Download - Space Shuttle Integration Lessons Learned
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Space Shuttle IntegrationLessons Learned
Bo Bejmuk
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning
Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned fromShuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Introduction
Two types of Shuttle Program Lessons Learnedare addressed
Problems How they were resolved and theirapplicability to Ares I
Success Stories How they were achieved and theirapplicability to Ares I
Lessons Learned are presented at a fairly highlevel
Each can be expanded to any desired level of detail
Top-level Lessons Learned from Zenit DerivedLaunch Systems Sea Launch are included
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning
Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned fromShuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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System Integration Approach
Shuttle Integration included:
Configuration tradeoffs early in the development phase
Mated system analysis and testing
On the ground
In flight
Mated vehicle checkout requirements at the launch site
Post flight data analysis
Independent evaluation of all elements changes
Definition and verification of system interfaces and interface
parameters and associated documentation Integrated Hazard Analyses
Integrated vehicle configuration management
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System Integration Organization
NASA was the Systems Integrator
Boeing, (Rockwell) was the Systems Integrationcontractor
The importance of integration was not fully appreciatedafter the initial development phase
NASA revitalized System Integration twice during theShuttle Programs life
After the Challenger accident After the Columbia accident
Each time a strong leader was put in charge ofIntegration and the Integration resources wererevitalized
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System Integration Organization
(continued)Lesson
It appears that the strength of Integration leadership
is very important to the success of a program Integration should remain the watchful eye as the
Program evolves to an operational status
Continue flight data evaluation for the life of theProgram
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Shuttle System Definitions &
Corresponding Analyses
1) Shuttle on Groundand Liftoff
2) Post Liftoff Configuration 3) Boost Configuration
Liftoff Loads Ground Winds Liftoff Clearances Acoustics ET Pressurization Main Propulsion System Avionics Sequencing & Timing Electrical Power Integrated Hydraulics Software Requirements Integrated Checkout
Requirements
Winds Aloft High Q Loads Heating Aero & Plume Flutter & Buffet Acoustics SRB Separation
Control Stability & ControlAuthority
ET Pressurization & MPS Integrated Hydraulics Software Requirements POGO
High G Loads Heating Aero & Plume ET Pressurization & MPS Integrated Hydraulics Power Control Stability & Control
Authority POGO Software Requirements ET Separation
Evaluation of flight test results and the establishment of operationalboundaries for all flight phases
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Shuttle Elements
Ground Systems
Solid RocketBoosters (SRB)
External Tank
Shuttle System
Main Engines
Orbiter*
* Two cargo configurations analyzed 65K lbs and 0 lbs payloads
Solid RocketMotor (SRM)
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System Integration Support to Element
Designers NSTS-07700 consisted of a series of requirements
documents that were imposed on the elements System Integration analysis results were documented in
Induced Environments Data Books and used by elementdesigners Loads
Aerodynamics
Aeroheating Plume heating
Vibro acoustics
Separations Main propulsion
Other Technical panels were established early in the development
cycle to provide a forum for the smooth interchange ofinformation between system integration and element experts
The Systems Integration technical effort was iterative and
involved several Design Cycles
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning
Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned fromShuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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STS-1 SRB Ignition Overpressure (IOP)
Problem
SRB IOP measured at the vehicle exceeded the 3-sigma liftoffdesign environment
Accelerations measured on the wing, body flap, vertical tail, andcrew cabin exceeded predictions during the liftoff transient
Support struts for the Orbiters RCS oxidizer tank buckled
Post flight analysis revealed that water spray designed tosuppress SRB IOP was not directed at the source of IOP
Source of IOP was believed to be at the plume deflector
STS-1 data analysis showed the primary source located
immediately below the nozzle exit plane
Tomahawk ignition transient used for preflight characteristicswere very different from that of the SRB
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STS-1 SRB IOP (Continued)
Corrective Actions Solution to the SRB IOP was treated as a
constraint to STS-2
