Key Takeaways: The legendary SR-71 is getting a hypersonic, unmanned successor: the SR-72 “Son of Blackbird,” capable of Mach 6 speeds (4,600 mph).
The Mission: Unlike its predecessor, the SR-72 is envisioned as a dual-role ISR and strike aircraft, capable of penetrating sophisticated anti-access/area-denial (A2/AD) zones.
SR-72 by Lockheed Martin. Image Credit by Lockheed Martin.
The Tech: It utilizes a Turbine-Based Combined Cycle (TBCC) propulsion system—merging turbofans for takeoff with scramjets for sustained hypersonic cruise.
The Status: Evidence suggests the Flight Research Vehicle may already be flying, supported by Lockheed Martin’s massive new “Building 648” factory and cryptic comments from executives.
SR-72 Son of Blackbird: A Hypersonic Fighter, Bomber?
The US SR-72, named Son of Blackbird (SOB) or Darkstar, should be another feather in Lockheed Martin’s Skunk Works’ cap. The much-anticipated aircraft, which is expected to travel at Mach 6 or higher (nearly 4,600 mph), will rewrite the book on stealth and speed.
Designed to replace the SR-71 Blackbird, the unmanned SR-72, named Son of Blackbird (SOB) will focus on intelligence, surveillance, and reconnaissance missions. The jet will feature a turbine-based cycle propulsion system, combining a turbofan and scramjet for efficient hypersonic travel.
The SR-71 Blackbird was well ahead of its time. It could streak across the sky at Mach 3.2 (some claim even faster) and simply outrun enemy missiles. During its operational life, more than 4,000 missiles were fired at it, but none ever hit it. Now, its namesake will be flying even faster.
However, the Son of a Blackbird is envisioned as a reconnaissance and strike aircraft. The aircraft is envisioned to have reconnaissance and strike capabilities, making it a versatile platform for intelligence gathering and potentially offensive operations.
SR-72 Darkstar or Son of Blackbird. Image Credit: Lockheed Martin.
The SR-72 could conceivably penetrate China’s sophisticated anti-access/area-denial (A2/AD) defenses and, after identifying high-value targets, launch a weapon capable of destroying them.
But how would a hypersonic bomber work?
How Would The SR-72 Conduct Air Strikes At Mach 6?
Launching missiles at Mach 6 is no easy feat, as the weapon bay doors will be under tremendous air pressure and heat, not to mention the possibility of the aircraft flying into its own weapon.
This was why the Air Force canceled any weapons placement on the SR-71 during the Cold War.
A possible solution to adding a hypersonic missile is the Defense Advanced Research Projects Agency (DARPA) program, specifically the Hypersonic Air-breathing Weapon Concept (HAWC) project.
“The Hypersonic Air-breathing Weapon Concept (HAWC) program is a joint DARPA/U.S. Air Force (USAF) effort that seeks to develop and demonstrate critical technologies to enable an effective and affordable air-launched hypersonic cruise missile.
SR-72 Son of Blackbird. Image Credit: Creative Commons.
“The program intends to emphasize efficient, rapid and affordable flight tests to validate key technologies,” the webpage reads.
The HAWC program plans to pursue flight demonstrations to address three critical technology challenge areas or program pillars—air vehicle feasibility, effectiveness, and affordability.
Technologies of interest include:
-Advanced air vehicle configurations capable of efficient hypersonic flight
-Hydrocarbon scramjet-powered propulsion to enable sustained hypersonic cruise
-Approaches to managing the thermal stresses of high-temperature cruise
-Affordable system designs and manufacturing approaches
SR-72 artist image. Image Credit: Creative Commons.
Lockheed Martin is developing its own High-Speed Strike Weapon (HSSW), which can fire hypersonic weapons faster than any other system and instantly achieve hypersonic speeds.
According to Lockheed Martin, “The HSSW will enable a responsive strike capability on time-critical, heavily defended targets and achieve high survivability through altitude, speed, and stealth.”
Rob Weiss, Lockheed Martin’s executive vice president and general manager for Advanced Development Programs, said in 2017, “We’ve been saying hypersonics is two years away for the last 20 years, but all I can say is the technology is mature and we, along with DARPA and the services, are working hard to get that capability into the hands of our warfighters as soon as possible.”
