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MATERIALS AND STRUCTURES TECHNOLOGY

WORKSHOP. VOLUME 1: EXECUTIVE SUMMARY

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NASA Conference Publication 3148, Vol. I

Space TransportationMaterials and Structures

Technology Workshop

Volume I--Executive Summary

Compiled byF. W. Cazier, Jr.

and J. E. Gardner

Langley Research Center

Hampton, Virginia

Proceedings of a workshop sponsored by theNASA Office of Aeronautics and Space Technology,

Washington, D.C., and the NASA Office of Space

Flight, Washington, D.C., and held in

Newport News, Virginia

September 23-26, 1991

NASANational Aeronautics and

Space Administration

Office of Management

Scientific and TechnicalInformation Program

1992

PREFACE

Space transportation materials and structures technologies have significantly advanced sincemost of the currently operational spacecraft and launch vehicles were designed. As the UnitedStates prepares to embark on new space missions and develop novel vehicle designs, it mustmake every effort to realize the potential of evolving materials and structures technologies forEarth-to-orbit, Earth-to-planet and space transfer applications. The Space TransportationMaterials and Structures Technology Workshop, held in September 1991, helped to accomplishthis goal by (1) developing important strategic planning information necessary to transitionmaterials and structures technologies from laboratory research programs into robust andaffordable operational systems, (2) providing a forum for the exchange of information and ideasbetween technology developers and users, and (3) providing senior NASA management with areview of current space transportation programs, related research and specific technologyneeds. The workshop provided a foundation on which the NASA and industry effort to addressspace transportation materials and structures technologies can grow.

The Workshop General Chairman and Co-Chairmen wish to thank all of the workshop partici-pants who contributed their time and talent to this vital effort. In particular, we also wish toacknowledge the contributions of the key individuals who played critical roles in planning andexecuting the workshop.

VEHICLETECHNOLOGYREQUIREMENTS

Del Freeman, LaRC

WORKSHOP ORGANIZING COMMI'FI'EE

Charles P. Blankenship, LaRCTom Crooker, HQ Salvatore J. Grisaffe, LeRC

Paul Herr, HQ Paul H. Schuerer, MSFCDavid Stone, HQ Donald C. Wade, JSC

WQRKSHQP pANEL LEADERS

VEHICLESYSTEMS

Tom Bales, LaRCTom Modlin, JSC

PROPULSIONSYSTEMS

Carmelo Bianca, MSFCBob Miner, LeRC

ENTRYSYSTEMS

Dan Rasky, ARCDon Rummier, LaRC

WORKSHOP PANEL RAPPORTEURS

VEHICLE SYSTEMS PROPULSIONSYSTEMS ENTRY SYSTEMS

Jack Suddreth, SRS Bill Hope, SRS Charlie Bersch, IDAEd Nielsen, WJSA Frank Stephenson, WJSA Sid Dixon, WJSA

Tom Wheeler, WJSA

WORKSHOP DIRECTOR: Bill Cazier, LaRC WORKSHOP LOGISTICS: Jim Gardner, LaRC

WORKSHOP SUPPORT: Brenda Wilson, WJSA & Bill Hope, SRS

General Chairman

Paul H. SchuererCo-Chairman Co-Chairman

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The use of trademarks or manufacturers' names in this document does not constitute an official endorsement, either

expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration.

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VOLUME1-EXECUTIVESUMMARY

SPACE TRANSPORTATION

MATERIALS AND STRUCTURES TECHNOLOGY WORKSHOP

CONTENTS

Preface ......................................................................................................................................... iii

List of Acronyms ...................................................................................................................... vii

1.0 Introduction ........................................................................................................................ 1

2.0 Findings and Recommendations .................................................................................. 6

2.1 Vehicle Systems Panel ..................................................................................................... 6

2.1.1 Expendable Launch Vehicles and Cryotanks Subpanel .......................... 6

2.1.2 Reusable Vehicles Subpanel ............................................................................ 7

2.1.3 Vehicle Systems Panel Conclusions .............................................................. 9

2_2 Propulsion Systems Panel ............................................................................................... 9

2_2.1 Liquid Propulsion Systems Subpanel ............................................................ 9

2.2.2 Solid Propulsion Systems Subpanel ............................................................... 9

2.2.3 Nuclear Propulsion Systems Subpanel ....................................................... 10

2_3 Entry Systems Panel ....................................................................................................... 12

2.3.1 Technology Needs ............................................................................................. 13

2.3.2 Entry Systems Panel Conclusions ................................................................ 13

2.4 Open Forum ...................................................................................................................... 14

3.0 Conclusions ...................................................................................................................... 17

4.0 Continuing Activities .................................. , ................................................................... 19

APPENDICES

A. Agenda .......................................................................................................................... A-1

B. Panel Topics Chart ..................................................................................................... B-1

V

LIST OF ACRONYMS

ACC ............................................. .Advanced carbon-carbonACRV .......................................... .Advanced Crew Rescue Vehicle

ACT ............................................. .Advanced Composites TechnologyAFRSL ......................................... .Advanced Flexible Reusable Surface Insulation

AIA .............................................. .Aerospace Industries AssociationA1-Li ............................................. Aluminum-lithium

ALS. .............................................. Advanced Launch SystemAMLS .......................................... .Advanced Manned Launch System

ARC .............................................. Ames Research Center

ASRM .......................................... .Advanced Solid Rocket Motor

CC ................................................ .Carbon-carbon

CFD .............................................. Computational fluid dynamicsCMC. ............................................ .Ceramic matrix composites

CPAS ........................................... .Composites Primary Aircraft Structures

CSM ............................................. .Computational structural mechanicsCST .............................................. .Computational surface thermo-chemistry

DoD .............................................. .Department of Defense

DOE ............................................. .Department of EnergyELV .......................................... .Expendable Launch Vehicles

ELVC ........................................... .Expendable Launch Vehicles and CryotanksET ................................................ .External tank

E T O ............................................. .Earth-to-Orbit

FRSI ............................................. Flexible Reusable Surface Insulation

GEO ............................................. .Geosynchronous Earth Orbit

GSFC ........................................... .Goddard Space Flight CenterJPL .............................................. .Jet Propulsion Laboratory

JPO .............................................. .Joint Project Office

JSC ............................................... .Johnson Space Center

L/D .............................................. .Lift-to-drag ratio

LaRC ........................................... .Langley Research CenterLDEF ........................................... .Long Duration Exposure FacilityLEO .............................................. Low earth orbit

LeRC. ........................................... .Lewis Research Center

LH2. ........................................ :....Liquid hydrogen

LN2. ............................................. .Liquid nitrogen

LO2 .............................................. .Liquid oxygenM&S ............................................ .Materials & Structures

MDSSC ......................................... McDonnell Douglas Space Systems Corporation

MMC. ............................................ Metal matrix compositesMSFC ........................................... .Marshall Space Flight Center

MTS ............................................. .Manned Transportation SystemNASA .......................................... .National Aeronautics and Space Adminstration

NASP. .......................................... .National Aero-Space Plane

NDE ............................................. .Non-destructive evaluation

NDT ............................................. .Non-destructive testingNEP ............................................. .Nuclear electric propulsionNIT. ............................................. .NASA-industry team

NLS ............................................ :.National Launch System

NTP ............................................. .Nuclear thermal propulsion

OAST. .......................................... .Office of Aeronautics and Space Technology

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LIST OF ACRONYMS (cont.)

OAET .......................................... .Office of Aeronautics, Exploration, and TechnologyORCC ......................................... .Oxidation-resistant carbon-carbon

OSF. ............................................. .Office of Space Flight

OSSA ........................................... .Office of Space Science and Applications

PLS .............................................. .Personnel Launch System

PMC. ........................................... .Permanent Manned CapabilityRCC ............................................ .Reinforced carbon-carbon

RP. ............................................. .Rocket Propellant (kerosene-based)

R & T ........................................... .Research and TechnologyRV ............................................... .Reusable Vehicles

SDIO ............................................ Strategic Defense Initiative Organization

SEI ............................................... .Space Exploration Initiative

SIP ............................................... .Strain Isolation Pad

SPI ............................................... .Significant Performance Improvement

SSME ........................................... .Space Shuttle Main Engine

SSTAC ....................................... .Space System and Technology Advisory Committee

SSTO ............................................ Single-Stage-to-Orbit

TPS. ............................................. .Thermal Protection System

TRL ............................................. .Technology Readiness Level

VSP. .............................................. Vehicle Systems Panel

viii""

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VOLUME 1- EXECUTIVE

SPACE TRANSPORTATION MATERIALS AND STRUCTURESTECHNOLOGY WORKSHOP

Newport News, Virginia

September 23 - 26, 1991

1.0 INTRODUCTION

NASA is establishinga challenging,long-range integrated space transportationprogram plan built upon NASA's strongcommitment to space science andexploration.In meeting the goals set forthby the evolving space transportationprogram, the vehicle designs developed forEarth-to-orbit,interplanetary,in-Earth-orbit,Earth/planetary entry and planetary/lunarorbit must incorporate advanced materialsand structurestechnologies. Many of the

transportation system concepts are beingdesigned in cooperativeprograms betweengovernment and industry organizations.Many of the transportationsystem conceptsinvolve cross-disciplinetechnologies that

require a new understanding of therelationships between traditionallyindependent areas such as structuraldesignand thermal protection. The integratednature of technology and programmaticswill require new levels of multi-organiza-tional communication and cooperation.Based on such requirements, the Space

Transportation Materials & StructuresTechnology Workshop was sponsored by theNASA Office of Aeronautics and SpaceTechnology (OAST) and the NASA OfficeofSpace Flight(OSF). The workshop was heldin Newport News, VA, September 23 - 26,1991.