IOP Wave Committee organized withparticipation of the NASA and the contractors
A 6.4% model was modified to allow simulation ofsimultaneous ignitions of two SRBs with the firingof one motor only Add a splitter plate in the flame bucket
A new scaling relation was developed based onblast wave theory
A series of 6.4% scale model tests were conductedto evaluate various concepts of IOP suppression
schemes Final fixes
Redirected water spray for SRB IOP suppression
toward the source of SRB IOP (Figure 1) Installed water troughs in the SRB exhaust duct
Very significant IOP reduction was achieved (Fig. 2)
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Figure 1: STS-1 and STS-2 SRB IOP
Suppression Configuration
STS-2 ConfigurationSTS-1 Configuration
Water spray for STS-1was designed for IOPSource at flame deflector
Water spray atThe flame deflectorand side pipesalong the duct
Water spray at theside of duct deleted
Water spray atthe crest of theflame deflector
Water troughs cover theSRB duct inlet
100,000 GPM of waterinjected into the SRBexhaust beneaththe nozzle exit plane
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STS-1 SRB IOP (Continued)
Lessons
1. SRB Ignition is a powerful driver in liftoff environments
2. System Integration, responsible for liftoff environmentdefinition, accepted the Tomahawk ignition test as asufficient simulation of SRB ignition IOP Did not fullyappreciate the effect of the differences between the SRBand the Tomahawk ignition characteristics
3. SRB ignition transient for Ares I should benefit from postSTS-1 efforts on the Space Shuttle
MLP configuration should be evaluated to account for a singleSRB
If the SRB propellant shape or type is changed, the effect onIOP should be re-evaluated
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Ascent Aerodynamics
Problem Plume simulation used during the preflight wind tunnel test
program was not adequately implemented
Observed significant wing lift and vehicle lofting in STS-1 Measured strains showed negative structural margins
Under-predicted ascent base pressures (base drag over-predicted) Temperature effects were not modeled in cold jet plume
simulation parameters used during testingCorrective Actions The Post-flight tests using hot plume simulations improved
base and forebody pressure predictions The ascent trajectory was changed to a flight with a greater
negative angle of attack through High Q The negative angle reduced wing lift The negative angle had to be evaluated for Orbiter windows and
the ET side wall pressures
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Ascent Aerodynamics (continued)
Lesson Although the hot plume re-circulation effect is less
significant on an axis-symmetric vehicle, it shouldbe accounted for when defining pressure on thebase and aft portion of the vehicle
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning
Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned fromShuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Structures
Problem
Throughout Shuttle development and the initial years ofoperations many costly structural modifications had to bemade to maintain the required 1.4 structural safety factor
The Shuttle structure was designed for a 1.4 safety factor with noadditional margin to accommodate changes occurring during thedevelopment phase
Corrective Actions
As mathematical models and definitions of the environmentsmatured, resulting changes required many hardware changesto eliminate areas of negative margin (below a 1.4 safety factor)
These hardware modifications were expensive and timeconsuming. Additionally, they increased workload at the launchsite
This tedious activity ensured safe flights and compliance with thesafety factor requirement, however it created a significant impacton Shuttle operations
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Structures (continued)Lessons
If development time is short, structural margin
management could be pursued to avoid costlyhardware changes as loads analyses mature
A suggested approach could be as follows:
Assign additional factor to be applied to the design loads forenvironments with the greatest uncertainties
For example, gravity and pressure loads could have a factor of1.0 but dynamic and aero loads could have a factor of 1.2
All factors would converge to 1.0 as a function of program
maturity
A method of structural margin management couldminimize costly hardware redesign, and program standdowns, but it may result in a somewhat heavier vehicle
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Structures - Aero Elasticity
Problem Flight data indicated a significantly higher buffet response of the
vertical tail and body flap during ascent (at transonic speeds) The importance of buffet loads was not fully appreciated in the early
Shuttle design (flutter was properly analyzed, safe boundaries wereestablished and stability was verified during flight)
Corrective Actions
Flight instrumentation and ascent photography were used tomeasure response in flight Ascent environments were updated to correspond to measured
response The body flap critical design case was entry (thank goodness), no
