AIAA-94-4674
`DC-X RESULTS AND THE NEXT STEP
`Dr. William A. Gaubatz
`McDonnell Douglas Aerospace
`Huntington Beach, California
`
`AlAA Space Programs
`and Technologies Conference
`and Exhibit
`September 27-29, 1994 / Huntsville, AL
`
`For permlsslon to copy or republish, contact the Amerlcan instltute of Aeronautics and Astronautics
`370 L'Enfant Promenade, S.W., Washington, D.C. 20024
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 1 of 15
`
`

`

`DC-X RESULTS AND THE NEXT STEP
`Dr. William A. Gaubatz
`McDonnell Douglas Aerospace
`Huntington Beach, California
`
`u
`
`Introduction
`
`Backmound
`
`Results from static and flight tests accomplished to date
`with the Delta Clipper-Experimental (DC-X) coupled with
`theground operations and maintenanceexperienceare proving
`out both the operational potentials for a reusable launch
`vehicle and the low speed flight Characteristics of a vertical
`takeoff and vertical landing, single stage to orbit (SSTO)
`system. These tests are part of the Single Stage Rocket
`Technology (SSRT) Program being canied out under the
`direction and sponsorship of the Ballistic Missile Defense
`Organization (BMDO). Five flight tests totaling
`approximately eight minutes of flight time have been
`completed. These flight tests together with fourteen static
`tests have provided an extensive verification of the
`autonomous vehicle management system and software,
`including the ability to recognize and to successfully recover
`from emergency conditions. Although major goals of the
`DC-X program have been accomplished, additional tests are
`still required to validate the aerodynamics, control stahility
`and propellant requirements for the low speed rotation
`maneuver required for vertical landing and to ohrain additional
`base drag and control flap effectiveness characteristics to
`substantiate and calibrate the computational fluid dynamic
`models and wind tunnel tests.
`
`A program is also underway with NASA to retrofit the
`DC-X with major subsystems andcomponents representative
`of the advanced structures and materials and components
`required to achieve the lightweight, rugged vehicle capable
`ofachieving singlestage toorbitandbeing used overandover
`again like an airplane. The resulting system is designated the
`DC-XAandwillbeaflying testbedtoevaluatetheadvanced
`launch technologies in the combined environments achieved
`during flight and ground operations.
`
`Few engineersnowdoubtthefeasibilityofusing today’s
`technology to develop and build a single stage rocket system
`capable of delivering useful payload to orbit and returning to
`be reused again. Lightweight, rugged materials exist which
`when coupled with the performance and thrust-to-weight of
`existing rocketengines enablethestructural efficiencies tobe
`achieved which satisfy the “physics” of getting to and from
`orbit with a single stage. Modem flight control approaches
`and software architecture coupled with processing power of
`today’s computers enable the efficiencies of totally
`autonomous flight control to be achieved. Operations and
`maintenance approaches developed through years of
`experience with military and commercial aircraft can be
`directly applied to achieve similarly low operational cost
`approaches for reusable rocket ships.
`
`Whathasbeenlacking is hardevidenceandexperimental
`data that wouldaddengineering, manufacturing and operations
`confmation to feasibility studies and concept designs.
`Concept designs based on highly sophisticated computer
`designs usingrealisticmaterialpropertiesanddesignmargins
`and real performance data and component properties add
`credibility to the achievability of the “physics” of SSTO
`flight. Final validity must await the actual manufacturing,
`assembly and flight testing of the integrated system. Even
`less certain has been the achievability of the low costs of
`operation that are promised by being able to repeatedly use
`the same flight and ground systems. And low operational
`costswill onlybeachieved ifthenumberofpeople,processes
`and replacement pans involved in operating the system and
`in preparing the same vehicle for flight are kept to a very
`small number and the time involvedbetween flights can also
`be kept very small.
`
`Based on the results from and plans for the DC-X and
`DC-XA,theU.S. willbeinapositiontopmeedrapidlywith
`the next step Advanced Technology Demonstrator to resolve
`engineering, manufacturing and operational uncertainties
`associated with building and operating a full scaleoperational
`SSTO system. Positive results from these developments and
`demonstrations would enable a full scale system to be
`operational shortly after the turn of the century.
`
`The objective of the SSRT project and the DC-X flight
`test program has been to provide the fmt step in demonstrating
`the achievability of the promised design and operational
`characteristics of the SSTO system. (Figure 1) Thus, the
`narrow focus of the DC-X has been to demonstrate the
`achievability of the low cost operations and maintenance of
`a rocket powered SSTO and to demonstrate the autonomous
`flight control capabilities, minimum number of flight
`
`4
`
`Copyright 0 1994 by the American Institute of
`Aeronautics and Astronautics, Inc. All rights reserved.
`
`1
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 2 of 15
`
`

