SR-72 “Son of Blackbird”: What We Know About Lockheed’s Hypersonic Spy Plane
The SR-71 Blackbird still holds the record as the fastest jet-powered crewed aircraft ever flown operationally. Since its retirement in the late 1990s, aviation fans have wondered what would replace it. Lockheed Martin’s answer, at least on paper, is the SR-72, nicknamed “Son of Blackbird”. Here is what is known and what is still speculation.
- Concept unveiled by Lockheed Martin Skunk Works in 2013
- Target speed around Mach 6, twice as fast as the SR-71
- Planned turbine-plus-scramjet combined-cycle engine
- Envisioned for both reconnaissance and strike
- Programme status remains largely secret
What is the SR-72?
Lockheed Martin’s famous Skunk Works division revealed the SR-72 concept in 2013. It described a hypersonic aircraft able to fly at around Mach 6, roughly twice the speed of the SR-71, for intelligence, surveillance and reconnaissance missions and potentially for strike. Most descriptions present it as an uncrewed or optionally crewed aircraft.
The engine challenge
The hardest problem is propulsion. Conventional jet engines cannot work at hypersonic speeds, while scramjets only start working at very high speed. The SR-72 concept relies on a turbine-based combined-cycle engine: a jet engine for take-off and acceleration, handing over to a ramjet and scramjet in the same airflow path for hypersonic cruise. Lockheed worked with Aerojet Rocketdyne on this concept. Heat is another major challenge, because the aircraft’s skin would reach extreme temperatures.
Why build it?
Satellites follow predictable orbits, and stealthy drones can still be detected. A Mach 6 aircraft could fly over a target and leave before air defences react, covering vast distances in an hour. In a strike role it could launch weapons with very little warning. These advantages are especially attractive for a war in the Pacific, where distances are huge.
What is confirmed and what is not
Lockheed has said little officially since the original announcement. Executives have hinted that key technologies have matured and that a demonstrator could fly, and the “Darkstar” aircraft in the 2022 film Top Gun: Maverick was designed with Skunk Works input, fuelling speculation. However, there is no public confirmation of a flying SR-72 or a production contract. Any such programme would almost certainly be classified.
The wider hypersonic race
The SR-72 is part of a broader race. US start-ups such as Hermeus are testing reusable high-speed aircraft, Stratolaunch’s Talon-A has flown at hypersonic speed as a reusable test vehicle, and China is investing heavily in hypersonic aircraft research. The US Air Force and DARPA have funded several programmes to mature high-speed engines and materials.
Verdict
The SR-72 remains one of aviation’s most intriguing projects: a plausible concept backed by serious engineering, but surrounded by secrecy. Whether it already flies in the shadows or is still years away, the idea of a hypersonic successor to the Blackbird shows where military aviation is heading: faster, higher and harder to stop.
Featured image: USAF / Judson Brohmer / Public domain, via Wikimedia Commons
