NASA Technical Reports Server (NTRS) 20060051840: NASA Crew Launch Vehicle Flight Test Options

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by  NASA Technical Reports Server (NTRS)

NASA Crew Launch Vehicle Flight Test Options

Charles E. Cockrell, Jr.*, Stephan R. Davis**, Kimberly Robinson**, Margaret L. Tuma**
National Aeronautics and Space Administration, U.S.A.

Greg Sullivan***
GPS Solutions, Inc., Reno, Nevada, U.S.A.

Abstract

Options for development flight testing (DFT) of the Ares I Crew Launch Vehicle (CLV) are discussed. The
Ares-I Crew Launch Vehicle (CLV) is being developed by the U.S. National Aeronautics and Space
Administration (NASA) to launch the Crew Exploration Vehicle (CEV) into low Earth Orbit (LEO). The
Ares-I implements one of the components of the Vision for Space Exploration (VSE), providing crew and
cargo access to the International Space Station (ISS) after retirement of the Space Shuttle and,
eventually, forming part of the launch capability needed for lunar exploration. The role of development
flight testing is to demonstrate key sub-systems, address key technical risks, and provide flight data to
validate engineering models in representative flight environments. This is distinguished from certification
flight testing, which is designed to formally validate system functionality and achieve flight readiness.
Lessons learned from Saturn V, Space Shuttle, and other flight programs are examined along with key
Ares-I technical risks in order to provide insight into possible development flight test strategies. A strategy
for the first test flight of the Ares I, known as Ares I-1, is presented.

Nomenclature LO2 Liquid Oxygen (LOx)
LSAM Lunar Surface Access Module
CaLV Cargo Launch Vehicle (Ares V) MGVT Mated Ground Vibration Test
CFD Computational Fluid Dynamics MLP Mobile Launch Platform
CDR Critical Design Review NASA National Aeronautics and Space Admin.
CEV Crew Exploration Vehicle OML Outer Mold Line
CLV Crew Launch Vehicle (Ares I) PDR Preliminary Design Review
CM Crew Module RCS Reaction Control System
DFI Development Flight Instrumentation RRF Risk Reduction Flight
DFT Development Flight test RSRM Reusable Solid Rocket Motor
DSS Deceleration Subsystem PBAN Polybutadiene Acrylonitride
EDL Entry, Descent, and Landing SM Service Module
EDS Earth Departure Stage SRB Solid Rocket Booster
ESAS Exploration Systems Architecture Study SSME Space Shuttle Main Engine
ETM Engineering Test Motor STS Space Transportation System
FSB Five-Segment Booster TLI Trans-Lunar Injection
FTA Flight Test Article TPS Thermal Protection System
HXLV Hyper-X Launch Vehicle TVC Thrust Vector Control
IOP Ignition Over-Pressure VSE Vision for Space Exploration
ISS International Space Station WSMR White Sands Missile Range
KSC Kennedy Space Center
LAS Launch Abort System
LES Launch Escape System Introduction
LEO Low Earth Orbit
LH2 Liquid Hydrogen The United States of America President,
George W. Bush, announced the Vision for
* Manager, Ares Project Implementation Office, NASA Space Exploration (VSE) in January 2004. The
Langley Research Center, Mail Stop 176, Hampton, VA, vision outlines a bold program for space
23681-2199. [email protected] exploration with the following components.1
** Flight and Integrated Test Office, NASA Marshall Space
Flight Center, JP10, Huntsville, AL.
***President, GPS Solutions, Inc., Reno, NV.
[email protected].
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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
• Return the Space Shuttle safely to flight. (This to dock with the EDS and LSAM in LEO prior
objective was accomplished with the STS-114 to trans-Lunar injection (TLI).
and STS-121 return-to-flight missions of the
Space Shuttle Discovery.) Initial development is focused on the Ares I
CLV and the CEV to accomplish the mission for
• Complete the International Space Station crew and cargo delivery to and from the ISS. A
(ISS) and retire the Space Shuttle by the year design reference mission for CEV transport to
2010. the ISS is shown in Figure 1.

