The Boeing B-52 Stratofortress has been with us for going on 50 years. In its life, it has been modernized several times and was last used in combat during the Gulf War. Granted, we have B-1Bs and B-2s; but their numbers are small.
One thing strikes me about the B-52: It still uses the old, inefficent turbojet engines; eight of them. Why have they not been replaced by four more efficient turbofans? Engineering and hardware costs are huge, but haven’t there been any experiments with re-engining these behemoths?
What makes you think that they are not using turbofans?
In 1963, the B-52H was equipped with the Pratt & Whitney TF33-P-3 turbofan. At the height of the Vietnam conflict, I know they totally re-built a bunch of B-52Ds, and I would guess that they got turbofans at that time.
I read once about a B-52 being used to test engines for the 747 program. Two of the B-52 engines were removed and replaced with a single large turbofan. A web search turned up a picture:
I also found a page with a description of the B-52H. There’s an interesting section in the middle about some problems that were encountered by using more powerful engines than the G model, and at the end there’s a brief mention of a proposal from Boeing to re-engine the aircraft:
Hm. Maybe I’m mistaken then. But I was thinking of the very large turbofans that you see on 747s and other commercial aircraft. I think that four large, modern, efficient engines would be better than eight smaller ones.
It could be anything from the Air Force preferring the safety factor of a greater number of engines to an issue with ground clearance for the wider diameter engines to design inertia.
It could certainly be done, and would indeed extend the range between refuelings of the aircraft. But it hasn’t because (WARNING: Speculation alert):
It might not pay off economically. B-52’s don’t fly 10-12 hours a day like airliners; that’s probably more like a month’s worth of flying. Meanwhile, those new engines are still having to be paid for, even on the ground. There would still be an extensive amount of engineering and flight testing that would cost real money, too.
Improving the range might not improve operational flexibility all that much anyway. The tankers still have to meet or escort the bombers on any long mission (and they’re pretty much all long, nowadays - i.e. bombing Iraq from bases in Guam and Louisiana).
(No, I’m not saying it - get a life) If you replace the engines, what else do you replace on these 50-year-old airplanes that arguably could also use modernization? At some point it becomes uneconomical and unhelpful operationally. The future of both strategic and tactical bombing is supposed to be the B-1 and B-2, anyway, not the flying dump truck.
The 757-size engine is not currently in the fleet (the VIP fleet at Andrews is maintained commercially), so it would entail its own training, spares, maintenance, etc. cost headaches. Can’t blame Boeing (and Pratt and Rolls) for going after any potential market, of course. Larger 747-size engines (GE CF6-80C2) are, for the KC-10 and the upcoming C5 re-engining programs, but they’re too big for the ol’ Buff.
The sexy, career-advancing assignments in the Pentagon are the ones with new systems with new names and new missions, not old ones. The people with the political pull to get this done aren’t the ones assigned to the same programs their grandfathers worked on. Anyone who feels that assessment to be unfair please say so.
<<<Quote from Johnny L.A. “we have B-1Bs and B-2s; but their numbers are small.”
Actually, there are about the same number of B-1s in service as there are B-52s. There are around 100 of each in service, although the numbers are slowly dropping due to accidents and aging with no new ones being built.
I’ve gotta agree with Elvis. The prime rationale for re-engining older airliners is fuel efficiency. Airliners spend a large percentage of their operational lifetimes in the air, so an improvement in fuel efficiency pays off.
In a bomber, the prime advantage of fuel efficiency is range, since the economics are totally different. Is the B-52 primarily range limited now?
Another reason for re-engining is an improvement in maintenance. Older aircraft with old engines become progressively more expensive to maintain. At some point, you just have to replace all the engines. At that point, it’s sometimes more economical to just put a more modern engine on the aircraft.
The always-excellent UK aviation magazine Air International for May 2001 has a lengthy article on the future of the B-52H. Essentially, the re-engining program involving RR RB-211’s was a private initative by Boeing, and internal cost studies by the Air Force dispute the savings claimed.
