I know B-52s are still in use, but is still there anything special about them? Could Boeing relatively easily modify a passenger plane to do essentially the same thing, maybe even better and cheaper?
They’re special because they’ve been used for decades, and they’re a proven and very reliable design. It usually takes a long time to develop an aircraft for military use, given the Pentagon’s very specific mission requirements. Tanker or transports aren’t too big of an adaptation of civilian airframes, but bombers are a whole different kettle of fish. If it could be done better and cheaper, I suspect it would already have been done.
Yes, there is something special about them. They have proven to be supremely adaptable, from the nuclear role they originally had to launching long-range cruise missiles and carrying various other weapons. The design has allowed it to still be flying, albeit heavily modified, for nearly 60 years, and likely for another 50 more (seriously, they’re not even close to the end of their overall service life).
A commercial plane could not be adapted to do anything like what the B-52 does, just as a B-52 could not serve as an AWACS platform, an aerial refueling platform, or a command and control platform.
There is a lot to it.
A B-52 is compared to a 747 very overpowered. The 747 has four engines (of some output) the bomber has eight (of some output). To say it another way, the bomber has a very slender fuselage. After all the bomber carries a dense payload while a passenger plane carries a fluffy one.
Then you have to consider balance. Think of what goes on when a bomber releases its payload. The Center of Balance is knocked all off kilter. That is why the bombs and stuff are as near to the CB as possible. I cannot imagine making a 747 into a bomber if only because the wing spar is right where you want the bomb bay.
Add on the need for air-to-air refueling as another balance problem and the bomber’s need for a long loiter time at full load.
One thing adds to another. Could a 747 be used as a bomber? Sure. Would it be a good bomber? No.
Thank you Paul. Good explanation.
I understand why they keep them in service, but I don’t understand why they haven’t re-engined them with some sort of modern high-bypass turbofan instead of the old TF33 low-bypass ones that they are currently equipped with.
At the altitudes and speeds that typical B52 missions are at (somewhat airliner-like) I can’t help but think that the 1950’s era engines guzzle fuel.
I mean, 2 GE90-115B engines (used on Boeing 777) would not quite double the thrust of the 8 TF33 engines, and I can’t help but imagine that 2 engines, however powerful, would be more efficient than 8 smaller ones.
If it works, why “fix” it? IIRC the last fix to the B-52 engines was to make them relatively smokeless. They also hang quite low in their engine pods and I question whether a modern high-bypass turbofan would fit. Then too, there is the expense. To design, test and field such a modification would probably cost more than the fuel savings. The USAF is currently dumping money into hi-tech aircraft, not these dinosaurs, as useful as they may continue to be. Money is better spent on defensive electronics and navigation equipment upgrades, if anything.
The idea has been tossed around. One proposal during the B-1 program was to instead convert 747s to CMCA (Cruise Missile Carrier Aircraft) where they would carry AGM-86 ALCMs internally in rotary launchers. Wiki says 50-100; my memory is the most commonly used number was 72.
Another problem is no one wants to spend the money to produce bombers that are only a marginal improvement on the still-flyable B-52s. We see this in other weapons systems too. If a proposed design isn’t so revolutionary in performance as to make it’s predecessor obsolete, it isn’t considered worth funding.
As the requirements for a strategic bomber’s main mission profile (penetrating Soviet air space in a nuclear war) changed over time, the planned replacements for the B-52 were intended to be dramatically superior to it: the XB-70 was going to be an ultra high altitude Mach-3 bomber, the B-1A would be a supersonic ground-hugger, and the B-2 would be nearly invisible to radar. Cost and performance concerns led to none of these completely replacing the B-52, and the end of the Cold War as well as the development of sophisticated cruise missiles removed much of the purpose of building them.
ISTM that would have been a more likely event in the earlier days when aircraft were a lot simpler, but as things became more specialized and mission-optimized it gets more difficult. The most recent major cross-purposing of that nature I can think of have been in the opposite direction – one by Boeing itself: start with a bomber airframe, heavily modify it (in Boeing’s case by adding an entire upper fuselage) into a freighter/tanker and then sell that in turn as an airliner. In the USSR Tupolev also used to do that, with the Tu16 and Tu95 bombers becoming the basis for the Tu104 and Tu114 airliners. In recent times airframes that started as civilian transports have been succesfully converted to gunships or COIN aircraft (AC47) or modified for Maritime Patrol/ASW (P3, CASA 235), but not as bombers, AFAIK .
I have to disagree a bit about cost being an issue - or perhaps agree in an oblique way. The B-1 was a fairly expensive aircraft but wasn’t intended to replace the B-52, and the B-2 is so obscenely expensive that the cost to replace the B-52 with it would be entirely prohibitive; the fly-away cost per plane is $750 million each and if the cost of the entire program (R&D, etc) is divided per plane, it works out to over $2 billion per plane.
