Exclusive: Skunk Works Reveals SR-71 Successor Plan

Gestart door jurrien visser (JuVi op Twitter), 01/11/2013 | 12:14 uur


jurrien visser (JuVi op Twitter)

NASA launches study for Skunk Works SR-72 concept

By: Dan Parsons / Dec, 17/14

Source: Flightglobal.com

NASA has awarded a contract to Lockheed Martin to study the feasibility of building a hypersonic propulsion system for a concept intelligence, surveillance and reconnaissance (ISR) aircraft dubbed the SR-72 using existing turbine engine technologies.

The $892,292 contract "provides for a parametric design study to establish the viability of a turbine-based combined cycle (TBCC) propulsion system consisting of integrating several combinations of near-term turbine engine solutions and a very low Mach ignition Dual Mode RamJet (DMRJ) in the SR-72 vehicle concept," the award document says.

A spokeswoman for Lockheed's Skunk Works development laboratory declined to comment on the contract award.

The SR-72 is envisioned as an unmanned, reusable hypersonic ISR and strike aircraft capable of Mach 6.0 flight, or nearly double the speed of its predecessor, the SR-71 Blackbird.

NASA is funding the validation of a previous Lockheed study that found speeds up to Mach 7 could be achieved with a dual-mode engine that combines turbine and ramjet technologies, says Paul Bartolotta, a senior aerospace engineer at NASA Glenn Research Center who specialises in hypersonic propulsion.

Skunk Works was responsible for developing the SR-71 Blackbird, which was able to achieve M3.2 with specially designed Pratt & Whitney J58 engines. The powerplants were able to function as a low-speed ramjet by redirecting intake air around the engine core and into the afterburner past M2.5.

Potential adversaries are working on technologies to counter US air force fighter and bomber stealth capabilities. The service sees hypersonic vehicles as the next logical step in that arms race.

The US Air Force has a hypersonics roadmap that envisions fielding a hypersonic strike weapon, to succeed the X-51 Waverider proof-of-concept demonstration. The Waverider successfully launched from a B-52 and was powered to M4.8 by a booster rocket. The X-51 then accelerated to M5.1 after igniting its ramjet engine.

The roadmap envisions a follow-on programme calling for a reusable unmanned aircraft with M6.0 speeds. At that speed, intelligence can be gathered or weapons delivered before enemy air defenses are even alerted.

Both AFRL and the Defense Advanced Research Projects Agency (DARPA) have been after a low-speed ramjet for years. The agencies' HTV-3X programme demonstrated that a ramjet that could operate below M3.0. That inspired Lockheed to partner with Aerojet Rocketdyne to develop a way to use off-the shelf engines like the F100 or F110 for short bursts of acceleration beyond M2.2 in an attempt to close the gap between the two propulsion technologies.

"This study is asking whether we can use existing technologies to create a dual-mode ramjet that in theory can light up at Mach 2 to 2.5," Bartolotta says. "The key to this whole effort is whether we can do it and finding the required technologies so we can plan for a programme in which we can spend some major dollars."

The problem with hypersonic propulsion has always been the gap between the highest speed capability of a turbojet and the lowest speed of a ramjet. Most ramjets cannot achieve ignition below M4.0. Turbine engines typically can accelerate to only M2.2, below speeds at which a ramjet could take over and continue acceleration.

Therefore, NASA and Lockheed must either develop a turbine engine that can accelerate to M4.0, or a ramjet that can function at speeds within a turbine engine's envelope, Bartolotta says.

"We're looking for a turbine-based combined system where at low speeds you have a turbine providing power, then at higher speeds a ramjet or scramjet takes over," he says. "We want to be able to go up to Mach 7 then transition back to the turbine to land it on a runway and recover it. The problem is how you can get the vehicle to fly fast enough to ignite the DMRJ and then have the DMRJ take over."

NASA is considering several existing turbofan engines for use in the project, including the Pratt and Whitney F100-PW-229 that powers both the Boeing F-15 and Lockheed Martin F-16, among other aircraft. The General Electric F414 used by the Boeing F/A-18E/F Super Hornet also is being studied, along with the supersonic turbine engine for long range (STELR) engine conceived by the Air Force Research Laboratory (AFRL).

If the study is successful, NASA wants to fund a demonstration programme. Lockheed would test the dual-mode ramjet in a flight research vehicle, and try to find solutions to issues like engine packaging and designing the thermal management system, Bartolotta says.