The Space Transportation Materials andStructuresTechnology Workshop provided aforum for the interchange of information

between technology developersand users inorder to define the future needs for spacetransportation materials and structurestechnologies. The workshop also providedan opportunity to build communicationlinks vitalto future program successes. Itwas the third NASA meeting on criticaltechnology areas for space transportation.The two previous space transportationsym-posia addressed avionics and propulsiontechnologies.

The workshop was chaired by Charles

Blankenship, Directorfor Structures,NASALangley Research Center. Co-chairmen ofthe workshop were Salvatore Grisaffe,Lewis Research Center, Paul Schuerer,Marshall Space Flight Center, and DonWade, Johnson Space Center. ThomasCrooker, OAST, Paul Herr, OSF and DavidStone, OAST, comprised the NASAHeadquarters organizing committee. Thestrong effortsof these individualsand thepanel chairmen led to the success of theworkshop.

To ensure that the workshop would addressthe broad scope of materials and structurestechnologies, the organizing committeecreated three working panels - VehicleSystems, Propulsion Systems and EntrySystems. The Vehicle TechnologyRequirements Panel was also formed topresent the current status of spacetransportation vehicle systems and toprovide requirements input to the workingpanels.

The workshop agenda is provided inAppendix A and the workshop organizationand panel structure are provided inAppendix B. The three-dayworkshop beganin the afternoon of September 23 with

introductory presentations by CharlesBlankenship, LaRC; Ronald Harris, OSF;and Gregory Reck, OAST. The VehicleTechnology Requirements Panel thenpresented the plenary session whichconcluded in the morning of September 24.The working panels met separatelythroughSeptember 25, following presentations bySamuel Venneri, Materials and StructuresDivision Director, OAST, and Chester

Vaughn, Office of Chief Engineer andDirector Technical Integration and

Analysis, OSF.

Panel summary presentations were givenby the panel chairmen on the morning of

1

September 26, after which an open forumprovided an opportunity for valuabledialogue between panel members andNASA management on technical andprogrammatic issues relative to materialsand structures technologies.

One hundred and forty-eight individualsfrom the federal government and industryattended the workshop. Figure 1.0.1 lists theorganizations represented.

At the time of the workshop, the Office ofAeronautics and Space Technology (OAST)was being created from the existing Officeof Aeronautics, Exploration and Technology(OAET). Therefore, many of the briefingmaterials prepared for the workshop refer toOAET instead of OAST.

Chairman's Introduction

Charles Blankenship opened the workshopby presenting the workshop objectives.These were to:

Identify key materials and structurestechnology needs for future spacetransportation systems.

Assess current materials and

structures technology program plan vs.space transportation needs.

Identify voids and/or opportunities inmaterials and structures technologyareas that have substantial benefits to

advanced space transportation systems.

Identify appropriate areas for anaggressive technology developmentprogram.

Identify approaches to bridge the gapbetween technology developers andusers.

Identify mechanisms for continuationof the technology transfer processinitiated at the workshop.

Meeting these objectives is necessary tomaximize the payoff of materials andstructures research. The fifth objective,

bridging of the gap between technologistsand users of technology, will only beachieved as the result of long-termcollaborative efforts, and this workshop

laid the groundwork for such technologybridging by generating ideas for NASA andindustry to jointly pursue.

A vital long-term goal of the workshop wasto continue building strong relationshipsbetween NASA centers and industry. Therole of NASA's space flight centers ascustomers of industry is clear, but therelationship of industry and the space flightcenters as customers of NASA's researchcenters is not as well known. Nor has

adequate attention been given to this criticallinkage.

In materials and structures, as in avionicsand propulsion, the technical communitymust develop a long-range strategic plan toensure that those technologies needed foradvanced space transportation vehicles, andwhich often take 10-15 years to develop, willbe available when they are needed.

Office of Space Flight Perspective

Ronald Harris, Director of Advanced FlightSystems, Office of Space Flight, furtherdiscussed the challenges identified byCharles Blankenship.

Space transportation programs are morecommonly established as joint effortsbetween both the civilian and militarysectors, such as in the National Aero-SpacePlane and the National Launch Systemprograms. A national perspective mustserve as the key driver in determining howto use limited resources to respond to sharedinterests. Commercial launch and spacevehicle needs must also be addressed.

Foreign capabilities are constantlyimproving and must not be ignored. NASAmust consider the advantages of U.S.cooperation with non-U.S, organizationspossessing common interests to achieve bothcost savings and improve U.S.competitiveness. The ever-growingscrutiny of the NASA budget and manage-ment structure by the Office of Managementand Budget and other federal oversightgroups further emphasizes the need for ahealthy and competitive agency.

Cost and performance are keys to theprioritization of future technologies. Thebenefits of new technologies must be clearlyidentified to justify flight testing, which isessential for building confidence within theuser community.

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Office of Aeronautics and SpaceTechnology Perspective

Gregory Reck, Director for Space, Office ofAeronautics and Space Technology,described OAST's perspective on materialsand structures technologies. Gregory Recksupported Ronald Harris' views regardingthe space transportation challenges facingthe materials and structures community,the need for better coupling of resources andapplications, and the need forcommunication between technologydevelopers and users.

OAST began a rigorous review of itsmission more than a year ago. It has beenreviewing its products and the means bywhich technology evolves from thelaboratory into focused programs and intothe hands of system developers. The officedefines its responsibility as providingtechnology for future civil space missions ofinterest to both NASA and the commercialsector. OAST must also provide a base ofresearch and technology capabilities tosupport national space goals. OAST intendsto incorporate commercial interests into itstechnology program and increase itsresponsiveness to commercial needs inareas such as communications satellitesand launch vehicles.

In December 1990, the Augustine Committeerecommended development of anexternally reviewed integrated technologyplan. The Augustine Committee observedthat development of basic technology hadbeen underfunded for years andrecommended that higher funding levelsshould be provided for the future. Theprocess which OAST used to respond to theAugustine Committee will be exercisedperiodically in the future to evaluate thestructure and priorities of the OASTtechnology program. This process resultedin the identification of NASA's futuremission needs and the capabilities.

Transportation technologies must addressthe needs of Earth-to-orbit systems as wellas in-space transportation systems. Specificareas of focus include:

Enhanced capabilities for the SpaceShuttle

Technology options for the nextmanned launch system

Development of low-cost heavy-liftlaunch vehicles

Development and transfer of low-costtechnologies to commercial ELV's andupper stages

Identification of high-leveragetechnologies for in-space transportationsystems, including chemical andnuclear systems for Earth-to-orbit andinterplanetary applications

Advanced materials and structurestechnologies can contribute significantly ineach of these areas, providing durablethermal protection systems for shuttleenhancement, as well as lightweight tanks,cryogenic tank fabrication processes, andlow mass space-durable materials for futurespace and launch vehicles. Critical to all ofthese efforts is an improved understandingof the space environment during long termspace exposure. The Long DurationExposure Facility (LDEF) is an importantsource of information on space envi-ronmental effects. LDEF data analysesand dissemination are progressing andwill continue for several years.

This workshop is of critical importance indetermining the activities of the highestpriority and is likely to producetechnologies with the highest payoffs.Cooperative ventures between NASA, themilitary and commercial sectors areneeded.

Vehicle TechnologyRequirements

The plenary session on Vehicle TechnologyRequirements, chaired by Delma Freeman,followed the introductory presentations.This session included current informationfrom systems studies on space transporta-tion vehicle systems, with an emphasis onrequirements that will drive futurematerials and structures programs and thebenefits that these programs will provide.

