Vol 3 No 3
January 2002
Ground Testing Technical Committee
CONTENTS
2 Outstanding Papers
3 Membership
4 Subcommittee News
6 Working Group News
7 GTTC Student Contest
8 Ground Testing News
17 Special Topics
18 Committee News
19 GTTC Calendar
20 Membership Information
Six-percent-scale X–37 model undergoes
wind tunnel testing in AEDC’s Tunnel A
(see p. 11).
Vice-Chairman’s Message
Greetings and welcome to this, the thirteenth edition of the
Ground Testing Technical Committee (GTTC) newsletter. For
the past 7 years, we have been using the newsletter as a way
to tell the ground testing community about the GTTC and to
highlight the work of its members. The GTTC is one of over 60
technical committees sponsored by the American Institute of
Aeronautics and Astronautics (AIAA). The GTTC is made up of
about 35 professionals (or more, counting associate and
international members) working in various areas of the ground
testing world. Our membership addresses important technical
issues that affect ground testing through several means,
including the development of guides and standards,
dissemination of information through technical sessions at
conferences, and the development and sponsorship of short
courses. The GTTC has also had good participation in
Congressional Visits Day, which is a vital tool for ensuring
that aeronautics and space-related research and testing is
supported at the required levels.
As you read through this newsletter, you will get an overview
of the various activities sponsored by the GTTC. One of the
primary functions of every technical committee is the
sponsorship and development of conferences and technical
sessions. The GTTC supports two conferences each year. Every
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January, the GTTC meets at the Aerospace Sciences Meeting,
where we have a dozen or so technical sessions. In the summer,
the GTTC alternates between the Joint Propulsion Conference
(odd-numbered years) and the Advanced Measurement
Technology and Ground Testing Conference (even-numbered
years). There isn’t enough space here to list all of the great
things being done in the subcommittees, like Publications and
Student Activities, but the information is inside; just keep
reading.
Over the past decade, the GTTC has been very active in attacking
specific technical issues through several working groups. The
working groups are chaired by a GTTC member, but the makeup
of these groups includes both GTTC members and experts from
outside the GTTC. The working groups are addressing issues
and development guides in the areas of wind tunnel calibration
and flow quality, internal balance calibration, and test
processes and thrust stands. Documents from the wind tunnel
calibration, internal balances, and test processes working
groups are currently going through peer reviews and will
hopefully be published soon.
As you can see, the most important part of the GTTC is the
membership. Without the dedicated professionals that staff
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January 2002
Ground Testing Technical Committee
the various committees and working groups, the GTTC could
not make the contribution that it does to the ground testing
community. Therefore, I’d like to take this opportunity to say
thanks to all of the GTTC members for a job well done.
If you have questions or comments about the GTTC, or are
interested in joining, please feel free to contact me directly at
Earnest.a.Arrington@grc.nasa.gov or by telephone at 216–433–
8507, or check out our web site (www.lions.odu.edu/
~dlandman/gttchome.html).
This is a transition month for the GTTC, where the gavel is
passed from the current chair to the chair-elect. Dan Marren
will be leaving the GTTC after the Reno meeting after nearly a
decade of service (he joined as an associate member, has led
several committees, and has been a part of the GTTC leadership
for the past 5 years). Dan has done a lot to promote the GTTC
and has been instrumental in many of the successes we have
had. Thanks, Dan, for your time and leadership.
testing that demonstrates outstanding research,
documentation, and presentation. The primary criteria are
technical quality and relevance to aerospace systems ground
testing. Chosen papers are recommended for publication in
the appropriate AIAA journals and the authors are presented
with a certificate recognizing their achievement.
2001 Ground Tes ting Award Presented to
Dr. Donald Wilson
The 2001 AIAA Ground Testing Award was presented at the
37th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and
Exhibit in Salt Lake City, Utah, in July 2001. The recipient was
Dr. Donald R. Wilson, professor and chairman of the
Department of Mechanical and Aerospace Engineering at the
University of Texas at Arlington.
Outstanding Ground Testing Papers From the
37th AIAA/ASME/SAE/ASEE Joint Propulsion
Conference and Exhibit
Established in 1975, this award is presented for outstanding
achievement in the development or effective utilization of
technology, procedures, facilities, or modeling techniques for
flight simulation, space simulation, propulsion testing,
aerodynamic testing, or other ground testing associated with
aeronautics and astronautics.
The GTTC is pleased to announce the selection of three
Outstanding Papers from the 37th AIAA/ASME/SAE/ASEE
Joint Propulsion Conference and Exhibit in Salt Lake City, Utah,
in July 2001. Three papers were selected as outstanding:
The citation for this award is as follows: “For the founding and
development of a comprehensive aerospace ground testing and
research center and educating a new generation of aerospace
professionals.”
“A Survey of Development Test Programs for LOX/Kerosene
Rocket Engines” (AIAA–2001–3985). J.L. Emdee, The Aerospace
Corporation.
We extend our congratulations to Dr. Wilson on his
outstanding achievement.
“Development of a Bellmouth Airflow Measurement Technique
for Turbine Engine Ground Test Facilities” (AIAA–2001–3676).
D.K. Beale, T.L. Hand, and C.L. Sebourn, Sverdrup Technology,
Inc., Arnold Engineering Development Center.
Special Notice: GTTC Elections
“Development of Temperature-Sensitive Paints for High
Temperature Aeropropulsion Applications” (AIAA–2001–3528).
Steven W. Allison and David L. Beshears, Oak Ridge National
Laboratory; and Timothy J. Bencic, NASA Glenn Research
Center.
We extend our congratulations to each of these authors, who
have made a significant contribution to the conference, the
ground testing community, the AIAA, and the aerospace
industry.
At the summer 2001 GTTC meeting, an election for the next
vice chair was conducted. The GTTC leadership operates on a
2-year rotation, with the vice chair (the only directly elected
office) automatically ascending to the chair. While this
requires a 4-year commitment for the vice chair/chair, it does
provide much-needed continuity in the GTTC leadership. The
newly elected GTTC vice chair is Nancy Swinford of Lockheed
Martin.
The GTTC selects papers from each of its conferences to
recognize important work in the field of aerospace ground
The new officers will take over at the next GTTC meeting
(January 2002 in Reno, Nevada). Dan Marren, the current
chair, will pass the gavel to the incoming chair (and current
vice chair), Allen Arrington of QSS at NASA Glenn. Since Nancy
is currently the GTTC secretary, a new secretary has been
appointed. Jean Bianco, also of NASA Glenn, will take over as
GTTC secretary at the January 2002 meeting.