action was required since including buffet loads on ascent was stillenveloped by entry
The vertical tail had sufficient margin to accommodate increased buffet
loads
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Structures - Aero Elasticity (continued)
Lesson Even though the Ares I has a significantly simpler
configuration, transonic buffet, particularly for thebulbous shape, should be addressed in the early loadsanalyses and test programs
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Liftoff Loads Analyses
Problem
Shuttle liftoff (L/O) loads were very difficult to analyze
Configuration complexity
SRB Ignition Overpressure
Twang during the SSME thrust buildup
Vandenberg experience showed that loss of the MLP compliance significantlyincreased L/O loads
Flexible washers were planned to restore compliance and avoid vehicle redesign
ET/Orbiteraxial interface
SRB
Growth
H2 TankCompliance
Shuttle
MLP
Ares I
SRB growthloads aretransmitteddirectly to 2nd
stage potentiallycreating more
sever L/O loads
Common Shuttle/Ares I
SRB grows 0.9 duringignition
MLP deflectsdownward
Forward interfacetranslates upward
SRB growthloads aretransmitteddirectly toOrbiter thru H2Tank. H2 Tank
providessofteningcompliance
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Liftoff Loads Analyses (continued)
Corrective Actions SRB ignition delayed until the SRB bending moment (due to
SSME thrust buildup) was at zero Four independent support posts modeled in L/O
simulations Monte Carlo method was incorporated Ground wind restrictions were implemented
Lesson In spite of the relative configuration simplicity of the Ares I,
L/O loads may be a significant design issue due to direct
load path between the SRB and the upper stage
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Structural Dynamics Testing
Success Story
Carefully developed Ground Vibration Test (GVT) program identifiedand facilitated correction of math model errors and precluded criticalproblems in-flight and potentially costly hardware redesign
Disciplines benefiting from GVT included Loads, POGO, Flutter & FlightControl Analyses
Building Block Approach
Starting with element GVT
Ending with full scale mated test at MSFC
Scale Model GVT followed by full scale GVT The stiffening effects of the internal SRB chamber pressure were evaluated in a
scale GVT
Element GVTs
SRB L/O & Boost Phase, & Burnout
ET with various liquid levels Orbiter FREE-FREE & constrained at ET interface
Mated GVTs
Orbiter/ET Boost Phase
4 Body mated, L/O, High Q, & SRB Burnout
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Structural Dynamics Testing (Continued)
Lesson
Extensive investment into the Shuttle GVT Program can save
money on Ares I
Dynamic Characteristics of SRB Verified including:
Liftoff, High Q and burnout configurations
SRB/MLP Interface
Dynamic response at rate gyro locations
Dynamic interaction of SRB structure with visco-elastic propellant
The effect of chamber pressure of the SRB dynamic properties
Upper stage alone in Free-Free and constrained at SRBinterface configurations could be a sufficient and costeffective GVT for Ares I
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Conversion of Static Test Article (STA)
to the Flight OrbiterSuccess Story
The Orbiter STA was originally intended for Orbiter structure strength
demonstrations
Planned to be subjected to ultimate loads
Demonstration of 1.4 times limit load
Very difficult to simulate combined thermal and mechanical loads
Prior to test start, the decision was made to limit loading to limit plus loadlevel
Test article was not stressed beyond yield This test was supplemented by component testing to 1.4 times limit loads in areas
of low margin and sensitive joints
The Orbiter test article was treated as flight hardware (configuration management,problem dispositions)
Post test, the STA was converted to flight hardware and used as theChallengers airframe
Lesson
Thoughtful planning of the test hardware and transitioning it to flight status
could result in significant cost savings
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Ascent Flight Control System (FCS)
Problem
During Filament Wound Case SRB integrated vehicle analysisthe first structural mode was 1.7 Hz, compared to 2 Hz forbaseline vehicle
Strong coupling with LOX slosh mode created (FCS) inadequatestability margin after liftoff
Very difficult to filter out due to the proximity of frequencies forthe 1st bending, slosh and FCS closed loop modes
Corrective Action
The Program was cancelled, but the lesson remained
Lesson
Consider imposing minimum modal frequency on the launchvehicle to avoid coupling with slosh and control systemmodes
May require stiffness requirements (in addition to strengthrequirement) for Stage I/Stage II interface hardware
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Ascent Flight Control System (Continued)
Success Story
SRB rate gyros were incorporated into the Mated VerticalGround Vibration Test (MVGVT) test articles
Large rotations were measured at the locations of the gyrosin low frequency modes
Modal gains were large enough to cause potential loss ofvehicle due to FCS instability
