B-52 Re-Engining

LowObservable

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Re. the discussion as to whether the eight-engine solution was or was not chosen because of the engine-out case - I believe that it certainly was a factor. But a lot of people overlook another issue: there are three candidate engines for an eight-engine layout, but since the last time re-engining was studied, the two engines that would work for a four-engine B-52 (RB211-535 and PW2000) have ceased production.
LO,

Back in 2005 we discussed this often amongst the crew dogs. The original proposal was for 4 RB211-535's, engine out had them looking at other options like CFM-56's on the outboard pods, but two engine types on the same airframe doesn't help the cost argument. Ultimately, the final nail in the coffin for the 4 engine proposals was low oil prices in the late 90's early 2000's and all of the spare TF-33's taken from C-141's and KC-135E's. They could mod the tail and rudder to address the engine out, but that also cut against the cost savings argument. Your points for today's proposal are spot on, the other thing I suspect is they've finally worked their way through the inventory of C-141/KC-135E spares.

FWIW, Boeing Wichita has a model of the 4 engine BUFF hanging from the ceiling down in the B-52 area, we saw it every time we went there.
Right. I heard that story too. But the DSB reviewed the USAF study and found that they had done the assessment based on commercial gas prices. Tanker gas costs a little more...
 

marauder2048

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Except the USAF has adopted commercial fuel (Jet A) and DSB came up with a fully burdened fuel cost for aerial refueling
that's some 45% higher than any other study published in the intervening ~ 20 years.
 

mkellytx

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Re. the discussion as to whether the eight-engine solution was or was not chosen because of the engine-out case - I believe that it certainly was a factor. But a lot of people overlook another issue: there are three candidate engines for an eight-engine layout, but since the last time re-engining was studied, the two engines that would work for a four-engine B-52 (RB211-535 and PW2000) have ceased production.
LO,

Back in 2005 we discussed this often amongst the crew dogs. The original proposal was for 4 RB211-535's, engine out had them looking at other options like CFM-56's on the outboard pods, but two engine types on the same airframe doesn't help the cost argument. Ultimately, the final nail in the coffin for the 4 engine proposals was low oil prices in the late 90's early 2000's and all of the spare TF-33's taken from C-141's and KC-135E's. They could mod the tail and rudder to address the engine out, but that also cut against the cost savings argument. Your points for today's proposal are spot on, the other thing I suspect is they've finally worked their way through the inventory of C-141/KC-135E spares.

FWIW, Boeing Wichita has a model of the 4 engine BUFF hanging from the ceiling down in the B-52 area, we saw it every time we went there.
Right. I heard that story too. But the DSB reviewed the USAF study and found that they had done the assessment based on commercial gas prices. Tanker gas costs a little more...
Right, tanker gas is just a multiple of commercial gas, I've sat on both ends of the boom. Big reductions, of the need of commercial gas greatly reduce the need for tanker gas as well and the multiple works in your favor. Also, when tanker gas is a must, cost is less of a concern, in other words, if the mission is that important, cost is a secondary concern.

At the end of the day it's the lifecycle costs that are supposed to tip the balance. When there are hundreds of spares sitting in crates, that undermines the case for a new engine. Now that they're all gone and the Strat Radar and other mod's are funded a new engine is suddenly "cost effective".
 

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So General Electric wants to keep the B-52's flying until about 2097? Looks like the USAF does not want to give up its BUFF's anytime soon in favour of a replacement bomber.
 

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So General Electric wants to keep the B-52's flying until about 2097? Looks like the USAF does not want to give up its BUFF's anytime soon in favour of a replacement bomber.
More like they don’t have/can’t get the budget to come up with an all-new replacement right now...
 

uk 75

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From discussions on various threads it seems that designing and building a modern B52 or converting a civil widebody would be less cost effective than keeping the tried and tested Buffs flying. Bit like an old wooden ship of the line. Re-engining ought to be a way of doing this.
 