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Vol 3 No 3
January 2002
AIAA/GTTC 2001 Membership
Technical Working Groups
2001 GTTC Officers
Chairman
Dan Marren
301–394–1750
Aerodynamics Subcommittee
Mathew Rueger
314–232–2832
Publications Subcommittee
David Minto
505–679–2133
Test Processes
Mark R. Melanson
817–763–1760
Vice Chairman
Allen Arrington
216–433–8507
Propulsion Subcommittee
Sam Stephens
228–688–7207
Standards Subcommittee
Gregory Addington
937–255–8490
Flow Quality Working Group
Frank Steinle
931–454–7716
Secretary
Nancy Swinford
408–743–1443
Awards Subcommittee
Brent Bates
931–454–4943
Steering Committee
Dan Marren
301–394–1750
Internal Balance Technology
Nancy Swinford
408–743–1443
Conferences Subcommittee
Tom Fetterhoff
931–454–5870
Student Activities Subcommittee
Gregory Addington
937–255–8490
Wind Tunnel Calibration
Methodology
Allen Arrington
216–433–8507
Membership Subcommittee
Allen Arrington
216–433–8507
Dr. Gregory Addington
Tom Aiken
Mark Amundson
Dr. Stephen Arnette
Allen Arrington
Brent Bates
Dr. Thomas Beutner
Jean Bianco
Richard Burrows
Julie Carlile
Ray Castner
Mark Cross
Dr. Georg Eitleberg
Jeffery Emdee
Eric Ernst
Tom Fetterhoff
Jeffrey Haas
Matt Hammond
John Hayes
Dennis Hergert
Dr. Susan T. Hudson
Dr. Jerry Kegelman
Joyel Kerl
John Lafferty
Dr. Drew Landman
Dr. Frank K. Lu
Dr. John Magill
Dan Marren
Dr. Thomas McLaughlin
Mark Melanson
David Minto
Dr. Richard Morgan
Dr. Sreedhara Murthy
Mark Perry
Juergen Quest
Dr. Mark Rennie
Joel Robinson
Mathew L. Rueger
Dr. Frank Steinle
Samuel Stephens
Todd Sterk
Nancy Swinford
Niek Verhaagen
Donald Wagner
Thrust Stands
Ray Castner
216–433–5657
Air Force Research Laboratory/VACA
NASA Ames Research Center
Arnold Engineering Development Center (AEDC)
Manager, Aeronautics Engineering Research/Sverdrup Technology, Inc.
Supervisor, Mechanical Operations/QSS Group, Inc.
Sr. Engineer/Sverdrup Technology, Inc. (AEDC)
Program Manager/Air Force Office of Scientific Research
PSL Facility Manager/NASA Glenn Research Center
Sr. Engineering Specialist/Boeing
Air Force Research Laboratory
NASA Glenn Research Center
Sverdrup Technology, Inc.
German-Dutch Wind Tunnel
The Aerospace Corporation
Cryogenics Testbed Manager/NASA Kennedy Space Center
Arnold Engineering Development Center (AEDC)/XPV
NASA Glenn Research Center
NASA Marshall Space Flight Center
Pratt & Whitney
Sr. Principal Engineer/Boeing Phantom Works
Ass’t. Professor/Mississippi State University, Mechanical Engineering
NASA Langley Research Center
Dynacs Engineering
White Oak (AEDC)
Old Dominion University
Assoc. Professor/University of Texas at Arlington
Physical Sciences, Inc.
Wind Tunnel Projects Manager/White Oak (AEDC)
Aeronautics Research Consultant/U.S. Air Force Academy
Engineering Chief, Model Design/Lockheed Martin Aeronautics
Holloman High Speed Test Track/U.S. Air Force
The University of Queensland
Sverdrup Technology, Inc.
Lead Projects Engineer/Lockheed Martin
European Transonic Wind Tunnel
Aerodynamicist/Aiolos Engineering Corp.
Sverdrup Technology, Inc. (MSFC Group)
Sr. Project Engineer/Boeing
Sr. Engineering Specialist/Sverdrup Technology, Inc. (AEDC)
Lockheed Martin Stennis Operations
Sandia National Laboratory
Manager II PEL, Aero/Fluids Group/Lockheed Martin Space Systems
Sr. Research Scientist/Vortex Aerodynamics and Acoustics
Sverdrup Technology, Inc.
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937–255–8490
650–604–6855
931–454–6513
931–393–6699
216–433–8507
931–454–4943
703–696–6961
216–433–8870
562–797–5651
661–275–5098
216–433–5657
931–454–5952
31–527–24–8521
310–336–7704
407–867–2133
931–454–5870
216–433–5718
256–544–1255
561–796–4397
206–655–4253
662–325–6602
757–864–8022
216–433–2339
301–394–6405
757–683–6008
817–272–2603
978–689–0003
301–394–1750
719–333–2613
817–763–1760
505–679–2133
61–7–33653592
650–604–1593
770–494–5619
49–2203–609–159
416–674–3017
256–544–3513
314–232–2832
931–454–7716
228–688–7207
505–844–4923
408–743–1443
31–15–278–6385
931–393–6407
gregory.addington@va.afrl.af.mil
taiken@mail.arc.nasa.gov
Mark.Amundson@arnold.af.mil
arnettsa@sverdrup.com
earnest.a.arrington@grc.nasa.gov
brent.bates@arnold.af.mil
tom.beutner@afosr.af.mil
jean.bianco@grc.nasa.gov
richard.burrows@west.boeing.com
julie.carlile@ple.af.mil
raymond.s.castner@grc.nasa.gov
mark.cross@arnold.af.mil
georg-e@nlr.nl
jeffery.l.emdee@aero.org
eric.ernst-1@ksc.nasa.gov
thomas.fetterhoff@arnold.af.mil
jeffrey.e.haas@grc.nasa.gov
matt.hammond@msfc.nasa.gov
hayesjoh@pwfl.com
dennis.w.hergert@boeing.com
hudson@me.msstate.edu
j.t.kegelman@larc.nasa.gov
joyel.kerl@grc.nasa.gov
john.lafferty@arnold.af.mil
dlandman@.odu.edu
lu@mae.uta.edu
magill@psicorp.com
dan.marren@arnold.af.mil
tom.mclaughlin@usafa.af.mil
mark.r.melanson@lmco.com
dave.minto@46tg.af.mil
morgan@mech.uq.edu.au
smurthy@mail.arc.nasa.gov
mark.l.perry@lmco.com
j.quest@netcologne.de
mark@aiolos.com
joel.robinson@msfc.nasa.gov
mathew.l.rueger@boeing.com
frank.steinle@arnold.af.mil
samuel.stephens@ssc.nasa.gov
tmsterk@sandia.gov
nancy.swinford@lmco.com
n.g.verhaagen@lr.tudelft.nl
wagnerda@sverdrup.com
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January 2002
GTTC Subcommittee News
The GTTC subcommittees are the backbone of our organization and create opportunities for the GTTC members to get involved
with the workings of this AIAA Technical Committee. The GTTC is subdivided into two primary subcommittees, Aerodynamics and
Propulsion. Each GTTC member is assigned to one of these primary subcommittees.
Membership in other GTTC subcommittees depends upon the member’s interest (for the Liaison, Publications, Standards, Student
Activities, and Awards and Upgrades subcommittees) or the office held within the GTTC (for the Steering, Conferences, and
Membership subcommittees).
If you have an interest in a specific subcommittee, please feel free to attend the next meeting. GTTC subcommittee meetings
coincide with GTTC-supported conferences. Specific dates, times, and locations can be found in the conference registration materials.
Steering Subcommittee
The Steering Subcommittee reviews GTTC policy, AIAA business,
and all matters of general interest to GTTC members. The
Steering Subcommittee is headed by the GTTC chair and
includes the vice chair, secretary, and all subcommittee chairs.
The success of our technical committee has been recognized
by AIAA Headquarters. The GTTC has prepared and presented
AIAA training sessions for new technical committee
chairpersons.