Corrective action was simple
Stiffening the shelf on which gyros were installed
Lesson
Instrument every FCS sensor location preferably with flight-like sensors in future GVTs
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Ascent Flight Control System (Continued)
Success Story
Conservative approach used in slosh baffle implementation
STS-1 8 LO2 baffles
STS-17 4 LO2 baffles SLWT 3 LO2 baffles
Slosh baffles are easily removed, but difficult to add as theprogram matures
Lesson Retain a conservative approach for slosh baffle
implementation
Avoids redesign to increase slosh damping
Allows easy weight reduction as FCS stability is confirmed byflight data
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Day-of-Launch I-Loads Update
(DOLILU) EvolutionProblem
The launch probability predictions for early Shuttle flights was lessthan 50%
More than half of the measured winds aloft violated the vehicles certifiedboundaries
Corrective Actions
System Integration led the evolution from a single ascent I-load,through seasonal I-loads, alternate I-loads, and finally arriving at
DOLILU
This process extended over a 10+ year period (Figure 3)
Concurrently the Program executed 3 load cycles (Integrated Vehicle
Baseline Characterization - IVBC) combined with hardware
modifications to expand vehicle certified envelopes (Figure 4) Current launch probability is well in excess of 95%
Lesson
Commit to a DOLILU approach during early development
Significantly improves margins
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Figure 3: Ascent Design Operations Evolution
1975 1985 1995 2005
50
0
100
Med
High
Low
Ope
rations
Overhea
d
Percen
to
fWin
ds
Violating
Cert
ifica
tion
(%)
AnnualSeasonal
MonthlyAlternate
Day-of-Launch
Lesson Learned: Reliance on Operations Processto Maintain Margin is Expensive
Certification Violations
Ascent OperationsOverhead
Fi 4 D f L h I L d E l ti
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Early FlightsSingle I-Loads
Present FlightsDOLILU
Qb
3-Hour Wind
Variation
DOLILU drives toward center of QaQbenvelope and reduces winds violation to < 5%
CertifiedEnvelope
Ares I can benefit by starting with DOLILU or Adaptive Ascent Guidance
Expanded CertifiedEnvelope
Over 50% of winds
violated certifiedenvelope
Annual WindVariation
Qa
Qb
Qa
Figure 4: Day-of-Launch I-Loads Evolution(10 years +)
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Avionics ArchitectureProblem
Prevention of loss of vehicle/crew or mission due to avionicsfailures considering mission duration up to approximately 12 days
Actions
Dissimilar solutions (primary, backup and two fault tolerance inavionics hardware/software)
Establishment of SAIL Simulation of hardware/softwareinteraction
Four LRU Mid Value Select (MVS) implemented with appropriatecross strapping to ensure two fault tolerance
The Redundancy Scheme was required to be test verified
Two fault tolerance became an avionics system mainstay on the
Shuttle OrbiterLesson
The Orbiter system provided a reliable avionics system. For ashort duration, missions such as Ares I ascent suggested atradeoff to be performed between one and two fault tolerance.
Overall system reliability could be used in the evaluation.
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1st Stage (SRB)2nd StageSM
Avionics Architecture (Continued)
The Shuttle approach of two fault tolerance* was robust, but
may be excessive for a boost only vehicle. The overallsystem reliability (for example 0.999) should driveredundancy requirements.
* With some compromises
Orion
High TimeExposure
Low TimeExposure Trade off study suggested: One vs.
two fault tolerance on Booster A tailored level of fault tolerance
could emerge as the best solution
Establishing the Fault Tolerance Requirements is a PrimaryAvionics Cost Driver
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
M i P l i
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Main Propulsion
Problem Pressure oscillations upstream of the SSME first
stage pumps were not fully appreciated and notincluded in the design environments
This caused inadequate design resulting in fatigue of theH2 temperature probe located 18 upstream of pump
Combined environments (vibroacoustics and pressureoscillations) also created fatigue cracks in the flowliners
Neither were protected by screens
Corrective Actions
Eliminated temperature probe and switched LCC toupstream manifold measurement impact 2 monthsProgram stand down
A massive analytical and test effort, resulting inpolishing flow liner slots, welding existing cracks andimplementing inspection after each mission impact
4 months Program stand downLesson
Based on Shuttle analytical and test experience,develop and incorporate pressure oscillations in theMain Propulsion System (MPS) hardware designenvironments
M i P l i ( ti d)
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Main Propulsion (continued)
Problem
Fill & drain valve shaft roller bearings failure in MainPropulsion Test Article (MPTA) spread debris throughout themain propulsion system.
System did not contain debris screens due to pressure dropconcerns.
