5 ms·

It's honestly a fantastic case for incremental improvements over time. There's practically no single part on a modern B-52 that's original to the 1960s since ev

It's honestly a fantastic case for incremental improvements over time. There's practically no single part on a modern B-52 that's original to the 1960s since everything has been overhauled and modernized decade by decade. Every attempt to replace it has been (or will be) retired before its EOL.

GartzenDeHaes 4y ago
I don't think you would say that if you had ever been inside one. They are ancient -- and very greasy.
ofrzeta 4y ago
Platonic question: is it still a B-52 then? cf. the Ship of Theseus
- geodel 4y ago
  I mean in this case yes. Since it is a brand and not a single B-52 physical plane which is being improved all these years.
  - runjake 4y ago
    To eliminate confusion, the current operational B-52Hs were originally manufactured in 1960-1961. They have undergone significant upgrades over the years, on all systems, including the airframe itself, since then.
- djmips 4y ago
  I think it is but they do rev the sub model number it seems.
- hef19898 4y ago
  Yes, it is. The current H generation has very little to do with the first build airframes so. Including certification. EDIT: Those upgrade programs, e.g. the F-15 is currently at "X", are complete development programs and involve a certain amount of certification and re-certification. That in the case of the B-52 those upgrades have been applied to existing, tremendously old, airframes, doesn't change that. It does make it quite impressive so, the B-52 turned out to be a very flexible and upgradeable design.
  - jeffdn 4y ago
    That's a little disingenuous, regarding the F-15 -- there is the A/B series, with A being single-seat and B being the two-seat trainer, and the C/D series, with the same distinction between the two models. Both the F-15A and the F-15C are air superiority fighters, with an exclusively air-to-air role. The F-15E is a multirole fighter-bomber, not an air superiority fighter. The F-15X is an F-15E repurposed as a beyond visual range (BVR) missile truck, with data links to AEWC planes that can provide targeting solutions for those missiles. All of the letters between E and X have not been used.
    - coredog64 4y ago
      The more useful identifier is the block number which identifies production changes.
- runjake 4y ago
  The earlier models were manufactured in the 1950s. Most of the H models were manufactured in 1960 and 1961, but they have undergone significant airframe improvements, several engine improvements, and of course, avionics improvements. It's still a B-52, but it's a "B-52H Block $whatever_design_block_they_are_on_these_days" model.
- GuB-42 4y ago
  At least in civilian aviation, it is a very relevant and practical question, and a major contributor to the Boeing 737-MAX fiasco. There is a thing called "type rating", that is qualification pilots need to have in order to fly a specific type of plane. For example, pilots need a type rating for the Boeing 737 in order to fly a Boeing 737. Manufacturers try to do everything they can not to require another type rating when they make changes to an existing aircraft, because type ratings require expensive and time-consuming training that pilots and their companies would rather avoid, and it influences purchase decisions. One of the root causes of the B737-MAX crashes is that Boeing tweaked some settings in order to make the B737-MAX behave like the original B737 when it was, in fact, a different plane, and they did it wrong.
  - KennyBlanken 4y ago
    > One of the root causes of the B737-MAX crashes is that Boeing tweaked some settings in order to make the B737-MAX behave like the original B737 when it was, in fact, a different plane, and they did it wrong. This is wildly wrong. The only thing you got right is that the MAX was designed to avoid needing a new type certification. Boeing radically shifted the Cg to accommodate changing trends in the commercial airline industry which were resulting in Airbus's planes being more competitive. They shifted it well outside what would be considered prudent. This required flight control software bandaids to keep the plane stable (or perhaps better put, from entering a flight envelope where loss of control would happen), but they then also cheaped out of providing redundancy for some critical sensors... AND cockpit