par13del wrote:

A couple of my concerns, not much discussion on metal fatigue on the BUFF but plenty on other a

There is something about being an old design that benefit from a fatigue stand point. The B-52 was started a a concept on a napkin the design back then was concentrated on strength and not really optimized to any degree like a modern airliner. There was no algorithm or computers, so designers build in extra margins in their calculations. That resulted in margins for fatigue.

Strange thing about fatigue is if you have extra strength and stay away from the metal deformation limit, your cycle life increases exponentially.

And of course, they probably cycled a frame through multiple life times to make sure.

bt

Most of the B-52 fuselage is unpressurized, a la DC-3. That kinda helps for cycle/fatigue life. Imagine buying scraps of a B-52 at 12 cents a pound!

https://www.boldmethod.com/blog/lists/2 ... tofotress/

I suspect there were some loading conditions considered that made it stout. Shock waves of a blast would seriously affect a plane.

I recall KC Top Boom bringing up that new wing skins need to occur as well as the number of other improvements that are under contract.

JayinKitsap wrote:

I suspect there were some loading conditions considered that made it stout. Shock waves of a blast would seriously affect a plane.

I recall KC Top Boom bringing up that new wing skins need to occur as well as the number of other improvements that are under contract.

Correct. Given the current flying hours/year, the B-52 will have to have the upper wing skin replaced around 2030. I have not seen anything about this, but my guess would be the reskinning would take place when the new engines are installed. The reskin would allow the BUFF to get at least another 30 years on the aircraft.

The shock wave from a nuke wouldn't be a factor as the BUFF does not carry gravity nukes anymore. The nuke role of the BUFF is just a cruise missile or standoff weapon carrier.

VMCA787 wrote:

The shock wave from a nuke wouldn't be a factor as the BUFF does not carry gravity nukes anymore.

I think the suggestion was the frame was designed for nuclear shock wave.

I guess if the wing skin will be replaced, then that is where you get your life extension.

bt

bikerthai wrote:

I guess if the wing skin will be replaced, then that is where you get your life extension.

bt

In reality, the upper wing skin will have to be replaced. They, USAF, aren't going to re-engine the BUFF and then park it. So, my guess is when the winner is finally decided and the cowl redesigned, that's when the upper skin will be done.

VMCA787 wrote:

the upper wing skin will have to be replaced.

I wonder if it has to do with the impact of stress concentration to fatigue life in a hole under compression is higher than a hole under tension.

I thought I heard that back in my college days.

bt

If I recall correctly some of the upper wing skin surfaces were replaced in the 70’s, already, but yes sheet metal under compression/flexing doesn’t tend to hold up forever. I wouldn’t think it would cost all that much to put new aluminum wing skins on them, we’re not talking about stealth coatings etc.

https://www.nap.edu/read/5917/chapter/6#93

texl1649 wrote:

If I recall correctly some of the upper wing skin surfaces were replaced in the 70’s, already, but yes sheet metal under compression/flexing doesn’t tend to hold up forever. I wouldn’t think it would cost all that much to put new aluminum wing skins on them, we’re not talking about stealth coatings etc.

https://www.nap.edu/read/5917/chapter/6#93

AFAIK, the upper wing skins haven’t been touched. I flew the D and the G and the Pacer Plank mod on the D did a lot of the skin. But, the G/H had different wing structures and as a result it wasn’t needed.

VMCA787 wrote:

texl1649 wrote:

If I recall correctly some of the upper wing skin surfaces were replaced in the 70’s, already, but yes sheet metal under compression/flexing doesn’t tend to hold up forever. I wouldn’t think it would cost all that much to put new aluminum wing skins on them, we’re not talking about stealth coatings etc.

https://www.nap.edu/read/5917/chapter/6#93

AFAIK, the upper wing skins haven’t been touched. I flew the D and the G and the Pacer Plank mod on the D did a lot of the skin. But, the G/H had different wing structures and as a result it wasn’t needed.