Several other cases of debris were found in MPS during earlydevelopment phase
Corrective Actions
Pre-valve screens were implemented. However, locations ofthe screens were not optimal due to the existing hardwareconfiguration constraints
Lesson
Decision to protect engine inlet from debris using screensshould be made early in the MPS development
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
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Flight Software Shuttle Experience
Problem
Concern over reliability of flight software (generic failure)during critical phases of flight
Corrective Action
Both Primary and Backup Flight Software were baselined inthe early stages of development
Primary & Backup run independently on separate computers Backup was never engaged over the life of the Program and
software reliability has improved since the ShuttleDevelopment timeframe
Lesson For Ares I, Backup software is not recommended for ascent
flight. However, for Orion, it should be considered for crewescape.
Flight Software (Continued)
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Flight Software (Continued)Problem
Significant duplication of development andverification facilities on Shuttle
Examples include:
FSL, FCHL, SAIL (STS & GTS), SES, SMS,JAEL, KATS plus dozens of non-real-timeperformance verification tools
These facilities played an important role but,once established, their existence perpetuated
This created unnecessary cost drag on theProgram
Lesson
Manage Ground and Flight Software and
avionics facilities on the Ares I Program topreclude unnecessary proliferation andduplication
Force labs to terminate when their role is
finished
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Li ht i R i t
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Lightning Requirements
Problem
The Shuttle started with strict requirements
TPS could not be certified
Avionics were difficult
Corrective Actions
Decision was made to transition to operationalrestrictions
Field Mills & catenaries on ground
Cloud cover restrictions before launch
Years of unnecessary cost and effort prior todecision
Lesson
Starting with a fair weather vehicle may be acost effective approach
Some avionics hardening could be worthwhile
Crew escape should be considered for
hardening
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Flight Vehicle Instrumentation
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Flight Vehicle Instrumentation
Problem In spite of extensive analysis and testing, during the development phase,
the flight vehicle frequently does not behave as predicted, as was the
case with the Shuttle This could create a flight safety issue (Eg. SRB overpressure, aero
ascent anomaly) Incorrect models, incorrect definition of the environments, incorrect
assumptions
Corrective Action The Program implemented a basic development flight instrumentation
infrastructure Technical discipline experts stated their specific requirements late, after
the vehicles were built
Late definition of instrumentation created the necessity for aninvasive design and installation
Program reluctance to accommodate late requirements Finally limited instrumentation implemented over several flights of
Columbia Limited instrumentation was continued into the operations phase
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Flight Vehicle Instrumentation (continued)
Lesson Mandate design organizations to define requirements
for flight instrumentation concurrently with systemdesign
Emphasis of verification and addressing uncertaintiesmay result in easier implementation
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management
Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
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RCS Thrusters
The Orbiter has two bipropellant RCS systems
Primary 870 lbs thrust used during
ascent from SRB separation through entry
Vernier 25 lbs thrust used on orbit for attitude adjustmentand maintenance
Only applicable lessons learned from the Primarythrusters will be discussed
Approximate thrust range of potential roll control Ares Ithrusters
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RCS Thrusters (Continued)
Problem
The fuel valve seat extrusion caused leakage, leading to fail-
off and deselect This was caused by a small oxidizer leak, which softened the
valve seat
Corrective Actions
Adopted thruster chamber purge
Developed a screening test and incorporated into the ATP
Tightened leakage requirements for oxidizer valves
Lesson
For the bi-prop system, avoid Teflon fuel valve contaminationwith the Oxidizer
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RCS Thrusters (Continued)Problem
Thrust chamber combustion instability
Acoustic resonance driven by high combustion chamber
pressure oscillations Caused by pressurant Helium bubbles in the fuel system
Corrective Actions
Combustion stability screening added to hot fire ATP (Helium
injection)
Incorporated wire wrap around combustion chamber to shutdown the thruster at the onset of burn through
Lesson
Avoid pressurant gas in the propellant if possible (eg. Usebladders)
Address combustion stability during the development andtest program
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RCS Thrusters (Continued)
Problem
Thruster Columbium injector intergranular cracking
Caused by residual stresses and inadequate rinsing of
pre-weld etchant, coupled with high temperature (~600Degrees F) insulation bake-out
Corrective Actions
Eliminated pre-weld etch for new build
Developed NDE to inspect for cracks at White SandsDepot and on vehicle
Lesson
Avoid processes or chemicals that would result withFluorine coming into contact with Columbium at
temperatures above 500 Degrees F
OUTLINE
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Materials and Processes
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Problem
