OK, I did some searching, but found no clear answer.
Why have the B-52 bombers not been retired?
This site indicates that the last B-52H was put into service in 1962. They are projected to last in service until 2040!
It is my understanding that the B-1B Lancer was intended to replace the aging B-52. It now appears that the B-52 may outlast its successor.
What is the point of maintaining an aircraft through its 8th decade of service? Is this really cost-effective?
It’s relatively cheap to operate, there’s lots of people trained on it, and it can carry more bombs farther than most anything else.
In short, it’s cheap and it gets the job done.
Well, why should they be retired? Just because they’re “old”? Uh-oh, do I detect a bit of “age-ism” here? 
“If it ain’t broke, don’t fix it.”
Personally I think they are the coolest-looking aircraft I have ever seen, and people are just in love with it.
So they do maintenance on those and keep the bird flying.
Actually, yes, it is cost-effective. The BUFF can do something that few, if any, other bombers can do: Carry massive bombloads around the globe, reliably, and delever them with a high degree of accuracy. The B-52 can also serve as a launching platform for a very wide range of ordnance, making it a flexible, as well as reliable, work-horse.
Designing a replacement bomber has been tried, and has only met with limited success, at very high costs (B-70, B-1, B-2).
Lastly, the military is extremely conscious of the cost of maintaining a weapons system, due to budget restraints (yes, despite huge budgets, the Mil has less money than they need to do everything with which we’ve tasked them), and they’ll try and ditch any system that doesn’t pull it’s weight, cost/benefit-wise.
Um, incidentally, why is it called BUFF? I mean, I know they’re in pretty good shape, and all, but…
Big Ugly Fat F*cker
Let me turn the question around. A great deal of money has been spent over the last 40 years designing replacements for the B-52, such as the B-70 and B-1B. The B-1B even went into production.
Why have the replacements (esp. the B-1B) proved to be such a failure?
Conversely, if the design of the B-52H is so great, why have no new ones been built for the last 40 years?
(I’m not really including the B-2 in the discussion, since its stealth capabilities were designed to penetrate well-defended airspace. OTOH, he BUFF is basically a flying dump truck.)
Tranquilis, I’m fully aware of this. I’m in the Navy, a sub guy like you are (I believe). In the sub force, we’ve had no trouble with effective replacements. We are not decommisioning 688-I subs while keeping Permit-class subs in service. (I know–not a perfect analogy, what with refueling schedules, etc.)
Chronos, BUFF stands for Big Ugly Fat (uh…) Fellow.
Also, in this age of overwhelming air superiority, they have few enemies.
An airliner that age would be extremely old, and probably have used up its structural fatigue life several times over. But a bomber doesn’t fly anywhere near as many hours or flights per year, so the primary concern is corrosion, and that’s a maintenance issue. Chronological age as such doesn’t mean anything, really.
Oh, btw, the A-7 Corsair II is the SLUF - Short Little etc.
Well, yes, I’d forgotton that you’re a ‘tuber’, too. Sorry about that. Actually, I did a lot of repair work in the Permit-class boats when I was on the tender, and frankly, they were decomissioned because they were no longer effective, cost/benfit-wise. They had become “Hanger Queens”.
If you’ll look around, you’ll find that the old Seawolf (SSN-575) was kept around a long time past it’s “natural” demise, because for what it was doing at the end of it’s life, it was still cost-effective. The USS Parche (SSN-693) was still going strong in '94, last I checked.
The B-70 just failed to live up to it’s intended purpose. Too ambitious, and technology, at the time, just couldn’t do what the designers wanted and still be cost-effective. It also had a bad habit of crashing. The B-1 was intended for a somewhat different attack philosophy, and also was more ambitious than technology could support. The B-2 is quite successful as a bomber, but is so damn expensive that it’s too valuable to use in daily warfare, needing to be reserved for the most important targets. Actually, in the case of the B-1B and the B-2, I’d suspect that there was too much “technology for technology’s sake”, resulting in capable, extrodinarily expensive platforms…
As for making more B-52s, well, there’d be an expensive re-tooling process, and besides, we’ve got as many as we need, so why build more?
