SR-72 ‘Darkstar’: Does the U.S. Military Really Need a Mach 6 Sequel?

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Key Points and Summary: The rumored SR-72 Darkstar or SR-72 Son of Blackbird aircraft could revolutionize U.S. reconnaissance and strike missions with hypersonic speeds up to Mach 6—double that of the iconic SR-71 Blackbird.

-Proposed by Lockheed Martin, “Son of Blackbird” would combine speed and stealth to penetrate modern defenses or perform precision strikes.

-Yet the U.S. Air Force has little incentive to fund such an ambitious project, especially while it fields subsonic, radar-evading drones like the RQ-180, and invests in other priorities.

-Although China and Russia’s assertive military expansions bolster the case for Darkstar’s high-speed surveillance, the Pentagon may have decided stealth trumps speed, leaving the SR-72 concept in limbo.

Stealth vs. Speed: Why the SR-72 May Never Take Flight

The ultra-secret spy plane already has an informal designation. It appeared in Top Gun: Maverick and has an impressive fan base. The only problem is the SR-72 strategic reconnaissance aircraft, nicknamed “Darkstar,” probably doesn’t yet exist.

But does the Pentagon need it? And if it doesn’t, who does?

The History 

One of the most storied and iconic aircraft of all time was the SR-71 Blackbird. Descended from the CIA’s A-12 spyplane, the SR-71 could cruise at Mach 3, flying so fast it could outrun Soviet and allied air defenses, sprinting beyond reach before they could react. Properly timed and armed with a suite of formidable electronic countermeasures, the SR-71 could even evade the mighty MiG-25 “Foxbat.” 

The SR-71 was retired in 1989, as relations between the United States and the Soviet Union warmed. Less than a year later, Iraqi President Saddam Hussein invaded Kuwait. In April 1991, after Operation Desert Storm, military intelligence officers lamented the wartime lack of “high quality, up-to-date photography” that the SR-71 used to provide.

Three aircraft were returned to service in the mid-1990s, as new crises with Iraq and the former Yugoslavia demonstrated a need for the SR-71’s unique capabilities. Still, even those planes were permanently grounded in 1999. 

Proponents of the grounding argued that the end of the Cold War and good relations with the newly opened Russia made the aircraft unnecessary. The former Soviet republics were in shambles politically, economically, and militarily, posing no serious strategic threat. In the event of new crises, satellites and U-2 spy planes could acceptably fill the role.

However, each had its drawbacks: satellites followed predictable orbits, making it possible to hide equipment as they passed overhead, and U-2s flew slowly and could not respond to fast-moving crises. The Department of Defense could live with such drawbacks regarding the cost of returning the SR-71 to service or developing a replacement. 

SR-72 Concept

In 2013, Aviation Week & Space Technology published an article, “Meet the Son of Blackbird,” on Lockheed Martin’s eagerness to develop a new high-speed aircraft.

Lockheed, the original developer of the SR-71, proposed a replacement aircraft informally named SR-72. The SR-72 was to be an all-new plane powered by both a turbine and a scramjet, taking off and landing from runways under turbine power but transitioning to the scramjet once airborne.

The aircraft would travel at Mach 6, or twice as fast as the SR-71. Unlike the SR-71, whose air-to-ground attack capability remained on the drawing board, the SR-72 would be capable of both reconnaissance and strike missions from the outset.

The SR-72 could encompass two conceptual missions: a retargetable, hypersonic strategic reconnaissance capability that can travel twice as fast as its predecessor and serve as a hypersonic bomber. The aircraft’s attack capability was a nod to Conventional Prompt Strike, an emerging concept that involved using ballistic missiles armed with conventional warheads to target fleeting, time-sensitive targets.

CPS might target a gathering of terrorist leaders in a remote location or stop a ballistic missile armed with a nuclear or chemical warhead preparing for launch. Although slower, an SR-72 could be recalled from a mission if necessary and would not alarm nuclear-armed rivals like a ballistic missile launch would. 

The Controversy on Darkstar 

The SR-72 proposal was just that, a proposal—at least to the U.S. Air Force. At the time, Air Force Chief of Staff Mark Welsh denied any knowledge of the program, though he would have undoubtedly liked to add it to the service’s inventory.

However, the cost to develop a brand new hypersonic aircraft would count in the billions of dollars, and high-end programs such as the F-22 Raptor and F-35 were already being canceled or slow-rolled due to a lack of a similarly equipped adversary.

America’s adversaries during the post-9/11 Global War on Terror, including the Taliban and the Iraqi resistance forces, were low-tech and could not project force outside of their own countries, not precisely the kind of adversary that demanded the SR-72’s capabilities. 

SR-72 in 2025? 

Today, of course, it’s a different story.

China’s military buildup now includes aircraft carriers, an expansion of China’s nuclear arsenal, and four new fifth-generation—or later—fighters and attack jets. Russia’s invasion of Ukraine is now approaching its fourth year, and Moscow increasingly targets NATO, claiming harassment.

An aircraft like the SR-72 could conduct reconnaissance missions over the South China Sea, for example, or keep tabs on Russian military assets worldwide. However, such reconnaissance assets already exist—just in much slower form. 

In the mid-2010s, rumors surfaced of a new stealthy reconnaissance drone. The drone, known as the RQ-180, resembled the B-2 Spirit stealth bomber and was subsonic, relying on stealth to surreptitiously approach a target and gather intelligence.

In the later years of the Cold War, the bomber community pivoted from fast supersonic bombers to subsonic stealthy ones, arguing that there was more of an advantage for an aircraft to be invisible to radar than for it to be fast.

That a subsonic stealth recon drone exists and a high-speed recon aircraft does not suggest the reconnaissance community made a similar decision and that, once again, stealth won out over speed. 

Does the Pentagon need a real-life SR-72 Darkstar? Perhaps that’s the wrong question: recall that the Central Intelligence Agency operated a high-speed recon jet, the A-12 Oxcart, before the SR-71 flew for the Air Force.

Perhaps the real question is whether the larger U.S. intelligence community decided it needed Darkstar—and whether it did something about it.

About the Author: Kyle Mizokami 

Kyle Mizokami is a writer on defense and security issues and has been at Popular Mechanics since 2015. If it involves explosions or projectiles, he’s generally in favor of it. Kyle’s articles have appeared at The Daily Beast, U.S. Naval Institute News, The Diplomat, Foreign Policy, Combat Aircraft Monthly, VICE News, and others. Kyle is also a Contributing Editor for 19FortyFive. He lives in San Francisco.