Launch Abort
• Develop the Crew Exploration Vehicle (CEV) System Jettison
no later than 2014 (with a goal of 2012) and Main Engine
Cutoff and burn
return to the Moon no later than 2020.
to circularize

orbit
• Implement a sustained and affordable robotic
and human exploration program and extend
human presence across the solar system. Separation
and Booster
The Exploration Systems Architecture Study Burnout
(ESAS) was conducted in the summer of 2005 in
order to define the design reference missions
and vehicle concepts for the CEV, launch Booster
vehicles, and other architectures necessary to Recovery
Launch
accomplish the VSE. The results of the ESAS
study served as the point-of-departure (POD) Figure 1. Design reference mission for CEV
vehicle architecture and the basis of the current access to the ISS.
NASA exploration program. The ESAS
architecture sought to maximize commonality
between missions to the ISS, the Moon, and
Mars. The architecture definition also sought to The ESAS final report further outlined a
separate crew and cargo payloads to the recommended development approach for the
maximum extent possible. components of the CLV, which includes the
following: 2
The major ESAS architecture components
are: • A first stage solid rocket booster (SRB),
derived from a 4-segment Space Shuttle
• A Crew Exploration Vehicle (CEV) will be Reusable Solid Rocket Motor (RSRM). (In
designed to support a crew of four for lunar trade studies conducted following release of
missions. The CEV will also support missions the ESAS final report, the design was modified
to the ISS from its initial operational capability to a Five-Segment Booster (FSB).) The first
through 2016. stage will also include separation and recover
systems, reaction control systems (RCS) for
• A Crew Launch Vehicle (CLV) designed to roll control, and SRB nozzle gimbal capability
launch the CEV into low Earth orbit (LEO). for thrust vector control (TVC).
The CLV is now known as the Ares I launch
vehicle. The major CEV subsystems are the • A new upper stage, powered by a
crew module (CM), service module (SM), and derivative of the Space Shuttle Main Engine
the launch abort system (LAS). (SSME). (Subsequent trade studies modified the
design to a J-2X engine, a derivative of the
• A heavy-lift Cargo Launch Vehicle (CaLV), Saturn V upper stage engine.) The upper stage
now known as the Ares V, designed to launch will also contain LH2 and LO2 fuel tanks,
the additional components needed for lunar avionics, RCS, and other sub-systems.
missions into LEO. These include an Earth
departure stage (EDS) and Lunar surface The integrated Ares I stack also includes the
access module (LSAM). The CEV is designed CEV components. A schematic of the major
Ares I hardware elements is shown in figure 2.

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
Upper Stage Engine
• Saturn J-2 derived
LAS Engine (J-2X) First Stage
CM • Expendable • Derived from Current Shuttle Reusable Solid
Rocket Motor/Booster
• 5-segment Booster
• Polybutadiene Acrylonitride (PBAN) propellant
Upper Stage
• Recoverable
• LOX/LH2 Stage
• New Forward Adapter
• Aluminum-Lithium structures
• RCS/roll control for 1st stage flight
• CLV avionics system
• Inter-stage section
Figure 2. Schematic of the Ares I Launch Vehicle.
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models are matured throughout the
development life cycle along with risk and
reliability assessments. As the design matures, Concept Configuration
uncertainty is systematically quantified and Assessment Trades Certification of
Flight
decreased to acceptable levels within design Readiness
margins. Certification of flight readiness is Fidelity • Uncertainties
Assessment • Critical Parameters
predicated on the ability to validate that system
• Key Risks
requirements have been met, uncertainties have
been quantified, and remaining risks are well T&V Risk and
understood and accepted. Requirements Reliability
Analyses
Model Fidelity
Increases with
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Figure 3. Notional “Concept-to-Flight” Process.

