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ATO # 91 - January 7, 2000

PART 1: Upcoming Chats
PART 2: Project News
PART 3: In a Nutshell, How I Came to Write Flow Simulations


QuestChats require pre-registration. Unless otherwise noted, registration
is at:  http://quest.arc.nasa.gov/aero/chats/#chatting

Tuesday, January 11, 2000, 10 AM - 11 AM Pacific
Aerospace Team Online QuestChat with Tom Benson

For almost 30 years, Tom Benson has used computers to address
problems associated with fluid mechanics. In addition he has written
interactive software for aerodynamics.

Tuesday, January 18, 2000, 10 AM - 11 AM Pacific
Aerospace Team Online QuestChat with Larry Young

Larry is a researcher who studies helicopters and tiltrotor airplanes.
He tries to make them quieter so they can help solve airport congestion.
He also brainstorms ideas for helicopters in space!


Look for the announcement of the Regimes of Flight a new resource for
teachers and students about flight at different speeds. This will be  
targeted for grades 4-8. You will find background material, lesson plans,
chats and contests!! For more information see

Because the Mars Airplane Technology is requires translation for K-12
classrooms we find that we will have to do more rewriting than we planned.
This means we will present that topic is September, 2000

[Editors Note: For almost 30 years, Tom Benson has used computers to address problems associated with fluid mechanics. In addition he has written interactive software for aerodynamics. Read his biography at http://quest.arc.nasa.gov/aero/team/benson.html ]


by Tom Benson

January 3, 2000

I'm an aeronautical engineer at NASA Glenn Research Center, in
Cleveland,Oh. I've been an engineer for a long time ... almost 30 years
now. I was in college in the 60's (which was a lot of fun !! .. especially
the music.) I received my degrees from Ohio State University and then had
to serve four years in the Air Force since I was drafted during the
Vietnam war. I was stationed at Wright-Patterson Air Force Base
during some pretty exciting times. I participated in wind tunnel testing
and evaluation of the Air Combat Fighter (YF-16 and YF-17), the B1-A
bomber, the EF-111, and the F5-E, specializing in installed engine
performance. I also did a little flight testing with the AC-130 gunship.

It was during wind tunnel tests for the F-16 inlet that I first visited
NASA Lewis (which has been re-named Glenn.) When my military service was  
finished, I returned to OSU to work on a PhD in aeronautical engineering,
with an emphasis on Computational Fluid Dynamics (CFD) for biological
flows. We used computers to model the flow of blood through the
circulatory system. I passed my qualifier exams and had begun building a
computer program for my dissertation work, but decided to leave school
and take a job with NASA before I had finished. I've been here at NASA
ever since.

I started here at Glenn in a group that was developing CFD programs for
inlet design and analysis. The inlet is the part of a propulsion system   
which brings the outside air into the engine. A well-designed inlet
can let you do some marvelous things, like cruise at Mach 3+ with the
SR-71, or maneuver to high angles of attack in an F-16. But a poorly
designed inlet can cause big problems .. engine stalls or flameouts, high
fuel consumption, or limits on the maximum speed of a hypersonic

Wind tunnel testing of inlets is very expensive and time consuming,
because you have to check many different flight conditions; different  
angles of attack, and yaw, and speed, and engine airflow conditions
for each inlet design. So we try to do as much of the design and   
evaluation as we can using CFD. Hopefully, we can uncover and solve some
problems before going to wind tunnel test. One problem that
occurs in high speed inlets is an interaction between the boundary layer 
on the surface of the inlet, and the shock waves generated to slow the
flow down and increase the pressure of the flow. In hypersonic inlets,
the interactions can be highly three-dimensional, with the low energy
boundary layer flow being pushed by the shocks into the corners of the
inlet causing flow separation and bad inlet performance. During the    
1980's I was involved with the National Aerospaceplane (NASP) program here
at Glenn where we studied shock- boundary layer interactions in hypersonic
inlets using CFD.

When NASP was cancelled, I used some of the visualization tools which had
been developed to study the flow that would occur in an experiment flown
move and stir fluids in microgravity using a small jet of fluid in a large
tank. The experiment was flown twice and we made comparisons between the
computer predictions and the results which were observed by video on the
flight. I also used the computer programs which were developed to
model this low speed flow to study the more fundamental unsteady flow past
a circular and a rectangular cylinder. I produced some videos from these
calculations which were made available to universities for students who
were studying these types of flow problems.

My interactions with universities, plus my familiarity with interactive
graphics packages, plus the increased speed, size, availability, and
affordability of PC's and workstations led me to my current
interests. For the last 5 years, I've been building and distributing small
interactive programs which run on PC's or workstations which simulate flow
problems which students encounter in undergraduate education.
I have packages to solve shock wave problems, basic airfoil problems, and
the thermodynamics (thrust and fuel flow) of jet engines. All of the   
programs are interactive ... you change an input using a slider or
type-in box and you get a new answer instantly. This lets students explore
the physics without getting bogged down in the math. I distribute the  
programs using the world wide web, so that anybody, anywhere
in the world, who has a PC or workstation can get the programs for free.

To support the distribution of the programs, I have also developed an
extensive web site called the Beginner's Guide to Aeronautics
which includes explanations of how airplanes and propulsion systems work 
including the mathematical equations.


This site is a web-based text book with problems developed by high school
and middle school teachers. Most recently, I have begun to include JAVA
applets on the pages to allow students to interactively explore some of
the ideas presented on the pages.
FoilSim download, FAQ, all kinds of other stuff is at:

EngineSim interactive Java applet is at:


I have found the past five years to be the most rewarding of my long
career and look forward to developing new educational programs for

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