The Super-Secretive SR-72 Program:
The SR-72 has reportedly already been flying. Back in February 2018, Lockheed Martin Vice President of Strategy and Customer Requirements in Advanced Development Programs, Jack O’Banion, told the American Institute of Aeronautics and Astronautics SciTech Forum that the SR-72 Flight Research Vehicle was already flying.
O’Banion said to the Wall Street Journal, “The aircraft is also agile at hypersonic speeds, with reliable engine starts.”
Shortly after that forum, all mentions of the SR-72 disappeared from Lockheed Martin’s website. But the project wasn’t shut down. Lockheed finished building a vast new factory, Building 648, in 2021.
The company touted it as an “intelligent, flexible factory” and immediately went on a hiring spree, adding more than 2,300 workers. Hopefully, we’ll soon get an honest look at it.
The SR-72 could serve as a launch platform for hypersonic strike weapons, integrating the High-Speed Strike Weapon (HSSW), which is currently under development. This groundbreaking project draws upon the operational legacy of the SR-71, enhancing speed and survivability with a fundamentally different propulsion system.
The program’s potential in-service date is supposed to be by 2030, when the Air Force plans to have its hypersonics online. However, this timeline hinges on overcoming the propulsion, thermal management, and materials challenges inherent to sustained hypersonic flight.
The SR-72’s high speed is designed to counter modern air defense systems by reducing time-on-target and exposure windows, marking a transformative milestone in aerial reconnaissance and strike capability.
New Propulsion Technology To Drive The SR-72:
Of course, the SR-72’s revolutionary propulsion system is at the core of its capabilities. The aircraft will feature a turbine-based combined cycle (TBCC) propulsion system that combines a traditional turbofan engine with a supersonic combustion ramjet (scramjet).
This dual-mode propulsion is essential as no single engine can efficiently operate across the full subsonic-to-hypersonic flight envelope. The turbofan engine is used during subsonic operations, such as takeoff and landing, while the scramjet sustains Mach 5 speeds above Mach 1.
This cutting-edge propulsion system is crucial to the SR-72 meeting its operational requirements. The SR-72 aims to redefine how the United States projects power in denied-access environments by leveraging next-generation propulsion technologies and uncrewed systems architecture.
The TBCC configuration is not merely a performance enhancement but an operational necessity, enabling the SR-72 to execute missions with unmatched speed.
Hollywood Even Hired The Skunk Works:
One of the coolest hints that the SR-72 Son of Blackbird aircraft is coming came in the 2022 film Top Gun: Maverick. In the opening scenes, Tom Cruise’s character pilots a hypersonic aircraft called “Darkstar”, which may broadly resemble what the real SR-72-like aircraft might look like.
We know filmmakers can create some awesome stuff with AI and CGI. However, Lockheed Martin and Skunk Works collaborated with the filmmakers to develop the aircraft’s outward appearance, concluding that the airframe is at least nominally grounded in actual aerospace design concepts.
The Darkstar featured in Top Gun might represent either a pre-production prototype, an early mock-up or nothing at all. However, if the SR-72 does actually resemble the film model, it would be a major curveball from Lockheed Martin to throw off everyone, though it is doubtful.
The Chinese had their interest piqued; they reoriented a spy satellite to get pics of it, thinking it was a real experimental aircraft.
The SR-72 Will Be A Versatile Aircraft:
The SR-72 aircraft will have the capability to perform high-speed intelligence, surveillance, reconnaissance (ISR), and strike operations. The full-scale aircraft is expected to enter service by 2030.
The new aircraft is expected to strike targets anywhere across a continent in less than an hour when equipped with hypersonic missiles such as Lockheed Martin’s High Speed Strike Weapon (HSSW).
If the Skunk Works finds a safe, reliable way to deliver the hypersonic weapons under development, the SR-72 will be a game-changing weapon, giving the Air Force a dominant edge.
About the Author: Steve Balestrieri
Steve Balestrieri is a National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing on defense, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications.
