04 raumtransportsysteme antriebe strukturen

DGLR / CEAS European Air and Space Conference 2007

DGLR Fachausschuss Raumtransportsysteme S4.1 / Propulsion, Structures and Subsystems 1

Space Transportation Systems

Propulsion and Structures

Status of Discussion of the DGLR Expert CommitteeDGLR-Fachausschuss S4.1

R. Lo (AI), W. Zinner (Astrium RT), R. Pernpeintner (MT Aerospace )



Introduction

• The DGLR S4.1 Working Group on Space Transportation Systems (Fachausschuss S4.1 Raumtransportsysteme) is a forum for members of agencies, institutions, industry and universities. Gathering and analysis of information, argumentations about past, present and future spacetransportation systems are the objectives of this particular group.

• Analysis and documentation is coordinated around the topics– Demand & Market– System Concepts & Subsets– Propulsion, Structures & Subsystems

(System related aspects)– Missions & Operations (incl. ground infrastructure)– Cost (Development, Production & Operation)– Projects / Programmatic (Development & Demonstration)

• This paper presents the status of information and analysis of DGLR-FAS S4.1 about propulsion and structures.



Content of Presentation

Jet and Rocket Propellant ClassificationPropellants in Use / Propellants of Current Interest Environmental Benignity: TEHF+Green HybridsDesign Examples of Liquid Rocket EnginesStructures of Liquid Propulsion StagesDesign Examples of Solid Rocket Motors Structures of Solid Propulsion Stages Design Examples of Hybrid Rocket Motors Structures of Hybrid Propulsion StagesPropulsion, Structures and Subsystems - Results and FactsSummary and Outlook

Σ: Propellants + Liquid-, Solid-, Hybrid-Propellant Engines


DGLR Fachausschuss Raumtransportsysteme S4.1 / Propulsion, Structures and Subsystems

Jet Propellant Classification and Consumption

Propulsion type Characterisation Remarks ~ Annual consumption*)

Airbreathing: Mixed hydrocarbons

Jet propellant / Aviation fuel

53,91 Mio.t /0,897 Mio. t

Rocket: LOX/LH2 < fully cryogenic 3-4000 tLOX/HC < semi cryogenic 9500 tN2O4/Hydrazines < hypergolic storable 10000 tN2O/Polymere < green storable 10-50 t**)AP/HTPB/Al < Solid storable 9000 t

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*) Rockets: estimated average 2006/6-2007; **) SS1 2003-2004 SL tests + 6 flights



(AI) Overview of Propellants in Use

Propellants currently used in operational space systems:Number of stages with individual propellants launched 1/2006 to 6/2007:

LOX/ LH2

LOX/ Kero

NTO/ UDMH

NTO/ UH25 MMH

Solids

China 6 0 30 0 2

EU 14 0 0 0 14

India 1 0 2 4 20

Japan 10 0 0 0 18

USA 13 20 11 0 74

Russia 0 104 85 0 5

Ukra-ine

0 18 15 0 5



(AI) Propellants of Current Interest

Some physical and chemical liquid propellant characteristics:

Prop. Fp °C Bp °C Sol.Ds. Liqu.Ds. Rem. + (Isp 68:1)

LH2 -259,2 -252,8 0,088 0,0711 +24% „100% slush“ (391)LOX

CH4 -182.5 -161.5 0.466 0.423 Tcrit = -82,7°C (311)LOX

C3H8 -190,0 -42,1 0,582 7,1 bar VP at 20°C (~305)LOX

O2 -218.8 -183.0 1.46 1,14 TEHF= MpMission/L50 = 0

N2O4 -9.3 21.15 1.45 TEHF = 11-14

H2O2 -0.4 150.2 1.44 TEHF = 3-5

RP-1 ~-40 177-274 0.820 TEHF = 0,09; (300) LOX

N2H4 1.4 113.5 1.004 TEHF = 2,8; (292)N2O4

UDMH -57.0 63.0 0.793 TEHF=3; (287)N2O4



(AI) Environmental Concerns: Green Propellants/greenHybrids

• Environmental concerns refer to storage and handlingrather than emissions !

• Comparison of space transportation emissions (100 launches/a)with air traffic pollution and terrestrial traffic yields 1 : 2000 : 5500

• HCl emission of solid rockets : coal combustion = ~1/200• In abs. numbers: solid rockets = 0,01MT HCl/a; coal combus-tion:1,8MT; volcanoes: 7,8 MT; oceans: 300MT

Prop. Fp °C Bp °C Density Fpkg/l

Density Bpkg/l

Rem.

