Aircraft

Lockheed Martin developing successor to the SR-71 Blackbird

Lockheed Martin developing suc...
Artist's concept of the SR-72 (Image: Lockheed Martin)
Artist's concept of the SR-72 (Image: Lockheed Martin)
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The SR-71 was derived from the earlier A-12 (Image: Lockheed Martin)
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The SR-71 was derived from the earlier A-12 (Image: Lockheed Martin)
Artist's concept of the SR-72 (Image: Lockheed Martin)
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Artist's concept of the SR-72 (Image: Lockheed Martin)
The SR-72 will fly at Mach 6 (Image: Lockheed Martin)
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The SR-72 will fly at Mach 6 (Image: Lockheed Martin)
The SR-72 uses technology from the HTV-2 (Image: Lockheed Martin)
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The SR-72 uses technology from the HTV-2 (Image: Lockheed Martin)
The engine of the SR-72 (Image: Lockheed Martin)
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The engine of the SR-72 (Image: Lockheed Martin)
The SR-72 is the replacement for the SR-71 blackbird (Image: US Air Force)
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The SR-72 is the replacement for the SR-71 blackbird (Image: US Air Force)
The SR-71 engine cycle (Image: US Air Force)
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The SR-71 engine cycle (Image: US Air Force)
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When the last SR-71 Blackbird was grounded in 1998 it was a double blow. Not only did aviation lose one of the most advanced aircraft ever built, but also one of the most beautiful. Lockheed Martin's Skunk Works has now revealed that it is building a successor to the Blackbird: the SR-72. Using a new hypersonic engine design that combines turbines and ramjets, the company says that the unmanned SR-72 will be twice as fast as its predecessor with a cruising speed of Mach 6.

The SR-71 Blackbird is one of history's great aircraft. It was built during the Cold War in the early 1960s by Lockheed at its secret Skunk Works facility and flew from 1966 to 1998. With black paint covering its unprecedented titanium fuselage, it was designed as a reconnaissance platform capable of flying 2,900 nautical miles (5,400 km) at sustained supersonic speeds at an altitude of 80,000 ft (24,000 m).

The Blackbird could fly so fast and so high that it could literally outrun enemy missiles, and routinely did. Needless to say, it left interceptors far behind and of the 32 that were built, not one was lost to enemy action. It even grew stronger over the years because the heat generated in flight was so great that the titanium hull annealed.

The SR-72 will fly at Mach 6 (Image: Lockheed Martin)
The SR-72 will fly at Mach 6 (Image: Lockheed Martin)

The SR-71 was also famous for holding a raft of records. It was the world's fastest and highest-flying operational manned aircraft, reaching 85,069 feet (25,929 m) in sustained flight, and it still holds the speed record. On September 1, 1976, a US Air Force SR-71 Blackbird flew from New York to London in 1 hour 54 minutes and 56.4 seconds at a peak velocity of about Mach 3.2 (2,436 mph, 3920 km/h). To this day, no aircraft exists that can match its performance.

To the end it was still breaking records. After the Cold War ended, many SR-71s ended up in museums as the program was wound up. When one SR-71 was delivered to the Smithsonian Institution in 1990, it broke four speed records flying from Los Angeles to Cincinnati, Ohio.

The idea of a hypersonic replacement has been kicked around for years, and now Lockheed is working on the SR-72. Unlike its predecessor, the SR-72 will be unmanned, but it will be twice as fast with a cruising speed of Mach 6 (4,567 mph, 7,350 km/h).

The engine of the SR-72 (Image: Lockheed Martin)
The engine of the SR-72 (Image: Lockheed Martin)

The SR-72's purpose is to provide the United States with not only a hypersonic recon platform, but also a strike aircraft as well. "Hypersonic aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour," says 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 battle space today."

According to Leland, a Mach 6 platform would not only leave very little time for an enemy to respond, but it also be a very effective way to launch hypersonic missiles. Since these wouldn't need a booster rocket when launched at six times the speed of sound, they can be of much lighter and simpler construction.

The key to the SR-72 is what Lockheed calls Turbine-Based Combined Cycle Propulsion, which incorporates Lockheed's experience in building the HTV-2 hypersonic demonstrator that flew at Mach 20 (15,224 mph, 24,501 km/h) in tests. In this new system, the twin engines of the SR-72 are actually two engines in one. Each engine shares combined inlets and nozzles connected to two very different powerplants as a way to significantly reduce drag.

