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Transatmospheric Vehicle
On April 6, 1987 the Greater New York Section of AIAA in
conjunction with the New York Society of Security Analysts and
the Space Commerce Roundtable Foundation sponsored a meeting at
the Wings Club in New York City. The subject was the air-
breathing hypersonic aircraft/space launch vehicle now under
development. This projected experimental aircraft is officially
designated the X-30. However, it has, up to now at least, been
more commonly known as the Trans-Atmospheric Vehicle (TAV) or the
National Aerospace Plane (NASP). It has also been referred to as
the "Orient Express," thanks to President Reagan's use of that
phrase in his 1986 State of the Union message. Likewise, one can
find scattered references to it as "Cooper Canyon," the name of a
now-declassified "black" USAF project.
By whatever name called, the project has become a major
focus of aerospace research. Some $300 million has been
earmarked for that purpose in the current fiscal year budget.
Even more importantly, if the vehicle lives up to the
expectations of its proponents it has the potential to
revolutionize both long distance transportation on Earth and the
launching of payloads into low-Earth orbit (LEO).
The speaker was Robert M. Williams, who is NASP program
director at the Defense Advanced Project Agency (DARPA).
Williams began his presentation by describing the X-30 as an
experimental aircraft similar to the X-15. (Noting the numerical
coincidence, he joked that it would be "twice as good.") He also
referred to the fact that the TAV had recently received at great
deal of attention, describing this as a "good news-bad news"
situation. As previously noted, President Reagan referred to it
in his State of the Union message. On that occasion the
President emphasized the role of the system for intercontinental
air transportation on Earth. Later Mr. Reagan presented a model
of the X-30 to teacher-in-space runner up Judy Garcia. This
time, as might be expected, he stressed its potential for
launching payloads into orbit. In either case, what is in
contemplation is an air-breathing vehicle capable of taking off
from an airport runway and accelerating to speed of approximately
twenty five times the speed of sound (Mach 25).
Williams then went on to describe DARPA. The basic
function of this agency is to look out into the future. More
particularly, its job is to try to predict where technology, and
especially synergy in technology can take us.
He then commented that the managerial challenge in
connection with the TAV, involving as it does a joint program
between five agencies, is probably equal to the technical
challenge. The program is headed by an inter-agency group
organized pursuant to a memorandum of understanding. It is
overseen by a steering group whose members include the technology
heads of the armed services the heads of DARPA and NASA's Office
of Aerospace Technology and General Abrahamson of the Strategic
Defense Initiative Office (SDIO).
Williams himself runs the program management office that
reports periodically to the steering committee. ("As
infrequently as possible," according to Williams.) Under
Williams are three deputies, a NASA official, an Air Force
colonel and a Navy Captain. They are responsible for giving
general direction top the program. Below them is a joint program
office headquarters at Wright-Paterson Air Force Base. This
organization consists of about sixty people who implement the
program and manage its overall execution from day to day. Beyond
that the "tentacles" (as Williams put it) extend to NASA, Air
Force, Navy and university centers of research throughout the
United States. There are probably about five hundred researchers
currently participating in the program, if those employed by
contractors are included, and this number is growing rapidly.
As of the time of Williams' presentation, major aerospace
companies competing for selection as prime contractor for the
airframe portion of the X-30 program included McDonnell-Douglas
(with whom Martin Marietta is teamed), Boeing, Rockwell, Lockheed
and General Dynamics. Competitors for prime contractor on the
engine side included General Electric, Pratt & Whitney and United
Technologies. Rocketdyne was also what Williams described as a
"dark horse candidate," in the power plant competition having
entered the program using their own resources. Williams implied
the contest for both airframe and engine prime contractor was
intense and close. He described it as "a horse race of the first
magnitude, trying to get the best ideas of this country ***" as
to what is the best way to move ahead with the TAV.