Dan Marren
White Oak (AEDC)
a related AIAA publication, “Guide for Assessing Experimental
Uncertainty—Supplement to AIAA S–071A–1999.” This
document will provide additional information and examples
to assist the experimenter in applying uncertainty analysis
techniques and performing an uncertainty analysis. The
information contained in the standard and this guide is not
limited to wind tunnel testing and can be applied to a wide
range of experiments.
Gregory Addington
Air Force Research Laboratory
Membership Subcommittee
Aerodynamics Subcommittee
The Membership Subcommittee, which comprises the vice
chair of the GTTC and vice chairs of the Aerodynamics and
Propulsion subcommittees, tries to provide a balance in
technical background and represented organizations when
reviewing applications for new members. Selected new
members are notified in March. Applicants who are not
selected in 1 year are eligible for consideration the following
year. The large number of applications to the GTTC has created
a considerable pool of eligible representatives from all arenas
of the aerospace community.
Allen Arrington
QSS Group, Inc.
The Aerodynamics Subcommittee promotes the advancement
of aerodynamic ground testing technology. Members of this
committee serve as liaisons to several other committees, such
as the High-Speed Civil Transport Coordination Committee,
the Thermophysics Technical Committee, the Applied
Aerodynamics Technical Committee, and the Institute for
Aerospace Research of the National Research Council of
Canada.
Mathew Rueger
Boeing
Conference Planning Subcommittee
The Standards Subcommittee consists of members from both
the Aerodynamics and Propulsion subcommittees. It promotes
the understanding of ground testing, the standardization of
uncertainty analysis methodology, and the widespread use of
uncertainty analysis techniques. Recently, the subcommittee
published a revision to AIAA Standard S–071A–1999,
“Assessment of Experimental Uncertainty with Application to
Wind Tunnel Testing.” The subcommittee is now working on
The Conference Planning Subcommittee, as its name implies,
plans and organizes GTTC conferences and sessions. The GTTC
sponsors a biennial ground test technical conference and also
supports two annual AIAA conferences with ground testing
sessions. Beginning in 1996, the conference has also been
supported by the AIAA Aerodynamic Measurements Technical
Committee as the Advanced Measurement Technology and
Ground Testing Conference. These conferences are typically
collocated with other AIAA technical conferences held in the
early summer months.
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GTTC Subcommittee News
The committee also plans and organizes the GTTC-sponsored
sessions for the annual Aerospace Sciences Meeting in January
and the Joint Propulsion Conference in the summer (on oddnumbered years only). Planning and organizing activities
include electing conference chairs; selecting session
chairpersons, the conference program, and the site and meeting
room; preparing the Call for Papers; and planning of
coordinated short courses, tours, luncheons, special exhibits,
and so forth.
Tom Fetterhoff
Arnold Engineering Development Center
of the AEDC) in June 2000 at the 21st AIAA Advanced
Measurement Technology and Ground Testing Conference in
Denver.
The Outstanding Paper Award recognizes the technical quality,
technical relevance, presentation, and readability of papers
presented at the various GTTC sessions. Three papers from the
39th AIAA Aerospace Sciences Meeting were given this award.
Brent Bates
Sverdrup Technology, Inc. (AEDC)
Publications Subcommittee
Propulsion Subcommittee
The Propulsion Subcommittee promotes the advancement of
ground testing technology related to aeropropulsion systems.
Members of this committee serve as liaisons to several other
committees such as the Propulsion Technical Committee, the
Turbine Test Facility Working Group, and the Turbine Engine
Testing Working Group.
Sam Stephens
Lockheed Martin Stennis Operations
Liaisons Subcommittee
The Liaisons Subcommittee was formed to foster
communications with AIAA Headquarters, other AIAA
technical committees, and independent societies and
organizations. GTTC members are encouraged to become
liaisons to groups that share their professional interests.
Representatives of liaison organizations are invited to attend
GTTC meetings and exchange information with members to
our mutual benefit. These exchanges may include sharing of
administrative methods, participation in joint endeavors and
innovative projects, or information about conferences and
technical programs. Liaison reports are summarized in a
standard format and published as addenda to the GTTC
minutes.
Dan Marren
White Oak (AEDC)
Awards and Upgrades Subcommittee
The Awards and Upgrades Subcommittee coordinates and
participates in the selection process for the annual Ground
Testing Award presented by AIAA. This award is presented for
outstanding achievement in the ground testing field. The 2000
Ground Testing Award was presented to Travis Binion (formerly
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The Publications Subcommittee promotes the efforts of the
various GTTC subcommittees through dissemination and
publication of technical information, journal articles, and use
of other forms of media.
In addition to the annual Aerospace America Highlights article,
the committee is responsible for preparing and publishing the
GTTC Newsletter and maintaining the technical committee’s
web site. Ground testing-related articles and news items for
use in Aerospace America Highlights and the GTTC Newsletter
are solicited from current and former GTTC members and
others in the ground testing community.
David Minto
Holloman High Speed Test Track/U.S. Air Force
Student Activities Subcommittee
The Student Activities Subcommittee coordinates a GTTC
Engineering Contest each year for undergraduate and graduate
students. The winners receive honoraria for their efforts, as
well as the chance to attend an AIAA professional conference.
Encourage students at your area universities to submit their
projects by handing out the flyer included in this newsletter
to your sections, and please volunteer to judge the projects
after they have been submitted.
The subcommittee also encourages interaction between GTTC
members and their local schools. New ideas for experiments
and/or testing kits for students who want to learn about flight
and aviation are always needed. Please send your ideas to Drew
Landman, along with any interesting web links on sciencerelated activities you may encounter.
Gregory Addington
Air Force Research Laboratory
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January 2002
GTTC Working Group News
GTTC Working Groups—Addressing Technical Issues
One of the key areas that the GTTC has focused on is the use of working groups to address specific technical issues
of major importance to the ground test community. These working groups are chaired by GTTC members but are
made up of experts from both the GTTC and from the community at large. Not restricting working group
membership to GTTC members allows for more people to get involved and work on a variety of issues. The GTTC
currently sponsors five working groups: Test Processes, Internal Balance Technology, Wind Tunnel Calibration
Methodology, Wind Tunnel Flow Quality, and Thrust Stands. These five groups address very specific topics with
the goal of creating recommended practices documents that will aid the community by helping to move toward
common methods of testing.
The first formal group established under the GTTC was the Test Processes working group in 1992. The group was
originally chartered to look into developing commonality in the design and fabrication of wind tunnel models
(test articles). It soon became apparent that the model and overall test process could not and should not be
decoupled. The focus of the working group was then broadened to investigate best practices for successfully
conducting a wind tunnel test program.
Chairman Mark Melanson (Lockheed Martin) assembled facility owners and operators, test customers, and model
builders to staff the working group. This group developed a two-volume document that highlights best practices
for conducting wind tunnel test programs from start to end. The first volume is an executive summary that
provides an overview of the key elements to successfully planning and executing a wind tunnel test program. The
second volume is the practitioner’s guide and delves into the details of these key best practices. Volume 1 was
completed about 2 years ago and has undergone a thorough review by wind tunnel personnel representing all
disciplines. The draft of volume 2 was finalized at the January 2001 meeting and is currently going through a peer
review. When published, these documents will serve as a valuable reference for any wind tunnel test project
engineer.
