It's not every day one of America's top airplane-makers announces, in the pages of Aviation Week & Space Technology, a design for a new hypersonic strike plane. The SR-72, a concept from Lockheed Martin's famed Skunk Works division, has been years in the making and - if built - would become would one of the fastest warplanes ever.

It's exciting stuff.

But the timing of the announcement is … curious. In late October, Lockheed also announced that it's teaming up with Boeing to jointly pursue a contract for the Air Force's stealthy new Long-Range Strike Bomber.

There's nearly $60 billion on the table for LRS-B, and the competition is intense between Lockheed-Boeing and rival Northrop Grumman. All details of the bomber project are secret, so Northrop - which built the current B-2 stealth bomber - has taken to discreet means of lobbying the Air Force for the contract. At the Air Force Association conference in Maryland in September, the company handed out copies of a free in-house book chronicling the history of the B-2.

The book's takeaway: Northrop knows how to build stealth bombers. Just not particularly fast ones, as the B-2 is subsonic.

But the Air Force is widely believed to want an LRS-B that's both speedy and stealthy. Lo and behold, now Lockheed has revealed its Mach-6 design. But nowhere in its published comments regarding the SR-72 does Lockheed state that the new jet is meant to meet the LRS-B's requirements. Instead, the company touts the SR-72 as a possible spy plane … that just happens to have add-on bombing capability.

Basically, it appears Lockheed is publicly claiming to be able to build a better next-gen bomber than Northrop, slyly circumventing the secrecy restrictions around the LRS-B bomber program by openly pitching its new strike plane without ever mentioning LRS-B.

Read the full article:
Curious Timing
"Speed is the new stealth"
 - Al Romig, Skunk Works engineering and advanced systems vice president
Since the early 1990s, there have been reports of mysterious sonic booms, unidentified aircraft sightings and a mysterious aircraft on a wall chart at Lockheed Martin.

The existence of an early replacement for the SR-71-which was permanently retired in 1998-has never been verified. Aviation buffs call the apparently mythical plane Aurora. It's the Bigfoot of the aviation world.

The story of Aurora began in 1990, when Aviation Week & Space Technology mentioned that "Aurora" had been a line item in the U.S. defense budget in 1986 for "black aircraft production." Aurora funding allegedly reached $2.3 billion in 1986, prompting speculation that a replacement for the SR-71 was in the works.

The name stuck, and the chase was on. But was it an Aurora chase, or a wild goose chase?

In the early '90s, a series of mysterious sonic booms began rattling the California coastline, noises that defied easy explanation. To this day, sonic booms are still reported across swathes of southern California. One such report from April 2009 was investigated by the local press, which could find no explanation for it.
There have also been sightings of mysterious aircraft attributed to Aurora. In 1989, Chris Gibson, a veteran plane watcher and former member of the Royal Observer Corps, reported seeing a mysterious aircraft while stationed on an oil rig in the North Sea. Gibson reported the aircraft resembled an isosceles triangle and was accompanied by a KC-135 tanker aircraft.

In 1992, aviation enthusiast Stephen Douglass photographed what came to be known as "donuts on a rope" contrails. The unusual contrails were said to be accompanied by an unusual, pulsating engine roar. Both have been attributed by Aurora buffs to the use of pulse-detonated wave engine technology allegedly used by Aurora to achieve hypersonic speeds.

In 1992, Aviation Week reported that military-monitoring hobbyists had listened in on an exchange between Edwards Air Force Base and an unknown, high-altitude aircraft identified as "Gaspipe." Edwards aircraft controllers could be overheard advising "Gaspipe" that it was being tracked at 67,000 feet-far above the normal operating altitude of military aircraft, where flight crews of the U-2 and SR-71 typically wear pressurized flight suits. The Air Force confirmed that neither U-2 nor SR-71 aircraft were being controlled at those times.

Then in got even weirder.

In the late 1990s, journalist Nick Cook of Jane's Defence Weekly traveled to Lockheed's famed Skunk Works to interview its head, Jack Gordon, and tour the facility. He later recounted a mysterious incident that left him scratching his head.

Just before I left the [Skunk Works] building, I stopped in front of a large chart on the wall of the lobby area. I hadn't noticed it on the way in.

It proudly illustrated the lineage of every Skunk Works aircraft since the XP-80. Past the picture of the U-2, past the SR-71 Blackbird and the F-117A Stealth Fighter, past the YF-22 and DarkStar, and there was something called "Astra."

Sitting at the top of the tree, Astra looked like an ultra-high-speed reconnaissance aircraft; every pundit's dream of how Aurora ought to look.

Cook asked Lockheed's press representative what "Astra" was, and weeks later was told it was a 30-year-old "concept for a high-speed airliner."

That a 30-year-old concept plane would be at the top of a tree of Skunk Works aircraft is … peculiar.

Read the full article here:

A vehicle penetrating at high altitude and Mach 6, a speed viewed by Lockheed Martin as the "sweet spot" for practical air-breathing hypersonics, is expected to survive where even stealthy, advanced subsonic or supersonic aircraft and unmanned vehicles might not. Moreover, an armed ISR platform would also have the ability to strike targets before they could hide.

The deep nacelles, mounted close inboard, indicate the "over-under combined cycle" engine configuration outlined for the HTV-3X, as well as integrated inward-turning turbo-ramjet inlets. "One of the differences with this demonstrator compared to the HTV‑3X is that with that, we were limited to small turbines with a low-drag design," Leland says. "With fighter engines, we accelerate much more briskly. It's a significant improvement in adding margins. It is also very important [that] you have a common inlet and nozzle because of the significant amount of spillage drag in the inlet and the base drag in the nozzle."
Aerodynamically, the forebody appears to be shaped for inlet compression at high speed, but without the characteristic stepped "wave-rider" configuration of the X-51A. "We are not advocates of wave riders," Leland says. "We found that, in order for a wave rider to pay off, you have to be at cruise and be burning most of your fuel at cruise. But these designs burn most fuel as they accelerate, so you want an efficient vehicle that gets you to cruise. You end up with a vehicle that is hard to take off and land, has little fuel volume and high transonic drag."

The planform is characterized by chines that blend into a sharply swept delta extending back roughly halfway along the hump-backed fuselage. The chine and delta are likely designed to provide increased directional stability as well as a larger amount of lift at high cruise speeds. Outboard of the engine inlets, the leading-edge angle abruptly aligns with the fuselage before the wing extends into a trapezoid. The angle of the cranked wing would provide vortex lift to assist with low-speed flight.

Read the full article:
Has the SR-72-or something like it-been flying all along?
SR-72 Revealed
SR-72 - Mach 6 Hypersonic Concept
The Skunk Works has been working with Aerojet Rocketdyne for the past seven years to develop a method to integrate an off-the-shelf turbine with a scramjet to power the aircraft from standstill to Mach 6 plus.
Nov 2, 2013