The Vehicles Technology Requirementssessions featured the following pre-sentations:

Cargo Vehicle Architecture Options by R.Eugene Austin of Marshall SpaceFlight Center

NLS Structures and Materials by JackO. Bunting of Martin Marietta

Advanced Manned Launch System by

Theodore A. Talay of LangleyResearch Center

Advanced Crew Rescue Vehicle /

Personnel Launch System (ACRV/PLS )by Jerry Craig of Johnson Space Center

Single Stage to Orbit / SDIO by James R.French of the Strategic DefenseInitiative Organization

National Aero-Space Plane (NASP)Airframe Structures and MaterialsOverview by Terence Ronald of theNASP Joint Project Office (JPO)

Lunar Transfer Vehicle Studies byJoseph Keeley of Martin Marietta

Mars Transfer Vehicle Studies byGordon Woodcock of Boeing

Aerobraking Technology Studies byCharles H. Eldred of Langley ResearchCenter

Earth-to-Orbit Propulsion R& TProgram Overview by Steven J. Gentzof Marshall Space Flight Center

Advanced Rocket Propulsion by ChuckO'Brien of Aerojet

Space Propulsion by John Kazaroff ofLewis Research Center

Nuclear Concepts/Propulsion byThomas Miller of Lewis ResearchCenter

Solid Rocket Motors by RonnCarpenter of Thiokol Corporation

Combined Cycle Propulsion by TerenceRonald of NASP JPO

A discussion of each of these presentationsand the complete briefing charts will becontained in Volume 2 of these proceedings.

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Figure 1.0.1

Space Transportation Materials & Structures Technology Workshop

._. _ Summary ©b,_/_,_

A forum for the interchange of information between technologydevelopers and users, in order to define the future needs ofspace materials and structures technologies for the research anddevelopment community

148 Participants Representing"

Government

- Los Alsmos National Laboratory- NASA Ames Research Center

- NASA Headquarters

- NASA Johnson Space Center

- NASA Langley Research Center- NASA Lewis Research Center

- NASA Marshall Space Flight Center

- National Aerospace Plane - JointProgram Office

- Oak Ridge National Laboratory

- Sandia National Laboratory- Strategic Defense Initiative

Organization

- U. S. Army Missile Command

- Wright Laboratory

Industry

- Aerojet- Alcoa

- Atlantic Research

Corporation- Babcock and Wilcox

- Boeing

- General Dynamics- Grumman

- Hercules

- ICI Fiberite

- Lockheed- LTV

- McDonnell Douglas- Martin Marietta

- Pratt & Whitney

- Reynolds Metals

- Rocketdyne- Rockwell

- Thiokol

- Westinghouse

- United Technologies

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2.0 FINDINGS AND

RECOMMENDATIONS

The efforts of the workshop participants ledto the identification of a number of

important findings and recommendations,and these are discussed in this section.

2.1 VEHICLE SYSTEMS PANEL

The Vehicle Systems Panel addressedmaterials and structures technology issuesrelated to launch and space vehicle systemsnot directly associated with the propulsionor entry systems. The Vehicle SystemsPanel was comprised of two subpanels -Expendable Launch Vehicles & Cryotanks(ELVC) and Reusable Vehicles (RV). TomBales, LaRC, and Tom Modlin, JSC,chaired the expendable and reusablevehicles subpanels, respectively, and co-chaired the Vehicle Systems Panel. TheVehicles Systems Panel started with aplenary session in which the followingpapers were presented:

"Net Section Components forWeldalite TM Cryogenic Tanks," byDon Bolstad

"Built-up Structures for CryogenicTanks and Dry Bay StructuralApplications," by Barry Lisagor

"Composite Materials Program," byRobert Van Siclin

"Shuttle Technology (and M&SLessons Learned)," by Stan Greenberg

The first two presentations provided aperspective on the current state of the art inaluminum-lithium (A1-Li) alloystechnology, especially with regard toAdvanced Launch System (ALS)applications. The third presentationidentified the status of compositetechnologies for space applications andstressed both technology and programmatic/ cultural issues associated with compositestechnology development efforts ongoing inthe U.S. The last paper identified many ofthe materials and structures issues thatarose as a result of Space Shuttle programexperience. These papers are included inVolume 2 of these proceedings.

2.1.1 Expendable LaunchVehicles and Cryotanks

Subpanel

The Expendable Launch Vehicles andCryotanks Subpanel had the followingperspectives:

New Materials Provide the PrimaryWeight Savings For Vehicles

- Provide robustness in design

- Yield systems cost savings

• Current Investment

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Disproportionately small

Significant benefits are apparentAbsence of focused materials andstructures technologies within NASAfor launch vehicles

Typically 10-20 Years to Mature andFully Characterize New Materials

- Manufacturing processes must bedeveloped concurrently

- User needs can accelerate materialsdevelopment

- Selected examples: A1-Li 8090 and2219

The Expendable Launch Vehicles andCryotanks Subpanel clearly recognized thatthe cost of characterizing a materialssystem could become extremely expensiveand could not be accomplished withoutanticipation of a future application. Thepanelists agreed that only a limited numberof materials systems would be matured foraerospace applications. The panelconcentrated on the processing andfabrication issues associated withdemonstration of low fabrication andassembly costs. Concern was expressed asto whether certain systems would receive thesupport necessary to fully characterize themfor these applications. Another concern wasthe evolution of advanced inspectionmethods that become more critical withmore complex materials.

The subpanel identified the prioritytechnical issues shown in Table 2.1.1.

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Table 2.1.1 Priority Technology Issues for Expendable Launch Vehicles & Cryotanks

i. Advanced structural materials

2. A1-Li technology3. Near-net shape fabrication technology for vehicle structures

4. Near-net shape metals technology

5. Near-net shape extrusions for structural hardware

6. Near-net shape forgings

7. Near-net shape spin forgings

8. Welding

9. In-space welding/joining10. Composites technology for cryotanks and dry-bay structures

11. Joining technology for composite cryotanks12. Tooling approach for manufacturing large diameter cryotanks

13. Develop a cure methodology for large composite cryotanks14. State-of-the-artbuckling structure optimizer program15. State-of-the-art"shell of revolution" analysis program

16. NDE for advanced structures

17. In-line inspection of composites

18. Scale-up of launch vehicles19. Launch vehicle TPS/insulation beyond 27.5 ft.diameter

20. Design and fabrication of thin-wall cryotanks for space exploration (5-20 ft.dia.)

Priority concerns of the Expendable LaunchVehicles and Cryotanks Subpanel wereidentified as:

1. The primary near-term issue regardingA1-Li is availability of funding to ensureincorporation in the National LaunchSystem.

Production capability is in place for

8090, Weldalite and 2090 AI-Li alloys

Near-net shape processes have beendefined; scale-up activities areunderway

Program management decisions arerequired to exploit the potential of A1-Lialloys

2. NASA materials technology programsshould include research on expendablelaunch vehicles and cryotanks.

A focused materials and structures

technology program for launch vehiclesis necessary.

Sustained programs to support userneeds and long-term NASA missionsare clearly needed.

3. Structural analysis and optimization,

computational methods and experimentalverification, particularly for long durationand complex space environmental conditions,are needed.

4. Non-destructive evaluation (NDE)

techniques and methods must be exploited toassure integrity, reliability and costreductions.

5. Joining and bonding techniques andconcepts must be developed andcharacterized for future large launch vehicle

applications.

2.1.2 Reusable

Subpanel

Vehicles

In creating a list of highest priority issues,the subpanel's primary framework fordiscussion was future reusable vehicles

requirements. The four most pertinentrequirements for reusable vehicles weredefined as low cost, high reliability, lowmaintenance and on-time launch or

deployment capability. However, currenttechnology gaps inhibit the achievement ofthese future vehicle goals.

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The RV subpanel identified severaltechnologies required for envisioned and

existing missions and vehicle programs, asshown in Table 2.1.2.

Table 2.1.2 Priority Technology Issues for Reusable Vehicles

1. Cryogenic tankage2. Cryogenic tankage with LH23. Cryogenic tankage with LO24. Launch vehicle TPS/insulation

5. Durable passive thermal control devices and]or coatings6. Development and characterization of processing methods to reduce anisotropy

of material properties in A1-Li7. Durable thermal protection system8. Unpressurized A1-Li structures (interstages, thrust structures)9. Near net shape sections10. Pressurized structures

11. Welding and joining12. In space joining13. Micrometeoroid and debris hypervelocity shields14. State-of-the-art shell buckling structure optimizer program to serve as a rapid

design tool15. Damage tolerant design for composite structures16. Test philosophy17. Reduced load cycle time18. Optimized system engineering approach to ensure robustness19. Structural analysis methods20. Optimization of structural criteria21. Develop an engineering approach to properly trade material and structural

concepts selection, fabrication, facilities and cost22. Maintenance and refurbishment philosophy

The priority concerns of the ReusableVehicles Subpanel included:

1. Although several Al-li alloys are currentlyunder development, specific knowledge aboutany one alloy has not progressed to a pointwhere a vehicle designer can safely baselineA1-Li for any application.

