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B-52 Re-engine Resurfaces As USAF Reviews Studies

marauder2048

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The replacement part timeline for the B-52 is still pretty dire since AMARG parts often have to be
reworked extensively to be usable. In some cases it's years.

The major difference is that the Air Force kept the production tooling for the B-1B and it has been restored
as needed to produce parts since a good number of the material suppliers at least are still around.
And there are some AM parts starting to make there way on the B-1B.

The B-52 does have a larger physical aperture for a new radar though and potentially more
electrical power generation from 8 x new engine. Though I suppose for a truly fair comparison
there you'd have to look at the various B-1B re-engining schemes that Boeing et al have described.
 

bobbymike

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Rolls-Royce McVay on Program to Re-Engine USAF's B-52 Bomber Fleet

https://www.youtube.com/watch?v=wkVf3_vTP2o
 

TomS

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Grey Havoc

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The Air Force Magazine article in question:

EDIT: You've beaten me to it.
 

jsport

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aeroengineer1

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The thought of the nacelles providing extra lift is not really why they air force is looking to keep it an 8 engined aircraft.

The prime reason has to do with fan blade out capability and the coupled dynamics to the wing and pylon. Going with 4 engines not only increases the loads that would be experienced in a fan blade out event, but it would then drive these changes into the wing structure increasing the overall cost and time to convert. This is not the only reason, but it is a major reason for the current path.

Staying with 8 engines will reduce the time to design the installation, reduce the number of structural modifications, and still provide the benefit of drastically reduced fuel consumption and maintenance.
 

_Del_

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Glade usaf want a similar size as a pure cylinder engine would not afford assisting lift to the wing..
BUFF needs more lift and drag?
 

TomcatViP

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It's interesting that they want more fan surface, what will drive them toward a smaller cores.
 
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jsport

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Glade usaf want a similar size as a pure cylinder engine would not afford assisting lift to the wing..
BUFF needs more lift and drag?
aeroengineer1--Going with 4 engines not only increases the loads that would be experienced in a fan blade out event, but it would then drive these changes into the wing structure increasing the overall cost and time to convert.
 

Josh_TN

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My understanding was that replacing the eight engined configuration with four engines created an asymetrical thrust problem during an engine failure that the rudder could not easily compensate for. Is this what is meant by " fan blade out event "? But it also seems like there would be greater structural changes to the airframe beyond just the nacelles if the four engined route was taken. A one for one replacement seems fine to me; I just hope they finally go through with it. Re-engining the B-52H has been discussed for most of my
natural life.

ETA: presumably the greater fan surface is driven by a desire to keep operating costs down over raw performance. Top speed and ceiling probably aren't priorities in this day and age in this aircraft type.
 
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_Del_

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Glade usaf want a similar size as a pure cylinder engine would not afford assisting lift to the wing..
BUFF needs more lift and drag?
aeroengineer1--Going with 4 engines not only increases the loads that would be experienced in a fan blade out event, but it would then drive these changes into the wing structure increasing the overall cost and time to convert.
Yes. One also doesn't have to worry about dragging engines 1 and 4 on the tarmac that way, nor build a new tail structure. None of that, however, has to do with augmenting lift...
 

Josh_TN

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From Hyten's testimony, New START looks likely to fall apart so the outsized loads that the B-1B can't carry internally
because of the treaty-compliant bulkhead would no longer be an issue.

And then the advantages of better hardening, great loiter and supersonic dash are compelling.
I'm assuming here that B-21 does not have supersonic dash....it was a possibility for NGB but
I doubt it got out of the Gates for the LRS-B scrub.
New START probably hinges on who wins in November. The Russians seem willing to stay in, the current administration is not, Biden is pro.

My understanding is the B-1 fleet is clapped out after a decade and change of steady use. Also a former Bone navigator told me that while he was in, they were the sole platform still training for low level ingress - which puts a lot more strain on the airframe. He thought it was a very pointless exercise and I suspect it ended shortly after he got out, but did not add life to the airframe.

As for super sonic dash - from what I understand, just barely with reheat at high altitude with no externals. Someone on another thread or board also implied that the current rotary launchers weren't rated for >Mach1 anyway, so that for practical purposes it was a high subsonic aircraft.
 

jsport

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If the USAF abandons supersonic and low altitude penetration altogether while defense academics believe the Russians are working toward a 1000mile rg S-500 series missile than USAF bombing is truly lost.
 

In_A_Dream

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If the USAF abandons supersonic and low altitude penetration altogether while defense academics believe the Russians are working toward a 1000mile rg S-500 series missile than USAF bombing is truly lost.
They know more than we do and Russian IADs is not our concern.
 

Josh_TN

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Also the PAK-DA isn't a low altitude Tu-160 follow on by all open source accounts. Not that it will ever exist anyway.
 

kaiserd

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Let's unearth the Hustler!
I gotta admit, I'm jealous of the Tu-22M3. Fast, external hardpoints for large weapons, internal weapons bay. Imagine what the USAF could do with something like that.
They had something better (B-1B) and they did lots with it (and continue to do things with it), no need to imagine anything in that regard.
And I wonder exactly how often and for how long either the Backfire or the Blackjack for that matter have ever operationally or in regular training gone at or spent at supersonic speed? Probably extremely rarely and briefly, along the lines of the B-1B experience.
 