They did toy with replacing the 8 engines on the B-52 with 4 bigger, more powerful engines. The thought being that maintenance costs alone would drop like a rock with half as many engines to work on, particularly with newer, more reliable designs. Fuel savings would also rise (fun irrelevant trivia: The B-52’s gas mileage when taxiing on the airfield is measured in gallons-per-feet. It is common to top off the tanks before starting the engines, then refueling via tanker once airborne.)
That said, long-term savings often take a back seat to short-term costs. The Air Force (or perhaps Congress, I forget where the decision got made) decided in the end that it cost too much to re-engine the BUFFs in the present day in return for money saved on future budgets years down the road. Somewhere in Arizona there is the remains of a scrapped B-52 that had 7 engines (three sets of two, and one big single turbofan on one of the pylons).
Also, as others have indicated, strategic bombers have a particular set of design requirements, mainly in how they carry (and remove) their payload. There was an Army Air Forces transport back in WWII called the C-87 Liberator Express, based on the B-24 Liberator, the B-17 Flying Fortress’s homely college room mate. These things had what was considered to be a truly appalling safety record, despite being based on a very solid design. What it came down to was that the B-24’s center of lift was far forward of where most transports’s CLs were, and the fuselage was very large compared to how much of it you could fill with cargo. Fill up the entire interior with cargo like you would with a C-46 Commando or a C-47 Dakota, and you’d throw the balance all off and greatly increase the odds of an aircrew investing in real estate. Unless the ground crews were specifically trained and took special care to avoid loading cargo too far aft, this was a very easy mistake to make.
That said, cargo planes can be used as ad-hoc bombers (and passenger planes, and refueling platforms, and command-and-control planes, etc.), but they typically aren’t as good at it and are only used as such when an appropriate bomber isn’t available. Basically, they load the bomb on a pallet like any other piece of cargo, and shove it out the back door at an appropriate moment. The only time the USAF does this is when the bomb is physically too big to fit in a B-52 (so the BLU-82 Daisy Cutter and the Massive Air Ordinance Bomb). Generally speaking, the B-52 is faster, more accurate, and designed to be much harder to kill on a battlefield than any transport plane will be, but the bomb bay was designed for relatively dense, small bits of cargo where a C-130 Hercules can carry bulkier items.
The B-2 has a much more effective combat payload, for one thing. 
Oh, yeah, I’d forgotten that. The Carter Administration favored that option when the President killed (for the moment) the B-1.
Here’s another interesting 747 variant: Stratospheric Observatory for Infrared Astronomy - Wikipedia
Well, Jimmy does not get credit for what he really said and did. You see, the USAF had two new bombers under development. The B-1 which was an evolutionary improvement over the B-52 and the Advanced Technology Bomber which was a risky, expensive high-tech gamble.
Jimmy did the risky thing. He cancelled the B-1 in favor of the ATB. The ATB then went deep black and was never spoken of again. Even when Ronald Reagan’s called Jimmy names for canceling the B-1 the Democrats did not utter the name of the ATB. The public thought nothing was in the pipeline. JC looked weak on defense.
So RR took over and brought back the B-1B (a much different airplane, but I digress) even though the ATB (now called the B-2) was past its most difficult development phase. So RR brought out two bombers (at huge expense) in his first term.
But he could only do it because of what JC had done. And, he did it even though the B-1 did not, and still does not really fill much of a need.
This thread has answered a question I have had for a long time, why didn’t they ever uprate the engines on the BUFF.
Thanks guys.
You may be thinking of this. Funny looking bird. I’d heard of it before, but not as an attempt to re-engine the B-52. It was a testbed for the P&W JT9D engine that was being developed for the 747. Quite possibly the only seven-engined aircraft to fly.
Which got me wondering what the lowest number of engines that have not been used on an airplane would be. 1,2, 3, and 4 are easy. I found pictures of a B-17 modified with a fifth engine in the nose. There are a couple with 6 engines. 7, and 8 we’ve already discussed in this thread. (I know of at least one 10 and one 12.) I’m going with 9, unless someone can tell me about a nine-engined airplane somewhere.
ETA: Found a few more pictures here. It says that picture in the previous link is with a GE TF-39 being tested for the C-5 programs, and that there was another B-52 testing the JT9D.
And the B-52 is not unique in its long service life. Bombers from the fifties like the Russian Tu-95 and the Chinese Xian H-6 are also still in service.
Similarly, the KC-135 was introduced in 1957 (still serving; all the current airframes were built in the early 60’s), the C-130 Hercules was originally introduced in the 1950’s (still in production, the newest ones have spiffy six-bladed scimitar props and a glass cockpit), and a few other airframes that have stood the test of time.
It’s amusing to see how many currently serving airframes in the Air Force (and even the Navy) are based on the Boeing 707 or its older brother the Dash-80.