"We're doing this at a lower Mach number so we need to figure out what are the issues for cocooning the turbine, what do we need to do to reignite that turbine once we come down from hypersonic speeds," Bartolotta says.

http://www.flightglobal.com/news/articles/nasa-launches-study-for-skunk-works-sr-72-concept-407222/

jurrien visser (JuVi op Twitter)

11/13/2013

Air Force Chief Noncommittal on Lockheed Martin's SR-72 Concept

By Valerie Insinna

Defense news websites and blogs ignited earlier this month when Lockheed Martin announced its successor to the famed SR-71 Blackbird spy plane, the hypersonic SR-72 aircraft. Lockheed has said a working demonstrator could be in the skies by 2030.

Air Force Chief of Staff Gen. Mark Welsh acknowledged that hypersonic capabilities would be advantageous for the Air Force, but he had not spoken to Lockheed officials about the SR-72 and would not comment on whether the service was interested in the aircraft.

Nevertheless, he said he was interested in hypersonic technology.

"It's something that appeals to me for a very simple reason, not because it's cool, but because speed compresses decision times," he told reporters on Nov. 13. "Anything you can do to decrease an adversary's decision timeline and give you the advantage in action is a good thing. So if it's practical to pursue hypersonics and create that ability to move at a much, much faster speed than we could in the past, it's worth pursuing. But how far we go, I don't have any idea."

The unmanned SR-72 would be equipped with an integrated turbine engine and dual-model ramjet, providing the thrust and acceleration needed to fly the aircraft at six times the speed of sound, according to company information.

"Hypersonic aircraft coupled with hypersonic missiles could penetrate denied airspace and strike at nearly any location across a continent in less than an hour," Brad Leland, Lockheed Martin program manager for hypersonics, said in a news release.

Earlier this year, the Air Force successfully flew its X-51 WaveRider demonstration aircraft at hypersonic speeds. The X-51, manufactured by Boeing, traveled 230 nautical miles in about six minutes during a May flight over the Naval Air Warfare Center Sea Range in Point Mugu, Calif.

The demonstration proved that hypersonic flight could be a plausible investment for the service, said Welsh. But if the Air Force pursues that capability, it may incorporate it in a weapons system such as a missile rather than an aircraft.

"Right now, we don't have the material to do anything other than the size of a WaveRider, which is not an [full-scale] airplane," he said. "I think it would probably start small, and who knows where it will go after that."

"Just think how cool you'd look in a hypersonic airplane. That drives all of our decisions, doesn't it?" he joked.

That moment of levity contrasted with the overall theme of his remarks: The Air Force is struggling to find a balance between capability, capacity and readiness as budget cuts and sequestration continue.

If sequestration extends through 2023, the service will have to cut about 50 percent of its modernization programs, Welsh said.

The Air Force is committed to protecting its three top acquisition priorities — the F-35 Joint Strike Fighter, the KC-135 refueling tanker and the long range strike bomber. As the service is challenged by aging aircraft fleets, those three programs will be necessary to keeping the service relevant in the next decade, he said.

For instance, when Boeing delivers the last KC-46 tanker in 2028, two-thirds of the tanker fleet will be more than 65 years old, Welsh said.

"By 2025, there will be fifth-generation technology produced by other countries that is in the battlespace," he said. "I certainly hope we're not fighting Russia or China, and I don't believe we will be, but we'll see their equipment. They export. ... It will be on the streets and we'll be fighting it. And their new stuff will be better than our legacy stuff."

The Air Force hopes to be able to field a new bomber at the price of $550 million a copy. That aircraft's design will not be based on unproven technologies, Welsh said. "That's when prices start to get out of control" and requirements start to change.

Acquisition of new platforms and weapons systems isn't the only thing that is feeling the pains of sequestration; readiness has taken a hit as well.

Realistically, the Air Force can only keep 80 percent of its combat units ready at any time, Welsh said. That allows the service to meet all of its demands, such as homeland defense, responding to combatant command needs and providing intelligence, surveillance and reconnaissance.

Before sequestration, that number had dropped to 55 percent. Today, less than 40 percent of combat units are ready for combat, Welsh said. "We think that's going to last for a while. The sequester cuts accounts like flying hours [and] weapons system sustainment. That takes directly from our ability to keep units ready day to day."

That can lead to a longer response time and fewer options for decision-makers, he said.

Ultimately, cutting training hours could end up being more expensive than keeping pilots ready for combat. It can take three times as much money to re-qualify someone to fly an airplane compared to someone who maintains that state of readiness, Welsh said.

http://www.nationaldefensemagazine.org/blog/Lists/Posts/Post.aspx?ID=1330

jurrien visser (JuVi op Twitter)

Lockheed Martin SR-72 is Only a Plane on Paper

By: Dave Majumdar
Tuesday, November 5, 2013

Lockheed Martin Skunk Works and Aerojet Rocketdyne have made a breakthrough in hypersonic propulsion technology, but the Mach 6.0-capable SR-72 remains more of aspiration than a real airplane.