Slip of the finger…
The USS Parche’s hull number is 683.
I don’t think I would call the B-1B a faliure. Its a very capable aircraft.
There’s another school of thought that the B-70 was intended as a technology development program, not as a real combat-capable aircraft. It can also be argued that any operational philosophy it might have represented was made obsolete by the development of reliable ICBM’s. It had a very small bomb bay, really only capable of carrying 1 nuke to Moscow faster and higher than the defenses could cope with. The BUFF can carry a lot more payload and a lot more types of it, too.
There were only 2 XB-70’s built, and the one that crashed did so because it was collided into by an F-4 in a photo formation that got caught in its wingtip vortex.
At the time it was conceived, maybe. By the time Reagan restored the program in the name of saber-rattling after Carter mercy-killed it, it was already conceptually obsolete. Even by the time of the Gulf War, decades later, the problem of the self-jamming radar was still so severe that USAF didn’t dare use it in actual combat.
[nitpick]
It was an F-104 that collided with it.
[/nitpick]
A couple of quibbles:
The XB-70 never failed to live up to its potential. It would have done what was asked of it very nicely. Unfortunately, the world changed. It was intended as a penetrator, but interception technology jumped to the point that no matter how high and fast it flew, its enormous radar signature would have simply been an airborne bullseye.
At the same time, there was growing concern about the effects of ozone depletion in the altitudes where the B-70 was intended to fly (a factor that also killed its cousin, the U.S. SST).
Similarly, they had no habit of crashing. It is rather difficult to keep a plane flying when another plane crashes across the wing and rips off the vertical stabilizers. That hardly counts against the Valkyrie.
The B-1B has had problems with various elements of its avionics (the technology controlling its navigation, radar, counter-radar measures, weapons delivery, etc.). The plane works fine, but we’re just a bit afraid to turn it loose in a combat situation. It actually has a slightly larger bomb capacity than the B-52. Who knows, maybe they’ll try a few out in the next few months. (There was a squadron that was considered for use in Desert Storm, but they were never deployed.)
OK, so I type slow.
ISTR that we used some B-1’s in the Kosovo campaign, tom. B-2s as well. Not sure how effective they were, though.
From this site:
Regarding the B-52:
To sum up, it just seems odd that we are putting money into “extensive upgrades” for 40-year-old airframes, rather than “simply” 
correct the problems of the much newer B-1Bs we seem so reluctant to depend on for conventional bombing.
It’s sort of a Catch-22. Justification requires that they fly missions, which they can’t do because their “great expense has yet to be realized”. Every aircraft has teething problems. Those are worked out over years of flying. I believe that the technical problems of the B-1B can be overcome if only the funds were allocated. But IIRC most of the crashes followed ingestion of large fowl. It’s kind of hard to fix that.
As for the XB-70, I think that as tomndebb said, “The world changed.” I think the XB-70 was designed to be a fast, high-altitude bomber because the Soviet SAMs at the time would not be able to reach it or catch it. But then the Soviets built missiles that could reach the XB-70’s altitude and that were fast enough to shoot it down. There wasn’t much sense in continuing development of an aircraft that was out of the reach of SAMs, when SAMs were developed that would defeat this defense.
The Soviets also built an interceptor, at great expense, specifically to counter the XB-70 threat. When the U.S. stopped development of the XB-70, the Soviets were stuck with the MiG-25 “Foxbat”. The West were in awe of the MiG-25 until we got our hands on one. Sure, it was fast; but not very maneuverable. Incidentally, the MiG-25 design was heavily influenced by the Navy’s North American A-5 Vigilante.
Since the Soviets had countered our high-altitude threat, we decided to go the other way: to build a supersonic low altitude bomber. The B-1A was supersonic, but was not good enough. The B-1B is a superior aircraft, but (officially – I don’t know about actually) is subsonic.
[QUOTE]
*Originally posted by Johnny L.A. *
**
Actually, officially is is supersonic. From http://www.af.mil/news/factsheets/B_1B_Lancer.html
Speed: 900-plus mph (Mach 1.2 at sea level)
Not much past Mach 1, but still…