You’d be the expert then, not me, but I read that Boeing did replace the upper wing skins on the H models in particular in the 70’s;

https://www.forbes.com/sites/davidaxe/2 ... ce067ebac1

texl1649 wrote:

I wouldn’t think it would cost all that much to put new aluminum wing skins on them,

It's not about the cost. It has to do with the backing structure (rib, spars, frames etc). Every time you replace the skin, you have oversize the rivets and bolt holes. The edge margins on the backing structures usually have enough margin for one or two oversize. So you can really only replace the skin once, or twice assuming the original wing was built perfectly (unlikely), then it starts to get expensive to work around the edge margins.

bt

[quote="texl1649]

You’d be the expert then, not me, but I read that Boeing did replace the upper wing skins on the H models in particular in the 70’s;

https://www.forbes.com/sites/davidaxe/2 ... ce067ebac1[/quote]

I don't think Forbes is correct. The Buff G/H was modified with new wing skin in the 60s as a result of the change from a high-level bomber to a low-level bomber. The upper wing skins (inboard) were changed from 7178-T6 to 7075-T6 aluminum. The projected life was 12,000 hours with a fatigue test of 72,000 hours. Further testing of a re-skinned bomber indicated the stress test was a little optimistic In the 1990s the stress test was reevaluated and the projected economic life was evaluated to be 31, 600 hours to 36,000 hours. That was based on an annual fly of 360 hours.
http://www.nap.edu/read/5917/chapter/6

CRJockey wrote:

Sooner787 wrote:

If the new administration passes this latest $6 Trillion Infrastructure bill
they're salivating over, I fear those funds will come from all the big ticket
items the Pentagon is planning on, like the new B-21, this B-52 NEO proposal,
and the future CVN-81 as well as F-35 procurement.

And it might well serve the nation better than more military toys.

Nonsense, we are already behind prepping for our next war with China and with the upcoming Taiwan elections and a weakened US leadership 2023-2025 should be very interesting.

IAHObserver wrote:

we are already behind prepping for our next war with

The best way to prep for the next war is to have a strong economy. War with China will not be won at with how many planes you have at the start.

Those who fear a quick capitulation of Taiwan failed to l learn the lessons of Afganistan. When fighting for your own freedom, you can overcome enormous odds.

bt

The award is getting close!!
https://www.airforcemag.com/contract-fo ... -imminent/

Sweet! As long as they don't choose the ~50-year-old, 10% less efficient-then all-the-others CF-34 I'll be happy.

I don't think the CF-34 would be such a bad choice. It's quite reliable with a long and proven record. There's a huge pool of parts and experience around that engine which facilitates support. It's still light years ahead of the TF33 in terms of efficiency.
It's also been massively updated since it came out as an evolution of the TF-34, especially the -10 (in fact, the USAF would likely call it something else now).
It looks like a low-risk/low-cost/high-reward solution to me.

The better solution might still be the F130 however, and I think the Passport and PW800 are too high-risk and costly.

That said, at the end of the day, whoever lobbies the hardest will get it.

Without knowing the performance curves of the engines and mission profiles for the B52 (these are going to be way different than the commercial and biz jet markets), it's not possible to figure out which is best fuel wise.

I'd wager the CF34-10 gets the nod. The high section is basically the CFM56-7B core, which is a huge plus considering how durable and cost effective it is. It's the only 1 of 4 engines with a single HT spool. The rest all use 2 HTs which is significantly more $$$. And considering it's limited to 20,000ft-lb, it's not stressed and will last a long time at lower altitudes the B52 often flies. It's the second-lightest engine on the list, proven in heavy-duty commercial service, relatively easy to ramp up, limited use of expensive exotic materials, and still provides quite good fuel economy. The PW800/Passport are at best 8% more efficient and considering integration into the B52 and it's more time at slower speeds, i'd wager maybe 5% more efficient. The -10 doesn't have the same old genetics as the 40-year old -8 series.It uses a modern wide-swept fan and as mentioned, the modern 7B core. Long term maintenance shouldn't be too expensive for GE as it's still being sold on the ARJ21, which should keep being produced for political reasons for a while, and there are still quite a few E190/195's floating around that will likely stay in service for a while.

The F130 (BR715) is also a pretty good fit and largely proven in commercial service. Downsides are it's the heaviest option and nearly 1,000lb heavier than CF34-10 and has some known maintenance cost issues historically. Compounding those maintenance issues is that there are no new builds going on and the main users are planning to retire. Bigger issue here is politics ... RR is not a USA company and I don't think they have manufacturing ability for these State-side, and given these are only going to repower USA owned aircraft, one cannot make the usual "broader market acceptance" pitch to NATO.

I highly doubt the Passport will be chosen. It's target market is business jets so it's missing the same "durability" expectations the CF10 has. It's way heavier but only about 8% more efficient.

