AEROSPACE TEAM ONLINE

ATO #115 - August 4,, 2000

PART 1: Upcoming Chats
PART 2: New Projects for Fall
PART 3: Testing Space Entry Vehicles in the Ballistics Range

UPCOMING CHATS

Beat the Heat: Thermal Protection Chats!

 
 We will be chatting and with researchers from the Space
 Technology Division at NASA Ames Research Center. I think you will find
 this fascinating and a worthwhile topic. This will introduce you to the
 topic of materials for thermal protection and the use of computer models
 for predicting the heat generated by vehicles entering different
 planetary atmospheres. This is a very important topic for those of you
 who plan to travel in space in the near future.
 
 Tuesday, August 8, 2000, 10 - 11 AM Pacific
 Aerospace Team Online QuestChat with Chuck Cornelison
 Chuck Cornelison, Ballistics Range Manager
 The ballistics range is the opposite of a wind tunnel. Instead of
 blowing air over an object, objects are fired by guns through still air.
 Learn all about it! Read Chuck's bio at
 http://quest.nasa.gov/aero/team/cornelison.html
 
 Tuesday, August 22, 2000, 10-11 AM Pacific
 Aerospace Team Online QuestChat with Susan Fehres
 Susan Fehres works with spacecraft insulation. She develops materials
 that protect astronauts and equipment from extreme heat and cold
 experienced by spacecraft during spaceflight and entry into Earth's
 atmosphere. Read her bio at http://quest.nasa.gov/women/bios/sf.html
 

NEW PROJECTS FOR FALL

 Virtual Skies is an air traffic management project for students and
 teachers in Grades 9-12. It will be a "project based learning
 activity" with hands on multimedia to enhance student decision making
 and problem solving skills. Topics to be covered include
 Aviation Navigation, Aviation Weather, Communication Air Traffic
 Management, Airport Design, and Air Traffic Research. Materials will be
 tied to the National Standards in Mathematics, Science, Technology,
 Geography and Language Arts. Stay tuned for more news as we crank up over
 the summer!
 
 Planetary Flight is an aerospace project for Grades 4-8. We know how to
 fly on Earth but what will it take to fly on Mars. This will be an
 inquiry based learning project to design an airplane to fly on Mars. The
 stuff dreams are made of!! We will also be keeping you posted on this one
 this summer.
 

AN INTRODUCTION TO THE BALLISTIC RANGE COMPLEX

by Chuck Cornelison

June 8, 2000

One of the facilities, the Hypervelocity Free-Flight Aerodynamic Facility,
(HFFAF) within the Ballistics Range Complex is an aeroballistic range.
Perhaps the easiest way to picture an aeroballistic range is to
think of it as being the opposite of a wind tunnel. In a typical wind
tunnel you mount a small scale model inside a big tube called a test
section, blow air over it and use various devices to measure aerodynamic
properties such as lift, drag, and pitching moment. In the aeroballistic
range, a large gun is used to launch a small scale model into a test
section containing still air.

This aeroballistic test section has many windows and reference wires. As  
the model flies through the test section it is photographed. These photos
along with the time history of the model's flight can be used to
reconstruct the model's flight path (trajectory).

This information is then fed into a sophisticated computer code, which  
model is held still while air is blown over it. Whereas, in an
aeroballistic range the air is still and the model flies through it. Both
types of test facilities are used to determine aerodynamic properties. An
aeroballistic range is particularly useful for studying very high-speed   
flight. In fact, practically all of NASA's spacecraft that have entered an
atmosphere (such as Mercury, Gemini, Apollo, Shuttle, Viking, and Galileo)
have had some testing performed at Ames' Ballistic Range Complex. The
information gathered in these tests was crucial to the successful design
of these vehicles.
The Ames Vertical Gun Range (AVGR) is the name of the other operational
facility within the Ballistic Range Complex. This facility
also uses a gun to launch particles at high speeds, but for this type of 
testing we are most interested in what happens when the particle hits a   
target, and not so much interested in what it does during its flight.

The gun is mounted on what is basically a large hinge so that the impact
angle can be varied from horizontal to vertical (0 to 9 degrees). The   
types of particles that can be launched include spheres, cylinders,
be metallic (i.e. aluminum, copper, iron), mineral (i.e. quartz, basalt),
or glass (i.e. Pyrex). These capabilities are important because crater
size, shape and the way material is ejected from the crater during an    
impact event is closely related to such things as impact angle, particle  
shape, composition, velocity, etc.

Scientists use experimental data they obtain from the AVGR when they to go
out to a crater site such as the Chicxylub (pronounced "chicks-ee-lube")
crater in the Yucatan peninsula. By comparing the crater characteristics
to their laboratory tests, they can develop a good idea as to the size,  
speed, composition and impact angle of the particle that crashed into the
earth at this location some 65 million years ago, and quite possibly  
triggered the extinction of the dinosaurs.

A discussion of the ballistic range wouldn't be complete if I didn't
mention a few words about some of the guns we use in these facilities. For
very high speed testing we use what are called two-stage light-gas guns.  
These guns are capable of launching particles at speeds in excess of
26,000 ft/sec (18,000 mph) which in metric terms is equal to 8 km/s. We 
have several different guns with barrels ranging in size form 0.28 to 1.50
inches in diameter. This allows us to launch models that are only a
fraction of an inch to models that are an inch or more in diameter and
several inches in length.