Facing the Heat Barrier:
A History of Hypersonics
T. A. Heppenheimer
Facing the Heat Barrier:
A History of Hypersonics
T. A. Heppenheimer
Hypersonics is the study of ight at speeds where
aerodynamic heating dominates the physics of
the problem. Typically this is Mach 5 and higher.
Hypersonics is an engineering science with close
links to supersonics and engine design.
Within this eld, many of the most important results
have been experimental. The principal facilities
have been wind tunnels and related devices, which
have produced ows with speeds up to orbital
velocity.
Why is it important? Hypersonics has had
two major applications. The rst has been to
provide thermal protection during atmospheric
entry. Success in this enterprise has supported
ballistic-missile nose cones, has returned strategic
reconnaissance photos from orbit and astronauts
from the Moon, and has even dropped an
instrument package into the atmosphere of Jupiter.
The last of these approached Jupiter at four times
the speed of a lunar mission returning to Earth.
Work with re-entry has advanced rapidly because
of its obvious importance. The second application
has involved high-speed propulsion and has
sought to develop the scramjet as an advanced
airbreathing ramjet. Scramjets are built to run
cool and thereby to achieve near-orbital speeds.
They were important during the Strategic Defense
Initiative, when a set of these engines was to
power the experimental X-30 as a major new
launch vehicle. This effort fell short, but the X-43A,
carrying a scramjet, has recently own at Mach
9.65 by using a rocket.
Atmospheric entry today is fully mature as an
engineering discipline. Still, the Jupiter experience
shows that work with its applications continues to
reach for new achievements. Studies of scramjets,
by contrast, still seek full success, in which such
engines can accelerate a vehicle without the use of
rockets. Hence, there is much to do in this area as
well. For instance, work with computers may soon
show just how good scramjets can become.
The NASA History Series
National Aeronautics and Space Administration
NASA History Division
Ofce of External Relations
Washington, D.C.
2007
Thomas A. Heppenheimer has been a freelance
writer since 1978. He has written extensively on
aerospace, business and government, and the
history of technology. He has been a frequent
contributor to American Heritage and its afliated
publications, and to Air & Space Smithsonian.
He has also written for the National Academy of
Sciences, and contributed regularly to Mosaic of the
National Science Foundation. He has written some
300 published articles for more than two dozen
publications.
He has also written twelve hardcover books.
Three of them–Colonies in Space (1977), Toward
Distant Suns (1979) and The Man-Made Sun
(1984)-have been alternate selections of the
Book-of-the-Month Club. His Turbulent Skies
(1995), a history of commercial aviation, is part
of the Technology Book Series of the Alfred P.
Sloan Foundation. It also has been produced as
a four-part, four-hour Public Broadcasting System
television series Chasing the Sun.
Under contract to NASA, Heppenheimer has written
that agency’s authorized history of the Space
Shuttle, in two volumes. Volume 1, The Space
Shuttle Decision (1999), has been reissued in
paperback by the Smithsonian Institution Press and
has been selected as an Outstanding Academic
Title. The present book reects his longstanding
activity in hypersonics, for which he has written
three technical reviews for Pasha Publications.
He holds a Ph.D. in aerospace engineering from
the University of Michigan, and is an associate
fellow of the American Institute of Aeronautics and
Astronautics. He has also held research fellowships
in planetary science at the California Institute of
Technology and at the Max Planck Institute in
Heidelberg, Germany.
About the Cover: Hypersonic Plane by Leslie
Bossinas. Artist’s concept of an aerospace plane
showing aero-thermal heating effects caused by
friction as the vehicle ies hypersonically through
the atmosphere. The National Aero-Space Plane
program provided technology for space launch
vehicles and hypersonic cruise vehicles. This
vehicle with advanced airbreathing engines would
have the capability to take off horizontally from
and land on conventional runways, accelerate to
orbit, and cruise hypersonically in the atmosphere
between Earth destinations. (NASA Art Program,
Image 86-HC-217).
Facing the Heat Barrier:
A History of Hypersonics
T. A. Heppenheimer
NASA SP-2007-4232
