USAF Fund B-52 Engine Replacement

[ORAC]

How many times has this done the rounds over the last 30 years? Is this the first time it has reached the funding stage?

AW&ST: U.S. Air Force Boost B-52 Funding For Engine Replacement (http://aviationweek.com/aviation-week-space-technology/us-air-force-boost-b-52-funding-engine-replacement)

The U.S. Air Force has requested funding and authorization from Congress to launch one of the largest military reengining programs since the Boeing KC-135R Stratotanker.

The service’s fiscal 2019 budget request seeks more than $1 billion through fiscal 2023 for a Boeing B-52 Stratofortress propulsion system replacement program. The initiative would replace the Pratt & Whitney TF33-103, which has powered the H-model B-52 since its introduction in 1960. But unlike the KC-135R refueling aircraft upgrade, which swapped four TF33s for four CFM International CFM56s, the Air Force is shooting for a straight “eight for eight” swap on the B-52, rather than attempting to install four large high-bypass turbofans.

This is a major opportunity for turbofan manufacturers GE Aviation, Pratt & Whitney, Rolls-Royce and potentially Safran, which are now lining up to compete.

The program has been gathering momentum over the past two years, but it received a significant bump on Feb. 12, when the Air Force released its budget proposal. Having now decided to keep the B-52 around until 2050, while replacing Rockwell B-1Bs and Northrop Grumman B-2s with Northrop B-21 Raider stealth bombers, the service’s fiscal 2019 proposal would launch nine new B-52 modernization programs. The largest of them is the reengining, which will be pursued concurrently with a major radar upgrade.

According to budget documents, funding for B-52 modernization will peak at more than $560 million in fiscal 2021. If the engine upgrade is approved and funded by Congress, the service will seek a prime system integrator and engine manufacturer to deliver up to 650 new engines, including spares. The initial buy would be 20 engines for integration and testing on the first two B-52s in the 2022-23 time frame.

GE Aviation tells Aviation Week that it could put forward its latest engine in the required thrust class, the Passport, which powers Bombardier’s newly developed Global 7000 business jet and has been selected for the proposed Global 8000......

Rolls-Royce would offer one member of its BR700 product range, most likely the 15,000-17,000-lb.-thrust-class BR725 that is the engine on Gulfstream’s long-range G650 business jet. Versions of the BR700 power the Air Force’s Gulfstream C-37A transport and Bombardier Global Express-based E-11A Battlefield Airborne Communications Node......

Pratt & Whitney previously has said as it could offer a new engine or a TF33 upgrade package, depending on the requirements..... The company has expressed preference for a TF33 upgrade, but may decide to offer the Pratt & Whitney Canada PW800-series turbofan, depending on whether the Air Force allows foreign participation. The PW800 powers Gulfstream’s latest business aircraft, the 15,100-lb.-thrust PW814 for the G500 and 15,700-lb.-thrust PW815 for the G600.

Safran also has been attending the industry days but has not yet announced its intention to bid......

[Heathrow Harry]

Funny really.. if you proposed a new v large relatively slow, totally unstealthy bomb truck you'd be laughed out of the industry or military

But that's what they need and will need for another 30 years.........

[George K Lee]

It was proposed in 1982, with PW2000s, and was rejected because all the B-52s were to be retired in the 1990s. Rolls tried in the mid-90s, with RB211-535s, and it was turned down because the AF did its sums wrong. (They forgot that gas from a KC-135 costs a bit more than gas at the pump.) Now it's back because there are efficient engines the right size for an eight-engine solution, which makes the engine-out case easier.

[XR219]

Having now decided to keep the B-52 around until 2050, while replacing Rockwell B-1Bs and Northrop Grumman B-2s with Northrop B-21 Raider stealth bombers, the service’s fiscal 2019 proposal would launch nine new B-52 modernization programs.

If they can stretch it out to 2052, then that would make a nice round 100 years of B-52s! :eek:

[Mr Mac]

Heathrow Harry
Totally agree, although the market would be very limited, most probably USAF only, and how many air frames would they want / need ?. The B52 has been around all my life, and the way its being upgraded it looks as though it will see me out ! I actually went to see them take off from RAF Fairford during GW1 as I thought (and hoped) that I would never have to witness a fully loaded bomber take off on a war mission again from UK. Sadly wrong on that count, as history has proven. Wonderful old A/C though !