The next working group started under the GTTC was the Internal Balance Technology Working Group in 1994. This
working group was founded and chaired by David Cahill (Sverdrup Technology AEDC Group) and has probably
drawn the most attention from the ground test community. The balances group was originally set up to be a
means for the exchange of ideas and information on internal strain gauge balance calibration, but expanded its
scope to cover any topics on internal balance technology. The balance working group attempted to define standards
on several aspects of internal balance application and calibration, a rather daunting task considering that nearly
all of the 20-plus member organizations had very different, if tried-and-true, techniques for balance calibration
and in-tunnel use. The amazing result was that the group was able to develop an agreed-upon standard that all
organizations could and would use for balance calibration and testing. The working group has basically completed
its work and no longer holds meetings. David Cahill is acting as editor of the document and is finalizing the draft
based on inputs from the working group membership. The draft should be ready for peer review in early 2002.
The Wind Tunnel Calibration Methodology Working Group was started in 1996, primarily as a means of sharing
information on tunnel calibration techniques. Allen Arrington (QSS at NASA Glenn) founded and chairs this
working group. The group comprises 15 member organizations, each of which is responsible for the calibration of
their facilities. Because of the wide range of topics pertaining to wind tunnel calibration, the group scoped the
work to concentrate on the empty test section calibration of subsonic and transonic wind tunnels. The working
group members are currently completing the draft of a best practices document on this topic. This document
draws upon the experience of the members to develop the best practices and uses case studies of actual tunnel
calibration procedures to illustrate the methodologies for different types of tunnels. During the June 2001 meeting
at Salt Lake City, the group approved the draft of the recommended practices document. Peer review is underway,
with comments due in November 2001.
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GTTC Working Group News
Related to the tunnel calibration group is the Flow Quality Working Group, which was originally organized in
1998, but was recently reorganized and rechartered by Chairman Frank Steinle (Sverdrup Technology AEDC Group).
Where the tunnel calibration working group is focusing on steady-state calibration and flow quality, the Flow
Quality Working Group is looking into the measurement of unsteady and/or fluctuating parameters, such as
acoustics, turbulence, and pressure. The Flow Quality Working Group is currently researching measurement
methodologies with the intent of providing information to the Wind Tunnel Calibration Methodology Working
Group for inclusion in their best practices document. The Flow Quality Working Group is focusing on defining
recommended practices on the measurement of unsteady pressure, velocity, and temperature.
The fifth working group organized under the GTTC is the Thrust Stands Working Group, which was formed by
Dan Cresci (GASL) in 1998. Leadership of the working group has recently changed, and Ray Castner (NASA Glenn)
has taken over as chair. The Thrust Stands Working Group will be operating similarly to the balances and tunnel
calibration working groups in that it will provide an open forum for the free exchange of information between
the member organizations. Ultimately, the group will be delivering a guide or best practices document on the test
techniques, operations, and/or calibration of thrust stands.
The working groups are just one of many ways the GTTC tries to aid the ground test community. The direct
exchange of information between working group members has already proven very beneficial to participants, and
the documents being published by the groups will have a much wider impact on the community. The GTTC is
always on the lookout for new technical areas to address, so please feel free to contact any GTTC officer or member
if you have a suggestion for a working group. We’ll be happy to help foster any ideas!
GTTC Student Contest
2002 Ground Testing Student Engineering Contest
The Ground Testing Technical Committee, in conjunction with the AIAA Student Programs Office and its numerous
sponsors, is pleased to offer the 2002 Ground Testing Student Engineering Contest. The purpose of this contest is
to provide an opportunity for interested engineering students to broaden their learning and understanding of the
role of ground testing in the aerospace discipline. The winning participant(s) will be awarded $1000 and will be
invited to attend an AIAA professional conference; the second-place participant(s) will be awarded $500.
The contest is open to all junior and senior undergraduate and graduate students in an Accreditation Board for
Engineering and Technology (ABET)-accredited engineering program or an equivalent engineering program offered
by a degree-granting institution recognized by the AIAA. Additional contest rules and instructions may be found
at www.aiaa.org by following the Educational Programs link to Student Design Competitions, or by contacting the
Student Activities Subcommittee chairman, Gregory Addington, at Gregory.Addington@wpafb.af.mil.
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January 2002
GTTC Ground Testing News
Enhanced Twin Sting Rig Now Operational at the
European Transonic Wind Tunnel
Contributed by Juergen Quest
Whenever a model is mounted in a wind tunnel by a
central support sting, the question of bias errors always
has to be addressed. Typical effects may be associated
with support system interference or nonrepresentative
rear fuselage geometry.
A common approach to the problem is to support the
model beneath its wings on twin stings and to split the
fuselage to generate an isolated rear part. The model is
then tested both with and without a central dummy
sting. The resulting differences in the forces measured
on the rear fuselage by an internally mounted strain
gauge balance yield the sting corrections. This technique
is also available at the European Transonic Wind Tunnel
(ET W) and is performed as the standard twin sting rig
investigation. But splitting the fuselage relies on two
basic assumptions: first, that aerodynamic interference
from the twin sting support system does not affect the
measured central sting interference; and second, that
the central sting will only cause negligible perturbations
to the flow forward of the split. Additionally, balancerelated compromises further limit the application of
this technique.
weights. Subsequently, both balances were connected
by a dummy wing to apply combined loadings down to
cryogenic temperatures. The results revealed an excellent
repeatability up to the maximum capacity of 20 kN in
normal and 1.5 kN in axial force. New small heated
inclinomet er pack ages allow a per manent online
determination of the individual incidence of each boom
during testing.
The perturbations generated by the ETSR along the
model axis were investigated by aerodynamic calibration
runs up to M = 0.96, with an axial probe to assess
buoyancy ef fects.
Recently, a test campaign was performed comparing the
two twin sting techniques on the model shown in the
photo. Comparative results were gained up to Reynolds
numbers of about 33 million and Mach numbers around
0.9. A typical medium-term increment repeatability
(dummy sting “on” minus “off”) with a drag of better
than 0.5 drag counts can be quoted.
The system has now been declared fully operational and
is available to clients upon request.
The development of the enhanced twin sting rig (ETSR)
technique shows promise for improving this kind of
testing. With this technique, in contrast to the classical
solution, no split of the fuselage is required, eliminating
comple x and costly modif ication. While t he t est
performance procedure with and without the dummy
sting is obviously retained, the force measurements are
taken over by two identical small-size strain gauge
balances housed in the nose area of the twin booms.
As part of a European research program, two new
c r y o ge n i c s i x - c o mp o n e n t b o o m b a l a n c e s w e re
manufactured and subsequently calibrated in the ET W
calibration machine over a temperature range from
ambient down to 115 K. A comprehensive checkout
procedure based on the applied quality standards of the
company has been developed for these unique tools.
To ensure system integrity, each balance was checked
over its full future operating range in pressure and
temperature in the cryovessel. In addition, each balance
under went an individual calibration at 13 distinct
t emperatures in t he balance calibration machine
followed by validation check loadings using dead
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The turbine performance data collected during the test
was within 1-percent repeatability when compared to
flight test data. Data was collected at 65,000; 55,000;
a n d 4 5 , 0 0 0 f t a n d p rov i d e d d o c u m e n t a t i o n o f
diminishing LPT per for mance wit h reductions in
Reynolds number in an actual engine f light
environment. This activity also provided a data base for
the development of engine analysis codes to be used
for future LPT performance improvements on a broad
class of new turbofan engines.