`

`The utility of the DC-X system will be extended under a
`project sponsored by NASA to use it as a test bed for
`evaluating advanced technology components, materials and
`structures in the integrated environment of a flight system.
`Thedevelopmentactivities forthisarecurrentlyundcnvay to
`producethelong-leadadvancedsubsystems which willreplace
`those currently in the DC-X. Theresulting vehicle willbe the
`DC-XA - Advanced Launch Technology Test Bed. Some of
`the major subsystems include a graphite-epoxy liquid
`hydrogenmain fueltank,an aluminum-lithium liquidoxygen
`main oxidizer tank (this will also evaluate the 1460 Al-Li
`alloy), graphite-epoxy intertank structures, and a liquid-gas
`converter for hydrogen.
`
`With the completion of the DC-X and the DC-XA
`projects, key design and operational data will be available to
`support a decision to move on the next level of technology
`development and demonstration. As shown in Figure 2, the
`next major decision p i n t in the development of a next
`generation reusable SSTO system will be made by or before
`December 1996. This will be a decision to move ahead with
`the large scale Advanced Technology Demonstration (ATD)
`of the engineering, manufacturing and operational readiness
`foran operational SSTOdevelopmentandoperation by 1999.
`Positive results from the ATD will support a decision to
`proceed with the development and certification of the full
`scale operational system which could be. available for initial
`use by the 2002 to 2004 time frame.
`
`Demonstratine the Delta Cliuuer Conceut
`
`e
`
`The operational Delta Clipper vehicle, Dc-3, together
`with its ground systems would be maintained, loaded, flown
`and serviced between flights like today’s modem military
`and commercial aircrafL (Figure 3) It would use. liquid
`oxygen and liquid hydrogen for its main engines and gaseous
`hydrogen and oxygen for its reaction control and power
`systems. Multiple engines would enable it to safely return to
`its spaceport in the event of equipment failure, including
`engines, any time during flight. On-board health monitoring
`systems would perform all system self checks prior to as well
`asduringflighttobothincreasesafetyandmissionreliability
`and todecrease themaintenanceand turnaround timesbetween
`flights. Its autonomous flight control system would enable
`rapid “reprogramming” for new missions, contributing to
`lower operations costs and increased responsiveness, as well
`as provide the robustness to recognize and respond to off-
`nominal conditions to assure mission success and flight
`safety. For example, the DC-3 would be able to both takeoff
`and land in winds and gusts, increasing its operational
`flexibility and utility.
`
`The turnaround process for the DC-3 would s m as it
`lands and srarts it automated shutdown operations and the
`ground crew tows it back lo its flight stand for unloading
`passengers and/or cargo, senicing and refueling and preparing
`for the next flight. This approach would be similar to that
`
`v
`
`3 Vertical takeoff and landing
`* Design for supportability
`
`- Autonomous control
`- All-weather operation
`
`0 Aircraft-like operation
`* Three-person flight crew
`*Small support crew
`0 Rapid system turnaround
`* Seven days
`* Three-day demonstration goal
`0 Rapid prototyping of hardware and software
`-Short schedule
`*Limited budget
`
`Figure 1. Delta Clipper-Experimental (DC-X)
`Demonstration Goals
`
`operations people and the low speed flight characteristics of
`a vertical takeoff and landing SSTO system. The objectives
`of the DC-X testing havebeen largely accomplished through
`the initial five flight tests and twelve static tests completed to
`date. During two of the flight tests, tests 2 and 5, system
`anomalies and subsystem failures caused by external events
`occurred. The overallcapabilitiesof the vehiclemanagement
`system and the ruggedness of the vehicle design enabled the
`DC-X to successfully recover from these emergencies and
`safely landthevehicle toberepairedandusedforsubsequent
`flight testing. The ability to design for safe, intact abort
`following anemergency isakey operational feature tobeable
`to achieve a low cost, safe operational system - this has been
`demonstrated by the DC-X.
`
`Test plans and supporting analysis are in place to complete
`the low speed rotation maneuver necessary to demonstrate
`the control authority and stability for reorienting the
`operational vehicle from its return from orbit nose forward
`position to its base downward landing position. These tests
`are necessary to complete the evaluation of and provide the
`design data for the vertical landing system.
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 3 of 15
`
`