bobbymike

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So General Electric wants to keep the B-52's flying until about 2097? Looks like the USAF does not want to give up its BUFF's anytime soon in favour of a replacement bomber.
More like they don’t have/can’t get the budget to come up with an all-new replacement right now...
If kept up to date, electronics/avionics/weapons, is there anything a non-stealthy clean sheet design could do “substantially” better than the B-52?
 

gtg947h

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So General Electric wants to keep the B-52's flying until about 2097? Looks like the USAF does not want to give up its BUFF's anytime soon in favour of a replacement bomber.
More like they don’t have/can’t get the budget to come up with an all-new replacement right now...
If kept up to date, electronics/avionics/weapons, is there anything a non-stealthy clean sheet design could do “substantially” better than the B-52?
IMHO that’s pretty much it... a clean-sheet non-stealthy “bomb truck” might well be more efficient, easier to support, more easily deployed, and everyone likes new shiny stuff, but the up-front cost is a whole lot higher compared to upgrades on the B-52 fleet. As I understand it the airframe is pretty robust and relatively low-time so they aren’t aging/cracking out like other aircraft in the inventory.

It’s sort of like continuing to drive your paid-for older truck or SUV, even though it’s less efficient, because the capital outlay for a new more-efficient vehicle would exceed the savings on fuel.
 

shin_getter

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If kept up to date, electronics/avionics/weapons, is there anything a non-stealthy clean sheet design could do “substantially” better than the B-52?
It can be a C-17? ;)

In that it can do other jobs while having fleet commonality. With the exact shape of future conflict being uncertain, multirole is a good thing.
 

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Air Force Life Cycle Management Center’s Bombers Directorate stated that this is a great initiative to repurpose a retired B-52H into a tool to advance the fleet’s modernisation and sustainment efforts for decades to come. Upon arrival in Oklahoma City, the left wing and fuselage will be reattached and used to test how new technology or modifications will integrate with B-52 aircraft.

The integration model or mock-up will support a number of current and future modification initiatives, to include the Commercial Engine Replacement Programme and Radar Modernisation Programme. Also, as new weapons are developed and come on hand, the B-52H integration model will show how the weapons attach, what needs to change, and if they fit on the aircraft. This is an asset that will help integrate different items and weapons onto USAF's Stratofortresses quicker.

 

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Air Force Life Cycle Management Center’s Bombers Directorate stated that this is a great initiative to repurpose a retired B-52H into a tool to advance the fleet’s modernisation and sustainment efforts for decades to come. Upon arrival in Oklahoma City, the left wing and fuselage will be reattached and used to test how new technology or modifications will integrate with B-52 aircraft.

The integration model or mock-up will support a number of current and future modification initiatives, to include the Commercial Engine Replacement Programme and Radar Modernisation Programme. Also, as new weapons are developed and come on hand, the B-52H integration model will show how the weapons attach, what needs to change, and if they fit on the aircraft. This is an asset that will help integrate different items and weapons onto USAF's Stratofortresses quicker.


I hope that this accelerates the re-engine programme, as it has been ages since I have seen any news about it for a while.
 

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The problem comes too often with the lack of deep understanding of mil. equipment Specifics.
I often take the case of the P-8 Poseidon and all the market counter-offers that simply strap sensor payload onto a civilian airframe thinking that mission profile will be completely compatible with that of an airliner...

With the B-52 the USAF came a long way back from the day most of the offers were big turbofans strapped under the wings.
 
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TomcatViP

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Discussing the Pratt&Withney offer for PW800 on B-52 re-engining program:

One unstated benefit of the PW800 is that it’s in the “sweet spot of its life cycle,” Moeller said. The Air Force will want an engine that is sustained by commercial market volume today and decades into the future. The Service doesn’t want an engine that is nearing its commercial sunset and is unsustainable in the future because the commercial market disappeared. The “sweet spot” is that period when a product is in its growth phase with an active commercial market for decades to come. This ensures spare parts availability with a pool of experienced maintainers working with a global sustainment support structure for the life of the program.
[...]
The PW800 will stay on wing for decades longer than the RFP requires, Johnson said, and will meet or exceed every capability requirement. While the engine is almost the same dimensional size as the legacy TF33, the combined weight savings over eight engines is 5,000 pounds. That means less wing stress, improved fuel efficiency, and increased capacity for under-wing payloads.

