Header Bar Graphic
Shuttle Image and IconAerospace HeaderBoy Image
Spacer TabHomepage ButtonWhat is NASA Quest ButtonSpacerCalendar of Events ButtonWhat is an Event ButtonHow do I Participate ButtonSpacerBios and Journals ButtonSpacerPics, Flicks and Facts ButtonArchived Events ButtonQ and A ButtonNews ButtonSpacerEducators and Parents ButtonSpacer
Highlight Graphic
Sitemap ButtonSearch ButtonContact Button

UPDATE # 4 - December 12, 1997

PART 1: New Web Chat Schedule to Be Announced Next Week
PART 2: Wind Tunnel Testing and Rotorcraft
PART 3: Aerospace Team Online T-shirts available
PART 4: Subscribing and Unsubscribing


We are putting together a schedule of Web chats that will be
held starting in January.  Hopefully this will give classrooms
plenty of time to plan to attend one of the upcoming chats.   
If teachers have suggestions as to the best times for chats we 
would appreciate hearing from you. Send email to slee@mail.arc.nasa.gov
Remember our flexabilty is somewhat limited by our 
experts' schedules as well.

[Editor's Note: Larry is working on the Tilt Rotor Aeroacoustic Model project. He specializes in rotorcraft aeromechanics research. (that means the aerodynamics, dynamics and mechanical aspects of helicopters and tiltrotor aircraft.)]

Wind Tunnel Testing & Rotorcraft

by Larry Young 

December 11, 1997 

Rotorcraft (helicopters and tiltrotor aircraft) are tested
in low-speed wind tunnels (speeds roughly less than 350
miles per hour). Wind tunnels are generally classed in
terms of their test section size and speed capability
(usually in terms of four different speed regimes: low
speed, transonic, supersonic, and hypersonic). The
world's largest wind tunnel is a part of the low-speed
40-by-80 and 80-by-120 Foot National Full-scale
Aerodynamics Complex (NFAC) at NASA Ames
Research Center. The NFAC has been used to test many
low-speed aircraft but, in particular, it is used to test
rotorcraft and powered-lift aircraft (such as the Harrier
jump-jet). Large- and full-scale rotorcraft can easily be
tested in the NFAC. I work in and consider the NFAC

Wind tunnel testing is conducted for various reasons for
-- and at different stages of -- an aerospace project.
Testing can be conducted to study: fundamental
aerodynamics and fluid mechanics; small-scale testing of
complete, or partial, models to support preliminary
design efforts for new aircraft; large- or full-scale
testing of complete, or partial, wind tunnel models (or,
sometimes, actual aircraft) to support aircraft
production launch decisions or pre-flight risk reduction;
and, even after an aircraft is flying, it sometimes
desirable to perform wind tunnel tests of the aircraft --
or a key aircraft component -- to identify and correct
problems observed in flight or improve the overall
performance/capability of the aircraft. 

Rotorcraft researchers at NASA Ames Research Center
conduct wind tunnel tests for all four general types of
experimental investigation to support aircraft
technology development. Rotorcraft researchers at
Ames also are involved in the development of new
analytical and computational prediction tools to model
and improve the performance and flight characteristics
of rotorcraft. A good engineer/scientist always tests
their theory/predictions against high-quality data from
well-thought-out experiments. 

I have personally conducted tests of small-scale models
in small wind tunnels. I have also tested large-scale
helicopter and tiltrotor models in large wind tunnels.
Not all of these tests have been at wind tunnels at NASA
Ames, though. I have also participated in, or supported,
wind tunnel tests at NASA Langley Research Center, at
Boeing Helicopter in Pennsylvania, and the
Duits-Nederlandse-Windtunnel (DNW) in The
Netherlands. Often times one wind tunnel has unique
advantages over another tunnel for a given set of test
objectives. Also, wind tunnel access is sometimes
difficult to get and so a wind tunnel may be selected for
a test on the basis of its availability. 

The planning, pre-test preparation, conduct, and
post-test data reduction and analysis of data from
rotorcraft wind tunnel tests takes a long time. This
whole effort can range from a few months to several
years. Rotorcraft researchers, wind tunnel test teams,
and aerospace professionals in general, have to be very
patient, dedicated, and persistent people. The TRAM
project that I manage has been in existence for over
seven years. I and the people and contractors that I
manage or oversee had to design and build the TRAM
models from scratch. This took a lot of time. It is only
now that the initial wind tunnel testing has begun. This
testing is currently underway in the DNW wind tunnel
in The Netherlands. After this initial set of tests is
complete the TRAM 1/4-scale wind tunnel model will
be tested in the NFAC at NASA Ames. This follow-on
testing will happen in a couple years. 

Safety is an important part of wind tunnel and
rotorcraft testing. Test models and wind tunnels are
very expensive facilities and great care has to be taken
to insure that no damage is caused to these facilities
during testing. And, always, care must be taken to
insure that people are not put in harm's way. A typical
rotorcraft test requires thousands of pages of
documentation to be generated during test preparation
phase -- most of this documentation is required to
insure safety during the test. This documentation
includes the test plan (defines the test objectives and the
run "matrix"), the Operations Plan (it outlines how to
operate and maintain the test model and the wind
tunnel), the Design Analysis Report (contains design
drawings and structural analyses to make sure the model
can handle the expected loads during the test), as well as
many other documents. All of this material is written
and reviewed by several people. 

In the end, after successfully completing a test program,
the project/test team can feel justifiably very proud of
their efforts. The test results are studied and then
reported in various types of formal reports including
technical conference papers and NASA-distributed
reports. Most NASA reports are openly available to the
public. Industry engineers, or other researchers, use
this information to plan new follow-on tests and/or use
the current results to develop new -- or refine existing
-- aerospace products. NASA engineers usually support
multiple test/research programs at a given time. So as
one test program comes to a close, the NASA engineer
will quickly ramp up to work on one of the other
programs he is on. 


If you'd like to take your Aerospace Team Online involvement to a
new level, consider purchasing a T-shirt. They make great gifts
(for yourself or others). For details, please see:


If this is your first message from the updates-aero list, welcome!

To catch up on back issues, please visit the following Internet URL:

To subscribe to the updates-aero mailing list (where this message
came from), send a message to:
In the message body, write these words:
   subscribe updates-aero


To remove your name from the updates-aero mailing list, send a
message to:
In the message body, write these words:
   unsubscribe updates-aero

If you have Web access, please visit our
site at http://quest.arc.nasa.gov/aero

Footer Bar Graphic
SpacerSpace IconAerospace IconAstrobiology IconWomen of NASA IconSpacer
Footer Info