Second RS-68 Certification Engine Wraps Testing
Contributed by Neil Bosmajian
PW545 High-Altitude Testing at NASA Glenn
Propulsion Systems Laboratory
Contributed by Ray Castner
The PW545 High Altitude Test was intended to develop
a high-altitude data base on small, high-bypass-ratio
engines, including information on both performance
and operability. Industry is interested in the use of highbypass engines for uninhabited aerial vehicles (UAV’s)
to perform high-altitude surveillance. The tests were a
combined ef fort between Pratt & Whitney Canada and
NASA Glenn Research Center. The testing was conducted
in two t est entr ies, designat ed t he Baseline and
Modified Engine entries, Phase 1 and Phase 2,
respectively. The Baseline test objective was to obtain
e n g i n e p e r fo r m a n c e a n d o p e ra b i l i t y d a t a t o t h e
maximum altitude that the basic engine would operate
safely, with only minor modifications to the electronic
control and fuel system. The engine was then modified
as dictated by the Baseline entry and tested to maximize
performance and confirm engine operability to an
altitude of 65,000 ft in the Modified Engine test entry.
Wit h a 375-second roar, the second of two RS-68
certification engines for the Boeing Delta IV program closed
out its hotfire test series at NASA’s Stennis Space Center.
The certification process demonstrated that the specified
manufacturing processes will produce an engine that
performs to requirements. The 14th test on Engine 20001
brings the cumulative total test time to more than 2,500
sec, well beyond the performance that will ever be expected
of the engine in its operational life.
A large portion of this test activity was to collect data
on turbulence levels in the low-pressure turbine (LPT).
Instrumentation to measure the turbulence intensity
was to be an array of infinite tube probes developed by
United Technologies Research Center. NASA Glenn’s
Research Ins tr ument ation and Sensor Technology
Branch used t he t est t o demonstrat e a new hightemperature beam probe, also designed to measure
turbulence intensity. Turbine turbulence levels and
turbine aerodynamic per formance at low Reynolds
numbers was collected and compared t o analytical
models developed by NASA and Pratt & Whitney Canada.
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“It’s awesome to get to this point so fast in the development
of a new rocket engine,” noted Rocketdyne Vice President
and General Manager Byron Wood. “We believe that this
is a good engine that has demonstrated over and over again
its robustness and performance capability. We’re working
hard to give our Air Force customer the same level of
confidence.”
Wind Tunnel Tests Aid in X–37 Design and Future
Flight Tests
Contributed by Danette Duncan and Rick Burrows
Data collected during two series of wind tunnel tests
at the United States Air Force’s Arnold Engineering
Development Center (AEDC) will contribute to the final
design and support of upcoming flight tests for Boeing’s
X–37 advanced technology vehicle.
Conducted for Phase II of Boeing’s X–37 Wind Tunnel
Test Program, the tests occurred in the center’s von
Karman Gas Dynamics Facility wind tunnels.
A 6-percent-scale, final configuration model of the
Boeing X–37 was tested in AEDC’s Tunnel A to examine
the effects of airf low on the vehicle’s aerodynamics at
speeds ranging from Mach 1.5 to 5.0.
Six-percent-scale model of Boeing’s X–37 advanced technology vehicle in
AEDC’s Tunnel C in preparation for wind tunnel tests to provide data
for final design and upcoming flight tests.
“This phase of our wind tunnel test program evaluates
the frozen vehicle lines, or exterior shape,” said Colin
McKinney, a Boeing aerodynamic engineer. “Data from
these tests will be used to generate the final verification
data base from which the flight controls system will be
designed, leading to development of its avionics and
software that flies the vehicle during the autonomous
(self-flying) entry phase.”
D u r i n g t h i s s e c o n d ro u n d o f w i n d t u n n e l t e s t s ,
engineers acquired data in AEDC wind tunnels A, B, and
C to determine aerodynamic jet interaction effects from
plumes of small reaction control system jets located
near the af t (rear) end of a 6-percent-scale vehicle
model. Andy Davenport, AEDC test engineer, said many
vehicles use jets on dif ferent parts of the structure for
attitude control instead of flaps, rudders, or similar
devices. This test entry has given AEDC the opportunity
to conduct testing for vehicles with jet interaction.
“I think the unique thing about this model was its
internal f low system,” Rick Burrows, a Boeing test
engineer said. “Using special plumbing, we routed highpressure air through an AEDC-supplied five-component
force and moment balance. We were able to control and
measure pressures and temperatures of the air and
selectively exhaust the air through each of the jet nozzle
groups. Ability to select and fire a particular nozzle
permitted us to examine the jet plume interaction
effects on the overall aerodynamics of the vehicle.”
Derived from the Air Force’s X–40A, a Boeing prototype
space maneuver vehicle, the X–37 is an offspring of the
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Six-percent-scale X–37 model undergoes wind tunnel testing in AEDC’s Tunnel A.
NASA Pathfinder Program, which focuses on reducing
t he cos t of space access t hrough advanced space
technologies. In December 1998, NASA entered into a
4-year cooperative agreement with the Boeing Company
to develop the Future-X Pathfinder flight demonstrator
vehicle, now known as the X–37.
According to McKinney, the X–40 and X–37 are similar
in some ways, but differ slightly in configuration. An
autonomous (self-flying) vehicle, the X–37 is about 27
ft long and weighs approximately 7,000 lb. Powered by
an AR–2/3 engine, which uses JP–10 jet fuel and
hydrogen peroxide as propellants, the vehicle has a
7,000-lb thrust capacity and currently cont ains no
ascent phase in its program.
“There are two flight test aspects,” McKinney said. “One
is t o release it from a B–52 aircraf t, to check out
approach and landing characteristics. The other flight
test involves taking the X–37 as payload on the Shuttle.
It’s designed to fit in the Shuttle payload bay. The
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Shuttle will deploy the vehicle into space.” A third
option for deployment from an expendable launch
vehicle is under consideration.
The first of several X–37 f light tests from the B–52
aircraft is scheduled for September 2002. According to
NASA officials, two orbital missions are planned, one
in 2002 and the other in 2003. During these missions,
the X–37 will remain in orbit up to 3 weeks before
reentering the Earth’s atmosphere and gliding to a
runway landing.
U.S. Navy Tes ts F/A–18C/D in Old Dominion
University Langley Full-Scale Tunnel
Contributed by Drew Landman
Bihrle Applied Research, Inc., was contracted by the U.S.
Navy to conduct static wind tunnel testing of an F/A–
18C/D model in the Old Dominion University (ODU)
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F–18 model on T-bar in LFST test section.
Langley Full-Scale Tunnel (LFST). Bihrle Applied Research
has been in business for over 25 years and specializes in
static and dynamic wind tunnel testing and analysis, as
well as complete aircraft simulation. The Navy requested
that this static testing be conducted at large angles of attack
and sideslip to augment the existing aerodynamic data base
being utilized for flight simulation.
The LFST was designed and constructed for testing fullscale aircraft by the National Advisory Committee on
Aeronautics in 1931. The open test section is extremely large,
30 by 60 ft2 in area and 56 ft in length. The aerodynamic
data for these tests were acquired in the LFST using the
large model support system. This device comprises two 12ft-high vertical support arms that support a pivoting
horizontal “T-bar.” A sting for mounting the strain gauge
balance and model is attached perpendicular to the
supported portion and is actuated by a hydraulic pushrod.