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
discovered during prior testing. Verification proximity aerodynamic testing to approximate
testing during this stage typically supports the stage separation conditions. Test data were
critical design review (CDR). supplemented with computational fluid dynamics
(CFD) and engineering code predictions. The
Flight testing may be performed during final aerodynamic and propulsion data bases
the development stage if system requirements were validated through comparisons with flight
cannot be validated, or risks and uncertainties data.5
fully quantified, through analysis and ground
testing. The benefits of flight testing may be The development stage is followed by
driven by the limitations of test facilities to the manufacturing and qualification of flight
simulate flight environments, limitations of scale hardware. During this stage, flight or flight-type
models to adequately simulate flight-like hardware is verified to meet functional,
responses, limitations in engineering models to performance, and design requirements. Flight
approximate flight conditions, and/or inability of verification tests are formal tests with a defined
engineering models to simulate complex qualification margin as part of the certification
physical interactions necessary to fully evaluate program.
key aspects of the system design.
ESAS Recommended Flight Test Program
A recent example of the use of analysis,
ground test, and flight test to mature engineering The ESAS final report made
models and predictive tools is the NASA X-43 recommendations for a flight test program that
Hypersonic Flight Demonstration Program included development and qualification testing of
(Hyper-X). The X-43 program demonstrated the Ares I CLV, the LAS, and the CEV crew
airframe-integrated supersonic combustion module. The ESAS-recommended test program
ramjet (SCRAMJET) propulsion in flight at Mach serves a baseline to mature possible flight test
7 and Mach 10 test conditions. The rationale for strategies for Ares I.
a hypersonic airbreathing flight demonstration
was that the correct aerothermodynamic and The ESAS report recommended a single
supersonic combustion environments could not development flight test, known as risk reduction
be adequately simulated in ground test facilities. flight 1 (RRF-1).6 The RRF-1 flight was
Flight data were required to fully validate recommended as a first stage ascent
engineering models used to predict scramjet performance test with a mass simulator upper
performance. The X-43 flight program included stage, representative CEV test article, and
significant ground testing and analyses to build booster recovery systems. The objectives of the
aero-propulsive performance databases to cover RRF-1 were to demonstrate first stage
the boost, stage separation, and powered test performance, stage separation, and SRB re-
phases of the flight, as depicted in figure 4. entry and recovery; and to obtain data to
Ground tests included un-powered scaled validate engineering models for structural loads,
aerodynamic models, sub-scale and full-scale acoustics, and aerodynamics. RRF-1 test
tip-to-tail propulsion flowpath tests, and static objectives also included demonstration of launch

Launch Vehicle
Aerodynamics
Performance

Flight Validation of Integrated
Aero-Propulsive Model

Comparison of prediction,
ground test, and flight data
Aerodynamic Coefficients
Stability Derivatives
Uncertainty Margins
Repeatability Assessments
Engine Performance Stage Separation
Figure 4. Flight validation of hypersonic airbreathing aero-propulsive models through the X-43
Hyper-X Flight Demonstration program.

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
vehicle sub-systems, such as avionics, thrust- Apollo/Saturn V Development
vector control (TVC), and reaction-control
systems (RCS). The recommended schedule The Saturn V launch vehicle was
however, was to conduct the RRF-1 flight after developed by the United States in the 1960’s to
the Ares I system CDR. Significant risk would be support the Apollo lunar exploration missions.
incurred if the results of flight testing showed Development of the Saturn V utilized a “building
that design changes were needed since the block” approach with many development flight
program would be well into the manufacturing vehicles prior to certification testing and human
phase by that time. Thus, the Ares I program flight.7 A summary of early Saturn flights with a
examined strategies for earlier flight testing. comparison to the ESAS baseline test strategy
and schedule if illustrated in figure 5.
The ESAS recommended flight test
program also included two certification flights The original Saturn I flew 4 sub-orbital
prior to the first crewed mission to the ISS. The test series flights, also known as “block 1”
successive RRF-2 and RRF-3 flights were flights. The block-1 flights, identified in the figure
recommended with increasing configuration as SA-1 through SA-4, included an inert upper
fidelity and test objectives. A production launch stage, known as the S-IV. Each of these tests
abort system, final flight control system, crew were conducted as first-stage ascent tests up to
module and service module systems, crew the booster burnout point, but did not test stage
module re-entry and recovery systems, and separation of the S-IV. The block-1 tests
upper stage engines would eventually be validated ascent performance of the first stage,
included in order to certify the design for human structural loads, and functionality of gimbaled
flight. nozzles on the outboard engines for vehicle
stability and control. The SA-4 flight included an
Alternative strategies for Ares I flight intentional check-out of engine-out capability,
testing were formulated by examining the with 7 out of 8 engines operating.
following:
The Block II flights, identified in the
• History of other launch vehicle development figure as SA-5 through SA-10, included a
programs, such as the Saturn V and the functional S-IV upper stage. The SA-5 flight was
Space Shuttle. the first orbital vehicle, delivering a prototype
crew module to orbit. Each of the SA-6 through
• Ares I technical risks that may not be SA-10 flights carried prototype crew modules
adequately mitigated through ground testing and the SA-6 carried the first crew module into
and analyses during the development orbit. The SA-6 and SA-7 tests also jettisoned
phase. the launch escape system (LES) after crew
module separation from the upper stage. Among
• Timetable for acquisition of flight test assets, other objectives, the block II Saturn I tests also
including boosters, upper stages, confirmed flight control, propulsion performance,
subsystems, and launch site infrastructure and structural loads.
needs.
The next phase of Saturn development
• Appropriate phasing of launch vehicle, CEV, included four un-crewed SI-B flight tests. These
and LAS flight test objectives. were prototypes of the Saturn V launch vehicle
and included a functional S-IV-B upper stage,
powered by a J-2 engine. Test objectives
Lessons Learned included qualification of prototype crew module
(CM) and lunar module hardware. The CM
Previous launch vehicle development separated and returned to Earth, thus also
programs for human space flight may be testing the thermal protection system (TPS). The
examined in order to assess potential strategies second SI-B flight included a re-ignition of the S-
for Ares I development flight testing. IV-B upper stage engine in orbit.