The companies have found a way to pair a conventional turbine jet engine, such as those in existing fighter aircraft, with a supersonic combustion ramjet—creating an engine that can operate effectively only if an aircraft is traveling at very high speeds.

The pairing—first reported by Aviation Week on Friday—makes a hypersonic plane a practical possibility, but Lockheed still faces scores of technological and funding challenges before the so-called Son of Blackbird becomes a reality.

The breakthrough is in the "proprietary way we join up those two systems," Bradley Leland, Lockheed Martin Skunk Work's portfolio manager for air-breathing hypersonics, told USNI News in a Monday interview. "The turbine, which works well up to Mach 2, and the scramjet (supersonic combustion ramjet) work well at Mach 4 and above. By making those work together down at Mach 3—below Mach 3—that's really the key."

Turbine engines would accelerate the notional SR-72 up to about Mach 3, before the jet transitions to scramjet propulsion. As the aircraft transitions into full scramjet propulsion, the turbines are deactivated. The scramjet would then accelerate the aircraft up to a maximum speed of about Mach 6.

Unlike the previous generation SR-71s' Pratt & Whitney J58 engines, which were a partial ramjet design, the new engine concept burns fuel at supersonic speeds—allowing it fly a lot faster. But it is also more technologically challenging.

"We're looking at dual flow-paths, an over and under configuration," Leland said.

The methodology to accomplish the transition between the turbines and scramjet was developed under the auspices of the Defense Advanced Research Projects Agency's (DARPA) HTV-3X hypersonic aircraft demonstrator project. The project—also called the Blackswift program—ultimately failed because of the technological inability to develop an advanced turbine engine that could boost the aircraft up to Mach 4.

"Those turbines just weren't read yet," Leland said. "As a result, we couldn't go forward with the demonstrator program called Blackswift. We couldn't go forward with that program because the turbine was the one technical weight that was not yet available."

The cost to develop a large-scale high-mach turbine engine would be astronomical, Leland said.

So, five years ago engineers from Lockheed and Rocketdyne came together to work on a project that would use off-the-shelf fighter-sized turbine engines to accomplish the same task, affordably using many of the lessons learned from the HTV-3X program, Leland said.

The prospective engines currently under consideration are the Pratt & Whitney F100 and the General Electric F110. Those engines are limited to between Mach 2 and Mach 2.5, depending upon the air inlet. Lockheed and Rocketdyne's solution removed that roadblock.

But the Lockheed-led effort has a long way to go before a demonstrator aircraft ever flies—much less an operational SR-72.

"Up until now we have spent a lot of company money on small-scale testing and some analysis," Leland said. "In order to go forward into the next steps there would be a series of critical demonstrations of some large scale systems."

One of those tests would be to directly connect a turbine engine with a scramjet to prove the concept works as expected, Leland said. That would take roughly three years. "That three-year phase would be beyond what we can fund on company money," he said. "That would be a government-funded program."

While the prospective government customers would be the U.S. Air Force and DARPA, Leland said Lockheed does not yet have a customer for the effort.

In order for the demonstrator to become a reality, a smaller version of the concept will need to be proved in the form of the Air Force Research Laboratory and DARPA's High Speed Strike Weapon (HSSW).

"[HSSW] is important because we need to show some clear definitive successes in hypersonics to demonstrate that we can make the systems modest in size, modest in cost and not exotic," Leland said. "I think that a successful flight testing of an affordable hypersonic vehicle in HSSW will be key to being able to proceed with the demonstrator aircraft."

The missile is effectively a small-scale expendable version of the SR-72 air vehicle. The HSSW will be roughly the same size as Boeing's X-51 supersonic combustion ramjet demonstrator and will draw upon much of accomplishments of that program.

"The first step on the roadmap to get to the operational hypersonic aircraft is really the [HSSW]," Leland said.

Lockheed hopes to launch the flight demonstrator program in 2018, he said. While the 2018 flight demonstrator is not currently funded and is more of a notional project at this time, he said the company has done a fair amount of design work on the aircraft.

"We have a very solid design for it," he said. "But once again, you wouldn't want to move forward with that aircraft design until you do the critical demonstrations to prove out the technology."

The prospective demonstrator would be about the same size as the company's F-22 Raptor stealth fighter. Unlike the operational SR-72 concept, it would be a single-scramjet engine design. The demonstrator would take off and land just like any normal aircraft, but would be able to cruise at Mach 6 for several minutes, Leland said. Lockheed hopes to fly the demonstrator in 2023.