Flexible metal hoses, many of them
Criticality 1, experienced damage,which caused leakage
Each Orbiter contains 208 flexible hoses
Ease of installation
Effective strain isolation
30 hoses were damaged and createdleaks over the Programs life
M t i l d P ( ti d)
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Materials and Processes (continued)
Corrective Actions
Educated workers on the vulnerability of flex hoses
Implemented inspection and replacement with spares andalso substituted with rigid lines whenever practicable
Could have caused Program stand down; was covered by theReturn to Flight schedule
Lesson
Try to avoid using metal flexible hoses, especially in hightraffic areas and incorporate hard protection wheneverpossible
Educate workers and visitors on the vulnerability of flexhoses from the Programs onset
OUTLINE
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Risk Management
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Problem Although risk was managed by good engineering practices, very
little formal risk classification and management was employed Probabilistic Risk Analysis (PRA) was rarely used on the Shuttle
Program
Distrust of the methodology, lack of suitable data, Apollo experience Frequently funds were expended pursuing corrective action for
extremely low probability threats no means to measureeffectiveness of a corrective action on the overall system reliabilityor safety
Corrective Actions A 5X5 matrix risk classification was implemented on the Shuttle
Program Up and down the organization, from individual technical disciplines to
the Program Manager (Figure 5) PRA implemented on several technical projects
Orbiter windows, debris, Kevlar Overwrapped tanks, MMOD
Response to CAIB criticism
Risk Management (continued)
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Risk Management (continued)
Lesson Formal risk management, including PRA, early in
development could produce many cost savingsfeatures such as: Ensuring that system reliability drives redundancy
requirements
Prioritizing safety and reliability enhancements Identifying highest value initiatives
Use competent PRA analysts Must have the data
PRA does not replace good engineering
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OUTLINE
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OUTLINE Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System
Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Initial Naive Concept of Operations
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Initial Naive Concept of Operations
Operational Reality
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Operational Reality
NASA, KSC Photo, dated September 25, 1979, index number KSC-79PC-500
Operational Cost Drivers
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p
Problem
Insufficient definition of operational requirements duringdevelopment phase
Concentration on performance requirements but not on operationalconsiderations
Shuttle design organizations were not responsible for operational cost
Very few incentives for development contractors
Corrective Actions
Very labor intensive (high operational cost) vehicle was developedand put into operations
Lesson
Must have the Concept of Operations defined
Levy the requirements on contractors to support the Concept ofOperations
Must have continuity and integration between designers, groundoperations, and flight operations requirements during thedevelopmental phase
Operational Cost Drivers (Continued)
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Problem The cost of reusability of complex, multifunctional, aging vehicle
Every Orbiter function whether used or not on a given mission must
be verified and checked out prior to flight
Every function must also be monitored and failures managed to
avoid a catastrophic event Reusability of aging complex systems requires ever increasing
attention to maintain performance and safety
Complex paper system touched by too many organizationsgoverns every step of the operation
Early 1980s heritage
Only limited streamlining over the life of the Program
Lesson
Complexity creates flight operational cost
Minimize complexity Manual approach adds to operational cost
Automate
Realistically define operational life prior to development
OUTLINE
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Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Structural and Ascent Performance MarginManagement
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Management
Problem Unrealistic ascent performance requirements eliminated the
possibility of effective margin management DOD insisted on 32K lbs polar orbit capability
Equivalent to 65K lbs due East NASA needed DOD support of the Shuttle Program
Continuous pursuit of the elusive 65K lbs due East ascentcapability precluded the possibility of holding back somestructural margin to avoid costly redesign changes as Programdevelopment matured
Prior to performance enhancement program the Shuttle had anascent performance shortfall of ~10K lbs
Actions Taken
All priorities were subordinated to the quest for ascentperformance Very few features supported effective operations
Costly structural modifications to maintain the required factor ofsafety were made
Structural and Ascent Performance Margin
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g
Management (continued)Lesson Set realistic ascent performance requirements
Hold back some margin to be used for problem areas
Use factors on not well understood environments toprotect against costly design modifications as Programknowledge matures
Transition to operations should be made consistent with
vehicle operational capabilities imbedded in the design
OUTLINE
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Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Significance of Shuttle Lessons Learned
G t SRB IOP2-Fault Tolerant Margin Mgmt.