`

`W
`
`-
`
`FY
`Base Technolog
`Program
`
`1994 1 1995 I 1996 I 1997 I 1998
`Phase IUTechnology * I
`
`outputs
`
`'hase I1 NRAsl
`
`-
`-
`-
`2001 -
`2002 -
`2003 -
`
`J
`
`NRAs
`
`Flight
`Demonstration
`Program
`
`OC-XA
`i Operations
`3 Advanced
`Technology
`
`Advanced
`Technology
`Demonstrator (AT
`aOperaiions
`3 Mass Fraction
`
`Operational
`System Program
`
`m
`
`Full-Scale
`Development and
`Certification
`i Commercial
`Involvement
`Figure 2. NASA Roadmap for RLV Next Generation System Development
`
`l+zL,,*
`
`...
`
`..~...
`
`-.l......".l",,
`
`I
`
`I
`
`I
`
`I
`
`I
`
`v
`
`Y300733 M18PE
`Deorbit, Reentry,
`and Cross-Range Manewers
`
`along withdemonstration ofkey low speed flightquality and
`control characteristicsofan autonomously controlled vehicle.
`These dual goals were incorporated into the DC-X
`demonstration system, consisting of the vehicle, ground
`support and flight operations. (Figure 4)
`
`Flight Test Res Ulb
`
`Figure 3. Delta Clipper Operational System
`
`The static and flight test data developed to date with the
`DC-X, coupled with the ground operations and maintenance
`experience gained, are proving out the operational potentials
`for a reusable launch vehicle and the low speed flight
`characteristics of a vertical takeoff and vertical landing,
`SSTO system. Five flight tests totaling approximately eight
`minutes of flight time have been completed. These flight
`tests together with fourteen static tests have provided an
`extensiveverification of the autonomous vehiclemanagement
`usedtoday for commercial andmilitary aircraft. Allofthese systemandsoftware,includingtheabilitytorecognizeandto
`performance and operability features would enable the successfully recover from anomalies and emergency
`DC-3 to dramatically reduce the cost of transportation to and conditions. (Figure 5 ) The following sections provide a
`from low Earth orbit while achieving operational safety and summary oftheresultsandinfomationobtained todate from
`these tests.
`reliability approaching that of today's aircraft.
`Because the success of the operational DC-3 is as Ooerations and SuDDortability
`dependent on being able to achieve its low cost operations as
`From the very beginning the design of the E€-X system
`itisonachievingitsSSTOperformancegoals, demonstration
`ofaircraft-likeoperability andsupportability wasconsidered was driven to achieve both vehicle performance capability
`to be an equally important demonstration goal for the DC-X andsystemsupportabilityobjectives. Thekey metrics for the
`3
`
`Y
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 4 of 15
`
`

`

`DAC123454
`
`Y300735 T I BWM
`
`Figure 4. Flight Testing Demonstrates Total System Concept
`
`Expanded Flight Envelope Testing
`o Extended ascent phase
`0 Extended landing phase
`o Rotational control and dynamics
`o Expanded aerodynamics
`o Incremental approach
`0 Rapid turnaround time
`
`lnltlal Flight Testing (5 Flights to Date)
`o Turnaround
` translation n Autoland
`
`Figure 5. DC-X System Provides Combined Environment Resolution of SSTO Flight and Operations Issues
`4
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 5 of 15
`
`