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
2004 2005 2006 2007 2008 2009 2010 2011 2012
LAS LAS
Vision ESAS LAS DFT 2 3 RRF RRFRRF ISS
Speech Roll-Out 1 1 1 2 3 1
1957 1958 1959 1960 1961 1962 1963 1964 1965
1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4 1 2 3 4
Kennedy 5/25 11/7 5/13 12/8 5/1 6/2
Apollo LES Sputnik Speech
PA-1 A-001 A-002 A-003 PA-2
“…before this
Saturn decade 10/2 4/2 11/1 3/2 1/2
1 ATP Is out…” SA-1 SA-2 SA-3 SA-4 SA-45
Saturn I SO SO SO SO SO
5/2 9/1 2/1 5/2 7/3
SA- SA- SA-98 10
6 7
Saturn I flew 4 times before adding an upper stage
Saturn IB Saturn I flew 6 times with S-IV before moving to S-IVB
Saturn IB flew 4 times before first crewed flight
SaturnVflew2timesbeforefirstmannedflight
Figure 5. Comparison of ESAS-recommended Ares I development program with Saturn launch vehicle
development.
An extensive series of tests was also
conducted for the Apollo LES, also shown in SSppaaccee SShhuuttttllee DDeevveellooppmmeenntt
figure 5.8 This test series included two pad abort
tests at the White Sands Missile Range (WSMR) The Space Transportation System (STS),
in 1963 and 1965. As mentioned previously, the also known as the Space Shuttle, conducted
Saturn I SA-6 and SA-7 tested a nominal LES four ascent test flights of the Shuttle system,
jettison mode after CM separation and orbital designated STS-1 through STS-4. The key sub-
insertion. There were no additional tests of LES system elements of the Space Shuttle are
functionality for post upper stage separation shown in figure 7. The main payload on the
abort modes (following first stage burnout). The STS-1 flight, conducted in 1981, was a
“Little Joe” test program utilized a booster to test development flight instrumentation (DFI)
the LES at transonic, maximum dynamic
pressure, low altitude, and power-on tumbling
boundary abort conditions. The latter condition
Launch
was designed to demonstrate the ability of the
Escape
LES canard system to re-orient and stabilize the Tower
heat shield after a power-on tumbling abort.
Prototype
Figure 6 shows a photograph of the abort test Crew
booster. module
Test
A key point in the Saturn flight series is Booster
the premise of keeping flight test objectives to a
minimum in early tests and building test
objectives with successive flights. Additional
flight test objectives were added during the
program once the key building blocks were well
understood. The program utilized sub-orbital
tteessttss ffiirrssttss bbeeffoorree aaddddiinngg ssttaaggee sseeppaarraattiioonn,,
uuppppeerr ssttaaggee pprrooppuullssiioonn,, ccrreeww mmoodduullee,, aanndd Figure 6. Apollo Launch Escape System
llaauunncchh eessccaappee tteesstt oobbjjeeccttiivveess.. (LES) testing.