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Applica
bility
toA
res
I
1
2
3
4
5
1 2 3 4 5
Significance to ShuttleLess Greater
Less
Greater SRB IOPAvionics
Ops Cost Drivers
Engine Inlet
Screens
Ascent Aero
Anomaly
MPS Pressure
Oscillations
RCS Combustion
Instability
RCS Inter-granular
Cracking
Flex Hoses
Software
Reliability
Buffet
DOLILU
Liftoff Loads
g g
Risk Management
Lightening
Flex Modes
Effects on FCS
RCS Seat
Extrusion
S/W Verification
Facilities
Risk of Crew/Vehicle Loss
Risk to Cost/Schedule
Instrumentation
RGAs in GVT
GVTSTA as Flight
Article
Slosh Baffles
OUTLINE
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Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned from
Shuttle development &operations can reduceConstellation life-cycle costand development schedule,and result in more reliable
and safer systems
Launch Platform
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Courtesy of the Sea Launch Company
Assembly and Command Ship
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Courtesy of the Sea Launch Company
Launch
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Sea Launch Zenit Derived Launch System
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Major integration of existing and newelements
Two stage Ukrainian Zenit
3rd stage Russian Block DM
New payload accommodation &composite fairing
Modified semi-submersible oil drilling
platform into a launch pad
New command and control and rocketassembly ship
System was built and brought to
operational state in less than 3.5 years
22 flights to date, 21 successful
Courtesy of the Sea Launch Company
Sea Launch Operations Integration of rocket stages
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and payload at home port inLong Beach, CA
Launches performed from the
Equator, 154 degrees west(south of Hawaii)
300405Totals
40
1405070
80
2005075
Americans
RussiansUkrainiansNorwegians
Launch
Team*
Ground Processing
Team
* Launch Team is a subset of the Ground Processing Team; GroundProcessing team members that are not required to participate in launch atsea are sent back to their companies and are off the Sea Launch payroll
Small Team performs ground checkout and launch
Courtesy of the Sea Launch Company
Lessons Learned from Sea Launch
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Zenit extremely automated launch vehicle
Very little interaction with crew during checkout, pre-launch, andflight
Single string accountability, no duplications of effort (tosome extent driven by export compliance restrictions)
Low operational cost benefited from original design criteriaof Zenit
Rollout to pad, fuel and launch in 90 minutes
Allows very little time for ground or flight crew involvement
Imposes requirements for automatic processes
OUTLINE
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Introduction System Integration Approach Liftoff and Ascent Aerodynamics Structures Ascent Flight Control System Day-of-Launch I-Loads Evolution Avionics Architecture Main Propulsion Software Lightning Flight Instrumentation
RCS Thrusters Materials and Processes Risk Management Operational Cost Drivers Margin Management Significance of Lessons Learned Other Applicable Lessons Learned
Zenit Derived Launch System Sea Launch Delta IV Separate Briefing
The Big Lesson
Lessons learned fromShuttle development &operations can reduce
Constellation life-cycle costand development schedule,and result in more reliable
and safer systems
The Big Lesson
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At least 2 critical design flaws existed in the flightsystem through design, testing and flight testing
Not detected or acknowledged as major problems
A gap existed between actual and perceived state ofvehicle robustness and safety
Although strong indications were present, neither thedesign nor the operations team identified the problem
The Big Lesson (continued)
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Big Lesson
WE WERE NOT AS SMART AS WE THOUGHT WE WERE!
Develop and maintain a strong integration team throughout theprogram life cycle
Empower integration to challenge the elements and program onissues of design flaws and interaction between the elements
Continuously monitor performance and safety throughout the transitionto operations and the operations phase
Integration and element engineering should be staffed with the bestin their fieldinquisitive by nature, respected by peers andmanagement, and who have the courage to take on the Programregarding issues
Transition to operations should be made consistent with vehicleoperational capabilities imbedded in the design
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BACK-UP
Seven Types of System Analyses will DefineInterstage Stiffness Requirements
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g q
1.) Response to Ground Winds
2.) Liftoff Loads and Clearances3.) Roll Control Authority
4.)Transonic Buffet
5.) FCS Flex Stability6.) High Q static Elastic Loads
7.) High Q Response to Gust
InterstageHardware