The pushrod is used to set and maintain the angle of attack
of the model. The entire structure is located in the center
of a turntable. To set a sideslip angle, the turntable, which
is driven by an electric motor, is rotated to the desired
position. The use of this mounting system allows the model
to be tested at up to a 65° angle of attack and ±90° of
sideslip.
order balance interactions were supplied with the balance.
This allowed for full correction of balance interactions
during the data acquisition process. This particular balance
had few load interactions with all errors less than 0.1
percent of full-scale limits. The data reduction process
utilized standard signal amplification and filtering, as well
as analog-to-digital conversion of each of the six balance
data channels and the tunnel dynamic pressure channel. A
time history of 1,000 samples was averaged and the model
tares removed to produce the final aerodynamic force and
moment coefficients. A series of these data points for
various angles of attack and sideslip were measured and
stored for analysis during the testing. The tests were
conducted in a specific order so that the results of previous
tests could be used to determine or modify the next test.
This optimized the test time and ensured the quality of
the measured data.
ODU has been operating the LFST for approximately 4
years under a memorandum of agreement with NASA
Lang le y. Testing has focused on g round vehicles,
primarily the race car industry with some heavy truck
entries. A new sensitive automotive balance became
operational in January of 1998, while upgrades to the
existing external balance facilitated light and heavy
truck testing. Other testing has involved traditional
aerospace vehicles, including subscale aircraft models,
uninhabited aerial vehicles (UAV’s), and propellers.
Architectural testing has also been a small part of the
LFS T t est schedule. An important aspect of ODU’s
operation of the LFST has been the opportunity to give
students practical hands-on experience with wind
tunnel operation, advanced instrument ation, f low
visualization techniques, and dat a acquisition and
analysis.
Large angle aerodynamic force and moment static data were
acquired on a 16-percent scale model of the F/A–18C/D
aircraft. The test model, which was on loan from NASA
Langley Research Center for these tests, was an aluminum
structure with a molded fiberglass skin. A six-component
strain gauge balance, also on loan from NASA Langley, was
used to measure the body axis forces and moments on the
model. The calibration constants and first- and second-
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In preparation for more aircraft model testing in the
LFST, an extensive test section f low sur vey is being
conducted by ODU. Because cars only occupy a small
portion of the test section, previous surveys were not
done over the entire test section. When using the T-bar
model support system and testing at large angles of
attack and sideslip, the test article can move almost 10
ft vertically and either side of the test section centerline.
This latest survey will provide valuable information for
t he correct dat a reduction of measured air plane
aerodynamic force and moment values.
damage to the test section and roll drive. Because of
the estimated cost of the repairs, a thorough costbenefit analysis for repairing the tunnel versus closing
it was done by the NASA Langley Research Center. As a
result of this study, it was determined that not only
should the tunnel be repaired, but it would also be cost
effective to make some significant investments in the
facility over the next few years. Repairs to the facility
were completed in June 2001, and it reopened for
research t esting on June 29. The tunnel has been
performing well since then and has returned to standard
two-shift operation. Currently, the schedule is booked
for FY02.
NASA Langley 16 Foot Transonic Tunnel Back in
Operation
Contributed by Jerry Kegelman
Improvements that have already been incorporated are
a temperature-compensated electronic pressure-sensing
system, a fully operational tunnel automation system,
and a new balance-monitoring system. Planned nearterm improvements are a new PC-based automation
system, a new model support system pitch drive, and
new model mounting hardware.
I n F e b r u a r y 2 0 01, t h e 16 Fo ot Tra n s o n i c Tu n n e l
experienced a model failure that caused major damage
to the tunnel fan blades and catcher screen, and minor
The 16 Foot Transonic Tunnel fan blades after repair.
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conducted on first- and second-stage pusher sleds. The first
full-scale demonstration of the capability will occur in early
2002 and deliver a 180-lb payload to 8500 ft/sec. In the
spring, a 10,000-ft/sec test will be conducted.
MARS 2007 Smart Lander in Langley Unitary Plan
Wind Tunnel
Contributed by Jerry Kegelman
Recent Holloman High Speed Tes t Tr ac k
Programs
Contributed by Dave Minto
During the summer and fall of 2001, the Holloman High
Speed Test Track (HHS TT) conducted test programs
supporting the development of several weapon systems.
The Compact Kinetic Energy Munition (CKEM) is a
lightweight anti-armor weapon being developed by the
Army Aviation and Missile Command. In testing at the
HHSTT, the CKEM was accelerated by a four-stage sled train
to over Mach 5 and then released to impact a rolled
homogeneous armor target. Exacting impact attitude
conditions (less t han 1° of f per pendicular) were
maintained, despite the shock interactions between the sled
and the penetrator.
The Langley Unitary Plan Wind Tunnel (UPW T) recently
conducted tests in support of the Mars 2007 Smart
Lander Project, a planetary exploration mission to Mars
proposed to NASA for launch in 2007. One of t he
requirements for the next generation of Mars Landers
is precision landing, which will allow scientists to reach
specific target landing sites of interest in areas that
would other wise be hazardous to land in safely. To
achieve precision landing, the entry vehicle must be
designed to provide the required lift-to-drag ratio to
steer the vehicle through the Martian atmosphere. In
a d d i t i o n , t h e a e ro d y n a m i c fo rc e s o n t h e ve h i c l e
throughout the atmospheric f light regime (from free
molecular f low to supersonic chute deploy at Mach 1.4
to 2.2) must be known to a high degree of accuracy.
The UPW T operates in a critical portion of this flight
regime and was recently used to define the aerodynamic
forces and moments from Mach 4.6 to supersonic chute
deploy. Computational fluid dynamics (CFD) methods
have also been applied in this speed regime. Modeling
the complex flow field at supersonic speeds, including
Several sled tests of improvements to the Air Force F–15
and F–16 ejection seats were also conducted. The testing
demonstrated improvements to the capability of the
ejection seats at adverse attitudes and higher ejection
velocities. The improvements included arm and leg restraint
systems to prevent injuries caused by limb flail. Additional
testing was conducted to evaluate the effectiveness of the
Army’s Suite of Integrated Infrared Countermeasures
(SIIRCM) on the MH–60 and Apache helicopters. To
evaluate IRCM systems, the HHSTT fires threat missiles at
aircraft that are crossing the test track at altitudes as low
as 50 ft above the ground. Since the track rail restrains the
missiles, very small miss distances can be simulated, and
the missiles appear to be realistic threats to the aircraft.
Development of a 10,000-ft/sec sled test capability in the
Hypersonic Upgrade Program also continued. Testing was
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the significant af tbody inf luence of these aeroshell
d e s i g n s , p o s e s a c h a l l e n ge t o C F D m et h o d o l o g y.
Consequently, the experimental data base derived from
wind tunnel t esting will play a prominent role in
defining the supersonic aerodynamic characteristics of
the precision landers and in validating the predictive
capability of CFD methods..
Vent exit
(closed for zero-boiloff tests)
Large-Scale Demonstration of Liquid Hydrogen
Storage With Zero Boiloff
Contributed by Leon Hastings
Extension of cryogenic propellant storage periods to
months and years has become increasingly important
within NASA, and the prospects for zero-boiloff (ZBO)
storage have improved substantially in recent years.