That said, the Air Force intends to keep the B-52H in service until 2040(!), thus there remains the possibility that a re-engining program may proceed. Heck, by 2040 they may be strapping antigravity lifters onto the thing.
All models earlier than the H have indeed been scrapped. As part of the START treaty, the absolute number of B-52’s had to be limited, and in a way that was verifiable with satellites. There is a section of the Davis-Monthan AFB boneyard where the previous models were all chopped with a hydraulic guillotine and the pieces arranged in such a way as to be clear from above.
The only exception is am ancient B model, on loan to NASA, that has been used for all air-dropped experimental aircraft from the X-15 on. The current Smithsonian Air & Space has an article about it, and how NASA is keeping it airworthy with duct tape and willpower.
Pratt & Whitney made an unsolicited re-engining proposal as well, 8 or 10 years ago, with the PW2037 (the other 757 engine option). GE never made an engine that size.
Yes they do! Maybe not every day, but when the stuff hits the fan, they have to stay up a long time-- i.e. Shreveport, LA to Baghdad, Iraq. Back in the “bad old days” half of the B-52s in the world were in the air at once, with the other half on 10-minute alert. 8 hours a day.
Every time I’m in Shreveport/Bossier near the AFB, I always see a few BUFFs flying around. It’s quite interesting when you’re on I-220 going through the center of town (the approach lights are on either side of the road and in the median) and one of the bombers crosses the road at 50 feet on final approach. Even more interesting is when they’re taking off from that runway. The proposed replacement engines are a lot cleaner, too–ever seen a B-52 taking off at max weight? (four huge trails of black smoke…)
[sub]BUFF = Big Ugly Fat…um…“Fellow”, the affectionate nickname for the B-52[/sub]
A B-52 in service in 2040 would be a ninety-one year old design (the present design was fixed in March 1949) and at least a seventy-eight year old airframe (the last B-52H was delivered in October 1962.) That should make any engineer pause and reflect. Consider that 91 years before the B-52 was designed, there was no telephone, radio, incandescent light bulb, hot dogs, recorded sound, zipper, or internal-combustion engines.
Consider that slavery only ended 84 years before 1949.
If it really lasts until 2040, I’d say the B-52 is one of the all-time great engineering achievements, up there with Hoover Dam and the Interstate Highway System.
Well, we’ve already got the DC-3, still used extensively around the world, which is coming up on 65 years old already. And I predict that in 2040 there will STILL be a few of them in service, making them about 105 years old.
There’s a DC-3 that flys regularly out of Long Beach (CA) Airport. One of these days I’ll have to find out what the deal is. Flight training? Sightseeing?
Of course the DC-3 isn’t nearly as complex as a B-52, but several have been modified with turboprop engines.
When people hear about the age of airplanes, I wonder if they are comparing the ages to their cars? A 20-year-old car is usually considered something people drive because they can’t afford to replace it. They are often falling apart. But most of the civilian aircraft fleet is pushing 30.
At the height of production in the 1970s, 15,000 airplanes (Cessnas, Pipers, Beechcraft, Mooneys, Maules, Grummans and the rest) per year were being built. In the 1980s maybe a tenth of that number were being produced. My dad bought a six-year-old Cessna 172 in 1976 for $10,200. That same aircraft today would sell for $30,000 to $40,000. (I found that plane, N84573, but it was not airworthy. I suspect that the owner couldn’t afford an engine rebuild or something. It was sitting at Fullerton Airport last year with a rusty chain around its prop, no rubber on the left main gear, and the right main was flat. Black oil streaked the nose gear olio strut – but there are many, many aircraft of similar vintage that fly frequently.) What’s a six-year-old Cessna go for now? A brief search shows a 1985 (16 years old) 172 for $69,900 and a 1998 model for $134,500. I think the price of a new C-172 is somewhere around $165,000.
Until aircraft production increases dramatically, prices for used aircraft will remain high. Since airplanes are expensive, it makes sense for owner-pilots to maintain and fly old aircraft. (And now to bring it back to the OP…) It seems strange that the U.S. military would fly an airplane until the grandfathers of its pilots are dead, but with proper maintenance and with some upgrades airplanes can last a long time.
