[The Great RJ]

Consider that the SR-71 was designed 50 years ago, it is inconceivable that there hasn’t been a successor developed and flown in the last five decades.

[Czar]

Actually, it is understandable when you consider there is no longer a Clarence “Kelly” Johnson around to develop that successor.

[mountn man]

Consider that the SR-71 was designed 50 years ago, it is inconceivable that there hasn’t been a successor developed and flown in the last five decades.

Yes...and no.

There is only so much that can be done with aeronautics and material strengths and friction heat.

Make no mistake, the SR-71 was probably the most revolutionary plane ever built, INCLUDING the Wright Flyer.

all done without CAD programs, using slide rules.

[ProtectOurFreedom]

The successors have been developed and flown. Their operating altitude is 200 miles, not 20 miles, and their speed is 18,000 mph, not 3,000 mph.

[kosciusko51]

There are several big issues to address to make something faster than the SR-71 and its predecessor, the A-12 (which first flew in 1962!), which includes the engine, materials, and thermal control for sustained flight at Mach 5+.

The interesting thing is that the body shape of the successor is very similar to body shape used for variants of the NASP back in the early 1990's.

LS might have more insight as he wrote The Hypersonic Revolution, Case Studies in the History of Hypersonic Technology: Volume III, The Quest for the Obital Jet: The Natonal Aero-Space Plane Program (1983-1995)

[discostu]

There are. It’s mostly a satellite job now. He also have drones we do that with. Then of course there’s the legendary Aurora which might or might not exist. Part of it though is that sometimes we get it right, spy planes have a relative simple concept: fly high, fly fast, carry good cameras. Once you do that well, well you’ve got it.