SR-72: What should we make of the rumors? As the fastest air-breathing manned aircraft ever to exist, the SR-71 spy plane has forever emblazoned itself upon any record of aviation history as a sleek-looking, high-altitude, stealthy aircraft which has made a difference for the Pentagon.
The aircraft, which had several retirements with the most recent being 1998, goes back many years to the 1960s, a development which suggests early sophistication among engineers thinking about building low-observability platforms.
Perhaps the aircraft was arguably ahead of its time, as it was conceived of and crafted by Lockheed Martin’s famous Skunk Works division.
The SR-71s fuselage does indeed look stealthy, as it is rounded with a blended fuselage and slightly curved wing formations devoid of sharp angles. As something that first flew in 1964, the aircraft features some impressive technologies, according to a Lockheed Martin essay called “Creating the Blackbird” which points to the aircraft’s side-looking radar, signals intelligence and long-range electro-optical cameras. Specs for the aircraft list it as being capable of flying Mach 3 and reaching altitudes of 85,000 feet. A PBS documentary in 2006 explained that the historic Blackbird simply used its unparalleled speed to essentially outrun ground-based radar and air defenses.
With a crew of 2, the Blackbird aircraft had both a pilot and reconnaissance officer for high-altitude surveillance missions, operations which later became performed by unmanned systems in later years following the retirement of the aircraft. Following its military service, the Blackbird supported NASA for many years until the late 90s. An interesting essay in the Business Times explains that the Blackbird’s missions were eventually absorbed by drones and satellites.
The SR-72: Coming Soon?
However, the Blackbird concept lives on, and the most enduring legacy of the famous spy plane may be the way it has inspired the current, fast-paced effort to engineer its successor, a hypersonic SR-72 – and likely unmanned in my view.
The new, “Son of Blackbird” as it is called, is slated to take to the sky by 2025, according to Lockheed’s paper. It would make sense that a Blackbird follow-on would be unmanned, given that it allows for the possibility of hypersonic flight and leverages decades of technological breakthroughs since the advent of the Blackbird in the 1960s.
It makes sense that the amazing Mach 3 speed of the 1960s-era Blackbird set the stage for its follow on, as a hypersonic Blackbird son SR-72 would simply need to stretch to Mach 5 or faster to qualify as hypersonic. Interestingly, in a manner similar to how the original Blackbird avoided air defenses with pure speed, hypersonic projectiles are particularly difficult to track. Objects, such as weapons or some day drones, travel at such high speeds from one radar aperture or “field of regard” to another, defenses simply cannot establish a “continuous” track and therefore succeed in targeting.
The dawn of hypersonic drones would indeed be a paradigm-changing breakthrough, and it was one anticipated by Air Force scientists many years ago. Former Air Force Chief Scientist Gregory Zacharias told Warrior years ago that he envisioned hypersonic development in terms of stairsteps, meaning progress and leaps forward would break through in increments with several years in between. His predictions have thus far held up pretty well, as he told me roughly 10-years ago that hypersonic weapons would emerge in the 2020s, to be followed by hypersonic drones in the 2030s and recoverable hypersonic drones in the 2040s.
Should Lockheed succeed in producing a hypersonic drone by 2025, they will indeed be ahead of Zacharias’ prediction. It takes little imagination to envision how hypersonic drones could radically change the tactical equation when it comes to air war and high-altitude reconnaissance. An ability to outpace air defenses with pure speed, and blanket sensitive, high-risk areas with forward reconnaissance at unprecedented speeds and stand-off distances certainly offers a yet-to-exist advantage. This is particularly true if the drone is networked with satellites, manned aircraft and even ground control stations.
The Future Is Almost Now…
The progress with the SR-72 may pertain to breakthrough technologies enabling larger platforms such as drones to maintain hypersonic speeds for longer-periods of time due to advances in thermal management. The primary challenges with achieving hypersonic flight relate, to a large degree, to an ability to withstand the “heat” generated at hypersonic speeds and effectively manage the “boundary layer” or air flow surrounding the projectile.
A laminar or “smooth” air flow can ensure a hypersonic projectile maintains its trajectory to a target, whereas a “turbulent” boundary layer where molecules shift quickly can throw a hypersonic weapon off course. The larger a platform is, and the more payload it carries, the harder it becomes to manage aerodynamic challenges and heat challenges as well.
There may be breakthroughs in the areas of thermal management, composite materials or cooling technologies of some kind which now enable sustained hypersonic flight of larger platforms such as drones.
Kris Osborn is the Military Affairs Editor of 19FortyFive and President of Warrior Maven – Center for Military Modernization. Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army—Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has appeared as a guest military expert on Fox News, MSNBC, The Military Channel, and The History Channel. He also has a Masters Degree in Comparative Literature from Columbia University.