Regards
Mr Mac

[KenV]

Now it's back because there are efficient engines the right size for an eight-engine solution, which makes the engine-out case easier.That's not really correct. A single large high bypass engine on the outboard pylons would end up too close to the ground. Some people claim this would cause an engine strike in a cross wind landing, but that's false. The B-52 does not bank into a crosswind. It has steerable landing gear and crabs wings level into a crosswind. The real problem is two-fold: FOD ingestion and wing flutter. In addition the airflow and CG distibution of a four engine layout would be very very different than the 8 engine layout. This would require recertification of every weapon and weapon combination from every store location and combination of store locations on the aircraft. That would require a LOT of very expensive test flying. The more we looked at the four engine solution, the worse it got. It quickly became a non player. The advent of modern engines in the required thrust range designed for biz jets made an eight engine solution possible again. There are still some issues, but they are miniscule compared to the four engine solution.

As for the B-52 vs the B-1, USAF preferred keeping the Bone flying over the Buff. For the past 10+ years USAF has been tearing down and doing deep-dive inspections of the Bone's structure. Sadly, keeping the structure safe to fly much past a single design lifetime is going to be very difficult and horrendously expensive. So the Buff gets the nod over the Bone and the Buff's new engines will pay for themselves if the Buff keeps flying for another 20-25 years. And to ensure that, USAF is investing heavily in corrosion inspections, abatement, correction and protection on the Buff. As for the B-2, that fleet is just too small to effectively manage and its stealth coating systems ludicrously difficult and expensive to maintain, so keeping it going after the B-21 comes on line would be foolish.

[cavuman1]

Back in the Second Millennium, mid-1990's to be slightly more exact, my then-wife was a Legislative Director for Speaker of the House Tom Foley (D-WA). Part of her job responsibilities included being the Speaker's Pentagon Liaison. She enjoyed this responsibility since it allowed her leave the Capitol, cross the mighty Potomac River, disembark upon the scented soil of the Commonwealth of Virginia, get lost in the World's largest office building, and spend several hours each week gazing at high-ranking Air Force officers in their freshly-pressed, medal-bedecked dress uniforms. :p

I returned home one evening to our Maryland digs to find her in a greater than usual state of agitation and distress. "What's the trouble?", I asked, fearful that she had just gotten the call to report to the secret bunker beneath the Greenbrier Hotel in West Virginia because we were under nuclear attack and she didn't have the right color shoes. "The House Armed Services Committee has indicated that they would approve the funds necessary to re-engine the KC-135 Tanker, the Pentagon is begging for the upgrade, and I've got to write the Bill!", she exclaimed. "It'll be for several Billion with a capital B dollars! And I don't even know how a jet engine works!", she whispered, growing increasingly crestfallen. :(

Seizing the opportunity to play the role of a veritable modern day Socrates, I asked in an even voice "Just out of curiosity, O Love of My Life, how do you think a jet engine works?" She responded without hesitation: "It spins around and sucks the plane forward like a giant vacuum cleaner..." I ran into our kitchen to grab a cold beer and to hide my guffaws from my aviatrix ingénue. :ugh: :eek:

It came to pass that she authored the multi-billion dollar bill that caused some 361 KC-135E's to be refit with GE/SNECMA CFM-56 turbofan engines to metamorphose into KC-135R's. Apparently this was a very efficacious modification which gave substantially greater payload capacity with significant fuel savings. :ok:

Epilogue: Though I never was able to tutor my former bride about the simple concept of Suck, Squeeze, Bang, Blow, she did exhibit a natural ability for two of those operations: she would bang me on the head with a frying pan while raining blows over my unprotected face! :E

Sic Semper Tyrannis...

- Ed :}

https://upload.wikimedia.org/wikipedia/commons/thumb/f/f1/KC-135_Stratotanker_Elephant_Walk.jpg/220px-KC-135_Stratotanker_Elephant_Walk.jpg

[Argonautical]

I remember talking to a B-52 pilot at an airshow years ago. I asked him why they didn't replace the 8 engines with 4 new ones like they did with the KC-135. He wasn't impressed with the proposal and asked me if I would want to lose one engine out of 4 on a fully laded take-off!

[KenV]

I remember talking to a B-52 pilot at an airshow years ago. I asked him why they didn't replace the 8 engines with 4 new ones like they did with the KC-135. He wasn't impressed with the proposal and asked me if I would want to lose one engine out of 4 on a fully laded take-off!What?!! As opposed to one engine out of TWO fully loaded on the vast majority of modern airliners?