There are, according to Williams, five key technologies
associated with the development of a TAV: Revolutionary,
unrestricted air-breathing propulsion; next generation
supercomputer aerodynamics structural and propulsion system
design; high strength, high temperature lightweight and fully
reuseable materials; high efficiency energy management; and
intelligent control systems. All of these, however, have
implications far beyond the TAV itself. The proposed aerospace
plane has in fact become a driver moving American aviation
technology forward along a broad front. The most important area
is propulsion, with aerodynamics and materials not far behind.
Turning first to propulsion, Williams displayed a graph
which plotted altitude against Mach numbers. The message behind
this chart, he said, was that "the faster you go, the fewer your
options for propulsion." Indeed, for speeds above Mach 6 the only
practical air-breathing propulsion system is the so-called
"scramjet." It is this propulsion concept, therefore, that will
be used for the NASP. Several systems are being looked at to
accelerate the vehicle to the speeds necessary for the scramjet
to operate. These include hydrogen turbojets, which have a very
high ISP. Since all of these involve conventional technology,
however, Williams did not included a discussion of them in his
presentation, although he did mention them in the question period
which followed.
A scramjet is a derivative of a conventional ramjet
(described by Williams as "nothing but a tube flying through the
air"). A ramjet flies so fast that the air in the tube is
compressed, raising the pressure so that "if you squirt in some
hydrogen" it will burn and provide thrust. The distinction
between a ramjet and a scramjet is that in the former combustion
occurs at subsonic speed. In a scramjet the internal geometry of
the engine is changed to produce a phenomenon known as
"swallowing the shock." This causes the air to flow through the
engine at close to the speed of the airplane. For example, at
speeds of Mach 25 in the outer reaches of the atmosphere (the
speeds and altitudes at which it is hoped the TAV will be able to
operate) the flow through the engine approaches speeds of 25,000
feet per second. (By way of comparison, the muzzle velocity of
the 30-06 rifle cartridge, standard for the U.S. Army's in both
World Wars, was on the order of about one-tenth this figure-2,700
feet per second.) At such speeds the only thing that will burn
is gaseous hydrogen.
If it can be successfully developed, such a propulsion
system, has, in addition to other applications, tremendous
implications for putting payloads into Earth orbit. Williams
described rocket propulsion as a system that requires us to "haul
air through the air to get out there." By breathing its own air
from the atmosphere the NASP will eliminate the need to carry
oxidizer aboard the launch vehicle. Moreover, hydrogen burns
very efficiently with air. Specifically, burning a pound of
hydrogen with air will produce about 40 million foot-pounds of
energy, vs. about 4 million foot-pounds for liquid oxygen.
(Approximately 11 million foot-pounds of energy are needed to put
one pound of payload into orbit.) For a vehicle launching Space
Shuttle size payloads this would, he asserted, enable us to
dispense with the solid rocket boosters and external tank. That
in turn will permit compressing the takeoff weight of the vehicle
by a very large factor.
During the question period that followed his formal
presentation Williams stated that even assuming vehicle
turnaround times of a few days to a week (and much shorter times
may be possible) the impact on costs would (in his words) "blow
your mind." He was understandably unwilling to commit himself to
specific numbers. Nevertheless he indicated that if the NASP
program was able to meet its technological goals launch costs on
the order of $100/lb to LEO were a definite possibility. Such
cost reduction would in turn have major effects space
entrepreneurship and space industrialization.
While subsonic combustion ramjets involve very well known
technology, supersonic combustion ramjets are another matter.
The upper limits of a scramjet's speed are not really known yet.
During the question period which followed his talk Williams was
asked what he foresaw as the upper speed limit of an aerospace
plane. He responded that calculations been made for speeds in
excess of Mach 30. Williams implied that no fundamental
limitations have as yet been encountered with respect to either
propulsion or chemistry. The limiting factor, he half-humorously
suggested, may be the point at which the airplane melts. The
goal of the NASP program is to attain speeds with air-breathing
propulsion which will enable the vehicle to achieve orbit. This
is approximately Mach 25. Williams suggested, however, that the
program would still be a success even if only lesser speeds could
be attained. In particular, he noted that some form of rocket
propulsion would be required for on-orbit and de-orbit manuevers
in any case.