The SR-72 is the replacement for the SR-71 blackbird (Image: US Air Force)
The SR-72 is the replacement for the SR-71 blackbird (Image: US Air Force)

The upper engine is a turbine, which is used to power the SR-72 as it takes off from a conventional runway and accelerates it to Mach 3. Then the lower dual-mode ramjet takes over and accelerates the plane to Mach 6. The significance of this design is that Lockheed collaborated for seven years with Aerojet Rocketdyne on figuring out how to use an off-the-shelf turbine that could be incorporated into a hypersonic jet system.

In an interview with Aviation Week, which broke the story, Leland explained that the retirement of the SR-71 left significant gaps in the satellites, subsonic manned and unmanned platforms meant to replace it, which the SR-72 will fill. The article went on to point out that the SR-72 program is meant to dovetail with the Pentagon's hypersonic research and weapons programs, which has dictated the timetable and many design parameters.

According to Leland, no new technologies needed to be invented for the SR-72 so a demonstration aircraft could fly by 2018, and the plane could be operational by 2030. "The demonstrator is about the size of the F-22, single-engined and could fly for several minutes at Mach 6," says Leland. "It will be about the size of the SR-71 and have the same range, but have twice the speed."

The video below is an interview with a former SR-71 pilot.

Sources: Lockheed Martin, Aviation Week

Pilot Recounts Tales of SR-71 Blackbird

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41 comments
notarichman
no matter how fast an aerial vehicle goes, it won't outrun the speed of light...so laser weapons could possibly knock it down. how long would it take to cross the visible sky on "flat ground"? the laser weapon would have to lock on to it and deliver it's punch before it leaves view. I'm just trying to be a devils advocate when it comes to military weapons. I'm certain that plans will be eventually stolen for the SR-72, but capability for mfg. those plans will take another 5 to 10 minimum. I wonder if the usa will ever be able to 3D print the components and auto-assemble them? Also, if the vehicle is un-manned; then how long will it take someone to hack the controls? would hate to have the SR72 attack us!
Mark A
Pilotless.. what fun is that.
worf2
sr-72: unmanned - how boring!
Sam Joy
This was my all time favorite plane growing up, I was fortunate to have seen it a few times in my life at air shows and Smithsonian. I even got to see it fly!, and that was something!, the SR-71 and the Space Shuttle first takeoff and landing was two of my best memories of aviation and space history in the making.
BigGoofyGuy
It might follow the SR-71 but - IMO - it would never truly replace it. I think the SR-71 is still the coolest.
Australian
"Leland explained that the retirement of the SR-71 left significant gaps in the satellites, subsonic manned and unmanned platforms meant to replace it, which the SR-72 will fill." Well of course he would say that - he is the Lockheed Martin program manager for Hypersonics. The only way he will get his program to float is to get the US Government (read US tax-payers) to fund it. I challenge him to elaborate on these "significant gaps". As much as I am a fan of the SR-71, it predated satellite, stealth, drone and internet intelligence surveillance methods and in it's day was the only viable way to rapidly gain specific critical information regarding the USA's international threats. Money aside, it looks good but somehow I suspect it will never fly (pun intended).
Gadgeteer
notarichman,
Surface-based laser weapons would have a hard time shooting down a plane at 80,000-100,000 feet, especially if it's not directly overhead, making the distance even longer. Seeing something and shooting it down are two different things. Between obstructions like clouds, atmospheric blooming, beam spreading and other phenomena, you'd be lucky to land 50 watts of energy on the SR-72, which would already be designed to withstand the extremely high temperatures encountered at hypersonic flight.
Australian,
Satellites have predictable orbits and limited fuel for maneuvering. It's not like the movies where someone can order an immediate repositioning for new shots of an area of interest. Drones have limited sensor suites, speed and range and are vulnerable to attack by any real air force. Internet monitoring doesn't help you at all for physical reconnaissance. For instance, Iran isn't going to go around transmitting the specs for its nuclear facilities for us to intercept, at least not without heavily encrypting it. Often, you just need an aircraft that can get to the target fast, shoot it with more than just cheap CCDs transmitting a few megabytes of images, and stay too high up to be shot down.
Seth Miesters
I'd feel more comfortable if this were a NASA program.
mem5000
I have a question. When I read that it was going to be unmanned... my mind immediately thought of that debacle where Iran stole one of our recon drones, by jamming it and then sending it fake GPS coordinates to make it fly into their waiting arms. What's to stop someone from doing this now?
Bob
What about airborne refueling? Do we have an unmanned high speed tanker in the works? Slowing down from Mach 6 to Mach .3 every 30 minutes to refuel would be a hassle.