Aurora - Secret Hypersonic
Spyplane
by Simon Gray
Source: First Science
http://www.firstscience.com/site/articles/aurora.asp
Does the United States Air Force or one of America’s
intelligence agencies have a secret hypersonic aircraft capable of a
Mach 6 performance?
Continually growing evidence suggests that the answer to
this question is yes. Perhaps the most well-known event which provides
evidence of such a craft’s existence is the sighting of a triangular
plane over the North Sea in August 1989 by oil-exploration engineer
Chris Gibson. As well as the famous "skyquakes" heard over Los Angeles
since the early 1990s, found to be heading for the secret Groom Lake
installation in the Nevada desert, numerous other facts provide an
understanding of how the aircraft’s technology works. Rumored to exist
but routinely denied by U.S. officials, the name of this aircraft is
Aurora.
The outside world uses the name Aurora because a
censor’s slip let it appear below the SR-71 Blackbird and U-2 in the
1985 Pentagon budget request. Even if this was the actual name of the
project, it would have by now been changed after being compromised in
such a manner. The plane’s real name has been kept a secret along with
its existence. This is not unfamiliar though, the F-117a stealth
fighter was kept a secret for over ten years after its first
pre-production test flight. The project is what is technically known
as a Special Access Program (SAP). More often, such projects are
referred to as "black programs". So what was the first sign of the
existence of such an aircraft? On 6 March 1990, one of the United
States Air Force’s Lockheed SR-71 Blackbird spyplanes shattered the
official air speed record from Los Angeles to Washington’s Dulles
Airport. There, a brief ceremony marked the end of the SR-71’s
operational career. Officially, the SR-71 was being retired to save
the $200-$300 million a year it cost to operate the fleet. Some
reporters were told the plane had been made redundant by sophisticated
spy satellites.
But there was one problem, the USAF made no opposition
towards the plane’s retirement, and congressional attempts to revive
the program were discouraged. Never in the history of the USAF had a
program been closed without opposition. Aurora is the missing factor
to the silent closure of the SR-71 program.
Testing such a new radical aircraft brings immense costs
and inconvenience, not just in the design and development of a
prototype aircraft, but also in providing a secret testing place for
aircraft that are obviously different from those the public are aware
of. Groom Dry Lake, in the Nevada desert, is home to one of America’s
elite secret proving grounds. Here is Aurora’s most likely test
location. Comparing today’s Groom Lake with images of the base in the
1970s, it is apparent that many of the larger buildings and hangars
were added during the following decade. Also, the Groom Lake test
facility has a lake-bed runway that is six miles long, twice as long
as the longest normal runways in the United States. The reason for
such a long runway is simple: the length of a runway is determined
either by the distance an aircraft requires to accelerate to flying
speed, or the distance that the aircraft needs to decelerate after
landing. That distance is proportional to the speed at which lift-off
takes place. Usually, very long runways are designed for aircraft with
very high minimum flying speeds, and, as is the case at Edwards AFB,
these are aircraft that are optimized for very high maximum speeds.
Almost 19,000 feet of the runway at Groom Lake is paved for normal
operations.
Lockheed’s Skunk Works, now the Lockheed Advanced
Development Company, is the most likely prime contractor for the
Aurora aircraft. Throughout the 1980s, financial analysts concluded
that Lockheed had been engaged in several large classified projects.
However, they weren’t able to identify enough of them to account for
the company’s income. Technically, the Skunk Works has a unique record
of managing large, high-risk programs under an incredible unparalleled
secrecy. Even with high-risk projects the company has undertaken,
Lockheed has a record of providing what it promises to deliver.
Hypersonic Speed
By 1945, only a small amount of jets had the capability
of reaching speeds of 500mph. In 1960, aircraft that could exceed
1,500mph were going into squadron service. Aircraft capable of
2,000mph were under development and supposed to enter service by 1965.
This was a four-fold increase in speed in two decades.
From this, the next logical step was to achieve
hypersonic speed. The definition of hypersonic isn’t as clearly
defined as supersonic, but aerodynamicists consider that the
hypersonic realm starts when the air in front of the vehicle’s leading
edges "stagnates": a band of air is trapped, unable to flow around the
vehicle, and reaches extremely high pressures and temperatures. The
edge of the hypersonic regime lies at a speed of roughly one mile per
second - 3,600mph or Mach 5.4. What is regarded by many as the most
successful experimental aircraft program in USAF history, the X-15
rocketplane was created in response to a requirement issued by NASA
(then NACA) for an air-launched manned research vehicle with a maximum
speed of more than Mach 6 and a maximum altitude of more than fifty
miles.
The X-15 program, which involved three test aircraft,
went on to exceed all goals set and provided valuable data which has
been used on many high speed/altitude aircraft of today, including
NASA spacecraft, and most likely, the Aurora aircraft.