One part of the X-15 aircraft program, as originally
planned, involved a so-called hypersonic research engine. The
system, which would have been housed in a module sitting below
the airplane, was in fact an actively cooled, gaseous hydrogen
scramjet engine. Theoretically this engine could have attained
speeds of Mach 7, faster than the airplane itself could handle.
As a result the system was never flown. Combined with this was
the decision to use rockets to go into space. As a result air-
breathing propulsion technology languished. However, the legacy
of the hypersonic research engine and other, similar, efforts has
now been picked up by the NASP program.
Since the inlet ducts of a scramjet engine will be
subjected to temperatures that will melt any known material, an
active cooling system is necessary. While, of course,
temperatures are enormously greater, the principle involved is
essentially the same as that demonstrated in grade school science
experiments where a flame is applied to paper containers filled
with water. However, instead of water liquid hydrogen (as one
option) is circulated around the engine to absorb the heat.
Williams conceded that cooling systems for scramjet engines
involved "exotic technology," but contended that the technology
"appears to be doable to us at this point in time."
A related problem with the design of the NASP's propulsion
system is calculating the flow of air through the "guts" (as
Williams put it) of a scramjet engine. The NASP project has been
able to make use of computational methods that are part of the
legacy of the X-15 hypersonic engine program. However, to
perform the calculations with the accuracy needed requires
supercomputers that have only become available within the last
five years.
Williams described a spaceplane as "the most integrated
system ever to be attempted in aeronautics. In fact, we do not
know were the engine starts and the airframe ends." For example,
the "bottom" of the airplane will function as a compressor by
generating the shock that compresses the flow going into the
engine module and the "back end" of the airplane will form the
nozzle of the engine. The engine will, in effect, be simply a
combustor. This situation, he indicated has created "all kinds
of turf battles" between the contractors working on the airframe
and those involved with the engine. Each group asserts that it
should be responsible for designing the bottom of the airplane.
The design of the TAV is, Williams stated, "replete with these
kinds of conflicts." It presents "a management challenge of the
first order (just) to figure out who owns what." Similarly, the
program has placed the space and aircraft divisions of the
various aerospace contractors involved on a collision course
because both have to cooperate in the design of the vehicle.
This, Williams asserted, was something easier said than done.
Indeed, he expressed the belief that the NASP will cause a
fundamental change in the nature of aerospace institutions in
this country.
Another major factor in the design of the TAV is
computational fluid dynamics. Not only must pressure contours be
calculated to a high degree of accuracy, but (as Williams put it)
we must also "make sure that our calculations have some bearing
on the real world." Twelve Cray supercomputers are being used in
connection with the program at the present time, including the
Numerical Aerodynamics Simulation Facility at NASA Ames.
An additional aspect of the aerodynamics of the NASP
vehicle is energy management. Drag produced friction on the
surface of an aircraft generates heat. At lower speeds this
simply can be thrown away by radiating it into the atmosphere.
Above Mach 3, however, it becomes advantageous to recapture the
heat and use it. Specifically, it is contemplated that the TAV
will use some of this drag-generated heat to preheat its hydrogen
fuel before the fuel is introduced into the engine. This will
result in increased thrust.
In addition to propulsion and aerodynamics, a major
consideration in NASP development is materials technology. That
is because one of the program's goals is to develop a truly
reusable space launch system. Williams described this as meaning
that "you can land that vehicle, roll it down the runway, roll it
into a hanger, change out your payload, refuel and go again. No
more tiles, no more refurbishing." Williams asserted that this
"goal drives a whole slew of technologies, but the most important
one it drives is reuseable metallic materials." According to
Williams, "this program is moving high temperature, lightweight
and reusable materials forward at a very rapid pace," with
implications that go far beyond NASP. These materials will be
the successors to the titanium alloys in use in the aerospace
industry today.