N2O -90.8 -88.5 1.22 Tcrit: 36,6°CPcrit: 7,27MPTEHF = 0(254)HTPB

Polyethylene ~110 (477) 0,92-0,96 n.a. 20°C



Design Examples of Liquid Rocket Engines

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Basic Principle of a Liquid Propulsion System

Pressurization System:Pressure- or turbopump-fed systems raise the pressure above the operating pressure of the engine

Thrust Chamber Assembly:Generates thrust by efficiently converting the propellant chemical energy into hot gas kinetic energy

Fuel/OxTank

Turbopump

CombustionChamber

Nozzle

Thrust

The Thrust Chamber is the Heart of All Liquid Propellant Rocket Engines



Design Examples for Liquid Rocket Engines

Non-Storable (cryogenic) PropellantsLiquefied gases stored at very low temperaturesLiquefied to minimize the sizes of tanks needed to store themMost common propellant used for today's rocket applications are:

Fuel: Liquid hydrogen (LH2)Oxidizer: Liquid oxygen (Lox)

Pros■ Lox/H2 provides the highest specific impulse (~450 sec)■ Lox/H2 is environmentally friendly■ Non corrosive

ConsThermally insulated tanksPrior to loading, tank evaporation to avoid frozen particlesVenting on the launch pad and refillingLow temperature designExpensive




Storable PropellantsDistinction between earth and space storable propellantsLiquid at environmental conditions (earth or space)Storable for a long time in sealed tanksMost common propellants for today's rocket applications are:

Fuel: Kerosene, MMH, UDMH, N2H4Oxidizer: N2O4

Pros■ Stable at ambient temperature and pressure, i.e. no boil-off■ Non reactive with tank materials■ Instant readiness of the rocket engine

ConsMedium performanceHypergolics are extremely toxic (N2O4/MMH)Surface contaminationHigh handling safety precautions




Engine CycleThe engine cycle (thermodynamic cycle) terminology refers to the source of energy to drive the engine's turbines.

Cycle AnalysisSelects the proper thermodynamic cycle, e.g. open versus closedDelivers:

Engine operating parameters (Isp, thrust, mass, etc.)Engine component parameters (temperatures, pressures, mass flow, flow areas, etc.)Concept trade-offs

Types of Engine or Power CyclesUp to now, only four cycles have been developed and flown:

Pressure-fed -, gasgenerator -, expander -, staged combustion cycleThe gasgenerator cycle was the first in use

One further cycle is currently part of a US R&T demonstration program (IPD)Full flow staged combustion cycle (FFSCC)



Pressure-Fed Cycle


Gagenerator (GG) Cycle

No pumps/turbinesLow thrustPressurized tanks feed thepropellants into the main chamberSimpler engine design

Open cycleMedium to high thrustA small amount of the propellant is burnedseparately in the GG to drive the turbines Turbine drive gas is pumped over boardand not routed back to the main injector

Cycles of Flight Engines



Expander or Bleed Cycle


Staged Combustion Cycle

Closed or open (bleed) cycleHigh performance/medium thrustNo gasgenerator/preburnerAll or a portion (bleed) of cooling channel gas is used to driveturbines

Closed cycleMedium to high performance/thrustPropellant is burned in two stages:preburner and main chamberAll propellant is mixed and burned inthe main combustion chamber (MCC)

Cycles of Flight Engines



Cycles of Flight EnginesFull Flow Staged Combustion Cycle

Synthesis/ConclusionEurope combined the high energetic propellant (Lox/H2) with the medium efficient gasgenerator cycleUS (SSME), Russia (RD-0120) and Japan (LE-7A) have already applied the high energetic Lox/H2 to the high efficient staged combustion cycleThe technology step combining Lox/H2 with staged combustion might be the next generation engine in Europe


Closed cycleHigh performance/medium thrustAll propellants pass the turbinesLower turbine gas temperature by using a full flow cycleLonger engine lifeChallenge: Oxidizer-rich preburnerMost efficient rocket engine cycle



Solid Rocket Propellant- and Motor-Classification: conventional

Motor/grain shape: >Conventionalpropellants:v

Cylinder grain with internal star cross section (below)

Spherical Solid Rocket Motor (Historic Black Arrow Waxwing)

Storable„conven-tional“AP/HTPB/Algrain (right):

Endburner:Very highcharge density(good for HEDM!)

Spherical kick-stage motor, in-space applications (above)



Solid Rocket Propellant- and Motor-Classification: cryogenic

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CSP use frozen liquids, e.g. based on solid hydr. peroxide or oxygen with polymers.

Grain design: >Cryogenic solid propellants CSP V

Modular cylinder grain: alternating stack of ox.-and fu-moduls; igniter, gasgenerator (below)

Quasi homogeneous cylindrical sponge grain

Modular end-burners with Rod-in-matrix, tube bundle and concentric layer design (right)



(MT) Design Examples for Solid Rocket Motors

Small In-line /Strap-on Booster

size: Ø up to 1,6 m

monolithic steel (roll-and-weld) or CFRP cases (filament wound)

Performance factorssteel: 2,7- 8,5 kmCFRP: up to 14 km

Solid propellant stages size: up to 350 to propellant

Ø up to 3,5 msegmented cases high strength steel or CFRPthrust vector controlled

In-Orbit MotorsUsed for: position / apogee motorsSize: Ø 4 inch – 1300 mm

monolithic casingMaterial: steel and Titanium, also

C- and Aramide-fibresPressure:up to 6 MPa



(MT) Design Examples for Solid Propulsion Stage Structures

Common features

Propellant



(MT) Design Examples for Solid Propulsion Stage Structures

steel segments welded from individual cylinders and domes

Clevis-Tang Intersegment Joint retaining „nose“ againstopening under pressureO-ring sealing