2. The benefits of composites for cryogenictanks warrant continued research in this

area, however, issues includingpenetratration effects (sealing), H2compatibility (liners), and H2 leakage mustbe priorities for research.

3. The potential of composites for L02 tanks

and the primary issue of flammabilityprotection were discussed.

4. Metal matrix composites (MMC's) arebeing studied by the NASP program,especially titanium based composites, becauseof their potential hot structure applications.MMC properties must be bettercharacterized.

5. Advanced thermal protection systemmaterials are needed which are durable,lightweight and can be used in a range oferosion environments.

6. For actively cooled structures, innovativestructural designs are needed to lowerstructural weight and improve coolingeffectiveness.

7. Fabrication techniques discussion focusedprimarily on A1-Li. For A1-Li alloys such as2090, technology is lacking in cryotankmanufacturing areas including stretch-forming gores, spur domes and large-scaleextruded net sections.

8. Test philosophy for advanced structurestechnologies should include a strongcommitment to test structures to failure.

9. Space vehicle developers should perhapslook to non-space industry philosophies torealize lessons learned.

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2.1.3 Vehicle Systems PanelConclusions

In summary, the conclusions of bothsubpanels emphasized A1-Li materials,composites, and fabrication and manufac-turing technologies. These technologieswill require additional funding to reachmaturation, as well as the development ofnew analytical methods and non-destructive evaluation (NDE) techniques.

2.2 PROPULSION SYSTEMS

PANEL

The Propulsion Systems Panel wasestablished to address the specializednature of the materials and structurestechnology issues of propulsion systems.This panel was co-chaired by CarmeloBianca, MSFC, and Bob Miner, LeRC.Because of the diverse range of missionsanticipated for the Space Transportationprogram, three distinct propulsion systemtypes were identified in the workshopplanning process: liquid propulsionsystems, solid propulsion systems andnuclear electric/nuclear thermal

propulsion systems. Three subpanels, onefor each of these propulsion system types,were created.

2.2.1 Liquid Propulsion Systems

Subpanel

The Liquid Propulsion Systems Subpanelwas chaired by Larry Johnston, MSFC.Advancement in materials technology andstructural analysis capability for liquidpropulsion systems has been a recognizedtechnology need for many years. Duringthe development of the high-performance,high-pressure, reusable Space Shuttle MainEngine (SSME), the fact that the designand analysis tools used for engine designsin the 1950's and 1960's were inadequatefor determining actual component designmargins became increasingly clear, andthe tools used to predict componentoperating life in advanced engine designssuch as the SSME were pushing the state ofthe art. As a result, the predicted servicelife of the SSME has never been achieved.Earlier engines were typically lowpressure, expendable designs with shortservice-life requirements (minutes insteadof hours) and apparently had more than

adequate (though actually unknown)design margins due to the relativelybenign environments in which enginecomponent parts were required to operate.

The need for new materials and betterstructural designs to tolerate the hostileinternal environments that componentsare likely to encounter in future enginedesigns also became apparent.Additionally, to help reduce spacetransportation operations costs, innovativemanufacturing processes will be needed tosignificantly reduce hardware productiontimes and cost and enhance hardwarequality and reliability. For expendablelaunch vehicle systems, such as theprojected National Launch System (NLS),minimum production costs are paramountsince the propulsion system will bediscarded every flight. In contrast, forreusable transportation systems such asAdvanced Launch Manned Systems(AMLS) or Single-Stage-to-Orbit (SSTO)vehicles, low production costs areimportant, but must be tempered withextended service life requirements.

The Liquid Propulsion Subpanel statedfindings and recommendations on thebase R&T program and on technologiesconsidered peripheral. These stressed theneed for a long-range technology plan andaggressive technology transfer.

In summary, the subpanel commented thata complacency problem exists, in whichproject management believes thatmaterials and processes will be there Whenneeded. Also, organizations tend to favorfamiliar materials, a situation which isexacerbated efforts. Since technologiesand priorities which emerge from thisworkshop represent a current snapshot, amechanism should be provided for aperiodic update.

2.2.2 Solid Propulsion Systems

Subpanel

The objective of the Solid PropulsionSubpanel, chaired by Raymond Clinton,MSFC, was to assess the state of the art insolid propulsion materials, structures andmanufacturing processes, compare this toneeds identified prior to and during theplenary session of the workshop, anddetermine the areas where additionaltechnology effort should be expended tomeet these needs.

9

The Solid Propulsion Subpanel dividedinto ten task teams representingeachofthe basic elementsof solid rocket motors.Thesetask teamswere 1) motorcases,2)propellants, 3) nozzles, 4) bondlines, 5)nondestructive evaluation, 6) motor caseinsulation, 7) materials properties, 8)analysis, 9) adhesives, and 10) hybridmotors.

The task teams prepared inputs prior to theworkshop regarding the state of currenttechnology and the needs in each of the tenareas. As a result of this thoroughassessment of current technology andfuture propulsion system needs, apreliminary determination of thetechnology required to satisfy these needswas completed. A total of 90 technologyneeds were defined by the task teams. Inthe order of greatest number, these werebondlines - 25; analysis - 14; propellants -13; nozzles - 8; NDE - 7; motor caseinsulation - 6; materials properties - 6;motor cases - 5; adhesives - 4; and hybridmotors - 2. The Liquid PropulsionSubpanel added to this list four additionalneeds in NDE and motor cases. After

review and combination of the needs, thefollowing list resulted: 1) bondlines/propellant - 42; 2) nozzles - 28; 3) motorcases - 11; 4) motor case insulation - 7; 5)hybrid rocket propulsion - 2.

Presentations in the following areas inwhich additional technology effort wasdetermined to be needed were made:

• Motor cases- Improved case materials/forms- Improved case joints/attachments- Self insulating case

Propellant/Bondlines- Material and process variability- Bondline design for inspectability- Propellant and bondline failure

criteria- Propellant test techniques

Insulation- TPE insulator fabrication technology

and bondline characterization forlarge motors

- Bondline design methodologies

Nozzles- Process understanding, optimization

and control for ablative nozzlecomponents

- Robust ablative nozzle material andprocess development

Analytical issues =

- Material response characterizationand constitutive modeling of

ablative materials

Hybrid propulsion- Hybrid propulsion feasibility

demonstration

2.2.3 Nuclear Propulsion

Systems Subpanel

The Nuclear Propulsion Subpanel waschaired by Bob Miner, LeRC, and co-chaired by James Stone, LeRC. The sub-panel meetings began with presentationson Nuclear Thermal Propulsion (NTP)and Nuclear Electric Propulsion (NEP)systems and materials. The titles andauthors of the presentations were

"Fuels Development for NuclearPropulsion Systems," by BruceMatthews, Los Alamos NationalLaboratory

"Materials for Space NuclearThermal Propulsion Systems" and"Refractory Alloys for Space NuclearElectric Propulsion Systems," by RoyCooper, Oak Ridge NationalLaboratory

"Fuel Materials Issues Involved in theDevelopment of Nuclear ThermalRockets" and "Non-Fuel MaterialsIssues Involved in the Development ofNuclear Thermal Rockets," presentedby Robert Long, Babcock & Wilcox

The primary driving force behind renewedinterest in space nuclear propulsion is SEI.The Stafford Synthesis Group labelednuclear thermal propulsion an enablingtechnology for SEI. During 1991, aninteragency (NASA / DOE / DoD) tech-nical panel evaluated nuclear thermalpropulsion concepts as well as planned ajoint technology development project innuclear propulsion. The present plan callsfor demonstrating Technology Readiness

10

Level (TRL) six for NTP and TRL five forNEP by the year 2006.

Table 2.2.1 outlines the Nuclear PropulsionSubpanel findings and recommendations.

The workshop participants also generateda prioritized list of material systemsdevelopment tasks, as shown in Table2.2.2. Enabling technologies are markedwith an "E_ and those that provide asignificant performance improvement aredenoted by "SPI ". Those that are not

labeled would provide marginal improve-ments in performance.

