The Lockheed SR-71 Blackbird is rightly viewed as a legend. Best known as a recon plane that nobody could hit, it even was considered as the basis for a fighter and was the second-fastest manned plane in history.
It served with the United States military from 1964-1998, and with NASA until 1999. The SR-71 had been developed from the A-12 OXCART (no relation to the A-12 Avenger), a single-seat plane capable of making high-speed recon runs as well.
It was thought satellites and drones could replace the SR-71. The problem was that satellites are predictable, and too many drones just don't have the performance or reliability. But Lockheed's Skunk Works, which created the A-12/YF-12/SR-71 family, is now developing a SR-72, and they promise it will be faster than the Blackbird.
Lockheed noted that the SR-71 was designed on paper with slide rules. Even without the benefit of high-technology, the SR-71 proved to be superb at its role.
The new SR-72, though, is going to leverage technology from the Falcon Hypersonic Technology Vehicle 2 to help it fly at speeds exceeding Mach 6. The HTV-2 hit Mach 20 during its flights.
According to a report by Popular Mechanics, the SR-72 will also have a strike mission. While the exact weapons are unknown at this time, Aviation Week and Space Technology reported that plans call for a "Flight Research Vehicle" to be constructed in the early 2020s, with a full-scale version to be in service sometime in the 2030s.
As for the lucky pilots who get to fly this plane, they will not need the very bulky suits that Blackbird pilots wear. That's because the initial plans call for the SR-72 to be a drone.
Well, no successor to the Blackbird can be perfect.