No other option delivers so much weight savings, Johnson said. “The nearest competitor is over 3,000 pounds heavier than the PW800 [for all eight engines],” Johnson said. The other competitors are as much as 6,000 pounds heavier.

 

Josh_TN

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Not that I think the PW800 isn't a good option, but it terms of life cycle, the USAF expects the engines to last for the rest of the aircraft's life and is buying a small number of spares on top of a one to one replacement for each aircraft. So I'm not sure the life cycle in the civilian market is really relevant. The weight savings on the other hand sounds dramatic.
 

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The Air Force must be really serious about confronting China and maintaining a higher state of readiness, wow.
 

Josh_TN

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Really thought Pratt would win that one. Whatever, as long as USAF does it and funds it, I'm not concerned who makes the engines.
 

Archibald

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So the BUFF will keep its familiar 8*turbofan layout, except with a modern engine in massive service across airliner fleets.
I wonder what range / payload will be.
Makes a lot of sense.

...except that 75*8 is 600, not 608 - that would be 76 airframes.

But I suppose the eight engines are *spares*
 

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TomS

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So the BUFF will keep its familiar 8*turbofan layout, except with a modern engine in massive service across airliner fleets.
I wonder what range / payload will be.
Makes a lot of sense.

...except that 75*8 is 600, not 608 - that would be 76 airframes.

But I suppose the eight engines are *spares*

I saw that too. But it turns out that 75 is a typo -- there are 76 operational aircraft (58 in the USAF active force and 18 in the Reserves).
 
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TomcatViP

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Interesting aspect discussed at the end of this report:

Boeing, the original builder of the B-52, will integrate the engines, radar, and other new systems onto the bomber but did not play a role in selecting the winner of the CERP competition. A Boeing official said the company provided data to the Air Force on the relative ease or difficulty of integrating each of the competing powerplants but did not make a recommendation on which one should be selected. Boeing will decide whether and how to mount the engines in twin-engine pods or nacelles, as the TF33s are now arranged, and will do the necessary aerodynamic calculations as to the placement of the engines for optimum performance and least interference with the aerodynamic structure. A Boeing official said the B-52’s disused nose-mounted infrared pods will likely be removed to improve airflow at the front of the bomber.

 

isayyo2

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Interesting aspect discussed at the end of this report:

A Boeing official said the B-52’s disused nose-mounted infrared pods will likely be removed to improve airflow at the front of the bomber.
Looking forward to seeing a "clean shaven" B-52 again; I've been wondering on those sensor's relevancy...
 

mkellytx

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Looking forward to seeing a "clean shaven" B-52 again; I've been wondering on those sensor's relevancy...
Not much really. since very few BUFF's fly low level anymore. The Nav's will miss it since I don't think can use the T-pod in the pattern. The upside of the clean nose is that the max Mach may return to .92.
 

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fair-use quote:
The US arm of Britain's Rolls Royce won a contract worth up to $2.6 billion Friday to supply engines for the US Air Force's B-52H bomber fleet, the Air Force announced.

The company's Indianapolis, Indiana manufacturing unit was awarded a $500.9 million "indefinite-delivery/indefinite quantity" contract over six years for replacement engines for the B-52s, the long-range Stratofortress bombers that have been a mark of US strategic power since the 1950s.
/
Looks like R-R beat out bids from GE Aviation and Pratt & Whitney...

So, will it be singles or twins on H's engine pylons ?? Or both, so twin inners and single outers ??
 

Foo Fighter

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Why would you expect a difference?
 

TomS

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So, will it be singles or twins on H's engine pylons ?? Or both, so twin inners and single outers ?

The competition calls for a one-for-one substitution of new engines for old, so there will be four twin nacelles, two under each wing. Anything else would have caused extensive redesign to retain acceptable handling with the loss of an outboard engine.
 

_Del_

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There was quite a bit of concern early about the change in airflow potentially caused by even another twin-engine nacelle, so I suspect the goal remains adding the new engines in nacelles as near the original in shape and location as possible.
 

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