The issues related to NTP and NEP mustbe addressed by the materials andstructures research community if theobjectives of SEI are to be met inaccordance with the recommendations ofthe Stafford report and the currentintentions of NASA.

• Operating conditions likely to be significantly outside current experience

• Multiplicity of uncertainties effect durability

• Large number of materials might be considered for various components

* Criticalmaterialsare not available

- No longer produced

- In laboratorydevelopment- In conceptualstage only

• Funding precludesconcurrent development of many candidates

RECOMMENDATIONS

• Ensure concurrent engineeringbetween system design and materialsdevelopment

• Ensure minimal duplicationin qualificationof materialsbetween differentprogramsand contractors

• Ensure advanced design methodology/validationis included earlyto assure a high-performance, durable, and safe design

Table 2.2.1. Nuclear Propulsion Subpanel Findings and Recommendations

11

ISSUES/TECHNOLOGY REQUIREMENTS

• NTP Fuels/Coatings (E)

J

E: Enabling SPI:

NEP Refractory Alloys (E)

NEP Fuels (E)

NEP Radiator Materials (E)

NTP Nozzles (SPI)

Turbopump Materials (SPI)

Lightweight Tankage/Insulation (SPI)

High-Temperature Thermal & Electrical Insulation (SPI)

Pressure Vessels (SPI)

Non-Fuel Coatings (SPI)

High-Temperature Seals

Neutronic Control Materials

Lightweight Radiation Shielding

Radiation Hard, High Temperature Electronics

Significant Performance Improvement

Table 2.2.2. Nuclear Propulsion Subpanel Issues and Technology Requirements

2.3 ENTRY SYS_MS PANEL

The Entry Systems Panel, chaired by DonRummler, LaRC, and Dan Rasky, ARC,considered subdividing into separatesubpanels for (1) Earth-to-orbit / orbit-to-Earthmissions and (2)Earth-to-planetary / plane-tary-to-Earth missions, but commonality oftechnical issues led to the panel's decision towork together.

Although encouraged in the plenary session todevelop more generic R&D programs similarto the CPAS (Composites Primary AircraftStructures) and ACT (Advanced CompositesTechnology) efforts in the aeronauticsprogram, the panel conceded that entrysystems technology could not be easilyseparated from specific mission requirementsbecause of such factors as heating peak andduration / total heat load, ground versus on-orbit assembly, and reuse requirements.

An important general finding was that afamily of TPS is needed for both optimumvehicle performance and varying vehiclemission requirements. The Shuttle Orbiter hasused metallics, several types of ceramic,carbon-carbon TPS, and, on some earlyflights, ablators in areas of uncertain highheating rates. Vehicles subject to the moresevere heating environments expected forplanetary entry missions will requireadvanced ceramics and carbon-carbonmaterials and/or ablators.

Flight testing was identified as a critical needfor aeroassist vehicles to resolvediscrepancies in various methods forcalculating heating loads, demonstrating on-orbit assembly deployment, and validatingnew TPS technologies.

A lesson learned from Shuttle experience isthe need to document the development historyas design drivers, such as loads, change during

12

the course of vehicle design, and as variousimplementation issues not addressed by R&Defforts are met and resolved. Though researchactivities and technology advancements areadequately documented, the developmenthistory, perhaps equally important fordesigners of future vehicles, is typically notdocumented in either archival publications orreadily-accessible company reports and it iseventually lost due to attrition of keypersonnel.

Another lesson learned is that test results arenot always adequately analyzed or completelyencompassing of all failure modes. Thepanel also noted that materials data are notreadily available in a certified, maintainedand accessible data base. Discussion alsoindicated the manner in which technologytransfer occurs in both directions between theU.S. and other countries.Therefore, several materials and structuralconcepts must be investigated and developed

to accommodate the significant variations inthe space transportation missions currentlybeing considered by NASA.

2.3.1 Technology Needs

Three key technology drivers for allanticipated vehicles were identified:

Improved TPS performance for safety /reliability

• Lower operating costs

Increased vehicle capability andsupportability

These technology drivers lead to theidentification of fourteen high-payoff technol-ogy needs in four areas, which are shown inTable 2.3.1.

1)

• Metallics

• Toughened ceramics

• Ablators

• TPS/Structural integration

New/Improved TPS materials and concepts

• Flexible ceramics

• Advanced carbon-carbon

• Special TPS components

• Water-based composite TPS & structures

2) Inspection and certification

• Inspection, NDE, and smart materials

• Simplified certificationYrecertification

3) Specific needs for planetary missions

• Environmental compatibility

• On-orbit activities

4) Improved test and analysis compatibility

• Test facilities

• Interdisciplinary modeling codes

Table 2.3.1 High-Payoff Technologies for Entry Systems

2.3.2 Entry Systems PanelConclusions

Pursuit of the fourteen technology itemsdescribed is recommended in order to lead to

the goals identified in Table 2.3.2.

To reach these goals, the following pointsmust be realized:

Technologists tend to overlook mundaneproblem areas, which is why problems

13

such as accessibility to equipment andstructures for inspection and servicing,weatherproofing of TPS, and extensivecheckout operations still exist.

A gap between technology products andprogram needs often exists. Advanceddevelopment programs should besupported (funded) to bridge this gap, orthe technologist should make his productsreadily accessible by the systemdeveloper and the system user.

Cultural and programmatic barriers toefficient technology transfer exist.Responsible and dedicated NASA-wide

working groups are recommended. Astep in this direction was the Ames -Johnson group effort on RSI and the Lan-gley - Johnson group effort on carbon-carbon, but technology transfer can stillbe improved, especially before NASAcommits to a project.

Entry systems test facilities in the U.S.are aging and must be upgraded. Flighttest facilities are also needed.

Certification for space-based/longduration flight entry systems will be amajor issue and our current methodologymust be augmented to accommodate it.

• New, very high temperature ceramic matrix composites/TPS for 4000+°F

reusability (Zr and Hf ceramics)

• High strength ceramic matrix composites for structural TPS applications

at 3000+°F (SiCfI_B2) matrix ceramics

• Durable, lightweight ceramic TPS for 3000+°F use

• Lightweight, rigid ceramic insulations for 3000+°F use

• Flexible lightweight ceramic insulationsfrPS for 2500+°F use

* New very lightweight ablators with 20-30% weight savings compared to state-of-the-artmaterials

* High emissivity, low surface catalytic efficiency, and reflective coatings for advancedTPS

• New 3-D computational surface thermochemistry (CST) code for predicting detailednear-surface fluid/material response interaction for advanced TPS/vehicle analyses

Table 2.3.2 Entry Systems Major Goals

2.4 OPEN FORUM

Following the summary presentations bythe chairmen of the three panels, NASAmanagement addressed the issues raised.This section summarizes the comments ofRobert Davies, OSF Advanced ProgramDevelopment Division; Samuel Venneri,

Director, OAST Materials and StructuresDivision; Marion Kitchens, OSFUnmanned Launch Vehicles and UpperStages Division; Salvatore Grisaffe,Materials Division Chief, LeRC; andCharles Blankenship, Director forStructures, LaRC.

Robert Davies, OSF AdvancedProgram Development Division

The Office of Space Flight sponsors threetypes of advanced development programs:

Studies of advanced concepts and theirtechnology requirements involvinginteraction with the Office ofAeronautics and Space Technology tofocus on potentially feasible conceptsfor long-term applications.

Advanced development programswhich lead to ground demonstrations

14 m

• Flight demonstrations

The workshop participants must duplicatethe success achieved by the previous spacetransportation avionics and propulsiontechnology symposia by sustaining themomentum developed by this initialmeeting. This is especially important forOSF because it is currently involved inonly a few materials development efforts.The panels recommended several advanceddevelopment efforts that the AdvancedProgram Development Division could applyto expand its efforts.

In summary, the workshop participantsperformed an excellent job axed produced avery impressive set of results. The dialogueestablished during the workshop shouldprove to be very beneficial to futureactivities.

Samuel Venneri, OAST Directorof the Materials and Structures

Division

NASA and industry must cooperateeffectively to realize the full potential ofadvanced materials and structures to meetthe needs of future spacecraft.

To most effectively use the informationproduced by the workshop, additional effortis required. Recommendations must beprioritized and packaged to illustrate howproposed efforts will benefit systemperformance. A complete story is neededthat explains the current state of the art ofrelevant technologies, future systemrequirements, ongoing programs to addressthese requirements, existing gaps, andproposed new efforts to bridge these gapswithout duplicating existing research anddevelopment projects. Without a clear andlogical rationale to support them, workshoprecommendations will be impossible toimplement.