Williams displayed a chart which plotted strength-to-weight
ratios of various substances against temperature. Noting that
all present state-of-the-art materials tend to fall off rather
rapidly as temperature increases, he stated that the NASP program
hopes to develop substances which will have at least twice the
strength-to-weight ratio and increased temperature capabilities
compared to present titanium-type materials. Among the
techniques being investigated are rapid solidification and
powdered metallurgy. Also under consideration are composite
metallic materials produced from graphite or silicon carbide
fibers using powdered metal as a matrix.
"Another exciting material," according to Williams is what
he called "the next generation of carbon-carbon." Noting that
carbon-carbon is used today on the Space Shuttle for thermal
protection, he asserted that it was also possible to use it for
structural components, and stated that this "next generation"
would be able to accommodate high structural loads. In this
connection he displayed a picture of an experimental turbine,
constructed entirely out of carbon-carbon, that has been spun at
speeds of 40,000 RPM. This turbine is was not intended as part
of the spaceplane, but it may be used in the next generation
cruise missile. However, Williams cautioned that a key problem
was preventing the carbon from combining with oxygen and forming
carbon-dioxide. When that occurs, as Williams noted, "it all
goes up in smoke." He asserted, however, that new coating
technologies were being developed to handle this difficulty.
A fourth area of interest to the TAV program is hydrogen
management, the efficient use of hydrogen. The X-30 will use
hydrogen for many purposes in addition, of course, to propulsion.
Hydrogen will be employed for cooling the nose, engine, equipment
bay and the crew itself. Indeed, Williams noted that it has been
humorously suggested that the best place to locate the crew
compartment would be inside the hydrogen tank. Other
contemplated uses of hydrogen on board the NASP include fuel
cells for power and thrusters to stabilize the vehicle when it is
outside of the atmosphere. (In the course of the question period
Williams indicated that an advanced version of the thrusters used
on the current STS is under consideration for this purpose.)
The NASP program has already given birth to one major
advance in connection with the former, which has now been spun
off and is proceeding independently. This is a new type fuel
cell which is constructed entirely from ceramics and is far more
compact than any fuel cell system presently in use. This system
can convert hydrogen and oxygen to electricity with efficiency of
approximately 75%, which is almost twice as efficient as today's
automobile engines. According to Williams, this new type fuel
cell could, in and of itself, result in a whole new generation of
electric powered vehicles.
Additional benefits of hydrogen-fueled aircraft are
independence from foreign oil supplies. Williams noted that
while the general public has in recent years tended to forget
about this problem the Department of Defense cannot afford so to
do, and is actively studying alternatives to hydrocarbons as fuel
sources. Hydrogen, he noted, can be obtained from a variety of
sources, including natural gas, water and biomass. One proposal
being put forth is to use genetically engineered bacteria to
produce hydrogen. Hydrogen has the additional advantage of being
non-polluting. Although it may produce some nitrous oxides at
very high temperatures, its primary end product is water vapor.
DARPA also believes that hydrogen is as safe as, if not safer
than, conventional hydrocarbon fuels. Williams admitted however,
that any proposal to use hydrogen immediately runs afoul of what
he characterized as "Hindenberg syndrome."
The final major technology involved in the NASP program is
advanced controls and avionics. The primary area of focus here
is on active flight controls and orbital controls. However,
according to Williams by creating such a focus for research and
development the X-30 is driving American industry towards finding
new applications in such areas as high speed integrated circuits,
parallel processing computers and fiber optics.
Williams then proceeded to discuss the utility of an
aerospace plane. He began by paying due deference to Mark
Twain's observation that prophecy is a very risky business
especially when it concerns the future, although he did not refer
to it directly. None the less, he asserted that while the X-30
was an experimental vehicle it would provide enabling technology
for a whole range of applications.