The operational SR-72 would be a twin-scramjet design, which Lockheed hopes would become operational in 2030, Leland said.

It would be primarily geared toward the intelligence, surveillance and reconnaissance (ISR) mission, but would have a secondary strike role using a pair of HSSWs.

It could hit any target on any continent in less than an hour. Leland said it could be a prompt theatre-strike weapon with more than 1,000 nautical miles of penetration into denied airspace (when the range of the missile is added to that of the SR-72).

Stealth would be of limited value in an aircraft like the SR-72, given that radar absorbent materials would not survive the extreme temperatures. Moreover, the jet would have a huge infrared signature, which would negate most signature reduction measures. The aircraft might also leave a wake that might be tracked on radar—much like the SR-71.

Survivability would be achieved through a combination of speed, altitude and some limited signature reduction, Leland said.

An area of potential concern is weapons separation at such extreme speeds and altitudes. But Leland said that Lockheed has a lot of experience with high-speed stores separation, which it gained on the 1960s-era YF-12 interceptor program. The company also has more recent experience, but Leland did not elaborate. "It's tricky, but we know how to do it," Leland said.

The SR-72 would have range comparable to its SR-71 forbear—3,200 nautical miles.

Like its predecessor, it might use a more exotic fuel like JP-7. But Lockheed is examining the use of conventional fuels to simplify logistics and reduce operating costs. "There is the fuel from the SR-71, which would be very useful, called JP-7, but we are certainly looking at using more conventional fuels," Leland said.

One of the biggest technical hurdles facing the SR-72 is thermal management—skin friction at Mach 6 is immense and generates incredible amounts of heat. There are two potential options to deal with the thermal stress of sustained high-speed flight: one is having a cold structure—similar to the tiles on space shuttles; the other option is a warm structure using materials like titanium.

Lockheed's preferred option is the latter. As such the SR-72 would have a metal structure that would be allowed to heat-up, Leland said. "We have a lot of experience with high-temperature warm structures like the SR-71," he said. "So we think that is very much achievable."

Extreme temperatures also will likely require a cockpit buried deep inside its fuselage to shield the crew from intense heat. The pilot likely will control the aircraft via a sensor system—probably a form of electro-optical cameras. Under those extreme conditions, designing an environmental control system that can keep the crew alive and the avionics functioning is not an easy task. When the original SR-71 was designed, Lockheed had to practically invent an entirely new system to deal with the extreme environmental conditions.

Affordability is a key concern for Lockheed, which is why the company targeted a cruise speed of Mach 6. "That's why we've been focusing on Mach 6," Leland said. "If you start to fly much above Mach 6, you are forced to go into some pretty exotic materials to survive those temperatures."

While Lockheed has not discussed its aspirations for the SR-72 in detail with the Air Force, Leland said that the company is aiming the design to overcome the vast distances of the Pacific theater. "Certainly, high-speed vehicles is one way to address the long distances involved," he said, noting that the USAF hypersonics roadmap does call for an aircraft similar in concept to the SR-72.

But only time will tell if the Pentagon has the financial wherewithal to fund Lockheed's dreams of the SR-72, even if the Defense Department wants such an aircraft.

http://news.usni.org/2013/11/05/lockheed-martin-sr-72-plane-paper

Poleme

Citaat van: jurrien visser op 01/11/2013 | 12:57 uur
Tweet van LM 1/11/13
Lockheed Martin ‏@LockheedMartin  5m 
We gave @aviationweek the exclusive: Meet the hypersonic SR-72, "Son of the Blackbird": http://ow.ly/qobO1  http://ow.ly/qoiYd
Ach, 30 jaar geleden waren er al 'Tweets' over een Mach 5 opvolger voor de SR-71 Blackbird.  Toen ging de NASA over tot ontwikkeling van het experimentele Single Stage To Orbit X-30A ruimte vliegtuig. Twintig jaar geleden geruchten en mensen, die een zeer snel ca. 60 meter lang vliegtuig hadden gezien en gehoord a la artist impression's in deze draad.  De X-30A werd toen geannuleerd, maar in feite was dit een 'wit front' voor een zwart hypersonisch spionage vliegtuig.  Ongeveer 15 jaar geleden doken er weer berichten op over een (NASA) hypersonisch vliegtuig, dat als een platte steen over de atmosfeer ketste.  De X-30A vond een opvolger in de X-43 en de X-51 Waverider.   Niets nieuws onder de zon.
Nulla tenaci invia est via - Voor de doorzetter is geen weg onbegaanbaar.