The PW800 is an interesting one to figure out. It uses the same high spool as the GTF 1500-series that powers the A220. This is plus as it's turned out to be fairly reliable so far. However, it's fan section is all new and focused on high speed biz jets. I suspect durability is a problem here. As Pratt didn't focus too heavily on core performance as they had to focus heavily on the low-spool and gear for the GTF series. I'm thinking it's at best 6% more efficient than the CF34-10 and may not do as well at lower speeds. Not to mention, that supply chain is already pretty stressed so there are competing priorities. Therefore, I tend to think it's at a technical disadvantage but Pratt has probably the tightest grip on influence, so it also wouldn't surprise me to see it be selected.

If I remember correctly from my own limited research on this last year, the BR715 is the most closely dimensionally similar and weighs close to, but slightly less than, the existing engines. As a result, I believe that it would require the least extensive modifications to the rest of the wing/pylon to integrate into the airframe. In addition, it has proven to tolerate rapid turn around in hot, humid weather, such as Hawaii (witness it's airline usage there) which speaks in favor of it's usage in the Pacific theater, which is a stated focus of the military going forwards.

Didn’t realise the massive IR blisters under the nose would be removed at the same time, that will probably be the most noticeable change visually (and imagine they would have a not insignificant effect on performance with drag).
Is there any chance we will see a name change to B52I?

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

747classic wrote:

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

Structurally I would imagine yes, but the number of system upgrades over the years would be a nightmare, wires etc everywhere

giblets wrote:

747classic wrote:

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

Structurally I would imagine yes, but the number of system upgrades over the years would be a nightmare, wires etc everywhere

AFAIK also a lot of sub-systems will be upgraded during the program, incl. (part of) the wiring.

747classic wrote:

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

Judging by the current pics, I think all the G models have been cut into sections to comply with START. I don’t have intimate knowledge of this, though. See the link for a list of all BUFFS, and their status.

https://docs.google.com/spreadsheets/d/ ... wbfU#gid=0

Buckeyetech wrote:

747classic wrote:

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

Judging by the current pics, I think all the G models have been cut into sections to comply with START. I don’t have intimate knowledge of this, though. See the link for a list of all BUFFS, and their status.

https://docs.google.com/spreadsheets/d/ ... wbfU#gid=0

According your link : many -G's and a few -H's are still stored at AMARC ?

747classic wrote:

Buckeyetech wrote:

747classic wrote:

Is it possible to use a B-52G (how many are left?) as an attrition aircraft for the re-engining program, because the major difference between the -H and - G are the engines.

Judging by the current pics, I think all the G models have been cut into sections to comply with START. I don’t have intimate knowledge of this, though. See the link for a list of all BUFFS, and their status.

https://docs.google.com/spreadsheets/d/ ... wbfU#gid=0

According your link : many -G's and a few -H's are still stored at AMARC ?

If you look at the satellite images of AMARG, all of the G models have been chopped, and at the time the image was taken (iOS), there were 11 H models stored (I believe a few have been re-activated). Cheers.

Excellent post Okc!

Okcflyer wrote:

I'd wager the CF34-10 gets the nod.

I sure hope so!

Okcflyer wrote:

The high section is basically the CFM56-7B core, ...
The -10 doesn't have the same old genetics as the 40-year old -8 series.

FWIW the -10 is a slightly bigger than 70% scale of the CFM fan coupled with a
slightly less than 70% scale of the CFM core.
The distinction from the elderly -8 series seems to be lost on the vast majority of armchair 'experts'.

Okcflyer wrote:

The F130 (BR715) is also a pretty good fit and largely proven in commercial service.
Bigger issue here is politics ... RR is not a USA company and I don't think they have manufacturing ability for these State-side...

It's actually the BR700-725 variant they're pitching, not the 715.
Having purchased Allison, they do have a stateside footprint in the form of Rolls Royce North America.
They have (not surprisingly) promised to assemble it (for B-52 application) in the US.

Rolls-Royce F130 engine wins up to $2.6 billion contract to replace 608 engines on 75 Boeing B-52s, beating Pratt & Whitney and GE Aviation.



https://www.af.mil/News/Article-Display ... -contract/

LAXintl wrote:

Rolls-Royce F130 engine wins up to $2.6 billion contract to replace 608 engines on 75 Boeing B-52s, beating Pratt & Whitney and GE Aviation.



https://www.af.mil/News/Article-Display ... -contract/

That’s awesome! Glad they went with a relatively newer engine.