`

`v
`
`4
`
`supportability objectives were: turnaround time (TAT) in 7
`calendar days or less and personnel required for TAT of 350
`man-days or Icss. These objectives were met through a
`system engineering process which integrated thesupportability
`approaches as an integral part of the system design.
`
`Traditional involvement of “-ility” disciplines (System
`Safety, Reliability, Maintainability, Human Factors Logistic
`Support System WS) elements and Life Cycle Cost (LCC))
`suggests that each “-ility” discipline is a separate group
`working from their own viewpoint, data base, ground rules,
`andorganizational structure. This traditional approach is not
`practical for “rapid prototyping” programs which must
`produceafusttimequalityproductwith tight budgetsas well
`as a compressed schedule. The supportability goal is fwed -
`improve reliability and maintainability, reduce equipment
`maintenance burden and reduce operating cost. Therefore,
`an efficient and cost-effective approach must be developed to
`meet and exceed the supportability goals within the allocated
`budget and schedule. The Integrated Supportabilityapproach
`met the challenge.
`
`tasks. Fourth, the IFT is staffed with multi-disciplined
`supportability engineers to perform the tasks and closely
`interface with the system engineering and design process.
`
`The “lessons learned” data show that the Integrated
`Supportability approach has been cost effective in building
`the supportability criteriainto theDC-X system design which
`is meeting the supportability requirements:
`
`During the SSRT program, only 3 full time and 4 part
`time supportability engineers were involved. In a traditional
`“-ility” approach for staffiig, it is estimated that 16 to 18 full
`time persons would have been used.
`
`In the first 9 months of the SSRT program. the
`supportability IPT formally submitted 116 Supportability
`Action Requests (SARs) to design engineering. 88 SARs or
`76% were accepted by the engineering and approved by the
`customer. Also, prior to test and evaluation, 12 deliverable
`reports werepreparedandsubmitted withouttheuseoflabor-
`intensive MIL-STD-1388-2B LSAR data base.
`
`The Integrated Supportability approach is shown in
`Figure 6.
`
`The DC-X maintenance and support program was
`“tailored” for the test and evaluation phase, using the
`Reliability Centered Maintenance @CM) process, modeled
`Firstallofthe“-ilities”areorganizedintooneIntegrated from commercial aircraft. On-equipment maintenance
`Product Team 0 and under one Team Leader. Second, manuals werepreparedandvalidatedusing an“aircraft-like”
`using “aircraft-like” methods and processes, coupled with ATA 100 Specification format. 84 scheduled maintenance
`the MIL-STD-1388-lA, the tasks, depth and scope of effort andgeneralsupporttasks wereidentiftedanddocumentedon
`and deliverable data are tailored to meet the program
`the Maintenance Requirements Cards (MRCs).
`supportability “measure of merit” parameters quantitative
`Logistic Support System (LSS) was prepared and
`requirements. Thud, the supportability IFTtasksscheduleis
`keyed to the program master schedule and its critical path validated for the E€-X system test and evaluation phase
`
`Lessons Learnec
`
`o Commercial programs
`0 Military programs
`o Space systems
`~Technoiogy
`
`$ 1
`
`~
`
`~~
`
`~~~~~~~
`
`Supporlab.lrty Engineering Mooels and Pioccsscs
`2 RCM DIoCCSS
`2 Salelv assessment
`~~,
`0 Manpower model
`process
`o R8M model
`oOMBS cost model
`oSimulation model
`oTradeofl process
`o MTAitimeline model
`oSDBUSAR process
`.)
`Maintenance Engineering
`o Maintenance concept
`o RCM process
`o OM8S cost analysis
`0 Testability
`o Risk analysis
`o Lcgistics resources
`o Site activation
`o Supportability Assessment
`oSupply SupporVPHST
`oSupport equipment
`0 Manpowerlskills
`
`Design Disciplines
`o Capability
`o Performance
` technology
`o Producibilily
`oVendorlsub specs
`I
`
`Design Guidance
`SDBUSAR Process
`4
`Safety. RBM. Human Factors
`
`o R&M T.A.F.F. (suppliers)
`o R8M allocations
`0 RBM demonstrations
`0 R8M predictions 0 Maintainerlmachine
`o Design-to criteria o Cost drivers
`
`Cost-ERective Logistics Support System
`
`0 Maintenance manuals
`o Data collection systems
`oOn-site management plan
`
`Figure 6. SSRT Program Integrated Supportability Approach
`5
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 6 of 15
`
`

