The U-2 is still flying, even though it was expected to be obsolete quickly. The SR-71 and F-117 are no longer operational, I think they both were retired before 30 years of service.

Military aircraft lifespans rarely fit their projected timeframes.

The F-117s are technically still operational, even after their official retirement. https://www.thedrive.com/the-war-zone/retired-f-117-nighthaw...

Flying is dofferent from being operational in the military sense.

Still impressive that those bird are still airworzhy so.

They're still operational systems in the military sense, just no longer front line combat assets. They've been relegated to R&D & training.

So they no longer have operational capabilitied for their initially intended role.

Yes, but this is splitting hairs a bit.

Are training systems considered operational? It depends. In a systems readiness point of view, yes, they're operational even if they've been re-roled, as opposed to being withdrawn-from-use or having another status.

But if you consider only front-line combat systems operational and exclude all other aircraft including training aircraft like the USAF's Texan IIs, then these wouldn't be included in that category.

The SR-71 officially served for about 32 years, although the last few years weren’t very active - there was a retirement followed by a brief comeback IIRC. NASA had one that might have flown a few times after that, I’m not sure.

What led you to believe the U-2 “was expected to be obsolete quickly?” It would be interesting to know who amongst Lockheed and Air Force personnel were right, and wrong, about something like that.

The U-2, being subsonic, was not expected to last long according to one of the books I read, don't ask me which. In addition to being vulnerable to high altitude interceptors, it was difficult to fly as the stall speed was just knots away from Vne. And landing it was an adventure all its own. That said, the airplane found its niche and outlived expectations.

> The U-2, being subsonic, was not expected to last long according to one of the books I read, don't ask me which

Probably either Skunkworks or Kelly: More than my share of it all. I recall that very soon after shipping the U2, they saw the writing on the wall for its operational limits and started working on the SR71 very soon after. Looking at the timelines, U2 first flight was 1955 and the first discussions for the SR71 were done in 1957 with work beginning in 1958. Powers was shot down in 1960 in his U2.

You can see how certain people would think the SR-71 would naturally be a permanent replacement for the U-2. It'll fly at the same extreme height a lot faster, etc. etc. If you're not aware of the enormous operational cost, which is what really killed the blackbird, it seems obvious which one should succeed. (or if it's not your money...)

Every time one of these threads comes up I think I should reread Ben Rich's book, which I read over twenty years ago and gave to a friend about five years ago. It would be interesting to recall his perspective on this. I think he had something in there about how proud they were about keeping the costs of the reactivation and final flights of the SR-71, which were sort of mandated by congress, as low as possible. They were still a lot more expensive than, for example, recent programs to equip the U-2 fleet with more modern avionics.

What? KC-135, C-130, B-1 and notably the B-52 Stratofortress would like a word with you.

The B-52 is the real star here. It is the primary reason that I included the word "rarely". For each of these aircraft, though, I could name two dozen types that did not last 30 years in service.