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
package to measure temperatures, pressures, pressurization. A re-designed water-spray
and accelerometer levels on the vehicle. system achieved significant reductions in
Correlation of engineering models, developed IOP for STS-2.
through ground testing, analyses, and
component flight tests, with the DFI data was • Inadequate modeling of plume interactions
key in declaring the Shuttle “operational” after between the SSMEs and SRBs led to
the STS-4 flight. The Shuttle test flight series significant differences in longitudinal forces
was unique in that these flights were crewed. and moments on STS-1 compared to pre-
flight predictions. As a result, the Shuttle
was approximately 10,000 feet higher at
External Tank
SRB separation than the nominal flight
profile. The ascent trajectory was altered
with a greater negative angle of attack
through the maximum dynamic pressure in
Reusable Solid
Rocket Motors order to correct this anomaly, but the
change in flight trajectory resulted in a
5,000-lbm reduction in payload capability.
Shuttle Orbiter
• STS early flight data indicated significantly
Space Shuttle higher buffet response on the vertical tail
Main Engines
and body flap during transonic speeds.
Fortunately, both components had sufficient
design margin to accommodate increased
buffet loads, but ascent environments were
updated based on flight measurements.

• Coupling with the liquid oxygen (LOx) tank
Figure 7. Components of the Space Shuttle slosh modes led to differences in 1st-mode
System. bending frequencies compared to pre-flight
predictions.
Prior to STS-1, the Shuttle conducted

extensive test programs on the re-useable solid
• There was an ascent performance shortfall
rocket motors (RSRM), the external tank, and
of approximately 10,000-lbm as a result of
the space shuttle main engines.9 Structural
loads increases, inaccurate aerodynamic
dynamics verification was accomplished through
predictions, and other flight environment
scaled testing, analysis, and a full-scale mated
measurements compared to design
ground vibration test (MGVT).10 Six drop tests
predictions. A Shuttle enhancement program
were also conducted for the RSRMs to qualify
subsequently realized back some payload
the deceleration subsystem (DSS). The Shuttle
capability gains with changes to the space
orbiter was also subjected to an extensive entry,
shuttle main engines, external tank, and
descent, and landing (EDL) program.11
RSRMs; as well as Orbiter weight

reductions.
Lessons learned from the early shuttle

flights demonstrate the significance of
Other Flight Programs
engineering model validation and impacts to the

flight vehicle design.12,13 Examples and findings
The first flight of the X-43 ended with a
and subsequent design changes to the Space
failure of the booster to deliver the X-43 vehicle
Shuttle based on early flight history, include the
to the Mach 7 test condition. The Hyper-X
following:
Launch Vehicle (HXLV) failure occurred due to a

control anomaly, characterized by diverging roll
• Accelerations measured on the Shuttle
oscillation, during the transonic pull-up
orbiter during STS-1 showed that ignition maneuver.14 The major contributors were found
over-pressure (IOP) exceeded the 3-sigma
to be modeling inaccuracies in the fin actuation
liftoff design environments. Tile damage was
system and aerodynamics, and insufficient
also observed on the Orbiter during post-
variations of modeling parameters via
flight inspections as a result of over-
parametric uncertainty analyses. The