`

`whichlasted6monthsandaccumulated24staticand5 flights FOCC equipment and GSS equipment relative to test event
`tests. During the Test and Evaluation (T&E), the average and actual flight.
`maintenance crew size was 35.
`
`SSRT Supportability assessment was conducted on an W
`A key element of the SSRT approach has been the noninterference basis to obtain actual data The objective
`validationofthe“aircraft-like”supportab~tymodels,methods was to collect data, as it happened, and learn from mistakes
`and processes by collecting and comparing predictions with as well as successes so hazards and faults can be eliminated
`real time data collected during the T&E. The T&E results
`from future designs.
`have shown the supportability goals required to achieve low
`operating cost space transportation system can be achieved
`Two of the key supportability “measure of merit”
`by a total system which has been designed-in from the onset parameters are Turnaround Time (TAT) and man-hours per
`TAT. TAT parameter is defined as: “lie total elapsed time
`for supportability.
`(measured in hours) required to perform maintenance and
`During the SSRTT&E, over2750datarecords related to service and prepare the SSRT system for the next test event
`-
`-
`on-equipment general support tasks, scheduled and or flight.” Figure 8 illustrates DC-X system TATpredicted
`unscheduled maintenance actions were collected. Fieure 7 and actual values exmrienced UD throueh the fourth flight at
`shows the total maintenance actions chargeable to DC-X,
`the Clipper test site in New Mexico.
`
`t
`
`2 w
`
`160
`
`II)
`
`8 140
`
`Y g 120
`2 z
`
`lO3
`E 8 0
`8
`0
`z 5 6 0
`40
`
`20
`
`Y403639 k
`
`, DC-X Maintenance Actions
`
`PW
`
`/ I
`
`\
`
`,GSS Maintenance Actions
`
`FOCC Maintenance
`Actions
`
`I
`1
`
`1
`
`I
`2
`
`1
`
`I
`3
`
`1
`
`I
`4
`
`I
`5
`
`I
`6
`
`1
`
`1
`
`
`
`,
`
`I
`I
`T
`I
`I
`0
`7
`1
`2
` 3
`6
`-1
`1
`0
`1
`8
`4
`5
`Test and Evatuatlon Events
`SSRT System On-Equipment Maintenance Actions
`
`0
`
`Figure 7.
`
`Figure 8.
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 7 of 15
`
`

`

`-
`
`Man-hours per TAT parameter is defined as: “The total
`man-hours (direct and indirect) required to accomplish all
`turnaround functions and tasks between test eventsand actual
`flights. Figure 9 iUustrates DC-X System turnaround man-
`hours predicted and actual values experienced up to the
`fourth flight.
`
`The Integrated Supportability approach implemented
`throughthel~hasbeendemonstratedandwillbeappliedto
`the future programs. An “aircraft-like” maintenance and
`support program, and Logistics Support System (LSS) does
`work for all rocket powered vehicle systems.
`
`Low SDWI Aerodvnamia and Control Characterlst&
`
`0.05
`
`0.04
`
`0.03
`NOS z
`2
`
`0.02
`
`Y403592.2 MlBXF-RA
`
`Measurement
`
`0.01
`
`0
`
`0
`
`Two of the key performance and control uncertainties
`associated with the design of the vertical takeoff and landing
`Delta Clipper are the potentially large base drag effects at
`relatively low flight speeds and the impact of the ground-
`plume interactions on vehicle control during landing
`maneuvers.
`Figure 10. Comparison of Flight Results with Preflight
`Windtunneltestresuluandcompu~tio~fluiddynamics Model for AxIal Force During Ascent
`(CFD) analyses have indicated that the interaction of the
`rocket exhaust plume with the external airstream can cause a date for ascent. Theopen symbolscorrespond to the preflight
`large reduction in base pressure. During ascent this results in model forthe flight conditions experienced whereasthe filled
`a large drag increase whereas during base fust descent, drag symbols are the axial force results derived from the flight
`data. Theerrorbars shown reflectuncertaintiesin interpreting
`is reduced compared to power-off conditions.
`the flight data.
`
`Preflight modeling was based on CFD solutions using a
`code that had been validated for ground test conditions in
`Normal force results were predicted to be unaffected by
`which the rocket plume was simulated with unheated air. rocket plume interactions for the flight conditions tested to
`Flight data indicate that the base pressure reduction is not as date. Figure 11 illustrates that the normal force results
`large as the preflight model predicted for both ascent and derived from the flight data are in excellent agreement with
`descent conditions. Figure 10summarizesresultsobtainedto the preflight modeling.
`
`v
`
`v
`
`6000
`
`5500
`
`5000
`
`4500
`
`4000
`
`0
`
`3500
`0
`2 3000
`0 I
`2500
`2 2000
`1500
`
`1000
`
`500
`
`0
`0
`
`I
`1
`
`I
`2
`
`I
`3
`
`I
`4
`
`I
`I
`I
`I
`7
`8
`10
` 6
`Captive Test and Flight Test Events
`Figure 9. SSRT System Man-Hours Per Test Event
`
`i
`
`5
`
`I
`
`i
`
`11
`
`I
`12
`
`I
`13
`
`I
`14
`
`I
`15
`
`16
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 8 of 15
`
`

