With all the talk lately of hypersonic missiles and spacecraft, one highly advanced piece of technology might be quietly flying under the radar. Pun intended. Lockheed Martin is developing a new hypersonic plane, the SR-72. If they are successful, it will be the fastest plane in the world, capable of reaching speeds of Mach 6.

The recent discovery that China launched a hypersonic weapon over the summer, has the world buzzing. The launch caught everyone off guard, including the U.S. intelligence community. The Chinese hypersonic technology is more developed than anticipated or believed. However, it did miss its intended target. This suggests they still have a long way to go in the development of guidance systems, and likely guidance and avionics systems shielding. China downplayed the launch calling the missile a “space vehicle.”

The United States has been developing hypersonic weapons and capabilities for some time. It is the next logical step in weapons technology. In fact, while recent and next-generation fighters and bombers are experimenting with stealth, speed might actually be better.

Developing hypersonic planes will possibly be the “new stealth,” as stealth can potentially be defeated. Speed, however, requires such a huge jump in technology, it might take a lot of time and development for everyone else to catch up. Pun also intended.

To Understand the SR-72, Look at the SR-71

The fastest and most advanced plane of its time is still the fastest plane of our time. The SR-71 Blackbird is considered ancient in the rapid technological development of aircraft in the last 100 years. Almost 60 years later, however, there is still nothing that flies faster or higher.

The SR-71 was the evolution of several different programs. The CIA wanted a high-flying, fast plane that was undetectable. The Air Force wanted a strategic, supersonic bomber capable of carrying nuclear weapons. After a few versions, and combining various roles, requirements, and planes, the SR-71 was the result. It was not, however, a bomber.

The Blackbird excelled at Intelligence, Surveillance, and Reconnaissance (ISR). These advanced planes carried extensive optics, imagery, and surveillance systems. It could operate at sustained altitudes of over 80,000 feet, with a peak altitude record of over 85,000 feet. That altitude is so high that SR-71 pilots basically wore spacesuits and helmets. When they looked up, they saw the blackness of space. The speed record for aircraft flight is also owned by the SR-71: Mach 3.3or 2,193.7 mph. A record that has stood since 1976.

By comparison, the fastest Russian aircraft ever built is about 500 mph slower.

SR-71s were able to outrun missiles, even if they were captured on radar. By the time a surface-to-air missile (SAM) radar could lock on the plane, and was launched and tried to intercept, it was impossible to catch. In fact, no SR-71 was ever shot down. An incredible 4,000 air-to-air missiles have been fired at the SR-71 without hitting it. It was extremely successful in every facet of its role, in every way. The Blackbird was the pinnacle of American aeronautical engineering.

The SR-71 Blackbird was finally retired in 1998. With the advent of better satellite technology, drone development, and the loss of a world adversary like the former Soviet Union, the lack of political and strategic justification did not merit the expense.

Even with better drones and satellite imagery, there is still a gap in the ISR world. Drones can fill much of that role, but not all of it. Stealth can be defeated, and satellites can be shot down.

SR-72 Development Has Been Ongoing for a Long Time

Although the geopolitical landscape changed in the late 80s and through the 90s, and the 2000s gave us the Global War on Terror, ISR will always be a requirement for any nation, and any military. Threats from non-state actors like terrorists still will require intelligence and surveillance. Future threats from political adversaries will also never go away. The resurgence of Russia, and the emergence of China as a new world power and threat, has brought those requirements and budgets, back to the list of priorities.

Just a few short years after the retirement of the SR-71, the development of the next generation began, or at least the public disclosure of development. While unconfirmed and classified by Lockheed Martin and the government, it’s likely the development of the next-generation replacement for the Blackbird began immediately. What we now call the SR-72, has been in some phase of development at the Lockheed Martin Skunk Works for 20 years. Whispers and reports started to emerge in 2007 of an Air Force plane capable of Mach 6, and over the last few years, information is more common.

Given the nature of the mission, and the length of time to develop such technology, these reports from the early 2000s are probably accurate. Developing hypersonic technology, speeds of Mach 6, has been theoretical for a long time. Scientists and engineers know what they need to do, and they probably already know how to do it. They know what needs to happen for the ramjet engines to be able to function at low and high speeds. They now need time for development and to make it all come together. At the latest, we publicly know that NASA gave Lockheed Martin a contract in 2014 to test the feasibility of the technology for dual-mode ramjets. They probably started sooner than that.

Speculation Abounds

It’s easy to find speculation online as to what that stage of development is, and to what the role will be. Some reports present a hypersonic spy plane, and others a hypersonic strike aircraft, and some imagine it will be both. Most reports call it a drone, with some calling it a drone with the option for manned flight. There is also speculation that it is already operational, or at least in advanced testing phases.

Two theories emerge as the more likely scenarios. The first is that given the high level of secrecy and operation (so we think) of the Northrop Grumman RQ-180 stealth UAV, the SR-72 will need to be more than just another drone. Being hypersonic might be “enough” of an answer to that, given it will be a huge jump in capability. However, a manned aircraft presents different advantages and capabilities to a drone, hypersonic or not. It will also fill a huge gap that is currently non-existent, and not quite covered by drones and satellites. It will also carry hypersonic missiles, based on statements and information that are known about the project. This will allow the SR-72 to be a high-speed interceptor, being able to catch just about any threat in the world or respond to crises and threats in extreme real-time.

The second theory is that even though Lockheed has made comments to the contrary, the development of the SR-72 is more advanced than acknowledged. That would make sense, of course, keeping the program as classified as long as possible. While it hasn’t received a large amount of attention, it still has received attention. The existence was known years before confirmation, so any statement to the contrary sounds like “damage control,” and trying to put the secret back into the bag.  Besides, there are decades of data on the SR-71 and decades for engineers to take that data and turn it into a new aircraft like the SR-72 which is an evolutionary design improvement on the Blackbird program rather than a revolutionary new design incorporating advances in computers, avionics, fly by wire, sensors, propulsion, and metallurgy.

Especially, the metallurgy.

Future Development and Expectations

As more conversation and speculation around hypersonic capabilities arise, and as China and Russia also develop their capabilities, the SR-72 and other hypersonic programs will continue to get more attention. And with more information, we will learn more about the SR-72 program and operational timeline.

At the same time, true capabilities are well-guarded secrets. The U.S. government will want the world to know it exists, yet they will never divulge the true potential and complete operational capability. One can also wager the Chinese and Russians, and others will be working hard to acquire as much information and secrets about the program as possible.

It will be exciting to see how the development plays out. It will be one of the biggest engineering advances the world has ever seen. The project, if successful, will be a significant feat of aeronautical success and will change the military world.

It is also interesting to note that even with more than 120 state-of-the-art spy satellites in orbit, there is still a need for hypersonic reconnaissance and/or strike aircraft like the SR-72.