In the past, introducing advanced materialsand structures technologies into the designof new spacecraft has been difficult. Interms of in-house research capability,NASA's centers are the government's bestlaboratories and their research anddevelopment activities must continue toemphasize long-term research needs.Establishing and maintaining a long-termfocus is also essential to avoid the crisis

management that too often interferes withan optimal allocation of resources.

NASA must emphasize integrated researchand development efforts, and it mustrecognize that timeliness and efficiency areimportant goals of new programs.

Current practice in the development of newaeronautics technology is a good example ofhow NASA should conduct its research and

development efforts. Although aeronauticshas only two primary centers, Langley andLewis Research Centers, the comparativelylarger infrastructure of space technologycan learn from the experience ofaeronautics. LaRC concentrates onadvanced airframes, while LeRCspecializes in new engines; the centersunderstand their roles and work very welltogether. They develop and execute projectswith a "skunk works" mentality thatrequires very little management structure.

NASA is currently making a concertedeffort to define its space strategy. Forinstance, the Office of Space Science andApplications has a strategic plan thatspecifies its overall objectives and goals.Although implementation of this plan wouldrequire a greatly increased budget, it servesas a roadmap and reference point forplanning future activities. Similarly, theOffice of Aeronautics and Space Technologyis defining a strategic plan for materialsand structures research and technology.This plan is intended to satisfy the needs ofpotential users of advanced materials andstructures within both NASA and industry.

NASA's materials and structurescommunity must develop the ability totransfer technology to industry. Industryinteraction is essential to the future successof materials and structures programs andNASA. The task before the materials andstructures community now is to determinehow to make inroads into the system inorder to develop needed technologies.Following is a discussion of key technologyareas.

Expendable Launch Vehicles

Expendable launch vehicles (ELV's) willrequire applications of advanced materialsand structures technologies. OAST wouldappreciate industry's assistance to fullyunderstand industry's perspective on thecapital equipment issue, which is a major

15

barrier to the insertion of technology.Inputs from space system primes regardinginvestment and alternatives for machininghardware for use in future ELV's isparticularly needed.

Reusable Launch Vehicles

Regarding the issues raised on non-destructive evaluation and launchphilosophy, possibly a small researchprogram on smart materials and structurescould focus on recertification. A top-downanalysis by industry is needed to ju_y alow-level research effort to investigate thisarea. In conjunction, NASA and industrymust benefit from the experience ofinternational aerospace efforts, forinstance, Soviet experience with A1-Lifabrication.

Nuclear Propulsion Systems

The potential difficulty of meeting the hightemperature material performancerequirements associated with some nuclearpower conceptual designs is a concern.System designers must be very careful notto assume that advanced materials able tosatisfy unprecedented operatingtemperatures will be available whenneeded. To a certain extent, allowingmaterials development to guide systemdesign may be advised.

Industry can help by identifying key issuesin nuclear propulsion and ensuring thatproposed research activities take fulladvantage of prior nuclear propulsionresearch and development sponsored by theDepartment of Energy. Although thegovernment is investing resources in thedemonstration of the SP-100 space nuclearpower system, whether the SP-100 programis using materials of greatest interest topotential nuclear propulsion systems is notcertain.

Solid Propulsion Systems

Initiating new materials researchprograms for nozzles and other solidpropulsion system components is verydifficult. Much of the research performedin this area has originated in the Office ofSpace Flight, which seems to most clearlyrecognize the need for such research.Industry help is needed to demonstrate thehigh payoff of advanced materials and

structures in terms of performance andsafety. Payoff of advanced materials andstructures may be best illustrated through aclean sheet approach to new vehicle designto derive system requirements and therebyshow the benefit of meeting theserequirements with new technologies.

Entry Systems

Some correlation is evident in ablative

materials research for entry systems andpropulsion systems. A possible solutionmight bea fundamental ]evel program tocharacterize ablative materials for a

number of applications.

NASA's strategic plan for space technologyis critical to the investigation of materialsand structures technologies for aerospaceapplications. Sub-scale demonstrations ofnew technologies will be needed to transferthem into operational programs. Input fromindustry is highly needed to complementand expand upon the workshop results.

Marion Kitchens, OSFUnmanned Launch Vehicles

and Upper Stages Division

Marion Kitchens strongly emphasized theimportance of Samuel Venneri's dis-cussion. He stressed that it is the

responsibility of NASA and industry, at theindividual level, to ensure that the efforts ofthis workshop are carried forward.

Salvatore Grisaffe, Materials

Division Chief, Lewis ResearchCenter

Salvatore Grisaffe observed that certainmaterial systems had been frequent topicsof discussion in the course of the workshop.These material systems included high-temperature refractory metals, carbides,lightweight low-temperature structuralmaterials for solid rockets and large spacevehicles, aerobrake and thermal protectionsystem materials, ceramic matrixcomposites and solid rocket fuel materials.These material systems share the need for:

Improved design methodology forreduced weight and built-in inspection

Improved fabrication methods to lowercost

16 :

Validation methodologies involvingground-basedtestbedsto improvesmallcomponent-leveltesting

As discussed earlier, one potential strategyto achieve materials and structures goalswould be to leverage the existing progressmade by aeronautics research anddevelopment programs. For instance,aeronautics applications of metal andceramic matrix composites are currentlybeing studied. With an additional smalllevel of funding from space technology,space requirements could be studied as partof the same effort.

An overlap of research efforts betweenNASA and industry is evident.Elimination of duplication is critical,especially in consideration of budgetconstraints. Technology funding isgrowing more difficult to obtain, and thematerials and structures community mustcooperate in solving problems and pursuingnew technologies.

Charles Blankenship, Director

for Structures, Langley ResearchCenter

Charles Blankenship expressed hisappreciation to NASA and industryrepresentatives for participating in theworkshop and contributing to thedevelopment of more effective NASAprograms. One key event currentlyunderway for the first time is the formationof a strategic long-range plan by both theOffice of Aeronautics and Space Technologyand the Office of Space Flight. The draftplans of both offices are under review. Theorganizers of the workshop intend to use theworkshop results to influence andstrengthen the high priority technologyareas discussed in the strategic plans aswell as the rationale behind them.

3.0 CONCLUSIONS

The findings and recommendationssummarized in this section should providean effective tool to further develop advancedmaterials and structures technologies forevolving space transportation systems.Because of the dynamic nature of materialsand structures technologies as well as spacetransportation plans, the directions takenfrom these conclusions should be

reevaluated over time as they areimplemented.

The workshop participants confirmed theneed to understand and apply newmaterials and structures technologies forEarth-to-orbit, Earth-to-planet and spacetransfer applications. More detailedinformation is provided in the individualpanel reports (Sections 2.1-2.3) and on thecharts presented in Volume 2 of theproceedings.

Current Capabilities and FuturePlans

For the U.S. to improve the reliability,operability and affordability of its nationalspace transportation system, both in absoluteterms and relative to the strengtheninginternational capabilities, an improvedspace materials and structures technologybase and systems capability is vital.Unfortunately, characterizing andmaturing new materials in the current U.S.system typically takes 10-20 years.Timeliness and efficiency must berecognized as important goals of technologydevelopment programs.

Resolving these problems is a majorchallenge. Manufacturing processes shouldbe developed concurrently with materialsdevelopment and testing to the extentpossible in order to reduce the totaldevelopment schedule for new materialsand structural concepts. Also, increasedlevels of effort are needed in specific areassuch as fabrication and manufacturingtechnologies for A1-Li and other metallics,composites, and ceramics which aresuitable for advanced structural concepts,propulsion systems, seals, coatings, ablatorsand other thermal protection systemelements. Non-destructive evaluation andinspection techniques, compatibility of newmaterials, and vehicle design, analysis,integration, testing, certification andrecertification facilities and methods arealso important topics which need moreemphasis in order to satisfy missionrequirements for future space vehicles.Future activities should also consider how tobenefit from and encourage the developmentof performance-enhancing technologies thatare not clearly within the purview ofmaterials and structures. Virtually everypanel emphasized the need for greater efforts

17

in every phase of the development cycle fornew materials and structural concepts.

Strategic Planning

A national space materials and structuresstrategic plan is needed to help meet therequirements of near-term and future spacetransportation systems for advancedmaterials and structures. Such a planwould serve to provide focus and directionfor future materials and structures researchand development activities, in part byemphasizing the need for integratedresearch and development efforts. Thematerials and structures strategic planshould define alternatives for improvingthe planning, development, testing, veri-fication, and transfer of space trans-portation materials and structurestechnologies from developers to users. Thegoal of the planning process should be toprepare a unified national plan which keypublic and private organizations willactively support. Funding will be necessaryto bring the plan to fruition.