`

`0 Flight data. 0.057cM_~0.122, 25.5<PdP_136.5
`A Wind tunnel data, M_ = 0.1, PdP, = 30
`del based on smoothed data
`
`I
`I - ACm is difference beween flight data and correlation model I
`1
`
`Y403591.1 MlBXF-RA
`is moment coefficient caused by ground effects
`
`- '2,
`
`0.05
`
`0.04
`
`CN
`~ a
`(deg)-'
`0.0:
`
`0.02
`
`1
`
`0.0:
`
`Pitch Postflight
`
`Yaw PosUlight
`
`A
`
`A
`
`0.0:
`
`7 s % -
`
`0.01
`
`O.O(
`
`0.01
`8
`
`12
`
`16
`a (deg)
`Figure 11. Normal Forces Agree with Preflight Model
`
`-
`24
`
`20
`
`Groundeffectsduring powered vertical landing generate
`an axial force that is significant and variable during the last
`two diameters of altitude above the ground. Lateral forces
`and moments are also produced if either the vehicle or the
`engine exhausts are not normal to the ground. For planar
`conditions, lateral forces and moments are correlated by the
`difference between the vehicle tilt angle.9, and the engine
`deflection, 6. For non-planar conditions several additional
`attitude parameters become imponant and it is difficult to
`obtain a sufficient ground test data base to construct a
`generalized model. However, correlation of the flight data
`bas resulted in an improved prediction model that is much
`more accurate than that based on && Figure 12, which
`presents results for pitch and yaw moment coefficient
`prediction errors during ground effects, illustrates this point.
`The moment coefficient prediction errors are defined as the
`difference between flight-derived values and the correlation
`model.
`
`Figures ofmeritforpoweredvertical landingperformance
`include the miss distance, vertical and horizontal velocities,
`and the tilt angle. Requirements for these parameters and
`flight results achieved are summarized in Table 1. As
`indicated, touchdown performance has been excellent.
`
`Future DC-X Flieht Tests
`
`Test Plans
`
`-0.01
`0
`
`1
`
`2
`IN
`
`3
`
`4
`
`Figure 12. FUght Data Base Yields Improved Ground
`Effects Data Correlation
`
`d
`
`P a r a m e t e r
`
`Y403683 MlBZM
`Reqt R e s u l t s From Flight
`
`450 Ft
`Miss Distance
`2-5 Ips
`Vertical Velocity
`Horizontal Velocity <5 Ips
`<2 Ips
`Tilt Angle
`
`I 1 1 2 1 3 1 4 1 5
`3.6 5.2 4.3 30.1 N/A
`3.6 3.7 3.7 3.6 3.9
`0.5 0.5 0.4 0.5 0.65
`0.36 0.92 0.75 0.17 0.78
`
`Table 1. DC-X Touchdown Performance Summary
`
`and to angles of attack up to 70 deg. The SSTO operating
`envelop that can be covered by DC-X flight testing includes
`ascent speeds up to b 0.4, descent speeds up to M ~ 0 . 3 ,
`and the rotationmaneuver from 10 to 180 deg. angleofattack.
`
`DC-X flights can match SSTOVTVL rotation maneuver
`scaling parameters including &, angle of attack, a , and the
`dynamic rate parameter, ado1 LN,. Although Reynolds
`numberislowbyafactorof3 to5,aturbulentboundarylayer
`is expected for both the M3-X and the SSTO vehicle, so this
`difference is not expected to produce a fust order effect.
`
`Flight testing to date has been restricted to ascent and
`descent Mach numbers (&)up
`to0.12and0.09, respectively,
`8
`
`Simulations have yielded successful rotation maneuvers
`for a wide range of off-nominal conditions. The largest
`
`v
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 9 of 15
`
`