annunciators to alert on failures of the sensors. Boeing then passed off the Cg shift and additional systems as very minor changes in the filing for their airworthiness certifications, the FAA rubber-stamped everything because they didn't have the staff to review all these certificate filings so they largely trust manufacturers... ...and then making things even worse, Boeing did very little to disclose the additional stability system and sensors to the airline's chief pilots who develop the in-house training. To say they were furious to learn they hadn't been told of the new systems would be an understatement. The MAX crashes would have been substantially less likely if the pilots had benefitted from their airline's chief pilots knowing of the safety systems and having training on how to handle failurs, as well as warning annunciators for sensor failures....but Boeing wanted to save a thousand bucks or so per plane - or more likely, wanted to avoid drawing attention to the situation and having people ask "why is a critical flight control system dependent upon a single sensor?", which is likely why they also did little to inform airlines of the new systems, train the chief pilots on it, etc.
chasil 4y ago
How long have the B-52 jet engines had monocrystalline fan blades? That must have an enormous impact on efficiency and performance. They became available in the late 60s. https://www.americanscientist.org/article/each-blade-a-single-crystal https://www.americanscientist.org/article/each-blade-a-singl...
- jabl 4y ago
  They're still using the original TF33 engine they were delivered with in 1961. Presumably the fan blades have been replaced many times over during maintenance, but I don't know if there's any advantage to switching to better blades if you don't change the operating parameters to take advantage of them. There's a plan to replace all the engines with a modern turbofan (RR F130).
  - yread 4y ago
    It's interesting that even though the bypass ratio changed from 1.4 to 4.2 (so it's quite a different engine, lot quieter for sure) the fuel consumption only went down 15% (22g/kN.s to 18.6g/kN.s)
    - jabl 4y ago
      Hmm, I'm not familiar enough with jet engines to say whether that is expected or not. 15% doesn't sound like a huge improvement, I agree. But I'll note the F130 is a medium bypass business jet engine producing 'only' around 75kN. 8 of those is about 600kN, which could be achieved with two of those newest generation civilian high bypass turbofans used e.g. in the B787 or A350. I suspect the motivation was to choose a new engine that is as similar to the existing one in order to minimize work needed to install them on the plane. There being AFAIU less than 100 B52's in service, I guess minimizing engineering cost has better payoff than minimizing fuel consumption with a high bypass engine.
      - chasil 4y ago
        So what happens if four newest-generation high-bypass turbofans are installed on a B-52? Is the airframe at risk in doubling the thrust at full throttle?
golemotron 4y ago
> It's honestly a fantastic case for incremental improvements over time. The trick is to design something solid enough to be a good base for incremental improvements over time.
tablespoon 4y ago
> Every attempt to replace it has been (or will be) retired before its EOL. Though that's probably because it's design is basically "big, boxy, utilitarian sky truck," which is so flexible you can always find something to use it for. Everything else seems to make tradeoffs for some flashy capability, which don't age as well.
bee_rider 4y ago
Wonder what a from-scratch B-52 equivalent would look like nowadays. I don't think they could resist the urge to give it a gimmick. Who wants to design a bomb truck?!?
- qbrass 4y ago
  You mean like a giant, tailless, stealth, flying wing? Or would that would be too gimmicky?
  - bee_rider 4y ago
    The B2 is great. But, while stealth is really useful, it does require some trade-offs. Since B-52 is only useful in cases where stealth isn't required, and it seems to still be in use, I guess if the B-52 were hypothetically retired there'd be room for a non-stealth replacement. Unless the techniques they developed to come up with the F-22 and F-35 opened up a possibility of a zero-compromise stealth design (I'm skeptical, but I don't know anything about plane development).
- HPsquared 4y ago
  The gimmick is that it's really big, I suppose.

