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The Legend of the Mach 6 SR-72 Aurora: A History of Hypersonic Flight

Mark has a BA from the University of Arkansas (Fayetteville).

Lockheed Skunk Works concept image of the SR-72 as envisioned in 2013. Like an aeronautical surfboard, a hypersonic plane rides its own shock wave. Planes like Aurora are called wave-riders.

Lockheed Skunk Works concept image of the SR-72 as envisioned in 2013. Like an aeronautical surfboard, a hypersonic plane rides its own shock wave. Planes like Aurora are called wave-riders.

Area 51 and the Super-Secret SR-72

When most Americans think of Area 51, we think of aliens, UFOs, and other controversial government cover-ups. It's easy to lose the fact that Area 51 is a real place that, since the mid-1950s, has been the site of beyond top-secret CIA and U.S. Air Force aircraft that have represented many of the most groundbreaking advancements in military technology.

This is my attempt to remove the veil surrounding the ultra-secret SR-72; it is perhaps one of America's intelligence agency's replacements for the retired Lockheed SR-71 Blackbird. There is so much more that remains unknown about what is taking place in that remote base near Groom Lake in the state of Nevada.

Like its predecessor, Aurora costs several million dollars per flight and is sent out only on missions where the plane's sensors can gather information unobtainable by satellite reconnaissance or other means. It's possible the Aurora was used to photograph Iraq's defenses during Operation Desert Storm in an attempt to provide tactical intelligence to ground-based military commanders.

Allocated $2.3 billion in 1985, there are possibly now at least 25 operational hypersonic spy planes flying from Tonopah Base Area 30 in Nevada. According to one retired DOD official, "With the SR-71 Blackbird, they knew we were there, but they couldn't touch us. With Aurora, they won't even know we're there!"

When Aurora was first mentioned in Aviation Week and Space Technology in 1989, the floodgates of speculation opened. After the recently exposed Lockheed F-117 stealth fighter and the Northrop B-2 stealth bomber, the world was anxious for further revelations from the world of dark airplanes.

Aurora was presented as "a possible hypersonic reconnaissance aircraft" that was a replacement for the recently retired SR-71. Since then, the Aurora has been a ghost sought out by airplane enthusiasts worldwide.

Around the world, numerous reports of unusual pulsing sounds in the sky were recorded, as well as many sightings of contrails described as resembling "doughnuts on a rope."

In 1989, an engineer named Chris Gibson working on the Galveston Key oil platform in the North Sea, reported an unidentified triangular aircraft being refueled by a KC-135 Strat tanker. Because Gibson had served with the Royal Observer Corps and was, as Britain's Guardian newspaper put it, "an expert on recognizing aircraft," his account was given "considerable credence," his sighting would add to the Aurora legend.

Bob Lazar, who had been thrust into international media attention through reports of extraterrestrial beings in the possession of the American government, added to the myth of the Aurora. He reported that he had also seen the Aurora aircraft while he was inside Area 51.

From the 1990s to the present day, numerous reports of unusual pulsing sounds in the sky were recorded, as well as many sightings of contrails described as resembling "doughnuts on a rope." These were most likely attributed to the Aurora, though another delta-winged aircraft, known variously as the "Brilliant Buzzard" or "The Mothership," were also mentioned in some of the conspiracy theories surrounding Area 51.

Since the 1990s, unexplained sonic booms have periodically shaken the citizens of Southern California. Officials at the United States Geological Survey, the agency that monitors earthquake activity, no doubt surprised the military with their statements that a very fast, high-flying aircraft was causing the "air quakes" registering on their array of seismographs.

Area 51

A satellite view of Area 51 at Groom Lake.

A satellite view of Area 51 at Groom Lake.

Area 51 and Bob Lazar

The X-15

Aurora

Aurora was almost certainly built by Lockheed's fabled Skunk Works, now called the Lockheed Advanced Development Company. Of all known design organizations, only Skunk Works has the proven track record to manage large projects that incorporate breakthrough technology in total secrecy. Detail analysis of Lockheed's financial statements makes it clear to estimate Aurora's price tag at about $1 billion per aircraft. At the most, 10 to 20 of the new spy planes were built.