The follow-on technology to the X-30 will probably take
several forms. Williams first discussed potential military uses.
He stated that the TAV would have such capabilites as launch and
recall from orbit on demand, unpredictable flight paths resulting
from the ability to perform plane change manuevers in the upper
reaches of the Earth's atmosphere, on-orbit loiter, and the
ability to and use multiple launch and recovery sites. Williams
suggested there were also military applications for X-30 derived
vehicles designed to cruise within the atmosphere.
Williams turned next to NASP-technology-based civilian
launch vehicles. In the question period that followed his talk
Williams was asked if he personally had any ranking of priorities
in the post X-30 development of the TAV as between military
vehicle, civilian space launch system and hypersonic airliner.
Williams responded that the top priority, beyond any question,
was the space launch system. The reason for this was the
potential an air-breathing launch system could have on launch-
cost reduction. For the same reason, as Williams stated during
his formal presentation, the number one priority within the
launch vehicle segment of the NASP program was cost reduction,
especially keeping life cycle costs down. As previously
indicated, particular areas of focus are reusability, utilization
(rapid turn around), elimination of large scale ground
infrastructure and logistics "tail" and greater efficiency
resulting from the use of air-breathing propulsion. The hope, as
he expressed it, is to transfer space launches from
"spectaculars" to routine operations. If this connection
Williams suggested that it might be possible to take off from New
York City's Kennedy Airport and go directly into orbit.
However, there will be differences between the NASP and an
ordinary airplane. For example, during the question period
someone asked if landing the TAV like a conventional aircraft
would provide sufficient cool-down time for the vehicle's skin,
and if not, would the need for special handling requirements on
the ground impact on the ability of the aerospace plane to make a
quick turnaround. Williams indicated that the answer to this
question was not yet known, and would depend on heat dissipation
capability. The program's goal is to avoid anything that would
significantly impact turnaround time. In particular, an attempt
will be made to avoid materials such as the tiles used on the
present STS which have a resident heat load. He commented though
that "I suspect that you're going to have to handle a fairly hot
vehicle."
The launch vehicle segment of the TAV program has been
fortunate to have received the support of several important
groups. These include the National Commission on Space (NCOS),
which recommended that this project receive the highest level
national priority.
Williams also noted that development of a NASP-related
launch vehicle has become important because international
competition in this arena is about to intensify. He specifically
mentioned the French HERMES (rocket powered), the British HOTOL
(air-breathing) and West German SANGER-II (air-breathing booster,
rocket powered orbiter combination) systems. He also stated that
the Japanese under the auspices of their Ministry of Technology
and Mitsubishi Heavy Industries were considering the possibility
of an air-breathing launch system. What was particularly notable
about the last three projects, according to Williams, was that
they were being put forward by countries that he described as
"have nots" in the space launch area. He suggested that it was
significant that countries which do not have a large investment
in rocket launch infrastructure are considering the air-breathing
propulsion option.
(As an aside, there was little specific mention of the TAV
at the May, 1987 Princeton Conference on Space Manufacturing,
which the writer attended. However, there seemed to be a
widespread feeling that truly efficient launch systems must avoid
the necessity of carrying all of the energy needed to get into
orbit aboard the vehicle. Air-breathing systems obviously lend
themselves to this objective, at least to some extent.)
In response to a question as to the amount of payload that
the TAV would be able to carry into orbit, Williams stated that
since the X-30 was an experimental research vehicle the only
thing planned to be carried into orbit by it was an
instrumentation package. It was not intended, for example to
supply payload to the space station. The payload capability of
the follow on launch vehicle has not yet been defined. He noted,
though that extensive studies on this subject are currently
underway, including the National Space Architecture Study. The
current outlook of the latter study, Williams indicated, is that
the country should adopt an unmanned heavy lift launch vehicle
for putting very heavy payloads into space and a manned system
for situations where flexibility or recallability was desired.
The latter is expected by Williams to be a derivative of the
NASP.