Several sources of information are

available to assist in the strategic planningeffort. For example, the Aerospace IndustryAssociation has drafted a report entitledKey Technologies for the 90's that addressesways to incorporate composite technologiesin the fabrication of space structures. TheAIA is also developing a NationalComposites Strategic Plan.

Lessons Learned

Lessons learned from past materials andstructures development and application pro-grams, aerospace and non-aerospace, mustbe intelligently applied to future programs.New materials and structures technologiesmay enable the use of new, effectiveengineering and management techniques.

Materials for Future Vehicles

More than any other new technology area,advanced materials offer the potential tosignificantly reduce the size and mass oflaunch vehicle structures and components.Nonetheless, the current materials andstructures research and development effortis disproportionately small, particularlywith regard to the development oftechnologies with focused launch vehicleapplications. Material systems of

particular interest include high-temperaturerefractory metals, carbides, lightweight low-temperature structural materials for solidrockets and large space vehicles, bearingmaterials, aerobrake and thermalprotection system materials, ceramicmatrix composites and solid rocket fuelmaterials.

Space vehicles, especially those that mustrepeatedly survive the rigors of reentry,face extremely harsh operatingenvironments. As a result, these vehicleswill typically require a family of structuraland thermal protection materials to meet allvehicle performance and lifetimerequirements. For this reason, and becauseit is very difficult to separate technologyrequirements from specific missionrequirements, a range of materials andstructural concepts must be developed andinvestigated.

Design Drivers

System development programs sometimesrely on projections of past improvements inmaterial performance as a basis forassuming that currently unavailablematerials and processes will be availablewhen needed. Developing appropriatecriteria for selecting and prioritizingresearch efforts to ensure that neededtechnologies will, in fact, be available onschedule is necessary. System safety, cost,performance and reliability are allimportant, but more detailed guidance isrequired to direct the path of materials andstructures research. One approach would beto assess subsystems and components offuture propulsion systems to determine crit-ical materials and structures performanceand compatibility requirements. Effectivetechnology management is impossiblewithout an accurate knowledge of the originand evolution of design drivers. Perfor-mance specifications often change duringthe course of vehicle design, and thesechanges must be transmitted to appropriateresearch and development activities.

Flight Testing

Flight testing is a key aspect of thevalidation effort which must occur prior tonew technology transfer to operational sys-tems. This is especially true for conceptssuch as aeroassisted vehicles, which requireflight testing to validate design and

F

18

analysistools. In addition, flight testing isimportant to verify the feasibilityof thermalprotectionsystemconceptsfor large plane-tary spacevehicles that require in-spacedeployment and/or servicing.

Operational Issues

Research and development efforts tend toemphasize the use of advanced technologiesto further the state of the art. Greateremphasis is needed on engineeringsolutions to less exotic, but nonetheless veryimportant operational issues such asequipment accessibility, inspection,servicing, and pre-launch checkoutprocedures.

Joint Efforts

Efficiency is achieved when departments,branches and agencies of the federalgovernment coordinate parallel andcomplementary development programs. Anaggressive program to establish technologysharing agreements between NASA, SDIO,the Air Force, industry and otherorganizations would pay large dividends.For example, aerospace applications ofmaterials such as metal and ceramicmatrix composites could be cost effectivelystudied by expanding upon ongoingaeronautics research and developmentefforts.

Technology Transfer

NASA should study ways to formalize thetechnology transfer process by promotingmore interaction between technologydevelopers, project managers and chiefengineers in the government and industry.Especially important is the need foreffectivetransfer of technology from theNASA research centers to the NASA

development centers.

Furthermore, technologistsshould be usedas an internal consulting resource when

technical problems arise,and operationalconsiderationsshould be more visiblein the

review process used to evaluate researchactivitiesand establish lists of needed

technologies. Effectivecommunications areobviously very important, and events suchas thisworkshop help to establishand buildthe informal relationships betweentechnology developers and users. Equally

important are the interactions betweentechnology developers, prime contractorsand their subcontractors.

4.0 CONTINUING ACTMTIES

A long-range goal of the materials andstructurescommunity must be toensure thatadvances in the state of the art are

incorporatedinto the design of operationalspacecraftand launch vehicles. The SpaceTransportation Materials and StructuresTechnology Workshop was the initialstepin the identificationof materials andstructures technology needs for the SpaceTransportation program and the definitionof how current effortscan best meet these

needs. However, realizingthe fullpotentialof new technologies will require a long-range plan and a continuous long-termcommitment to the plan in the form ofresearch activitiesconsistent with the

plan'sobjectives.

The previous space transportationtechnology symposia for avionics andpropulsion were also initial steps inmeeting long-term technology developmentobjectivesforother disciplines.The resultsof these symposia and the follow-onactivitiesthat have evolved should providean experience base from which NASAmaterials and structures managers cancreatethe most effectiveeffortto continuetosustain the momentum developed by this

workshop. As the firstphase of continuingactivities,an initialplanning meeting ofkey NASA personnel should be convened todiscuss alternativesfor future action. The

proposed planning meeting should includea discussionofthe merits of establishingadhoc committees to address early action ontasks such as prioritization,strategicplanning and communication.

Prioritization

The recommendations produced by the

workshop should be reviewed andprioritized.High-priorityrecommendationsshould then be packaged to illustratehowproposed efforts will benefit specificmission applications in terms of systemperformance, cost,risk,etc. The product ofthiseffortshouldincludea discussionofthecurrent state of the art of relevant

technologies,future system requirements,areas where existing programs fail to

adequately address these requirements, and

19

how proposed new efforts can fill these gaps.This should produce a clear and logicalrationale for program managers to supportimplementation of workshoprecommendations.

Strategic Planning

A long-range strategic plan for materialsand structures research, development andapplication could be an extremely usefultool for NASA management as they respondto changing requirements for a strong andaffordable national space transportationinfrastructure. Inherent within the strategicplan should be clear direction on itseffective implementation. Some of the keyfactors that should be considered in theplanning process are

A comprehensive representation of thenational space transportationinfrastructure and the supportingsystems that will be required into thenext century

A critical and comprehensiveevaluation of current national spacetransportation capabilities,plans andactivities

A timetable for those technologicaladvancements that are critical to thenational space transportationinfrastructure of the future

Retention of current capabilities whilebuilding our national technicalexpertise in space transportation

A summary of "cultural changes"necessary for improving the effec-tiveness and efficiency of the spacetransportation industry

A plan to upgrade existingtestcapabili-ties and acquire new space trans-portation facilitiesto meet the testrequirements of expanding technologyvalidation and system development

programs

Note that many of these topicsmay havebeen addressed by other recentlycompletedor ongoing studiesby groups sponsored byNASA and other federalagencies. For thematerials and structures community, fol-low-on activitiesshould be aware of the

results established by these other efforts,and maximize the use of this information.

Communications

Current activities should catalyzecommunications within the materials andstructures community and between it andthe broader space transportationcommunity. Improvements incommunications between the developers andusers of space technology are particularlyimportant.

Industry Participation

Industry participation is a key aspect ofcontinuing activities. Specific examples ofindustry's ability to enable the applicationof materials and structures technologies inthe future include the following:

Demonstration of the payoff ofadvanced materials and structures interms of performance and safety

Participationin a top-down analysisofrequirements for non-destructiveevaluationand theirrelationto launchactivities

Identification of key issues related tonuclear propulsion and assistance toensure that proposed research activitiestake full advantage of prior nuclearpropulsion research and development

Coordination of research activitieswithin the aerospace industry andbetween industry, government andacademia to avoid duplication ofresearch efforts

Space system primes' identification ofalternative fabrication processes forfuture ELVes and other space vehicles

As much as possible,continuing activitiesshould be structuredto fullyincorporatetheperspectiveofall relevantpartieson issuesof interest. Participation from theDepartment of Energy, Department ofDefense, SDIO, other government agencies,academia and professionalorganizationsisnecessary to develop and implement keymaterials and structures technologies forspace transportation. w

20

APPENDICES

21

.,t

n

y_

9:00 a.m.

1:00 p.m. -

1:10 p.m.

1:30 p.m.

1:50 p.m.

2:00 p.m.

2:20 p.m. -

2:50 p.m. -

3:10 p.m. -

3:40 p.m. -

4:10 p.m. -

4:35 p.m. -

5:00 p.m.

6:00 p.m.

7:30 p.m.

Structures

Omni

Space Transportation

and Materials Technology Workshop

Hotel, Newport News, Virginia

September 23-26, 1991

Monday - September 23, 1991

Appendix A

- 1:00 p.m. Check In: Badging; Final Agenda; Banquet Tickets; Information

1:10 p.m.