Analytical trade studies indicate significant weight
b e n e f i t s fo r l o n g - t e r m m i s s i o n s , a s we l l a s
improvements in mission flexibility and adaptability to
changing environments. The ZBO concept involves using
a cryocooler-radiator system to intercept and reject
cryogenic storage system heat leak such that boiloff and
the necessity for venting are precluded. A cooperative
ef fort by the Ames Research Center, Glenn Research
Center, and Marshall Space Flight Center has been
i mp l e m e n t e d t o d e ve l o p a n d d e m o n s t ra t e Z B O
hardware and concepts for in-space storage of cryogenic
propellants, particularly liquid hydrogen and oxygen.
In the interest of costs and scheduling, existing and offt h e - s h e l f h a rd wa re h a s b e e n u s e d t o m a x i m u m
advant age t o assemble a t est ar ticle for an early
d e m o n s t ra t i o n o f t h e Z B O c o n c e p t w i t h l i q u i d
hy d ro ge n . A c c o rd i n g ly, M a rs h a l l ’ s M u l t i p u r p o s e
Hydrogen Test Bed, a large-scale liquid-hydrogen test
article with a 639-ft 3 tank, has been modified for the
int egrat ed operation of a commercial cooler wit h
already existing passive insulation, destratificationmixing, and pressure control subsystems. The cooler is
a Cryomech GB37 unit, which has a cooling capacity of
30 W at 20 K. Since the cooler thermal extraction rate
cannot be directly controlled, the test procedure strategy
was to first establish a heat leak below the thermal
extraction capability of the cooler. Then, an internal
heat er was adjust ed, based on t he measured t ank
pressure decay rate, to achieve steady-state pressure
conditions; that is, the incoming and extracted thermal
energy were balanced. The cooler integration concept
involved connecting the second-stage cold head with a
copper heat exchanger inser t ed int o t he existing
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LH2
Concentric
tube vent
flow (closed)
Bulk liquid inlet
Joule-Thompson
valve (closed)
Circulation pump
Cryocooler
position
recirculation line that, in turn, interfaces with the pump
and spray bar mixer system. The spray bar recirculation
s y s t e m i s d e s i g n e d t o p rov i d e d e s t ra t i f i c a t i o n ,
independent of ullage and liquid positions, in a zerogravity environment. During the mixing process, fluid
is withdrawn from the tank by a pump and flows back
into the tank through the spray bar, which is positioned
along (or near) the tank longitudinal axis. The fluid is
expelled radially back into the tank through 45 spray
bar or if ices. Unlike a f light-type unit, t he cooler
compressor system is positioned outside the vacuum
chamber and is linked to the cold head with stainless
steel helium lines penetrating the chamber walls.
T h e t h e r m o d y n a m i c a n a ly t i c a l m o d e l a n d u l l a ge
pressure control system were integrated such that tank
pressure could be automatically controlled and real-time
analytical model adjustments could be simultaneously
enabled. Additionally, since the control algorithm could
be exercised with proposed test parameter changes,
more prudent real-time decisions regarding the test
matrix were made. The testing, which required 28 days,
was completed on October 18, 2001, and is considered
very successful. The ullage pressure was held constant,
within ±.02 psia, for 5 days at each liquid level tested
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(98, 50, and 25 percent). This testing opens up a new
era of thinking regarding the application of cryogenics
to long-term missions.
New Aeronautical Sciences Laboratory
Contributed by Gregory Addington
On October 15, 2001, the Air Vehicles Directorate of the
Air Force Research Laboratory (AFRL) established a new
aeronautical technology demonstration team that was
charged with establishing the directorate as a national
center of excellence in military aeronautics and related
science and technology laboratory demonstrations. This
team has both experimental and computational fluid
dynamics tools at its disposal to aid in the development
of new and innovative aeronautical concepts.
A major short-term focus of this team is to bring stateof-the-art diagnostic capabilities to the three active
wind tunnels located at Wright-Patterson Air Force Base.
These three facilities are
• The Subsonic Aerodynamics Research Laboratory, a
7- by 10-ft facility capable of speeds to Mach 0.5
T h e s e fa c i l i t i e s a re t o s u p p o r t t h e A i r Ve h i c l e
Directorate’s long-term vision for the Aeronautical
Sciences Laborat or y. This laborat or y will use an
integrated experimental and numerical approach to fill
the Nation’s milit ary aeronautics technology needs,
facilitated by rapidly advancing technologies such as
rapid prototyping of wind tunnel models and integrated
c o mp u t e r- a i d e d d e s i g n a n d c o mp u t a t i o n a l f l u i d
dynamics grid generation tools. Combined within a
s i n g l e l a b o r a t o r y, t h e s e c a p a b i l i t i e s w i l l a l l o w
technologists to evaluate concepts with high-fidelity
aerodynamic data in days rather than in months or even
years.
Plasma Dynamics Testing
Contributed by Gregory Addington
Under the leadership of Dr. Joseph Shang, the Air Force
Research Laboratory Air Vehicles Directorate generated
a volumetric plasma at hypersonic flow conditions for
the first time in the United States on August 3, 2001.
This capability was installed into the Mach 6 wind
tunnel located at Wright-Patterson Air Force Base. It is
b e i n g u s e d t o e va l u a t e e m e rg i n g m a g n e t o hydrodynamic technologies and to provide benchmark
data for comparison with computations.
• The Vertical Wind Tunnel, a 12-ft rotary test facility
• The Mach 6 Wind Tunnel, a 12-in. open-jet hightemperature facility
Also, two new pilot facilities are to be brought online,
the 2-f t horizontal water channel and the Mach 5
plasma channel.
Another major focus of the team is to reactivate the
Trisonic Gasdynamics Facility (TGF). This facility is being
reactivated after a 5-year dormant status to support
new activity in various areas of supersonic flow research.
The TGF is a 2- by 2-ft continuous-flow facility capable
of continuous subsonic speeds to Mach 0.9 and discrete
speeds of Mach 1.5, 1.9, 2.3, and 3.0.
Additionally, the team will act as the technical and
administrative liaison between directorate technologists
and other wind tunnel laboratories. This function will
assure that the most appropriate facility for a particular
experimental need is utilized in a time-efficient manner.
The team is also evaluating other facilities located at
Wr i g h t - Pa t t e r s o n A i r F o rc e B a s e fo r p o s s i b l e
refurbishment or reactivation.
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Some General Notions in Measurement Uncertainty Analysis
Contributed by Michael J. Hemsch
Uncertainty Analysis
Uncertainty analysis often means different things to different people. The narrow definition refers to a distinction called
“error propagation.” This is an old definition, but it is still used by some. The larger, more common definition refers to
the act of estimating the uncertainty of a particular measurement, in a particular laboratory, at a particular time, by
whatever means available. The uncertainty is defined to be a parameter associated with the result of a measurement that
characterizes the dispersion of the values that could reasonably be attributed to the measurand.
Statistical process control (SPC) in measurement is an important aspect of credible uncertainty analysis (in the larger
definition). The U.S. Guide to the Expression of Uncertainty in Measurement, ANSI/NCSL Z540–2–1997, gives a detailed
description of what is rapidly becoming standard nomenclature regarding uncertainty and its analysis. Anyone who
attempts to measure things precisely should have a copy of this standard. Another excellent source of information on
this whole subject is the National Institute of Standards and Technology (NIST)/SEMATECH Engineering Statistics Internet
Handbook (http://www.itl.nist.gov/div898/handbook/).
