Some 24 years after the SR-71 Blackbird made its last flight, there are hints its alleged replacement, the SR-72, could be in development.
Commentary
Some 24 years after the SR-71 Blackbird made its last flight, Lockheed Martin has
hinted at the existence of the Blackbird’s alleged replacement, the SR-72 unmanned aerial vehicle (UAV).
Previous reports have suggested that a prototype could make its first flight as soon as 2025 and that the SR-72 will be a Mach 6-capable aircraft. But because the decades-long development program went dark in 2018, recent specifics are scarce. However, based on
details that were released prior to the program being made top secret and based on what a hypersonic plane design must incorporate, we can come up with a good general overview of what the SR-72 should be able to do should the hints become reality.
Further, since the “Darkstar” mockup designed by Lockheed Martin’s Skunk Works for “Top Gun Maverick”
may look something like the SR-72, we may also have gotten a sneak
preview of what it'll look like. Of course, the biggest difference between the Darkstar in “Maverick” and the SR-72 is that the movie Darkstar is a manned aircraft, while the SR-72 will be a UAV. This also greatly differentiates the SR-72 from the SR-71 Blackbird, which was manned. It also means that the SR-71’s speed records for manned flight are in no immediate danger.
For the SR-72 to be successful, Skunk Works and Aerojet Rocketdyne must be successful in turning the prototype hybrid turbojet engine/scramjet engine they
announced in 2013 into a reliable production engine. It’s thought that this engine works by having the turbojet portion of the engine accelerate the plane up to somewhere between Mach 2.5 and 3.5, and then a dual-mode ramjet/scramjet will take over, moving from ramjet mode to the scramjet mode on its way to accelerating the SR-72 to a speed somewhere in the neighborhood of Mach 6.
As was the case with the SR-71, but even more so, the SR-72 faces the challenge of having different areas of the aircraft being subjected to extreme cold and extreme heat.
To deal with that, the SR-71 design team made major use of titanium because of its excellent strength-to-weight ratio and resistance to heat. For the cold, insulation and other solutions were utilized. No doubt, the SR-72 will also use titanium, but it‘ll also make use of lightweight, heat-resistant composites that weren’t available when the SR-71 was designed in the late 1950s and early 1960s. And like the SR-71 Blackbird, it’ll also use insulation as necessary to protect vulnerable areas from heat and cold. But it should be noted that the SR-72, not having a pilot, doesn’t have to devote the weight and space to protect a pilot from the extreme conditions that the SR-72 will face. Nor does the SR-72 design team have to figure out a safe way/mechanism (a pod?) to safely eject a pilot at Mach 6.
The SR-71’s typical mission was executed at an optimum cruising speed of Mach 3.2 (2,193.97 miles per hour) at 80,000 to 85,000 feet in altitude. But even with the air density at 80,000 feet only being about 3 percent that of sea level, the heat generated by the SR-71’s tremendous speed heated the leading edges of the SR-71 wings to 800 degrees Fahrenheit.
While it’s likely that the SR-72 will be able to handle marginally higher temperatures than the SR-71, it'll still almost certainly need to mitigate the heat issues by flying at altitudes greater than those of the SR-71 to reap the benefits of lower air density and lower heat generation. Consequently, we should expect to see a typical operational flight for an SR-72 take place at a minimum of 90,000 feet to
more than 100,000 feet at a speed of roughly 4,100 miles per hour (Mach 6 at 90,000 feet).
Regarding the SR-72 strike capabilities, opening weapons’ bay doors to launch bombs or missiles while traveling at hypersonic speeds has never been executed, to my knowledge. Consequently, it would be very surprising to see this capability incorporated into the SR-72. So before getting excited about the SR-72’s strike capability, we'll need to see this capability very thoroughly demonstrated. Instead, the SR-72 could pinpoint the targets and have a
B-52 loaded with hypersonic missiles launch those missiles at the targets from outside of enemy-controlled airspace.
Another challenge facing the SR-71 design team was achieving a good measure of stealth while maintaining an aerodynamic profile that would allow it to achieve its tremendous altitude, speed, and range goals. However, with the kind of speed and altitudes projected for the SR-72, stealth may not be as important for it as it was for the SR-71.
Indeed, Al Romig, then-Lockheed Martin’s Skunk Works engineering and advanced systems vice president, proclaimed in 2013 that “
speed is the new stealth.“ Still, having some measure of stealth will combine with the speed of the SR-72 to further reduce an opponent’s time to respond to the SR-72’s penetration of their air space. And it’s worth noting that Russia does have Mach 14 anti-air missiles fired from its highly capable S-400 and S-500 air defense systems that can reach altitudes of well above 100,000 feet. Hence, even a modestly reduced radar cross-section would be a plus.
So we have a plane that on paper looks good, but even if it’s realized in full, does the United States need a plane like the SR-72, given the ever more pervasive and powerful satellites and the other drones available to conduct surveillance and intelligence gathering? The answer is a qualified “yes.”
Satellites are certainly effective for surveillance and intelligence gathering, but satellites aren’t always in a position to provide continuous surveillance. And because their orbital paths and timings are known, activities of interest can be ceased or hidden during times when they’re in range. Additionally, a growing number of nations can destroy satellites should hostilities break out. And while there are plenty of other powerful drones and UAVs capable of doing surveillance, the SR-72’s speed and altitude would allow it to execute and survive missions that lower, slower-flying drones couldn’t.
Of course, all the above is just speculation as we’ve yet to see an SR-72 fly, much less be able to perform regular missions at a cost that makes sense. However, should the SR-72 perform as hoped, it would go down in aerospace history as a major accomplishment. And it would help close gaps in surveillance coverage, which would be a good thing.
Views expressed in this article are opinions of the author and do not necessarily reflect the views of The Epoch Times.