TomcatViP

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The B-58 was a high altitude Mach2 long range Bomber with a demonstrated outsized load carrying capability.
That remains uniques aside of the not-in service Carter era B-1A.
 

Josh_TN

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It was by most accounts a hard plane to fly, or more specifically land. It was an amazing aircraft, especially considering its vintage, but I do not think it was well liked by its air crews. But it is quite the hipster aircraft; it was flying the Tu-22 M3s envelope before it was cool.
 

kaiserd

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The B-58 was a high altitude Mach2 long range Bomber with a demonstrated outsized load carrying capability.
That remains uniques aside of the not-in service Carter era B-1A.
There are good reasons for that.
The B-58 was a beautiful technical achievement but a procurement and in-service near-failure. Horrendously expensive to buy and operate, over taken by SAM defences that forced it low, subsonic and even shorter ranged. Barely 10 years in service and lack of any following dedicated high altitude supersonic bombers suggests not too many looked to follow.
 

TomcatViP

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I don't think that we are here debating the Hustler as being an operational success or not (since there are no Hustler left sadly anywhere but in Museum). My goal was to remind on a decomplexed way that this has already been achieved and lost (high alt high Mach long range large outsized load carrying Bomber able to penetrate the heart of Enemy defenses).
 

Josh_TN

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There was the aborted B-70 effort, but yes the general consensus was that low altitude was a better ingress method. It's actually surprising to me that the first iteration of the B1 was a high altitude, high mach aircraft - the idea still had proponents even in the 70's.
 

mkellytx

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My understanding was that replacing the eight engined configuration with four engines created an asymetrical thrust problem during an engine failure that the rudder could not easily compensate for. Is this what is meant by " fan blade out event "? But it also seems like there would be greater structural changes to the airframe beyond just the nacelles if the four engined route was taken. A one for one replacement seems fine to me; I just hope they finally go through with it. Re-engining the B-52H has been discussed for most of my
natural life.

ETA: presumably the greater fan surface is driven by a desire to keep operating costs down over raw performance. Top speed and ceiling probably aren't priorities in this day and age in this aircraft type.
Correct Josh_TN. Losing a pod was a major emergency and often briefed pre-flight. Prior BUFF aircrew here, above certain weights the tail lacks the ability to maintain directional control. During those heavier weight take-off's the EP brief usually went something like the pilot will maintain as much altitude as he/she can turning into the dead pod to give the crew enough time to eject.

Neat fact, when we tested the synthetic jet fuel blend on the BUFF in 2006-7 we specifically used the BUFF since we could isolate the fuel system to feed only the outboard pod. Our THA for losing the pod was to fly light enough that the EP was to retard the opposite pod and push the inboards to the stops for a post V2 failure.

As also mentioned the CFM-56 and Rolls engine would drag the out board engines in some conditions. Also it can be really nice to have 8 generators for your electrical system...

Cheers,
 

aeroengineer1

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My understanding was that replacing the eight engined configuration with four engines created an asymetrical thrust problem during an engine failure that the rudder could not easily compensate for. Is this what is meant by " fan blade out event "? But it also seems like there would be greater structural changes to the airframe beyond just the nacelles if the four engined route was taken. A one for one replacement seems fine to me; I just hope they finally go through with it. Re-engining the B-52H has been discussed for most of my
natural life.

ETA: presumably the greater fan surface is driven by a desire to keep operating costs down over raw performance. Top speed and ceiling probably aren't priorities in this day and age in this aircraft type.
This is not what I was referring to for a fan blade out event. This is a very specific event that is designed for in which a blade from the fan leaves the engine at high speed and causes a major imbalance at high speed. It takes some time for the engine to spool down, and during that time, all these dymanic loads go into the engine and then into the pylon/wing structure. If you have a smaller engine, you will have smaller loads in a fan blade out (FBO) event. Everything from the components of the engine needing to contain this event to the wing and pylon needing to keep the engine mass contained on the wing are all very challenging, and a major sizing factor in the design of these components.

Here are a few videos of this even during either cert or engineering testing:

As to the issue of the rudder not having sufficient authority in an in flight shutdown event, I do not believe that this would be limiting. This aircraft has a very large rudder and a very long moment arm comparable to other 4 engined aircraft. Ground clearance to the outboard pylons would be a bigger issue, though, with the current design trend of high bypass engine pylons, I imagine that the engine could be brought very close to the wing and slightly forward similar to the solution that was done for the 737 series when they went to the CFM56 engines. The GE proposed CF34-10 has a fan diameter of around 57" vs 72" that would be required for the CFM56 engine. Those outboard pylons hang down substantially already from the wing, and it would not be hard to shorten them up 15" and save weight in the process (it will be interesting to see if pylon shortening happens with any of the new engine proposals or not even with similar diameter fans as what is currently installed).