Coming finally to the "Orient Express" part of the NASP
program, Williams noted that the White House's Office of Science
and Technology Policy had considered the direction that the
nation should be taking with respect to its R & D goals. The
study looked in particular at the area of high speed
transportation. The White House staff endorsed pursuit of
research in the area of trans-atmospherics and hypersonic
propulsion systems.
Williams also commented that the Orient Express concept had
been taken out of context. He reiterated that the X-30 will be
an experimental vehicle and will not itself be a hypersonic
transport. However, it will develop the technology applicable to
an Orient Express. He also noted that, while a hypersonic
transport was a major focus of the NASP program, it was only one
of many focuses.
Williams described the Orient Express as a vehicle that
would operate off of conventional runways using liquid hydrogen
or perhaps liquid methane fuel, flying at very high altitudes
over ranges typically in excess of 3,000 miles. At block speeds
of Mach 6, almost anyplace in the world would be within two hours
of Los Angles. He also commented that for a system designed to
be capable of attaining speeds of Mach 25 block speeds of Mach 6
would not be difficult to achieve.
The motivation for developing such an aircraft can be found
in industry and Commerce Department studies looking at the
economic impact of increased speeds on air transportation. These
project vast increases in revenue passenger kilometers in the
Pacific Rim area. In particular, one Commerce Department study
suggested that by the year 2000 the Pacific Rim countries will
constitute the world's economic center. This may justify the
establishment of a new high speed transportation system to
service these routes.
Combined with this is the fact that 80% of the direct
operating cost of an aircraft is attributable to fuel. Moreover,
the curve of cruise efficiency (the equivalent of miles-per-
gallon) vs. Mach number is U-shaped. The lowest efficiency is
found at speeds slightly in excess of Mach 2, or approximately
the speed of present day supersonic transports such as the
Concorde. At speeds of Mach 6 or Mach 8 projected fuel
efficiency equals that of present day high-efficiency air
transport systems such as the Boeing 747. At such speeds overall
productivity will also vastly increase because aircraft can fly
two round trips per day over transpacific distances. (In
contrast with a single one-way trip for current airliners.)
These factors may combine to make hypersonic transports
economically viable.
Williams also discussed the environmental implications of
the TAV, with particular emphasis on current concerns over
depletion of the ozone layer. He displayed a chart showing ozone
distribution as a function of altitude. The main point,
according to Williams, is that the ozone shield, the protective
layer that keeps out ultraviolet radiation exists mainly at
altitudes of 60-80,000 feet. He noted that the main
environmental objection to a U.S. supersonic transport was that
it would cruise at those altitudes and the nitrous oxide it would
emit would cause the ozone layer to deteriorate. It is hoped
that NASP-derived aircraft, on the other hand can operate at
altitudes of approximately 120,000 feet. At that level the ozone
content of the atmosphere is relatively low. Not only that, but
according to Williams, studies indicate ozone levels will remain
stable despite such operations. While some ozone depletion will
occur, high altitude radiation will reestablish the loss. He
cautioned, however, that this was only a "first look" and that
confirmatory investigation was needed.
Another important environmental concern is noise. Studies
of this problem have shown that for planned TAV takeoff and climb
modes overall engine pressure and jet velocity noise levels will
be on the same order as conventional turbofan-type aircraft. The
aircraft will transition from subsonic to supersonic flight while
in a steep climb. This will cause the sonic boom to be
propagated upward and away from the Earth's surface. Since it is
planned that the TAV will cruise at very high altitudes, it is
calculated overflight noise at ground level be about one-sixth
that generated by present day supersonic aircraft. This will
result not only from the distance of the aircraft above the
ground but from the thinness of the atmosphere at such extreme
altitudes. Williams admitted, however, that there will be a
sonic boom on descent. He stated that it is not yet clear how
strong this will be. In particular, it is not presently known
whether this will necessitate that the aircraft make its descent
over water. However, Williams noted that most of the routes over
which hypersonic transport aircraft are expected to operate will
provide opportunities for such overwater descents if required.
