Key Points – The SR-72 “Darkstar,” envisioned as an uncrewed hypersonic successor to the SR-71, aims to achieve Mach 6+ speeds, relying primarily on this extreme velocity for survivability against advanced air defenses like Russia’s S-400/S-500 systems.
-This speed is designed to outpace interceptors and disrupt enemy radar tracking, much like the SR-71 evaded thousands of missiles.
-While modern defenses are more capable, the SR-72’s combination of speed, high-altitude operation, advanced materials to manage thermal stress (likely carbon-carbon composites), and stealth features intends to maintain its operational advantage for future ISR and potential strike missions.
SR-72: Can It Outrun Missiles?
If all we hear about the SR-72 Darkstar or Son of the Blackbird is true, then this aircraft will be a game changer for the US. The SR-71 was the fastest air-breathing aircraft built, zipping along at Mach 3.56 (2,731.458 mph). The SR-72 plans almost to double that.
The Darkstar (a really cool name, by the way) can reportedly fly at Mach 6 +, which is 4,603.61 mph. It could fly from New York to Los Angeles in 30 minutes.
One of the SR-71’s main advantages was speed. When it encountered enemy air defense missiles, the Blackbird’s best defense was accelerating away from the threat instead of attempting evasive maneuvers.
Modern Air Defenses Are Better Today
It goes without saying that the technology comprising today’s modern air defense systems is far better than what the Soviet Union operated in the 1960s and 1970s.
The Soviets had nothing that could touch a Blackbird flying at 80,000 feet at Mach 3+. They would simply outrun the missiles launched at them. The Soviets launched more than 4,000 missiles at the SR-71 and didn’t record one hit.
Today, every country is working on developing hypersonic missiles for air defense and offensive scenarios. High-speed missiles, like the British Starstreak, can reach speeds of Mach 3.5. Other modern interceptors could pose a significant threat even to a hypersonic aircraft.
Speed Is The Best Weapon Of the SR-72
In 2023, Lockheed posted on Twitter or “X” that set tongues wagging.
The first, with an image of the SR-71, reads, “The SR-71 Blackbird is still the fastest acknowledged crewed air-breathing jet aircraft,” implying an even faster aircraft is out there.
Another tweet, posted to celebrate the success the latest Top Gun film enjoyed, featured an image of the high-speed aircraft featured in that film. Interestingly, Lockheed Martin said, “To celebrate, we are sharing some Maverick-worthy images of real aircraft.”
The SR-72 streaking along at Mach 6 will not be crewed, so making incredibly high-G turns won’t affect the pilot since there probably won’t be one.
In June 2017, Lockheed Martin’s executive vice president and general manager for Skunk Works, Rob Weiss, told the media that testing was complete on the turbine-based combined cycle hypersonic propulsion system for the SR-72 and that they were “getting close” to beginning work on what he described as an SR-72 Flight Research Vehicle (FRV).
“Hypersonic aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour,” Brad Leland, Lockheed Martin’s hypersonics manager, said in a Lockheed Martin press release that has since been taken down.
“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 battlespace today.”
Protection Against Thermal Stress
The SR-72 incorporates advanced materials to withstand extreme thermal stresses, likely involving carbon-carbon composites, which are a step beyond the SR-71’s titanium skin designed for heat dissipation at high speeds.
The SR-72’s design emphasizes speed and operational versatility, integrating advanced avionics and possibly even AI-assisted systems for autonomous operations, which were not features of earlier hypersonic aircraft.
Defending Itself Against Russian and Chinese Missiles
The SR-72’s best weapon against missile defenses is speed. Engineers at Skunkworks have minimized the radar cross sections and reportedly are placing the best radar-defeating technology in the aircraft.
With China and Russia constantly trying to upgrade their air defenses, the Darkstar’s speed is paramount. Even if enemy sensors could detect the Darkstar, it would be moving too fast to intercept.
The high altitude makes it very difficult for advanced air defenses like the S-400 and S-500 systems to destroy it.
Russia’s S-400 Air Defense System. Image: Russian Military.
The SR-72 is a strategic, intercontinental aircraft that can gather intelligence, deliver strike capabilities to important enemy targets, and escape while the enemy is powerless to stop it. While modern air defense systems are much better today, could they take down an aircraft flying at Mach 6?
Not anytime soon.
About the Author:
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
Dewayne C.
May 16, 2025 at 2:03 pm
Nice story about a nonexistant aircraft. There is no SR-72.