Buckeyetech wrote:

747classic wrote:

Buckeyetech wrote:

Judging by the current pics, I think all the G models have been cut into sections to comply with START. I don’t have intimate knowledge of this, though. See the link for a list of all BUFFS, and their status.

https://docs.google.com/spreadsheets/d/ ... wbfU#gid=0

According your link : many -G's and a few -H's are still stored at AMARC ?

If you look at the satellite images of AMARG, all of the G models have been chopped, and at the time the image was taken (iOS), there were 11 H models stored (I believe a few have been re-activated). Cheers.

The two H's that got reactivated replaced hull losses;
60-0034 "Wise Guy" https://www.airforcetimes.com/news/your ... -boneyard/
61-0007 "Ghost Rider" https://www.airforcetimes.com/news/pent ... r-service/

Buckeyetech wrote:

LAXintl wrote:

Rolls-Royce F130 engine wins up to $2.6 billion contract to replace 608 engines on 75 Boeing B-52s, beating Pratt & Whitney and GE Aviation.



https://www.af.mil/News/Article-Display ... -contract/

That’s awesome! Glad they went with a relatively newer engine.

Congratulations to RR! Funny to think the program is scheduled to end in 2038!!!

Congrats to RR! I wonder if any of the other parties will contest the contract.

Personally, I think this is a mistake on the basis of pedigree. Such a huge pool of spares and widespread maintenance for the PW and GE CF-34. With all the troubles RR has been in the last decade, is this going to affect the program?

stratable wrote:

Congrats to RR! I wonder if any of the other parties will contest the contract.

Oh God, that would be a nightmare. Unfortunately that seems to be the way these things go in today's world, with the whiney losers ending up with the contract more often than not.

Great engine choice though!

RobertoMugabe wrote:

Personally, I think this is a mistake on the basis of pedigree. Such a huge pool of spares and widespread maintenance for the PW and GE CF-34. With all the troubles RR has been in the last decade, is this going to affect the program?

The Rolls Royce BR700 series engines are also very widely supported engines, being found on numerous business jets around the world.

The USAF is taking an commercial off-the-shelf engine, and will have Boeing do the integration work to integrate the engine to the airframe.

Congrats to RR, I was expecting PW or GE but this is good. I wonder where the others were.

$ 2.6B / 608 = $4.276M each. The savings of overhauls at $2M each 6,000 hours comes into focus well.

With Power by the hour hit by Covid, this will be a great revenue stream. 608 is a large % of the 3,600 BR700'x in service.

ThePointblank wrote:

RobertoMugabe wrote:

Personally, I think this is a mistake on the basis of pedigree. Such a huge pool of spares and widespread maintenance for the PW and GE CF-34. With all the troubles RR has been in the last decade, is this going to affect the program?

The Rolls Royce BR700 series engines are also very widely supported engines, being found on numerous business jets around the world.

The USAF is taking an commercial off-the-shelf engine, and will have Boeing do the integration work to integrate the engine to the airframe.

Congrats absolutely to the RR team, happy my pick/preference/guess won. Also, keep in mind the BR700 is already in inventory for USAF (as the F130). It’s going to have a lot more in inventory in the future, obviously, but the spares system/training etc. to support the engine already exist.

https://www.thedrive.com/the-war-zone/4 ... mber-fleet

Bloomberg article;

The deal could grow to $2.6 billion if all options are exercised. The Air Force wants to keep the B-52 in service until about 2050. The engine replacement is part of an upgrade program estimated at $11 billion that includes new flight systems, cockpit throttles and cockpit displays.

The B-52, which first flew Cold War missions in 1954 with nuclear bombs, has since evolved into a non-nuclear, precision-guided weapons platform. It’s known affectionately among aviators as BUFF, an acronym sometimes described as “Big Ugly Fat Fellow.”

Work will be performed at the Rolls-Royce facility in Indianapolis and is expected to be completed by September 2038, the Pentagon said. Rolls-Royce said it has invested more than $600 million in Indianapolis in advanced manufacturing and technology “to create the most advanced engine manufacturing site in the U.S.”

https://www.bloomberg.com/news/articles ... f=IYQ5mP1s

ThePointblank wrote:

RobertoMugabe wrote:

Personally, I think this is a mistake on the basis of pedigree. Such a huge pool of spares and widespread maintenance for the PW and GE CF-34. With all the troubles RR has been in the last decade, is this going to affect the program?

The Rolls Royce BR700 series engines are also very widely supported engines, being found on numerous business jets around the world.

The USAF is taking an commercial off-the-shelf engine, and will have Boeing do the integration work to integrate the engine to the airframe.