He therefore asserted that, while the aircraft will not be
silent, acoustics do not appear to present a serious drawback.
In response to a question Williams stated that it is too
early to say how air transportation variants of the NASP might be
integrated with national air traffic control system. Replying to
another question, Williams admitted that the necessary
infrastructure for hydrogen production and transport, especially
to support operations of hypersonic airliners, still remains to
be developed. He stated however that there are a number of
different options in this regard. For example, Space Shuttle
operations have already resulted in the production of hydrogen in
larger quantities than ever before. He also pointed out that the
United States has a very well developed natural gas pipeline
system. Natural gas in its simplest form is methane (CH4). One
potential method of obtaining hydrogen is by combining methane
with water which produces carbon dioxide (CO2) and hydrogen.
These factors might make possible the use of natural gas to
produce hydrogen either at central locations or in situ on
airports without the need for much additional infrastructure.
However, the focus at present is on the development of the X-30
vehicle itself. It is hoped that as a spinoff the X-30 will
drive the country towards thinking more of hydrogen as a major
fuel source for aviation.
Turning from what he described as the "programatics,"
Williams proceeded to make some historical comparisons. He
displayed a slide of the Bell XP-59A, the first manned turbojet
airplane to fly in the United States. The X-30, Williams
contended could be thought of as being analogous. He pointed out
that the XP-59A had led first to jet fighter aircraft and then to
the KC-135 tanker, which in turn gave birth to the 707 airliner.
He believes that the NASP program will progress along similar
lines. It will start with an experimental aircraft and then
proceed to hypersonic cruise and/or space launch type
applications. He envisions the scramjet having the same impact
on the aviation community as did turbojet vis-a-vis the piston
engine.
Williams then returned to the NASP itself and discussed the
overall development schedule. Phase one of the program is
complete. In 1989 a choice will be made between General Electric
Pratt & Whitney and Rocketdyne as prime contractor for the
engines. On the airframe side, the planning at the time of
Williams' talk was for the program to downselect from five to two
or three competitors in October of 1987. (As of the time this is
uploaded the writer has not seen any report indicating this has
in fact been done.) The major reason for this is to allow the
airframe contractors to work more closely with those involved in
the propulsion portion of the program. This in turn results from
the need for integrated airframe and engine design previously
alluded to. At this point each of the remaining airframe
contractors will be alloted contracts worth about $35 million for
the technology development phase of the program.
The most critical juncture in the program, however, will be
what Williams called the "assessment milestone." This will be
the point at which DARPA will have to first decide itself and
then inform Congress whether we are ready to proceed with
building the X-30 aircraft. At the point that the decision is
made to build the vehicle, DARPA will cease to be responsible for
program. The NASP will be turned over to the Joint Program
Office which will oversee the development of the X-30 to flight
configuration.
In the final part of his presentation, Williams discussed
some of the financial applications of the NASP program. Total
funding is $3.3 Billion. This will fund the development of one
ground test and two flight vehicles. About $230 million will be
spent on technology maturation. This part of the work is taking
place mostly in government laboratories and small companies. In
answer a question, Williams said that 1% of the total program
budget was spent on looking at potential applications, civil and
military, space and atmospheric, for the technology being
developed. Some of this applications, he asserted, will see
application sooner than the final vehicle.
NASA's share of the NASP program will increase by 50% in
fiscal year 1988. This increase only relates to funding. The
management structure will of the program will not change. The
increase in NASA's share of the NASP vis-a-vis DoD was ostensibly
due to the civil applications of the vehicle. Williams implied,
however, that is was really an outgrowth of the debate over which
agency's budget should be charged with the cost of paying for a
replacement Shuttle orbiter. He suggested that, in effect, funds
which DoD had planned to spend on TAV research were charged to
the cost of the new orbiter and in return additional funds from
NASA's budget were allocated to the NASP.