`

`v
`
`uncertaintyisthemagnitudeof"dynamiclift"which depends
`on adotW,. Thatparameter is difficult tomatch in ground
`tests. Test data on &I airfoil have indicated that dynamic lift
`can double the lift coefficient (Figure 13) whereas a CF'D
`analysis performed on an axisymmeuic body yielded a
`substantially larger normal force amplification.
`
`The proposed flight testprogram, which is summarized
`inTable2, willenablealowriskapproachfortheDC-X flight
`envelop to be expanded to investigate and assess the effects
`of combined environments. The last two columns, which
`present the moment required to trim divided by the moment
`available, are a measure of risk. Since the vehicle is not
`trimmed during the rotation maneuver, it is permissible for
`that parameter to exceed 1.0. Figure 14 depicts a candidate
`flight profie for flight 8. Flight test trajectories will not be
`finalized until all learning from previous flights can be
`incorporated.
`
`M-
`9-
`a
`0.13 13.90,180 20
`6
`0.23 0-180 50
`7
`0.26
`0-180
`70
`8
`9
`0-180
`100
`0.29
`i o 10.321 0.180 11201
`
`adot.Llv-
`-2.0
`0.85
`0.15
`
`Yaw
`0.06
`0 . a
`0.67
`
`Pitch
`0.26
`0.50
`0.85
`
`I
`
`I
`
`v
`
`Table 2. Proposed DC-X Flight Test Program
`
`Concern
`Trajectory Phase - Rotation Maneuver
`
`Issue
`
`Importance
`
`- In-plane forces and
`m o m e n t s
`
`- Larger than control
`authority over portion
`of trajectory
`
`.i '1
`
`"
`2 1
`
`2
`
`I
`
`NACA 0015 Airfoil
`
`00- -
`
`0
`0
`0 0
`
`
`
`Tunnel DC-ynd,O Data
`
`1 1
`
`--d
`
`I
`DC-X +--+
`I
`e,
`DC-Y
`
`v
`
`Key aerodynamic and flight control issues that would be
`resolved in the proposed program include whether the higher
`than expected base pressure experienced to date persist at
`higher speeds, and the effects of all combined environments,
`in particular high pitch rates, during the rotation maneuver.
`
`Emereencv Landine CaDability
`
`The unplanned use of autoland and touchdown on the
`unprepareddry lakebed during flight test 5 demonstrated the
`value of margin and accommodation of failure modes in the
`design. This flight test experience further opened up new
`understanding of the landing environment and, potentially,
`will enable future tests of the DC-X to expand the flight
`envelope with planned down range landing on a site which
`has minimum preparation.
`
`The ability for recovery and reuse of the DC-X in the
`event of anomalous events has been a major thrust of the
`Delta Clipper system design from the outset This has an
`especially practical side where funding prohibits duplicate
`testarticles. Additionally, it providesatangibledemonstration
`of responding to failure modes of subsystems with system
`level solutions, rather than redundancy at the subsystem
`level. This approach also reduces system costs. Autoland
`and autoclimb are two features which reside in the system
`with no increase of hardware and provide the ability to place
`the system in a safe mode from any preconceived anomalous
`environment PartsoftheBIT anddataretrievalsystemsalso
`use this approach, with the same higher level system and
`
`Present Model
`Scaling Parameters
`
`Basis
`
`Y403663 M18XJ
`
`a
`
`Ground Test
`
`M-.pc/p_(a > 45 deg)
`
`Ground Test
`
`Groundllight
`test of aircraft
`
`Data Expected and Value
`
`150
`100
`50
`Total Angle of Attack (deg)
`
`-200
`
`&W,
`
`2.0T
`
`Y
`
`0
`
`oObtain data free of model
`support interference
`o Assess importance of LW,
`on in-plane forces and moments
`
`Figure 13. DC-X is Effective Test Bed for Assessment of Dynamic Lift
`9
`
`Downloaded by UNIVERSITY OF MARYLAND on June 25, 2014 | http://arc.aiaa.org | DOI: 10.2514/6.1994-4674
`
`Space Exploration Technologies; NEW PETITION
`Exhibit 1116
`Page 10 of 15
`
`