Thank you for the info, I still wish the PW or GE options had won based on previous use. I meant the recent troubles RR has been in, are they going to have issues meeting production commitments?

Way for the BUFF to morph into a bespoke Roller.....

https://www.flightglobal.com/fixed-wing ... 26.article



https://farm66.static.flickr.com/65535/ ... 2486_c.jpg

JayinKitsap wrote:

Congrats to RR, I was expecting PW or GE but this is good. I wonder where the others were.

$ 2.6B / 608 = $4.276M each. The savings of overhauls at $2M each 6,000 hours comes into focus well.

With Power by the hour hit by Covid, this will be a great revenue stream. 608 is a large % of the 3,600 BR700'x in service.

From the article https://www.thedrive.com/the-war-zone/42517/rolls-royce-will-provide-long-awaited-new-jet-engines-for-the-b-52-bomber-fleet

I see it as a cashflow of 100 mio a year the first 5 years for engineering till the first two B52NEO's are delivered(2025). After that the remain 2.1B will be spend on the remaining 74 B52NEO up until 2035. So that's 210mio a year or about 3.5mio a piece.

I'm also curious to the performance. BR725 currently rated at 71.6 kN. Where as the TF33 are 75.62 kN. The fuel usage will be better i'm sure. Means less refuelling in the air.


BTW what will the designation be for the re-engined B52?

vnauta wrote:

BTW what will the designation be for the re-engined B52?

B-52J or better. DoD won't allow and I or an O in an MDS designation.

vnauta wrote:

BTW what will the designation be for the re-engined B52?

B-52J would be next in sequence. B-52M would follow the convention of the re-engined C-5 fleet.

Is 61-0009 going to be the test bed for the reengine?

zanl188 wrote:

Is 61-0009 going to be the test bed for the reengine?

That aircraft was appropriated/authorized in 1961 and probably delivered in 1962.

What will be the consequences for range? +30-40% ? Noise -50%, Maintenance -70% ?

keesje wrote:

What will be the consequences for range? +30-40% ? Noise -50%, Maintenance -70% ?

I wished suppliers would provide more specific in their press information; "Once installed, the F130 will provide vastly greater fuel efficiency while increasing range and reducing tanker aircraft requirements"

http://www.newB-52engines.com

No actual B-52 missions have been limited by range over the past 40 years, to my knowledge. The main benefit is lower maintenance costs, increased mission capable rates, period. Decreased stress on tankers is a plus, as well, of course.

texl1649 wrote:

No actual B-52 missions have been limited by range over the past 40 years, to my knowledge. The main benefit is lower maintenance costs, increased mission capable rates, period. Decreased stress on tankers is a plus, as well, of course.

Truth. Although that’s a really big plus for not just the BUFFs, but for everyone else, too. You can’t be range-limited when you’re equipped with a receptacle and there’s a tanker, but having decreased fuel burn helps tremendously with complex missions: less admin (tanking) means longer vuls and fewer critical phases of flight, fewer choke points in a mission requiring contingencies (missed AR point, etc), and it frees up tankers to do other things. Considering tankers will have their hands full in the Pacific, already, a B-52J will be one fewer jet for tankers to bend over for.

For reference, every two-ship of B-52s sent to project power for the BTF requires at least a two-ship of KC-10s (or 3 KC-135s) for every AR. And there are multiple ARs per mission. That’s ~ 10 tankers just to send two jets on their merry way. F that.

A couple of bits:

To the earlier poster, the BR725 will be code plugged for roughly the same thrust as the TF-33 at 17K lbs.

It looks like the sfc on the 725 is roughly 20% better than the tf-33. Ignoring every other factor, the change should give the buff an unrefueled range of about 10,500 miles. That's enough to essentially get from Barksdale to almost every other air force and allied base in the world without refueling.

The air force believes that, save for catastrophic failure, these engines will never accumulate enough hours to ever need to come off the wing for the rest of the life of the bombers. The spares are essentially a contingency, and not ever planned to be used. The planned maintenance needs are just for wear items and inspection replaced items. Having a lot of global commercial support really isn't a factor.

LightningZ71 wrote:

A couple of bits:


It looks like the sfc on the 725 is roughly 20% better than the tf-33.

I'm pretty sure its quite a bit more than that... more like 40%. At least that's what I've been hearing, and it makes sense as the TF-33 is ~60 years old. TIT alone is probably less than half of what the BR725's is.