Propulsion Sub-system Mission System Motor Design Requirements Performance parameters Trade Space Inert & energetics Materials Studies Development Material characterisation Article through- Sub-system life S3 TLS not always testing considered during system design Sub-scale testing & integration 8
UNCLASSIFIED Rocket Design – multi-variable compromise System Constraints Performance Requirements Thrust Burn duration Motor design is a balance of competing Mass Volume Length priorities, i.e. – Operating Grain shape dictates thrust and pressure profile Temp – Burn rate is a function of pressure, influences thrust and pressure via throat diameter Ageing – Batch Increased thrust leads to increased peak pressure, Properties requiring thicker (heaver) case and increased Variation Grain thrust requirement to maintain acceleration Chamber Shape Pressure Iterative design procedure to distill Grain Grain Nozzle Web system & motor requirements into actual Case Stress Throat Thickness 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 – Density Fly the motor differently? – Different motor design? Problem ripe for optimisation approaches Mechanical Burn Rate Propellant Properties – not just motor optimisation, but system level optimisation integrating platform Specific performance and constraints Impulse 9
UNCLASSIFIED Improved rocket design: CGHOST CMAES with GPOPS for Hypersonic Optimal Solid rocket Trajectories • Stochastic & derivative free • “ Black box” implementation • Especially suited to non-linear problems 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 “ 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 10
UNCLASSIFIED 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 optimisation 11
UNCLASSIFIED Inert Component Development & Characterisation DST rocket motor insulation torch testing Carbon Fibre Reinforced Plastic (CFRP) case design and burst testing 12
UNCLASSIFIED Inert Component Develop & Characterise Vulloy bodies prior to Densification Flame testing setup Graphite post flame testing Vulloy post flame testing Validation of thermal models using an instrumented BATES rocket motor CFD analysis of heat flux through the nozzle 13
UNCLASSIFIED Propellant Development DST solid propellant manufacture, test and characterisation 14
UNCLASSIFIED Propellant Development DST advanced booster technologies development 15
UNCLASSIFIED Propellant Development DST experimental rocket motor design DST static firing of development rocket motor 16
UNCLASSIFIED Propellant Development DST vulnerability assessments of propellants 17
Propellant Characterisation Life-Limiting Factors (safe-life/performance) Material Properties Sub-scale tests System integration test capabilities • Burn rate and thrust (K- • Stabiliser (HPLC) • Non-destructive round; BATES) diagnostics (X-ray, CT) • Composition (GC, FTIR) • Thermal vulnerability • Static testing (GP1, LA5) • Sensitiveness (EHDS) (SSCO) • Dynamic flight tests • Heat evolution (HFC) • Fragment impact (2 stg • Thermal transitions (DSC, light gas gun) 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) 18
UNCLASSIFIED Through-Life Health Assessment DST Specialist Capabilities: – Propellant mechanical & chemical test laboratories. – Rocket motor structural, thermal and dynamic modelling (FEA). RMSL – Accelerated ageing of propellant Program samples and/or rocket motors. DST health assessment facilities and capabilities, environmental chambers, structural modelling, propellant testing and dissection 19
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