Like the SR-71 Blackbird, Aurora has a crew of two. Flying it is quite unlike piloting a conventional aircraft. There is little, if any, outside view because a normally angled windshield would cause too much drag and gets too hot. For these reasons, Aurora has a retractable windshield used only for takeoff and landing. During hypersonic flight, the Aurora's windshield would be covered by a heat shield.

Choosing the right fuel was important to Aurora's design. Because of this, a cryogenic fuel was selected, cold liquified gas. Liquid methane was selected since it does well for a plane speeding along at Mach 5 or 6. Since various sections of the aircraft will reach cruising speed temperatures ranging from 1000°F to more than 1400°F, its fuel must both provide energy for the engines and extract destructive heat from the aircraft's structure.

The Aurora can fly at subsonic speeds because its entire body is a lifting surface. It also has sharply swept leading edges, like the Concorde's wings, which generate a powerful vortex at nose-height flight that boosts the body's lift. Aurora's wedge shape is structurally efficient and not bound by aerodynamic freeloaders such as a conventional fuselage.

The Aurora uses daylight and infrared cameras for ultra-detailed work in clear weather. And unlike a satellite, the Aurora can be scheduled to make reconnaissance passes in the early morning, the golden hour for covert imaging. By planning its missions when the low sun provides even illumination, the spy-craft can deliver crystal clear images to American intelligence agencies.

A phased array antenna built into Aurora's upper surface, most likely near its tail, where aerodynamic hearting is at its lowest, allows the airplane to transmit real-time or near real-time imagery to the Pentagon's satellite network from trouble spots around the world.

The Son of the Blackbird

Combined-Cycle Jet Engine

According to Dr. Fred Billing at the Applied Physics Laboratory of Johns Hopkins University, who experimented with the combined-cycle engine in the 1960s, one of the attractive features of this engine was that it delivers high thrust per unit of frontal area, a drag-reducing factor helpful in pushing efficiently past the sound barrier. Most importantly, the combined-cycle engine can recover energy that most engines throw away. By using cold fuel to cool the airplane's structure and engines, for example, the system converts heat into mechanical energy used to supercharge the ramjet and generate additional thrust.

Aurora's top speed has been set at 3,000 miles per hour with a cruising altitude of 28.4 miles. Some independent information places Aurora's top speed closer to 5,000 miles per hour and an operating altitude of about 40 miles.

Code name, Aurora, once thought to belong to the B-2 Bomber or the F117A Nighthawk programs, is now known to refer to a super-secret hypersonic long-range stealth aircraft designed and built for the USAF and CIA at Lockheed's ADP facility in Burbank, California. Skunk Works, named after a cartoon character's secret still, made for brewing moonshine, in the "Lí'll Abner" comic strip. Several sources have reported that the Aurora flies out from Nellis Air Force Base's Watertown Strip and (Area 51) at Groom Dry Lake, Nevada.

Aurora's engines run on supercooled liquid methane. After taking off from Watertown Strip and refueling once in flight, Aurora can cross the Pacific Ocean in about two hours. Its external shape is a double delta design. Aurora's radar signature is low, probably near that of the F117A Nighthawk, which is from 0.1 to .2 3 square meters.

Sources

Annie Jacobsen, Area 51 An Uncensored History of America's Top Secret Military Base., Back Bay Books / Little, Brown and Company., Hachette Book Group 237 Park Avenue, New York, NY 10017.

Rich Ben. Skunk Works Little, Brown and Company. Hachette Book Group Park Avenue, New York, NY 10017.

Bill Yenne. Black Jets: A History of the Aircraft Development at Groom Lake, America's Secret Aviation Base., Zenith Press, A member of Quarto Publishing Group USA Inc., 400 First Avenue North, Suite 400 Minneapolis, MN 55401 USA.

© 2022 Mark Caruthers