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
aerodynamic modeling uncertainties resulted appropriate scale and to obtain flight
from misinterpretation of ground test data due to measurements for descent aerodynamics, flight
insufficient data, especially in regions where dynamics, thermal, and structural models
non-linear effects may dominate, and un- through parachute deployment and recovery.
modeled outer mold line changes associated Inclusion of stage separation test objectives will
with the thermal protection system (TPS). The also provide flight measurements for proximity
flight mishap could only be re-produced when all aerodynamics and environments in the vicinity of
of the modeling inaccuracies with uncertainty the J-2X engine following separation (to validate
variations were incorporated in the simulation altitude starting conditions). Upper stage flight
models conducted during the mishap dynamics and structural stability after separation
investigation. After performing additional ground can also be measured.
testing and making changes to the booster, fin
actuation system, flight control system, and flight Since the integrated Ares I launch
profile, the X-43 was able to successfully return vehicle stack includes the CEV crew module,
to flight. service module, and LAS, test objectives for
these systems may also be considered in Ares I
Ares I Risk Reduction Objectives Development Flight Test (DFT) planning. The
LAS must function successfully from pre-launch
Key factors in determining development conditions through orbital insertion. During
flight test strategies are the technical risks that ascent, key points which may require validation
may be candidates for risk mitigation through of LAS functionality include maximum dynamic
flight testing. pressure condition, transonic conditions, and
high-altitude (post stage separation) abort.
The five-segment solid rocket booster Demonstration of the high-altitude abort
(FSB), which forms the first stage of the Ares I, scenario from the upper stage could be included
will be a new flight system derived from heritage as a flight test objective along with Ares I test
Space Shuttle hardware. Significant hardware objectives. CEV test objectives may also include
developments are required to upgrade the aerodynamic performance, stability and control;
existing four-segment SRB. These include the TPS survivability; and functionality of landing
addition of a fifth propellant segment, new and recovery systems following abort scenario
propellant grain structure, new structural demonstration.
subsystems, new electrical and instrumentation
systems, and new separation and deceleration Successfully establishing operational
subsystems. The FSB integration with the Ares I capability of the Ares I necessitates the need for
launch vehicle system is significantly different new ground processing, launch operations,
than the STS. The Ares I “in-line” concept will infrastructure, and processes. Ares I ground
lead to low bending mode frequencies, which in processing and launch operations will be
turn will present significant challenges for the conducted from NASA Kennedy Space Center
flight control system design and validation. (KSC) in Cape Canaveral, Florida. Development
Additionally, the SRB nozzles are used to flight testing provides an opportunity to become
provide thrust-vector control (TVC) for pitch familiar with ground operations for a new vehicle
stability and reaction control systems (RCS) are and make improvements before certification and
used for roll stability on ascent. Validation of roll operational status.
torque to size and qualify RCS systems is a key
technical risk which could be mitigated with flight One of the key benefits of flight testing
measurements. is that it provides simultaneous testing in a real
environment of multiple subsystems and
Stage separation of the Upper Stage complex interactions which cannot be
occurs after first stage burnout. The Ares I flight adequately modeled in engineering analyses or
profile has a stage separation point at a higher ground test facilities. Figure 8 shows a notional
Mach number and altitude, and a lower dynamic illustration of how integrated engineering models
pressure, than the current Shuttle system. for aerodynamic, thermal, structural, and control
Therefore, re-design of deceleration and system performance through first stage ascent,
recovery systems will be required. Flight testing stage separation, and booster descent and
provides an opportunity to demonstrate new recovery may be developed through ground
deceleration and recovery systems at

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
♦ Vehicle Environments ♦ Structural Integration
• Wind Tunnel Test Data • Analysis of load paths, dynamics.
• Loads, Thermal Environment • Component-level modal testing.
Predictions • Aeroelasticity Wind Tunnel Test and
• Pre-Flight Databases Analysis.
Flight Validation of Integrated
Aero, Structures, and
Performance Models
Comparison of prediction, ground test,
and flight data
♦ First Stage Performance ♦ Stage Separation
• Propulsion performance. • Static and Time-Dependent CFD.
• Flight control laws. • Quasi-static Wind-Tunnel testing for
• TVC Models. interference aero.
• Roll Torque Predictions and RCS • Descent Aerodynamic and Thermal
Models. Loads.
• Parachute Deployment Models and
Testing
Figure 8. Integration of vehicle engineering models through ground testing and analysis with flight test
validation through first stage ascent, stage separation, and booster descent and recovery.
testing and analysis, and validated through flight • First stage ascent performance, including
measurements. measurement of roll torque, validation of the
basic flight control system methodology, and
measurement of flight data to validate
Options for Ares I CLV Flight Testing aerodynamic, thermal, structural, and other
engineering models.
The VSE established an objective of
conducting the first crewed mission of the CEV • Stage separation, including proximity
to the ISS no later than 2014, but with a goal of aerodynamics, and measurement of
2012. Developmental flight testing with the goal environments for the upper stage engine
of informing the Ares I design process is of through separation.
optimal value if conducted prior to the critical
design review CDR. Therefore, strategies for • Demonstration of FSB descent, deceleration
early flight testing focus on windows of systems, and recovery operations.
opportunity in late 2008 or early 2009.
Assessments of flight test options must weigh • Demonstration of upper stage un-powered
the technical value of performing a flight test and powered performance after separation.
with the associated schedule, budget, and
technical risks.
• Demonstration of LAS functionality after