In the early 1960s, Lockheed and the USAF Flight
Dynamics Laboratory began a hypersonic research program which would
provide data on travel at hypersonic speed as well as more efficient
shapes for hypersonic vehicles. From this program came the FDL-5
research vehicle, which beared an amazing resemblance to the North Sea
Aurora sighting of Chris Gibson. Building on both the FDL-5 Project
and Aurora, the aircraft which may have been seen over the North Sea
could have been Northrop’s A-17 stealth attack plane. Possible forms
of hypersonic propulsion that Aurora could be using include: Pulse
Detonation Wave Engines, Pulsejet Engines, Advanced Ramjets
Hypersonic Requirements
There are three reasons why the North Sea sketch drawn
by Chris Gibson is the most persuasive rendition of the Aurora
vehicle. Firstly, the observer’s qualifications, with which he
couldn’t identify the aircraft; which would have been instantaneous if
the aircraft was known to the "white world". Second is the fact that
the North Sea aircraft corresponds almost perfectly in shape and size
to hypersonic aircraft studies carried out by McDonnell Douglas and
the USAF during the 1970s and 1980s. The third factor is that the
North Sea aircraft looks unlike anything else. No aircraft other than
a high-supersonic vehicle, or a test aircraft for such a vehicle, has
ever been built or studied with a similiar planform. At hypersonic
speeds, traditional aerodynamic design gives way to aero-thermodynamic
design. In order for a hypersonic vehicle to remain structurally
intact at such high speeds and stresses, the vehicle must produce
minimum drag and be free of design features that give rise to
concentrations of heat. The aircraft design must be able to spread the
heat over the surface of the structure.
Thermal management is critical to high-speed aircraft,
especially hypersonic vehicles. Skin friction releases heat energy
into the aircraft and must be pumped out again if the vehicle is to
have any endurance. The only way to do this is to heat the fuel before
it enters the engine, and dump the heat through the exhaust. On a
hypersonic vehicle, thermal management is very critical, the cooling
capacity of the fuel must be used carefully and efficiently or else
the range and endurance of the aircraft will be limited by heating
rather than the actual fuel tank capacity.
So how will an aircraft reach such speeds? Conventional
turbojet engines won’t be able to handle the incoming airstreams at
such speeds, they can barely handle transonic speeds. In the case of
hypersonic propulsion, an aero-thermodynamic duct, or ramjet, is the
only engine proven to work efficiently at such speeds. Even ramjets
have drawbacks though, such as drag created in the process of slowing
down and compressing a Mach 6 airstream.
To make a ramjet engine efficient is to spread the air
over the entire length of the body. In a hypersonic ramjet aircraft,
the entire underside of the forward body acts as a ramp that
compresses the air, and the entire underside of the tail is an exhaust
nozzle. So much air underneath the aircraft serves another purpose, it
keeps the plane up. The ramjets need a large inlet area to provide the
high thrust needed for Mach 6 cruise. As a result, the engines occupy
a large area beneath vehicle and the need to accomodate a large
quantity of fuel means that an all-body shape is most feasible.
Structurally, the all-body shape is highly efficient. As
well as being extremely aerodynamic, the average cross-sectional area
being very large provides a great deal of space for load, equipment
and fuel. This being inside a structure that is light and compact
having a relatively small surface area to generate frictional drag.
The spyplane’s airframe may incorporate stealth
technology, but it doesn’t really require it should its mission simply
involve high altitude reconnaissance. Hypersonic aircraft are much
harder to shoot down than a ballistic missile. Although a hypersonic
plane isn’t very maneuverable, its velocity is such that even a small
turn puts it miles away from a SAM’s projected interception point.
Choosing The Right Fuel
Choosing the right type of fuel is crucial to the
success of Aurora. Because various sections of the craft will reach
cruising-speed temperatures ranging from 1,000 degrees fahrenheit to
more than 1,400 degrees fahrenheit, its fuel must both provide energy
for the engines and act as a structural coolant extracting destructive
heat from the plane’s surface.
At hypersonic speeds, even exotic kerosene such as the
special high-flashpoint JP-7 fuel used by the SR-71 Blackbird can’t
absorb enough heat. The plausible solution is cryogenic fuel.
The best possibilities are methane and hydrogen. Liquid
hydrogen provides more than three times as much energy and absorbs six
times more heat per pound than any other fuel. The downfall is its low
density, which means larger fuel tanks, a larger airframe and more
drag. While liquid hydrogen is the fuel of choice for spacelaunch
vehicles that accelerate quickly out of the atmosphere, studies have
shown that liquid methane is better for an aircraft cruising at Mach 5
to Mach 7. Methane is widely available, provides more energy than jet
fuels, and can absorb five times as much heat as kerosene. Compared
with liquid hydrogen, it is three times denser and easier to handle.
Current Knowledge of Aurora
On 16 November 1998, a camcorder video was taken of a
mysterious "fireball" in the sky. While this was very interesting,
what was even more amazing was the aircraft which was seen shortly
after flying at very high speed producing the mysterious
"donuts-on-a-rope" contrails. Does this video, which is currently
undergoing intense study at JPL, show the mysterious Aurora spyplane?
(From
FirstScience Website)
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