Composite casings

VEGA P80 at AVIO

Ariane 5 MPS segment S1:

Infiltration technique



Load Introduction Structure – Ariane 5 Front Skirt

The EPC Front Skirt (JAVE-C) is located at the top of the cryogenic main stage (EPC) of the Ariane 5 launcher and transmits the thrust of the solid boosters into the central body of the launcher and equalizes it regarding payload compatibility

Diameter 5 400 mmTotal height 3 288 mmMass 1 785 kgLoad capacity 6 000 kNMaterial Aluminum alloy,

CFRPThermal protection PROSIAL®



Large Liquid Propellant Tank Structures – Ariane EPC Domes

• Comparison with gore panel methodadvantages of concave spin-forming:

– less parts to manufacture reduced costs, logistics easier– T8 of complete dome

plate welds exhibit T8 condition, too weight saving

Spin-formed dome

Dome with gore panel method



Large Liquid Propellant Tank Structures – Domes for H II-A

MT Aerospace AG manufactures for Mitsubishi Heavy Industries the1st stage and LRB tank bulkheads of Japans launch vehicle H-IIA. The elliptical bulkheads are spinformed of one Al 2219 plate to final T8 temper. MT's spinforming technique leads to tank bulkheads with less weight, better material properties and lower cost than the conventional method used for H-II.

Diameter 3 860 mm (12.7 ft) Height 738 mm (29.1 in)Material Al 2219 T8 Propellants LOX/LH2

Mass 230 kg (507.1 lb) (LOX) Pressure 4.3 bar (62.4 PSI) (LOX)180 kg (396.8 lb) (LH2) 3.4 bar (49.1 PSI)

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CMC Elements of Re-Entry Vehicles - X38 and CRV Heritage

wing leading edge nose cap

„chin panel“

high temp. bearing



CMC Elements for Re-Entry Vehicles - X38 and CRV Heritage

XPERT hot metal TPS configuration with ODS metal cone, CMC nose and flaps (Image Courtesy Dutch Space - EADS Astrium)

X38 Hypervelocity re-enty.(Img.:NASA)



Design Examples of Hybrid Rocket Motors

• SpaceDev SS1 Hybrid Motor Development 2003 / 2004(Poway, Cal.USA)

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(AI / ASTRIUM) Design Examples of Hybrid Rocket Motors

(above) SpaceDev Hybrid Propulsion Module Test Facility / (right) “Dream Chaser” SD Hybrid Suborbital Plane (Img. Courtesy SpaceDev)



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• Chemical rocket propellants will be used for the next 50 years + !!• Specific energy of available propellants will increase tenfold within

the next 20 years (Isp triples)• Environmental benignity will be the most important design driver of

new propulsion systems within 5 years• Liquid Rocket Engines will be used where-ever throttling and

reusibility are prime requests• Solid Rocket Motors will go cryogenic within 15 - 20 years (HEDM)• Hybrid Rocket Motors will continue to be used wherever their chaotic

combustion is not a concern• Structures of liquid propulsion stages will see very high degrees of

integration• Solid Propellant stage structures will need adaptation to reusibility.

Propulsion, Structures and Subsystems - Results and facts



Propulsion, Structures and Subsystems - Results and facts

Subsystems still to be investigated:• Integrated solid propulsion for winged vehicles• Replaceable units for propulsion, in particular ORPUs • HEDM additive production and application• Soft boundary layer (low noise) HEDM rocket nozzles• Lunar infrastructure (+ transportation): design to specific structures• ....

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Summary and Outlook

Summary and Outlook (1)• Annual launch numbers of stages with LOX-LH2 / Solids / LOX-Kero

/ NTO-Hydr. = 1 : 3,14 : 3,22 : 3,36• Environmental loads caused by space traffic are negligible

compared with aircraft emissions, but are unique above ~12km • Propellant handling- and environmental risks can be evaluated by a

characteristic hazard number (TEHF)• Liquid propulsion is a mature technology but still able to see some

further improvements towards advanced combustion cycles• Conventional storable quasi-homogeneous solid propellant grains

will be replaced by cryogenic modular ones in all missions without long term storability requirement

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Summary and Outlook

Summary and Outlook (2)

• Ceramic Matrix Composites are a key technology for hot re-entry structures

• Advanced production methods can reduce costs (e.g.: spin formed tank domes)

• Hybrid propulsion is fashionable but will never make it without active regression rate control

• One last time: high thrust propulsion will remain chemical for all foreseeable future

Thats all folks! Thank you for your attention!

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04 raumtransportsysteme antriebe strukturen

Documents

dglr s4

analysis of dglr

space conference

flights dglr ceas european

fas s4

propellants liquid

operational space systems

subsystems results