Lynxian

Citaat van: Jellington op 02/11/2013 | 15:21 uur

Ooh ik dacht dat joun "Thanks to Germans" een reactie was op dit

Maar dat is niet zo, wel idioot dat al onze moderne stealth rotzooi gebaseerd is op technieken uit WO2...
Wat denk je van die gloednieuwe SR-72 waar dit topic over gaat? Die scramjet die ze als mach 6 motor willen gebruiken is bedacht door de Duitsers.

Het doet je afvragen waarom die Duitsers toen zoveel fantastische ideeën hebben weten te bedenken en het tegenwoordig relatief tegenvalt. Misschien was de dreiging van oorlog zo'n grote motivatie, maar ik weiger te geloven dat dat de enige factor was.

Jellington

Citaat van: Huzaar1 op 02/11/2013 | 15:11 uur
De amerikanen en russen roofden tijdens en direct na ww2 Duitsland leeg.
De amerikanen verkregen bijna alle raket en vliegtuig prototypen.

De B-2 stealth bomber komt voort uit Horten, Duits vliegtuig tijdens wo2 in project fase.


stamt af van de horten.





Zo zijn er nog tig vergelijkingen.

De U2 kwam voort uit informatie opgedaan met de roof van het Sanger project. Silverbird.





naar uiteindelijk onder andere de U2.


Meeste fascinerende vliegtuig werkzaamheden zijn gebaseerd op materieel, kennis en informatie uit Nazi Duitsland.
Vandaar, thanks to the germans :P






Ooh ik dacht dat joun "Thanks to Germans" een reactie was op dit

CitaatAls dit idee geen vroege dood sterft en als deze ideeën in het oosten worden overgenomen en succesvol geproduceerd kunnen worden tegen het midden van deze eeuw, dan hebben we hier in Europa nog iets te doen.

Maar dat is niet zo, wel idioot dat al onze moderne stealth rotzooi gebaseerd is op technieken uit WO2...

Huzaar1

Citaat van: Jellington op 02/11/2013 | 14:52 uur
Hoe bedoel je?

De amerikanen en russen roofden tijdens en direct na ww2 Duitsland leeg.
De amerikanen verkregen bijna alle raket en vliegtuig prototypen.

De B-2 stealth bomber komt voort uit Horten, Duits vliegtuig tijdens wo2 in project fase.


stamt af van de horten.





Zo zijn er nog tig vergelijkingen.

De U2 kwam voort uit informatie opgedaan met de roof van het Sanger project. Silverbird.





naar uiteindelijk onder andere de U2.


Meeste fascinerende vliegtuig werkzaamheden zijn gebaseerd op materieel, kennis en informatie uit Nazi Duitsland.
Vandaar, thanks to the germans :P



"Going to war without France is like going deer hunting without your accordion" US secmindef - Jed Babbin"


Huzaar1

"Going to war without France is like going deer hunting without your accordion" US secmindef - Jed Babbin"

jurrien visser (JuVi op Twitter)

Citaat van: www.lockheedmartin.com Vandaag om 10:28
Speed is the New Stealth


Als dit idee geen vroege dood sterft en als deze ideeën in het oosten worden overgenomen en succesvol geproduceerd kunnen worden tegen het midden van deze eeuw, dan hebben we hier in Europa nog iets te doen.




jurrien visser (JuVi op Twitter)

Speed is the New Stealth

Meet the SR-72

In 1976, U.S. Air Force SR-71 Blackbird crews flew from New York to London in less than two hours, reaching speeds exceeding Mach 3 and setting world records that have held up for nearly four decades.

But those world records may not stay unbroken for long.

That's because today, at the birthplace of the Blackbird – Lockheed Martin's Skunk Works® – engineers are developing a hypersonic aircraft that will go twice the speed of the SR-71. It's called the SR-72.

Son of the Blackbird
The SR-71 was developed using 20th century technology. It was envisioned with slide rules and paper. It wasn't managed by millions of lines of software code. And it wasn't powered by computer chips.  All that changes with the SR-72.

Envisioned as an unmanned aircraft, the SR-72 would fly at speeds up to Mach 6, or six times the speed of sound. At this speed, the aircraft would be so fast, an adversary would have no time to react or hide.

"Hypersonic aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour," said Brad Leland, Lockheed Martin program manager, Hypersonics. "Speed is the next aviation advancement to counter emerging threats in the next several decades. The technology would be a game-changer in theater, similar to how stealth is changing the battlespace today."