The funding for the TAV has been fully approved by both DoD
and NASA. However, stated Williams, that Congressional approval
fluctuates from day to day. This is in part attributable to the
fact that the program must deal with some 47 Congressional
committees. While Williams was necessarily restrained in
discussing this aspect of aerospaceplane development, he did
remark during the question period that the NASP program needed a
patron on the Senate side. He also indicated that a dilemma
existed in attempting to obtain political support. On the one
hand, the NASP program office did not wish to raise high
expectations by emphasizing the potential of the program and then
have "to turn around and say 'look, folks, this is a tough, tough
job.'" On the other hand, Congress tends to be reluctant to fund
programs where no specific requirement is claimed to exist.
In conclusion, Williams reiterated that on the one hand the
X-30 program was a technology development program, unconstrained
by any operational requirements. On the other hand it represents
an effort to focus the national technology base and laboratory
structure on a specific vehicle. In this apparent dichotomy, he
implied, lies the program's major strength.
Responding to a questioner who asked if he could say "with
certainty at this point" that the TAV's propulsion system would
be able to power a vehicle into low Earth orbit, Williams
described the NASP as a "high risk-high payoff program." This is
why DARPA has been selected to lead it. At the present time
DARPA feels comfortable in saying that there are no technology
barriers to achievement of the program's objectives. "At the
same time," he stated "we are concerned about the engineering
challenges that lie ahead." He indicated that if the program
were subject to a very tight time schedule and a specific set of
operational requirements DARPA would be a lot less confident.
However, since it involves an experimental vehicle, the X-30
program has the advantage of being able to proceed at the pace at
which technology develops.
In response to another questioner who asked about the
design of the leading edge of the wing, Williams stated that the
projected vehicle would have the ability to fly at subsonic
speeds. In particular, it would be designed so as to have ferry
capability as well as the ability to safely abort by doing a go-
around in the event of an engine failure on takeoff. The space
launch derivative will additionally be designed so that if the
payload is sacrificed it will be able to re-enter, restart its
engines and fly in the atmosphere to its destination.
The writer then asked Williams to comment the assertions by
proponents of rocket propulsion that air-breathing space launch
systems were impractical, or at least not cost effective.
Williams reiterated his earlier remarks that what he called a
"cultural conflict" existed in this area. He attributed this to
the fact that people who have been making their living designing
or building one type of system tend to experience "heartburn"
when somebody else asserts that there is a better way of doing
the same thing. Williams indicated, however, that a good
indication of the true feelings of the aerospace industry towards
scramjet powered launch vehicles is the investment by the
Rocketdyne division of Rockwell of extensive amount of its own
resources to investigate air-breathing propulsion. (According to
Williams the head of that organization had jokingly offered to
change its name to "Aerodyne.")
Williams told another questioner that the TAV will have a
much higher lift/drag ratio than the Space Shuttle, which he
described as a "flying brick."
Williams also stated that there were ample opportunities
for other contractors who wished to participate in the aerospace
plane program to do so. The subcontractor base is extensive and
the list of participants in the program is constantly changing.
Very little about the NASP program is classified. Even as to
those areas that are classified, it is not difficult for
companies or individuals who have the proper clearances.
Companies that are interested should contact the program office.
If a potential participant has something in particular that he
wishes to talk about the program office will listen to a
feasibility briefing and direct the applicant to the right prime
contractor or agency.
A person attending the meeting commented that while the
potential of the NASP was mind-boggling, one of the most massive
problems associated with the program was the need to generate the
necessary political support. In particular, this person posed
the rhetorical question "if $3 billion is the cost of two
experimental aircraft, what will be the cost of developing the
potential applications?" He also remarked that among those
present were "a bunch of pragmatists from Wall Street *** (who)
want to know 'how do you make a buck on this program.'" As a
result it was, this commentator believed necessary to "make it
clear that the development of the technology itself is going to
be very, very important to the country."
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