Error Propagation
This almost always means the act of propagating the instrument errors (and any other errors one might be lucky enough
to be able to estimate) through the data reduction equations to the final result of interest, e.g., drag coefficient or heat
transfer coefficient. The error propagation can be done by symbolically differentiating the data reduction equations to
get the sensitivity coefficients for the various errors to be propagated or by numerically carrying out the differentiation
(e.g., using a jitter program). The problem with relying on this approach exclusively is that it will usually generate a
lower bound to the uncertainty. The unaccounted-for sources of uncertainty are the ones that seem to bite us most
often and are the scariest for risk analysis. In any case, one should always measure those uncertainties that one can, such
as repeatability and reproducibility (within-lab and across-lab), over time. This leads to the statistical process control
(SPC) and modern design of experiments (MDOE) approaches. Of course, if the system has not yet been built or put into
service, error propagation is the only approach available, except for comparison with the behavior of similar systems.
Statistical Process Control
The objective of SPC is to establish the stability and levels of variation of the measurement system, in its entirety, by
measuring repeatability and reproducibility for a reference model (NIST calls such an artifact a “check standard”) in a
given laboratory periodically over its entire functional life. The NASA Langley Research Center version of this process is
described in AIAA 2000–2201. At each tunnel condition, a time-series chart is kept for tracking the mean and standard
deviation (or range) for the results in each check standard test over a never-ending series of tests. If the results for both
of those statistical parameters stay within certain limits, we can claim that the measurement process is stable for
uncertainty purposes and we will have excellent estimates of repeatability and reproducibility. Scaling of the scatter
results to customer conditions is required to be able to check the customer repeat information against the check standard
data. This is yet another story that requires knowing how to model the scatter in the facility as a function of instrument
type, output, and facility setpoint condition. Note that one cannot achieve (or even talk about) SPC by using uncertainty
analysis in either the narrow or the larger definitions. SPC depends on testing the check standard regularly and analyzing
the results using Shewhart’s statistical control charts. Of course, if any data points fall outside the limits, one must act
to correct the system. It is this philosophy that allows us to call this approach data quality assurance instead of uncertainty
estimation.
Modern Design of Experiments
It is not possible to do this subject justice in a few lines, but many contemporary practitioners of the modern design of
experiments (MDOE) method actually measure the repeatability and reproducibility during a test to estimate the withintest variation. This is thought to be the best approach for any type of testing. The MDOE estimate of the within-test
variation can then be compared to the check standard results for quality assurance. Adding the across-test reproducibility
from the check standard results completes the estimate of the within-lab reproducibility.
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Vol 3 No 3
January 2002
GTTC Committee News
GTTC Bobsledding Team Far From Making Olympic Finals
At the Joint Propulsion
Conference summer sessions in July in Salt Lake
City, Utah, attendees enjoyed an of fsite event
consisting of an extensive
tour of the Olympic Park
training facilities, an outdoor BBQ, a brilliant
display of Utah thundershowers, and a spectacular
exhibition by the U.S.
freestyle ski jumping
team—what a show! Not
even intermittent downpours could dampen the
spirits of the would-be
GTTC bobsledding team
(pictured right). They may
not be ready for the 2002
Olympics, but look out,
Anheuser-Busch!
GTTC Hiking Team Reaches Summit at Solitude
Some members of the
GTTC participated in a
hike at the Solitude Ski Resort just outside of Salt
Lake City. Although the
group struggled at first to
find an actual trail (one
without heavy machinery
and a swamp at the bottom), the scenic overview
was spectacular. After the
5,000-ft climb, cold refreshments really hit the
spot!
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January 2002
GTTC Committee News
GTTC Sports—Tiger Was a No-Show
Several GTTC members and spouses hit the links last summer in Salt Lake
City. Because we had so many technical activities going throughout the
week, there was not much time left for golf, so we tried something a little
different: a two-person scramble on a par-three course. It was tougher
than it sounds, particularly considering the caliber of golfers (hackers) on
the TC. The venue was the par-three course at Jordan River State Park, a
nice little course with postage stamp greens (a whopping 1,215-yard par
27).
Six teams vied for a prize of a few golf balls and the coveted GTTC bragging
rights. There were also prizes for pin shots on each hole. Everyone had a
really good time, especially the winning team of Jeff Haas and Richard
Morgan. Jeff’s dazzling iron play was somewhat overshadowed by Richard’s
ability to drain several pretty long putts. Jeff was also the most accurate of
all duffers, winning three pin shots; Allen Arrington, Mark Cross, John
Lafferty, and Dave Minto had one pin shot each.
Jeff and Richard’s score of 30 gave them a one-stroke victory over Dave
Minto and Chuck Hudson. Three teams tied at 34: John Lafferty and Nancy
Swinford, Dan Marren and Susan Hudson, and Mark Cross and Mark
Melanson. High-score honors went to Allen Arrington and Nancy Lafferty,
with a final tally of—well, never mind the score. We had a lot of fun!
GTTC Calendar of Upcoming Events
2002
January 14 to 17
40th AIAA Aerospace Sciences Meeting and Exhibit; Reno, Nevada
March
AIAA Congressional Visits Day
April 1
Input due for AIAA GTTC Newsletter
April 15
Nominations due to AIAA for Associate Fellow
May
Abstracts due for 41st AIAA Aerospace Sciences Meeting and Exhibit
June 24 to 27
22nd AIAA Aerodynamic Measurement Technology and Ground Testing Conference; St. Louis, Missouri
August 1
Input due for Aerospace America Highlight December issue
October 1
Nominations due for AIAA Ground Testing Award
November 1
Nominations due to AIAA for TC membership
November 1
Input due for AIAA GTTC Newsletter
December 1
Aerospace America Highlights Issue
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Vol 3 No 3
January 2002
Request for GTTC Membership Information
The purpose of the Ground Testing Technical Committee (GTTC) is to advance the state of the art and technologies
associated with ground testing and ground testing facilities. The scope of the committee’s interests includes duplication
and simulation of aerodynamic and aerospace flight environments for the testing of aerospace systems, subsystems, and
components. The ground test facilities of interest include wind and shock tunnels, ballistic and high-speed test track
ranges, space environment facilities, and aeropropulsion test facilities.
The GTTC is composed of over 40 AIAA professionals from commercial, government, and academic sectors representing the
technical spectrum for state-of-the-art ground testing of aerodynamic, propulsion, and space systems. The Committee
continually seeks members from all parts of the ground testing community.
The membership term on the GTTC is 4 years with approximately 25 percent of the membership rotating off each year.
Prospective members should be willing to make a commitment to GTTC activities and attend the semiannual GTTC meetings.
If you are interested in receiving further information concerning membership in the GTTC, please fill out the form below
and mail to
ALLEN ARRINGTON
QSS GROUP INC MS 6–2
NASA GLENN RESEARCH CENTER
21000 BROOKPARK RD
CLEVELAND OH 44135
216–433–8507
fax 216–433–8551
Name:
Title:
Company:
Address:
City:
State:
Zip:
Phone:
Country:
E–mail:
Professional responsibility:
Professional membership: AIAA
Years experience:
SAE
ASME
ITEA
Other
Educational background (degree, discipline, year):
Prior service on AIAA Technical Committees:
Name:
Prior experience organizing conferences, sessions, short courses:
Area of interest: Aerodynamics
Aeropropulsion
Space systems
Does your company currently support other AIAA Technical Committees?
Other comments:
M–0702–2
Jan 01
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