A hypersonic plane does not have to be an expensive, distant possibility.  In fact, an SR-72 could be operational by 2030. For the past several years, Lockheed Martin Skunk Works® has been working with Aerojet Rocketdyne to develop a method to integrate an off-the-shelf turbine with a supersonic combustion ramjet air breathing jet engine to power the aircraft from standstill to Mach 6. The result is the SR-72 that Aviation Week has dubbed "son of Blackbird," and integrated engine and airframe that is optimized at the system level for high performance and affordability.

Hypersonic Research and Development

SR-72 is not the first hypersonic Skunk Works® aircraft. In partnership with the Defense Advanced Research Projects Agency, engineers developed the rocket-launched Falcon Hypersonic Technology Vehicle 2 (HTV-2). The HTV-2 research and development project was designed to collect data on three technical challenges of hypersonic flight: aerodynamics; aerothermal effects; and guidance, navigation and control.

The SR-72's design incorporates lessons learned from the HTV-2, which flew to a top speed of Mach 20, or 13,000 mph, with a surface temperature of 3500°F.

A hypersonic aircraft will be a game changer.

November 1, 2013

Zie link voor de plaatjes

http://www.lockheedmartin.com/us/news/features/2013/sr-72.html

jurrien visser (JuVi op Twitter)


Lex

Voor een tweetal impressies van de vorm, klik hier.

jurrien visser (JuVi op Twitter)

This is the successor to the SR-71 Blackbird, and it is gorgeous

By Brian Fung   

November 1, 2013

The SR-71, arguably the country's most recognizable spy plane after the U-2, was retired in 1998. But like many human retirees of the same generation, what became known as the Blackbird has had a healthy post-retirement career. From appearances in the "X-Men" franchise to cameos in the "Transformers" series, this super-speedy jet has taken off in modern popular culture.

So it's only natural that the Blackbird's successor might inspire similar appeal. More than a decade after the last SR-71 was decommissioned, Lockheed Martin has unveiled the gorgeous-looking SR-72. It flies just as far and twice as fast as its predecessor — and, in a twist, it's now lethal, according to Aviationweek:


The SR-72 is being designed with strike capability in mind. "We would envision a role with over-flight ISR, as well as missiles," Leland says. Being launched from a Mach 6 platform, the weapons would not require a booster, significantly reducing weight. The higher speed of the SR-72 would also give it the ability to detect and strike more agile targets. "Even with the -SR-71, at Mach 3, there was still time to notify that the plane was coming, but at Mach 6, there is no reaction time to hide a mobile target. It is unavoidable ISR," he adds.

The jet accelerates by way of a two-part system. A conventional jet turbine helps boost the aircraft up to Mach 3, at which point a specialized ramjet takes over and pushes the plane even faster into hypersonic mode.

From Lockheed's mock-ups, there doesn't appear to be a bubble for the pilot — which suggests a windowless cockpit or fantasies about a future unmanned version of the plane. But let's not get ahead of ourselves.

http://www.washingtonpost.com/blogs/the-switch/wp/2013/11/01/this-is-the-successor-to-the-sr-71-blackbird-and-it-is-gorgeous/

jurrien visser (JuVi op Twitter)

Tweet van LM 1/11/13

Lockheed Martin ‏@LockheedMartin  5m 
We gave @aviationweek the exclusive: Meet the hypersonic SR-72, "Son of the Blackbird": http://ow.ly/qobO1  http://ow.ly/qoiYd


jurrien visser (JuVi op Twitter)


jurrien visser (JuVi op Twitter)

Exclusive: Skunk Works Reveals SR-71 Successor Plan

By Guy Norris guy.norris@aviationweek.com
Source: AWIN First

November 01, 2013

Ever since Lockheed's unsurpassed SR-71 Blackbird was retired from U.S. Air Force service almost two decades ago, the perennial question has been: Will it ever be succeeded by a new-generation, higher-speed aircraft and, if so, when?

That is, until now. After years of silence on the subject, Lockheed Martin's Skunk Works has revealed exclusively to AW&ST details of long-running plans for what it describes as an affordable hypersonic intelligence, surveillance and reconnaissance (ISR) and strike platform that could enter development in demonstrator form as soon as 2018. Dubbed the SR-72, the twin-engine aircraft is designed for a Mach 6 cruise, around twice the speed of its forebear, and will have the optional capability to strike targets.

Guided by the U.S. Air Force's long-term hypersonic road map, the SR-72 is designed to fill what are perceived by defense planners as growing gaps in coverage of fast-reaction intelligence by the plethora of satellites, subsonic manned and unmanned platforms meant to replace the SR-71. Potentially dangerous and increasingly mobile threats are emerging in areas of denied or contested airspace, in countries with sophisticated air defenses and detailed knowledge of satellite movements.

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.

