Key Points and Summary – Lockheed Martin’s Skunk Works has hinted for years at an SR-72 hypersonic successor to the SR-71, but the U.S. Air Force has never confirmed a program of record.
-This piece separates rumor from reality: what Aerojet Rocketdyne’s scramjet research and DARPA efforts suggest, why “Darkstar” from Top Gun isn’t the SR-72, and the engineering hurdles—turbine-to-scramjet propulsion, extreme heating, materials, guidance, and JP-7-style fuel logistics.
SR-72 Darkstar. Image Credit: Creative Commons.
-Even if a twin-engine “Son of Blackbird” doesn’t reach service until the 2030s—if at all—the enabling tech is already shaping U.S. hypersonic weapons and complicating Chinese and Russian planning.
Lockheed’s Mysterious SR-72 ‘Son of Blackbird’ Could Shape the Pentagon’s Arsenal for Decades
The so-called SR-72 Darkstar has existed in a state between rumor and reality since 2007, when reports first surfaced that Lockheed Martin’s Skunk Works division was considering a successor to the legendary SR-71 Blackbird.
For years, despite the research, the project seemed to be little more than just speculation – until “Top Gun: Maverick” put the name “Darkstar” on the big screen and reignited public curiosity about what Lockheed Martin could be planning.
But whether such an aircraft exists remains uncertain, even in 2025, at least in my humble opinion.
Lockheed has acknowledged the program in broad terms, but the United States Air Force has not confirmed the authorization of a prototype. Analysts have, however, suggested that the program exists and that a twin-engine platform could be operational by the 2030s. With that date approaching and little tangible evidence to suggest that it’s coming, however, many questions still remain about whether the aircraft is actually coming.
There are, however, some things that we do know about the project, from cryptic tweets by Lockheed, misconceptions about the project’s name, and the engineering challenges the project faces – if, indeed, it exists.
SR-72 Darkstar Plane. Image Credit: Lockheed Martin Handout.
SR-72: Lockheed Hasn’t Denied It
To date, Lockheed has not denied studying hypersonic aircraft or working on experimental craft designed to reach speeds exceeding Mach 5.
Not only that, but executives have even occasionally referenced the SR-72 by name, suggesting that the project at least exists in some form. The question is whether or not the project still exists, or how far it has gone.
The U.S. Air Force, however, has never formally confirmed a requirement—a formal statement from the military that specifies its need for an aircraft that meets certain criteria—let alone contracted for a prototype.
More Details…
Aerojet Rocketdyne, a subsidiary of defense company L3Harris, has been linked to propulsion studies for the platform – and was even chosen by DARPA in 2017 to build a new kind of aircraft engine designed to deliver hypersonic speeds up to Mach 6.
Even if the SR-72 remains elusive as a project, the research that would allow such an aircraft to be developed is currently underway and has already fed into America’s hypersonic missile programs.
A series of breakthroughs have already been made in this field, involving scramjet propulsion, the development of materials that can withstand high temperatures, and the creation of new guidance systems that can survive Mach 5+ environments.
The development of these systems being underway suggests that programs like that of the SR-72 are also underway – but there’s no telling how far behind those programs may be, or what kind of complications may have occurred that have pushed any formal announcement so close to the rumored goal of achieving operational status by 2030.
Not only has Lockheed not denied its existence, but the company has even hinted at the existence of the jet in a series of carefully worded statements.
Following the release of Top Gun 2, Lockheed’s official Twitter account posted that the “SR-71 is still the fastest acknowledged crewed air-breathing jet aircraft” – a post that sparked a flurry of analyst activity, speculation, and reports. The post seemed to suggest that there is an unacknowledged aircraft in the works that can reach higher speeds than the SR-71.
This Isn’t the “Darkstar”
One persistent misconception is that the SR-72 is the same as the “Darkstar.”
While the two are often conflated, they are distinctly different; “Darkstar” was a Hollywood creation built with Lockheed’s input. The prop, which is 70 feet in length and fitted with genuine prototype cockpit components, is not a real jet.
The exterior of the jet is actually an F/A-18, which was used for flight scenes before being digitally replaced with a fictional hypersonic jet. The prop itself never flew, but it was convincing enough that some audiences mistook it for reality.
Within aerospace circles, the SR-72 is better and more commonly known as the “Son of Blackbird.” The nickname reflects its supposed lineage from the SR-71.
Engineering Challenges
Creating an aircraft that can reach hypersonic speeds is no mean feat – and it presents vastly different challenges than building a missile that can travel at the same speeds.
The SR-72 would need to combine jet turbine and scramjet technology into a hybrid propulsion systems, using turbines for low speeds and scramjets to reach hypersonic speeds. B
ut beyond those technical challenges, engineers must also grapple with the fact that traveling at such high speeds would put immense temperature-related pressure on the aircraft.
At six times the speed of sound, surface temperatures could easily reach thousands of degrees. While, in theory, an unmanned design could solve some of these problems, temperatures that high could pose a risk to crucial components of the aircraft, not just its pilot.
Some reports have suggested that engineers are considering carbon composites and titanium alloys that can survive this level of stress.
More Challenges to Overcome for Son of Blackbird
We also know that the engineering team faces a challenge with regards to fuel. The SR-71, for example, used a specialized blend known as JP-7, which doubled as a coolant for its systems. While effective, HP-7 was costly and logistically complex.
SR-71 Blackbird at USAF Museum July 2025. Image Credit: National Security Journal.
If the SR-72 is ever built, Lockheed will need to explore whether conventional fuel could meet requirements or whether a new kind of fuel needs to be delivered, while also ensuring that supply chains can be simplified to reduce operational costs and ensure the longevity of the program. Without fuel, the most advanced, hypersonic aircraft in the world would be effectively useless to the U.S. Air Force.
It Could Be a Game-Changer
Whether the SR-72 becomes an operational platform may ultimately matter less than the technologies that come along with the program, however. Just as the SR-71’s development revolutionized materials science, the SR-72’s research could lay the foundations for the next generation of American hypersonic weapons.
If the aircraft does emerge, it could be a direct heir to the Blackbird – but if it doesn’t, the “Son of Blackbird” may still shape the Pentagon’s arsenal for decades to come.
And in the meantime, even just the rumor of an aircraft like the SR-72 complicates planning for adversaries like China and Russia.
About the Author: Jack Buckby
Jack Buckby is a British author, counter-extremism researcher, and journalist based in New York who writes frequently for National Security Journal. Reporting on the U.K., Europe, and the U.S., he works to analyze and understand left-wing and right-wing radicalization, and reports on Western governments’ approaches to the pressing issues of today. His books and research papers explore these themes and propose pragmatic solutions to our increasingly polarized society. His latest book is The Truth Teller: RFK Jr. and the Case for a Post-Partisan Presidency.
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William H Warrick III MD
September 17, 2025 at 11:05 am
This plane does not have use that I can see. It’s not a fighter plane or a bomber. Only a handful of them could be made so it’s a complete waste of time to build even one of them. It’s just a wet dream of overpaid engineers.
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