Adam

As a side note, while I work for one of the engine manufacturers that has a proposal submitted for this effort, I do not speak for them, nor do I have any specific program knowledge that I am sharing in these posts beyond what is in public domain.
 

sferrin

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There was the aborted B-70 effort, but yes the general consensus was that low altitude was a better ingress method. It's actually surprising to me that the first iteration of the B1 was a high altitude, high mach aircraft - the idea still had proponents even in the 70's.

For escape. The run in would have been at low altitude. Also, enemy SAM effectivity was grossly over sold. Pretty sure those flying B-52s over Vietnam would have happily traded them for B-70s. ;)
 

kaiserd

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There was the aborted B-70 effort, but yes the general consensus was that low altitude was a better ingress method. It's actually surprising to me that the first iteration of the B1 was a high altitude, high mach aircraft - the idea still had proponents even in the 70's.

For escape. The run in would have been at low altitude. Also, enemy SAM effectivity was grossly over sold. Pretty sure those flying B-52s over Vietnam would have happily traded them for B-70s. ;)
The B-70 was not designed for low altitude operation or for that type of mission profile - is that a reference to the B-1A?
That statement re: SAM effectiveness is highly dubious in the context of when the B-1A would have entered service and against what the Soviets had and were bringing into service as opposed to early 60’s SA-2s over Vietnam.
And the point re: B-70s over Vietnam is simply absurd. Even if bought they would have been on nuclear alert (like the B-52H in real life) and if bought much fewer ICBMs sitting on alert back home. And how effective as a conventional bomb truck would the B-70 been at Mach 3 at approx 70,000 feet (and proof that it could even do this?) And how would it’s operational costs and sortie rate have compared to the B-52s that did see service over Vietnam?
 
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taildragger

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Let's unearth the Hustler!
The incoming Reagan administration apparently had this on their "to do" list in 1981 and was disappointed when the USAF reported back that the fleet had been turned into beer cans. Whatever the merits of taking the B-58 out of service, scrapping them almost immediately after withdrawal seems an unusual decision and is usually the type of thing done amid political controversy to drive a stake through the heart of a program to prevent a resurrection. That seems like an unlikely goal for the Nixon & Ford administrations. The Carter administration's failure to destroy the B-1A prototypes and tooling made the B-1B program much more feasible.
Perhaps scrapping the fleet was required by the SALT treaty.
 
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taildragger

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The Air Force Magazine article in question:

So what happened to the B-52I?
Two theories:
- the designation was already used by a Secret Project to supply a strategic bomber force to an I airforce (8 candidates starting with Iceland, ending with Italy)
- the USAF is skipping the letter so that the airplane won't be perceived as an Apple product (made in China, designed in California)
 
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GeorgeA

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So what happened to the B-52I?
Two theories:
- the designation was already used by a Secret Project to supply a strategic bomber force to an I airforce (8 candidates starting with Iceland, ending with Italy)
- the USAF is skipping the letter so that the airplane won't be perceived as an Apple product (made in China, designed in California)
[/QUOTE]

Or, MDS naming logic skips letters I and O for modifiers due to the potential for confusion with numerals 1 and 0.
 

taildragger

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So what happened to the B-52I?
Two theories:
- the designation was already used by a Secret Project to supply a strategic bomber force to an I airforce (8 candidates starting with Iceland, ending with Italy)
- the USAF is skipping the letter so that the airplane won't be perceived as an Apple product (made in China, designed in California)
Or, MDS naming logic skips letters I and O for modifiers due to the potential for confusion with numerals 1 and 0.
[/QUOTE]
That's probably it, although the rule isn't always applied (see F-15I for the Israelis). Still, I like the idea of a secret squadron of Viking iBombers (What, Iceland doesn't have an air force? Now who's being naive?)
 
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TomS

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Perhaps scrapping the fleet was required by the SALT treaty.
SALT I (the interim agreement) doesn't even talk about bombers. SALT II considers only the B-52 and B-1 as US heavy bombers, plus any future aircraft that could perform the same mission. Not sure where a reactivated B-58 would fall. It might not even count as a heavy bomber. Its direct replacement was the FB-111, after all, which was never treaty counted.

It seems like between 1970 when they were retired and 1977 when they were sold for scrap, someone decided that bringing back the Hustler was pretty unlikely. Seven years in the boneyard would have been really hard on them, for sure.
 

chimeric oncogene

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So what happened to the B-52I?
Two theories:
- the designation was already used by a Secret Project to supply a strategic bomber force to an I airforce (8 candidates starting with Iceland, ending with Italy)
- the USAF is skipping the letter so that the airplane won't be perceived as an Apple product (made in China, designed in California)
Or, MDS naming logic skips letters I and O for modifiers due to the potential for confusion with numerals 1 and 0.
[/QUOTE]

You know, like the B-21/B-2i fiasco?

Or has that since been debunked as a myth?
 
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