1:30 p.m.

1:50 p.m.

2:00 p.m.

Session 1 -Workshoa Overview

Welcoming Remarks

Headquarters Perspective,Office of Space Flight

Headquarters Perspective,Office of Aeronautics, Exploration

and Technology

Introduction to Sessions 2 through 5

Charles Blankenship (LaRC)

Ron Harris

(Hdqrs., Code MD)

Greg Reck(Hdqrs., Code RS)

Del Freeman (LaRC)

2:20 p.m.

2:50 p.m.

3:10 p.m.

Session 2 - Earth-to-Orbit Cargo Systems

Cargo Vehicle Architecture Options

NLS Structures and Materials

Break

Gene Austin (MSFC)

Dr. Jack Bunting(Martin-Denver)

Session

3:40 p.m.

4:10 p.m.

4:35 p.m.

5:00 p.m.

3 - Manned Earth-to-Orbit Systems

Advanced Manned Launch System

ACRV/PLS

Single Stage to Orbit/SDIO

National Aero-Space Plane

Adjourn

Social

Banquet

U. S. Competitiveness: The Rules of the Game

Dr. Ted Talay (LaRC)

Jerry Craig (JSC)

Jim French (SDIO)

Dr. Terence Ronald (NASP)

Dr. Will Stackhouse,

(USAF Space Division)

A-1

Tuesday - September 24, 1991

8:00 a.m. - 8:30 a.m.

8:30 a.m. - 9:00 a.m.

9:00 a.m. - 9:20 a.m.

9:20 a.m. - 9:50 a.m.

9:50 a.m. - 10:10 a.m.

10:10 a.m. - 10:30 a.m.

10:30 a.m. - 10:50 a.m.

10:50 a.m. - 11:20 a.m.

11:20 a.m. - 11:40 a.m.

11:40 a.m. 12:00 noon

Session 4 - Manned Transfer Vehicles

Lunar Transfer Vehicle Studies

Mars Transfer Vehicle Studies

Aerobrake Technology Studies

Session 5 - Advanced Propulsion

Earth-to-Orbit Rocket Propulsion

Advanced Rocket Propulsion

Break

Space Propulsion

Nuclear Concepts/Propulsion

Solid Propulsion

Combined Cycle Propulsion

Joe Keeley(Martin-Denver)

Gordon Woodcock

(Boeing-Huntsvine)

Chuck Eldred (LaRC)

Steve Gentz (MSFC)

Chuck O'Brien (Aerojet)

John Kazaroff (LeRC)

Tom Miller (LeRC)

Dr. Ronn Carpenter(Thiokol)

Dr. Terence Ronald (NASP)

12:00 noon - 1:00 p.m, Lunch

1:00 p.m. - 1:30 p.m.

1:30 p.m. - 2:00 p.m.

2:00 p,m, - 5:00 p.m,

5:00 p.m.

Session 6

Charge to Panels

Charge to Panels

Session 7

Panels Convene:

Vehicle Systems Materials and StructuresEntry Systems Materials and Structures

Propulsion Systems Materials and Structures

Adjourn

Sam Venneri

(Hdqrs., Code RM)

Chet Vaughan(Hdqrs., Code MZ)

Ballroom DBallroom C

Amphitheatre,Junior Ballrooms 2,3

r

r

A-2

Wednesday - September 25, 1991

8:30 a.m. - 12:00 noon

Session 8

Panels (_onvene:

Vehicle Systems Materials and StructuresReusable Vehicles

Expendable Launch Vehicles and Cryotanks

Ballroom CBallroom D

Entry Systems Materials and StructuresEarth to Orbit/Orbit to Earth

Earth to Planet/Planet to Earth

Room 901Room 911

Propulsion Systems Materials andLiquid PropulsionSolid Propulsion

Nuclear Propulsion

StructuresJunior Ballroom 2

AmphitheatreJunior Ballroom 3

12:00 noon - 1:00 p.m. Lunch

1:00 p.m. - 5:00 p.m.

5:00 p.m.

Session 9

Panels Conv.en.e:

Vehicle Systems Materials and StructuresReusable Vehicles

Expendable Launch Vehicles and Cryotanks

Ballroom CBallroom D

Entry Systems Materials and StructuresEarth to Orbit/Orbit to Earth

Earth to Planet/Planet to Earth

Room 901Room 911

Propulsion Systems Materials and StructuresLiquid. Propulsion Junior Ballroom 2Solid Propulsion Amphitheaa'e

Nuclear Propulsion Junior Ballroom 3

Adjourn

7:00 p.m. The following rooms have been reservedfor evening sessions if needed

Propulsion Systems Materials and StructuresEntry Systems Materials and Structures

Vehicle Systems Materials and Structures

AmphitheatreJunior Ballroom 2Junior Ballroom 3

A-3

Thursday - September 26, 1991

8:30 a.m.

9:00 a.m.

9:30 a.m.

10:00 a.m.

10:30 a.m.

12:00 noon

- 9:00 a.m.

- 9:30 a.m.

- 10:00 a.m.

- 10:30 a.m.

- 12:00 noon

Session 10: Panel Reoor[s

Vehicle Systems Panel Report

Propulsion Systems Panel Report

Entry Systems Panel Report

Break

Open Forum

Workshop Concludes

Tom Bales (LaRC)Tom Modlin (JSC)

Carmelo Bianca (MSFC)Bob Miner (LeRC)

Don Rummler (LaRC)

Dan Rasky (ARC)

Charles Blankenship

m

A-4

Appendix B

B-1

Form Appro red

REPORT DOCUMENTATION PAGE OMSNo. o7o4-olssi

Public reporting burden for this collection of information is estimated to average J hc_urper response includlng the time for reviewinK instructions, searchlng existing data sourcesgathering and malnta;nlnf; _e data needed, and completing and revlewln s the collection of ;nformatioa Send con'men ts regardinl_ this burden estimate or any other aspect of thiscollect;oh of informatlon_ including suggestions for reducing this burden, to Washington Headquarters Services Directorate for Information Operations and Reports 1215 JeffersonDay s H;t;hway Suite 1204 Arllngton_ VA 22202-4302 and to the Ofr_ce of Management and Budget Paperwork Reduction Project (0704-01118). Washington. DE- 20503.

1. AGENCY USE ONLY(Leave b/ank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

April 1992 Conference Publicationm =T

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Space Transportation Materials and Structures TechnologyWorkshop, Volume 1 - Executive Summary 506-43-31-07

6. AUTHOR(S)

F. W. Cazier, Jr. and J. E. Gardner, Compilers

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research CenterHampton, VA 23665-5225

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) ...........

NationalAeronauticsand Space Administration

Washington,DC 20546-0001

1"]'. SUPPLEMENTARY NOTES

8. PERFORMING ORGANIZATION

REPORT NUMBER

_17_8

10. SPONSORING/MONITORING

AGENCY REPORT NUMBER

NASA CP-3148, Vol. 1

i2a. OISTRIBtI_TIO_I/_VAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Unclassified-Unlimited

Subject Category 16

13. ABSTRACT (M_imum 200 words)

The Space Transportation Materials and Structures Technology Workshop was held on September 23-26,1991, in Newport News, Virginia. The workshop, sponsored by the NASA Office of Space Flight and theNASA Officc of Aeronautics and Space Technology, was held to provide a forum for communication withinthe space materials and structures technology developer and user communities. Workshop participants wereorganized into a Vehicle Technology Requirements session and three working panels: Materials and StructuresTechnologies for Vehicle Systems, Propulsion Systems, and Entry Systems. The threefold workshop goalsaccomplished wcrc (1) to develop important strategic planning information necessary to transition materialsand structures technologies from laboratory research programs into robust and affordable operational systems;(2) to provide a forum for the exchange of information and ideas between technology developers and users; (3) toprovide senior NASA management with a review of current space transportation programs, related research,and specific technology needs. The workshop thus provided a foundation on which aNASAand industry effortto address space transportation materials and structures technologies can grow.

14. SUBJECT TERMS

Space transportation; Materials; Structures; Vehicle; Propulsion; Entry

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

4SN 7540-01-280- 5500

18. SECURITY CLASSIFICATIO/_

OF THIS PAGE

Unclassified

19.SECURITYCG I;ICAT,O OF ABSTRACT

Unclassified

15. NUMBER OF PAGES

34

16. PRICE CODE

A0320. LIMITATION

OF ABSTRACT

Standard Foem 2gS(Rev. 2-89)Prescribed by ANSI Std. Z3_18298-102

NASA-tangley 1992