GartzenDeHaes 4y ago

I don't think you would say that if you had ever been inside one. They are ancient -- and very greasy.

ofrzeta 4y ago

Platonic question: is it still a B-52 then? cf. the Ship of Theseus

geodel 4y ago
I mean in this case yes. Since it is a brand and not a single B-52 physical plane which is being improved all these years.
- runjake 4y ago
  To eliminate confusion, the current operational B-52Hs were originally manufactured in 1960-1961. They have undergone significant upgrades over the years, on all systems, including the airframe itself, since then.
djmips 4y ago
I think it is but they do rev the sub model number it seems.
hef19898 4y ago
Yes, it is. The current H generation has very little to do with the first build airframes so. Including certification. EDIT: Those upgrade programs, e.g. the F-15 is currently at "X", are complete development programs and involve a certain amount of certification and re-certification. That in the case of the B-52 those upgrades have been applied to existing, tremendously old, airframes, doesn't change that. It does make it quite impressive so, the B-52 turned out to be a very flexible and upgradeable design.
- jeffdn 4y ago
  That's a little disingenuous, regarding the F-15 -- there is the A/B series, with A being single-seat and B being the two-seat trainer, and the C/D series, with the same distinction between the two models. Both the F-15A and the F-15C are air superiority fighters, with an exclusively air-to-air role. The F-15E is a multirole fighter-bomber, not an air superiority fighter. The F-15X is an F-15E repurposed as a beyond visual range (BVR) missile truck, with data links to AEWC planes that can provide targeting solutions for those missiles. All of the letters between E and X have not been used.
  - coredog64 4y ago
    The more useful identifier is the block number which identifies production changes.
runjake 4y ago
The earlier models were manufactured in the 1950s. Most of the H models were manufactured in 1960 and 1961, but they have undergone significant airframe improvements, several engine improvements, and of course, avionics improvements. It's still a B-52, but it's a "B-52H Block $whatever_design_block_they_are_on_these_days" model.
GuB-42 4y ago
At least in civilian aviation, it is a very relevant and practical question, and a major contributor to the Boeing 737-MAX fiasco. There is a thing called "type rating", that is qualification pilots need to have in order to fly a specific type of plane. For example, pilots need a type rating for the Boeing 737 in order to fly a Boeing 737. Manufacturers try to do everything they can not to require another type rating when they make changes to an existing aircraft, because type ratings require expensive and time-consuming training that pilots and their companies would rather avoid, and it influences purchase decisions. One of the root causes of the B737-MAX crashes is that Boeing tweaked some settings in order to make the B737-MAX behave like the original B737 when it was, in fact, a different plane, and they did it wrong.
- KennyBlanken 4y ago
  > One of the root causes of the B737-MAX crashes is that Boeing tweaked some settings in order to make the B737-MAX behave like the original B737 when it was, in fact, a different plane, and they did it wrong. This is wildly wrong. The only thing you got right is that the MAX was designed to avoid needing a new type certification. Boeing radically shifted the Cg to accommodate changing trends in the commercial airline industry which were resulting in Airbus's planes being more competitive. They shifted it well outside what would be considered prudent. This required flight control software bandaids to keep the plane stable (or perhaps better put, from entering a flight envelope where loss of control would happen), but they then also cheaped out of providing redundancy for some critical sensors... AND cockpit annunciators to alert on failures of the sensors. Boeing then passed off the Cg shift and additional systems as very minor changes in the filing for their airworthiness certifications, the FAA rubber-stamped everything because they didn't have the staff to review all these certificate filings so they largely trust manufacturers... ...and then making things even worse, Boeing did very little to disclose the additional stability system and sensors to the airline's chief pilots who develop the in-house training. To say they were furious to learn they hadn't been told of the new systems would be an understatement. The MAX crashes would have been substantially less likely if the pilots had benefitted from their airline's chief pilots knowing of the safety systems and having training on how to handle failurs, as well as warning annunciators for sensor failures....but Boeing wanted to save a thousand bucks or so per plane - or more likely, wanted to avoid drawing attention to the situation and having people ask "why is a critical flight control system dependent upon a single sensor?", which is likely why they also did little to inform airlines of the new systems, train the chief pilots on it, etc.

chasil 4y ago

How long have the B-52 jet engines had monocrystalline fan blades? That must have an enormous impact on efficiency and performance. They became available in the late 60s. https://www.americanscientist.org/article/each-blade-a-single-crystal https://www.americanscientist.org/article/each-blade-a-singl...

jabl 4y ago
They're still using the original TF33 engine they were delivered with in 1961. Presumably the fan blades have been replaced many times over during maintenance, but I don't know if there's any advantage to switching to better blades if you don't change the operating parameters to take advantage of them. There's a plan to replace all the engines with a modern turbofan (RR F130).
- yread 4y ago
  It's interesting that even though the bypass ratio changed from 1.4 to 4.2 (so it's quite a different engine, lot quieter for sure) the fuel consumption only went down 15% (22g/kN.s to 18.6g/kN.s)
  - jabl 4y ago
    Hmm, I'm not familiar enough with jet engines to say whether that is expected or not. 15% doesn't sound like a huge improvement, I agree. But I'll note the F130 is a medium bypass business jet engine producing 'only' around 75kN. 8 of those is about 600kN, which could be achieved with two of those newest generation civilian high bypass turbofans used e.g. in the B787 or A350. I suspect the motivation was to choose a new engine that is as similar to the existing one in order to minimize work needed to install them on the plane. There being AFAIU less than 100 B52's in service, I guess minimizing engineering cost has better payoff than minimizing fuel consumption with a high bypass engine.
    - chasil 4y ago
      So what happens if four newest-generation high-bypass turbofans are installed on a B-52? Is the airframe at risk in doubling the thrust at full throttle?

golemotron 4y ago

> It's honestly a fantastic case for incremental improvements over time. The trick is to design something solid enough to be a good base for incremental improvements over time.

tablespoon 4y ago

> Every attempt to replace it has been (or will be) retired before its EOL. Though that's probably because it's design is basically "big, boxy, utilitarian sky truck," which is so flexible you can always find something to use it for. Everything else seems to make tradeoffs for some flashy capability, which don't age as well.

bee_rider 4y ago

Wonder what a from-scratch B-52 equivalent would look like nowadays. I don't think they could resist the urge to give it a gimmick. Who wants to design a bomb truck?!?

qbrass 4y ago
You mean like a giant, tailless, stealth, flying wing? Or would that would be too gimmicky?
- bee_rider 4y ago
  The B2 is great. But, while stealth is really useful, it does require some trade-offs. Since B-52 is only useful in cases where stealth isn't required, and it seems to still be in use, I guess if the B-52 were hypothetically retired there'd be room for a non-stealth replacement. Unless the techniques they developed to come up with the F-22 and F-35 opened up a possibility of a zero-compromise stealth design (I'm skeptical, but I don't know anything about plane development).
HPsquared 4y ago
The gimmick is that it's really big, I suppose.