`

`Y4036MRA MlSXK
`Key hiaher Qbar rotation test results
`. -
`i Dynamic pitch plane moments
`3 Out of planelroll-yaw dynamics
`LI Controller performance
`
`Rotation
`o Pitch down 20" below horizon
`o Peak pitch rates - 60"Isec
`o AOA sweep - 10" to 180°
`o Gimbal angles s 8"
`o Qbar - 10 psf to 70 psf
`o Mach numbers 0.26
`3 Height - 8,900 ft to 7500 ff
`0-15seconds
`
`0 High Qibase first
`o Mach numbers 0.19
`o Qbar s 40 psf
`o-45seconds
`
`o Pitch 30' off vertical
`0 Mach number 5 0.15
`o Qbar < 40 psf
`o Height - 8900 ft
`o u p range - 3700 ft
`0-7Oseconds
`
`9000
`8000 -
`
`7000
`
`6000
`
`-
`
`5000
`
`I -
`4000
`E
`0, .-
`I" 3000
`
`-
`
`-
`
`2000
`
`1000
`
`0 -
`
`'
`
`-1 000
`-3500
`
`-3000
`
`-2500
`
`-2000
`
`-1000
`
`I
`-500
`
`I
`0
`
`5
`
`0
`
`I
`-1500
`Range (fl)
`Figure 14. FUght Test No. 8 Demonstrates Higher Qbar Rotation Dynamics and Control Performance
`
`subsystem performance data available from different
`groupingsofparameters ratherthan redundantsensors. These.
`features wereimbedded in the designand operationsplanning
`from the beginning.
`
`The flight 5 anomaly resulted from a hydrogenlair
`explosion which occurred external to the DC-X vehicle just
`prior to lakeoff. The resulting overpressure followed by a
`rarefaction "tore" a hole in the side of the graphite epoxy
`aerosbell. The DC-X took off normally and started into its
`flight before ground ObSeNerS noted the problem. The flight
`manager initiated the "autoland which caused the DC-X to
`stopitsplannedfligbtandland. Itlandedabout500feetfrom
`the landing pad on the dry lake bed. (Eigure 15) All post
`flight operations were carried out normally.
`
`DAC127120
`
`Y403509.1RA T16ZH
`
`"If space travel is ever to
`become practical, spacecraft will
`not only have to be reusable and
`more economical to operate than
`today's rockets, they will have to
`be more forgiving . . . bring you
`home safely even if everything
`isn't working perfectly.
`What the June 27 flight of the
`DC-X showed was that the error-
`recovery problem is solvable, that
`it is possible to design rockets that
`can absorb enormous damage
`and keep flying. Although it was
`totally unintended, the June 27
`flight of the DC-X was proof of
`principle experiment of supreme
`importance"
`
`Landing on the unprepared dry lake has proven to be a
`much more benign environment than expected. The
`environmentproducedbythatunpreparedlanding site actually
`decreasedthethermalenvironmentonthe baseofthevehicle.
`The decreased plume energy reflected to the base by eroding
`the "soft" landing surface by and the cloud produced which
`also decreased connectiv