Although there has been evidence to suggest that work on various classified successors to the SR-71, or some of its roles, has been attempted, none of the tantalizing signs have materialized into anything substantial. Outside of the black world, this has always been relatively easy to explain. Though few question the compelling military imperative for high speed ISR capability, the astronomical development costs have made the notion a virtual nonstarter.

But now Lockheed Martin believes it has the answer. "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," says Brad Leland, portfolio manager for air-breathing hypersonic technologies. "Our approach builds on HTV-3X, but this extends a lot beyond that and addresses the one key technical issue that remained on that program: the high-speed turbine engine," he adds, referring to the U.S. Air Force/Defense Advanced Research Projects Agency (Darpa) reusable hypersonic demonstrator canceled in 2008.

The concept of a reusable hypersonic vehicle was an outgrowth of Darpa's Falcon program, which included development of small launch vehicles, common aero vehicles (CAV) and a hypersonic cruise vehicle (HCV). As structural and aerodynamic technologies for both the CAV and HCV needed testing, Lockheed Martin was funded to develop a series of unpowered hypersonic test vehicles (HTV).

In the midst of these developments, as part of a refocus on space in 2004, NASA canceled almost all hypersonic research, including work on the X-43C combined-cycle propulsion demonstrator. The Darpa HTV effort was therefore extended to include a third HTV, the powered HTV-3X, which was to take off from a runway on turbojet power, accelerate to Mach 6 using a scramjet and return to land.

Despite never progressing to what Leland describes as a planned -HTV-3X follow-on demonstrator that "never was," called the Blackswift, the conceptual design work led to "several key accomplishments which we didn't advertise too much," he notes. "It produced an aircraft configuration that could controllably take off, accelerate through subsonic, supersonic, transonic and hypersonic speeds. It was controllable and kept the pointy end forward," adds Leland

Fundamental lessons were learned, particularly about flight control systems that could maintain stability through the transonic speed regime. Lockheed Martin's work proved the configuration could "take off without departing," Leland notes. "We were able to drive down the takeoff speed and keep it stable and controllable. We proved all that in a whole series of wind-tunnel tests."

Just as importantly, the Skunk Works design team developed a methodology for integrating a working, practical turbine-based combined cycle (TBCC) propulsion system. "Before that, it was all cartoons," Leland says. "We actually developed a way of transforming it from a turbojet to a ramjet and back. We did a lot of tests to prove it out, including the first mode-transition demonstration." The Skunk Works conducted subscale ground tests of the TBCC under the Facet program, which combined a small high-Mach turbojet with a dual-mode ramjet/scramjet, and the two sharing an axisymmetric inlet and nozzle.

Meanwhile, the U.S. Air Force Research Laboratory's parallel HiSTED (High-Speed Turbine Engine Demonstration) program essentially failed to produce a small turbojet capable of speeds up to Mach 4 in a TBCC. "The high-speed turbine engine was the one technical issue remaining. Frankly, they just weren't ready," recalls Leland. This left the Skunk Work designers with a familiar problem: how to bridge the gap between the Mach 2.5 maximum speed of current-production turbine engines and the Mach 3-3.5 takeover speed of the ramjet/scramjet. "We call it the thrust chasm around Mach 3," he adds.

Although further studies were conducted after the demise of the HTV-3X under the follow-on Darpa Mode-Transition program, that fell by the wayside, too, after completion of a TBCC engine model in 2009-10. So, Lockheed Martin and Aerojet Rocketdyne "sat down as two companies and asked ourselves, 'Can we make it work? What are we still missing?'" says Leland. "A Mach 4 turbine is what gets you there, and we've been working with Rocketdyne on this problem for the last seven years."

Finally, he says, the two achieved a design breakthrough that will enable the development of a viable hypersonic SR-71 replacement. "We have developed a way to work with an off-the-shelf fighter-class engine like the F100/F110," notes Leland. The work, which includes modifying the ramjet to adapt to a lower takeover speed, is "the key enabler to make this airplane practical, and to making it both near-term and affordable," he explains. "Even if the HiSTED engines were successful, and even if Blackswift flew, we'd have had to scale up those tiny turbines, and that would have cost billions."

Lockheed will not disclose its chosen method of bridging the thrust chasm. The company funded research and development, and "our approach is proprietary," says Leland, adding that he cannot go into details. Several concepts are known, however, to be ripe for larger-scale testing, including various pre-cooler methods that mass-inject cooler flow into the compressor to boost performance. Other concepts that augment the engine power include the "hyperburner," an augmentor that starts as an afterburner and transitions to a ramjet as Mach number increases. Aerojet, which acquired Rocketdyne earlier this year, has also floated the option of a rocket-augmented ejector ramjet as another means of providing seamless propulsion to Mach 6.