stage separation.
Phasing of Ares I, LAS, and CEV flight

test objectives may be considered in order to
• Demonstration of CEV re-entry, descent,
provide the best approach for development of
and landing following crew module
each system. Based on assessments of Ares I
separation.
technical risks, the following possible test

objectives may be formulated.
There are multiple options for a first

stage flight test booster to achieve development
test objectives. These include an existing 4-

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NASA CREW LAUNCH VEHICLE FLIGHT TEST OPTIONS
segment RSRM, obtained from the Shuttle • An Inert upper stage, with both a functional
program, a prototype FSB, or various hybrid LAS and a prototype crew module, which
options. The advantage of a flight test would demonstrate functionality of the CEV
configuration with the four-segment booster is TPS, RCS, deceleration, and landing
that an initial DFT could be done prior to 2009 systems for the CEV after a high-altitude
without significant risk. However, there would abort and subsequent re-entry and landing.
significant differences in first stage performance
compared to the Ares I operational vehicle with • A prototype upper stage that would validate
an FSB. Development of a prototype FSB for structural integration with flight-like structural
flight testing prior to CDR would be challenging sub-systems, fuel tanks, and load paths.
from both a schedule and budget perspective. A
5-segment engineering test motor (ETM) is • A prototype upper stage engine which would
available from ground test programs.15 The ETM enable demonstration of second-stage
may provide more representative boost performance up to orbital insertion.
performance than a 4-segment RSRM, but
would require a substantial effort to re-configure Implementing each of these options, with the
the test article as a flight system. A hybrid option exception of the fully inert mass simulator
is to utilize an existing 4-segment RSRM with an option, would likely require designs and sub-
added inert segment. This option is referred to systems that would not be mature enough by the
as the 4-segment XL booster. Preliminary Ares I CDR to conduct a meaningful test. The
analysis shows that this configuration would mass simulator option represents a reasonable
provide a representative dynamic response, level of technical, budget, and schedule risk for
which would provide a meaningful test of a an initial DFT. Higher-fidelity booster and upper
prototype Ares I control system. The 4-segment stage designs could be utilized in subsequent
XL option does not match the aerodynamics, flight tests as sub-systems are matured and
trajectory, and ascent performance of the FSB, additional test objectives are added.
but does provide the capability to match a
limited number of specific trajectory points. Therefore, the optimal strategy is to
conduct an initial Ares I DFT before mid-2009 to
Several options also exist for upper provide a representative test of the first stage
stage DFT flight test articles (FTA). Any FTA booster performance, separation, and recovery,
design should replicate the outer mold line as illustrated in figure 9. Such a development
(OML) and mass properties of the Ares I flight test would also obtain data to validate the Ares I
vehicle configuration in order to provide flight control system design as well as
meaningful flight data to validate aerodynamic aerodynamic, structural, and thermal models.
and structural models. However, the upper stage Additional test objectives will be added in
FTA need not include all flight-like sub-systems subsequent flights.
in order to achieve the basic test objectives of
demonstrating first stage performance and Ares I-1 Flight Test Strategy
control system functionality. Options for upper
stage FTA design and development are based The first Ares I DFT, now known as Ares
primarily on the inclusion of post-separation test I-1, will utilize the 4-segment XL booster option
objectives. The options include the following.

• Inert simulators for the upper stage, CEV, Post-Separation
and LAS. This design concept assumes no Flight Data
post-separation test objectives.
SRB Re-Entry
Separation
• Inert simulators for the upper stage and Flight Data
CEV, and a functional LAS that would
Ascent
demonstrate the high-altitude abort scenario Performance Data
by separating the crew module from the
Launch SRB Upper Stage /
upper stage after first stage burnout and
from Recovery CEV Impact
stage separation. KSCLC-39

Figure 9. Reference mission concept for
initial Ares I development flight test.

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