Although details of the proposed thrust-augmentation concept remain under wraps, Leland says a large part of a successfully integrated mode-transition design is the inlet. "That's because you have to keep two compressor systems [ramjet and turbine] working stably. Both will run in parallel," he adds.

Lockheed has run scaled tests on components. "The next step would be to put it through a series of tests or critical demonstrations," Leland says. "We are ready for those critical demonstrations, and we could be ready to do such a demonstration aircraft in 2018. That would be the beginning of building and running complete critical demonstrations. As of now, there are no technologies to be invented. We are ready to proceed—the only thing holding us back is the perception that [hypersonics] is always expensive, large and exotic."

The 2018 time line is determined by the potential schedule for the high-speed strike weapon (HSSW), a U.S. hypersonic missile program taking shape under the Air Force and Darpa (see page 36). "We can do critical demonstrations between now and then, but we don't believe it will be until HSSW flies and puts to bed any questions about this technology, and whether we can we truly make these, that the confidence will be there." In spite of the recent success of demonstration efforts, such as the X-51A Waverider, Leland observes that "hypersonics still has a bit of a giggle factor."

The timing also dovetails with the Air Force hypersonic road map, which calls for efforts to support development of a hypersonic strike weapon by 2020 and a penetrating, regional ISR aircraft by 2030 (AW&ST Nov. 26, 2012, p. 40). Key requirements for the high-speed ISR/strike aircraft is the ability to survive a "day without space"—communication and navigation satellites—and to be able to penetrate denied areas. With a TBCC propulsion system, the Air Force has pushed for increasingly greater speeds since defining Mach 4 at initial planning meetings in December 2010. The latest requirements are thought to be at least a Mach 5-plus cruise speed and operation from a conventional runway.

The path to the SR-72 would begin with an optionally piloted flight research vehicle (FRV), measuring around 60 ft. long and powered by a single, but full-scale, propulsion flowpath. "The demonstrator is about the size of the F-22, single-engined and could fly for several minutes at Mach 6," says Leland. The outline plan for the operational vehicle, the SR-72, is a twin-engine unmanned aircraft over 100 ft. long (see artist's concept on page 20). "It will be about the size of the SR-71 and have the same range, but have twice the speed," he adds. The FRV would start in 2018 and fly in 2023. "We would be ready to launch the SR-72 shortly after and could be in service by 2030," Leland says.

According to Al Romig, Skunk Works engineering and advanced systems vice president, "speed is the new stealth." This is perhaps just as well, given the inherent challenges involved in reducing the signature of hypersonic vehicles. With large engine inlets and aerodynamic requirements overriding most considerations, the SR-72 concept shows little in the way of stealthy planform alignment. Although the surfaces could be coated with radar-absorbing material, the requirement for thermal protection along sharp leading edges is likely to be a complicating factor. Like the HTV-3X, the vehicle may also feature hot metallic leading edges and a "hot/warm" metallic primary structure designed to handle the high thermal flux loads.

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.

The SR-72 is being designed with strike capability in mind. "We would envision a role with over-flight ISR, as well as missiles," Leland says. Being launched from a Mach 6 platform, the weapons would not require a booster, significantly reducing weight. The higher speed of the SR-72 would also give it the ability to detect and strike more agile targets. "Even with the -SR-71, at Mach 3, there was still time to notify that the plane was coming, but at Mach 6, there is no reaction time to hide a mobile target. It is unavoidable ISR," he adds. Lockheed envisages that once the FRV has completed its baseline demonstrator role, it could become a testbed for developing high-speed ISR technologies and supporting tests of the SR-72's weapons set, avionics and downlink systems.

"It is time to acknowledge the existence of the SR-72 because of the HSSW going forward," says Leland. Together with the strategic "pivot to the Pacific," the concept of high-speed ISR is "starting to gain traction," he notes. "According to the hypersonic road map, the path to the aircraft is through the missile, so now it is time to get the critical demonstration going." These would test individual elements of the propulsion system, which would then be integrated for the full-scale FRV evaluation.

"We have been continuing to invest company funds, and we are kind of at a point where the next steps would require large-scale testing, which would significantly increase the level of investment we've had to make to-date. Between Darpa and the Air Force, it would be highly likely they'd have to fund the next steps," Leland says. The FRV will also give the Skunk Works a better idea on overall development costs, he adds.

As for rumors of an existing high-speed ISR aircraft, Leland is dismissive. "It's been almost 20 years since the SR-71 was retired. If there was a replacement, they've been hiding it pretty well," he says.

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