But it does bring to mind the dreaded 7-engine approach in a B-52.

[ORAC]

What?!! As opposed to one engine out of TWO fully loaded on the vast majority of modern airliners? On the other hand, they have automated flight controls and flight surfaces designed to kick in and take the stress....

https://hips.hearstapps.com/pop.h-cdn.co/assets/17/31/1024x634/gallery-1501608322-b52h.jpg?resize=980:*

[Just This Once...]

The replace 8 with 4 idea was a non-starter as aerodynamically the aircraft was not built with that in mind. VMCA issues abound when the OEI is now equivalent to a simultaneous double-hush on a pylon pair.

[Bevo]

As for the B-52 vs the B-1, USAF preferred keeping the Bone flying over the Buff. For the past 10+ years USAF has been tearing down and doing deep-dive inspections of the Bone's structure. Sadly, keeping the structure safe to fly much past a single design lifetime is going to be very difficult and horrendously expensive. So the Buff gets the nod over the Bone and the Buff's new engines will pay for themselves if the Buff keeps flying for another 20-25 years. And to ensure that, USAF is investing heavily in corrosion inspections, abatement, correction and protection on the Buff. As for the B-2, that fleet is just too small to effectively manage and its stealth coating systems ludicrously difficult and expensive to maintain, so keeping it going after the B-21 comes on line would be foolish.

Ken - it's a shame that the Bone structural upgrades will be overly expensive. I'm not sure many folks appreciate the B-1's capabilities. The B-1 has a number of advantages over its B-2 and B-52 counterparts. Its internal payload capacity is the highest at 75,000 pounds, which is 5,000 more than the B-52 and 25,000 more than the B-2. Reaching Mach 1.2, it is the only supersonic heavy bomber the U.S. possesses. It is also the cheapest to fly at $63,000 per hour of flight, compared with $72,000 for the B-52 and $135,000 for the B-2.

Furthermore, as a testament to its preference among U.S. commanders, from October 2001 to September 2012 the B-1 flew 10,940 combat sorties over Iraq and Afghanistan versus the B-52's 2,891 and the B-2's 69. In fact, the B-1 dropped 40 percent of the bomb tonnage in the first six months of the war in Afghanistan, and, by 2012, had released 60 percent of the weapons overall.

Moreover, if the United States were to find itself in conflict in Asia, for example, shorter-range aircraft fighters stationed at bases in Japan and South Korea would be vulnerable on the ground to long-range missile strikes. But the B-1, with its longer-range and ability to carry 24 Joint Air-to-Surface Standoff Missiles (JASSMs), could operate from far-off bases and beyond the limits of advanced air defense systems.

[Piltdown Man]

Any engine? Or only engines manufactured in the US?

PM

[Buster Hyman]

If they can stretch it out to 2052, then that would make a nice round 100 years of B-52s! :eek:

So, in comparison, who would be interested in taking one of these into combat today?

https://s-media-cache-ak0.pinimg.com/originals/02/91/51/02915179f6f679a2416f26dabf303496.jpg
https://www.militaryfactory.com/aircraft/imgs/airco-dh10-amiens-medium-biplane-bomber-united-kingdom.jpg

[etudiant]

So, in comparison, who would be interested in taking one of these into combat today?

https://www.militaryfactory.com/aircraft/imgs/airco-dh10-amiens-medium-biplane-bomber-united-kingdom.jpg

Has the B-52 been in combat in the last 40 years?
Dropping bombs on designated targets, absolutely, but no combat.

[Dan Winterland]

I should think the crew of this B52 would have considered themselves to have been in combat.

https://acesflyinghigh.files.wordpress.com/2014/12/b-52-lake-hanoi-2-1024x768.jpg

It's the remains of a B52 in a lake in Hanoi, still visible today.

[tdracer]

Ken
I fear the USAF is going to find out just how expensive it is to retrofit modern FADEC engines onto an analog airplane and discover they would have better off fixing the B-1 structures.
They will basically need to update the B-52 as comprehensively as they did the C-5 - all new avionics to go with those fancy new engines. That was a major factor in killing the PW2000 early on, and it's FADEC was primitive compared to the new FADECs. I don't think we got far enough with the RB211-535 to look at aerodynamic and flutter effects, but systems wise it would have been relatively easy (the RB211-535 was basically an analog engine even though it was fitted to a digital 757).
Heck, by the time it's all said and done, they might be cheaper turning a 747-8F into a bomber - it's new, fuel efficient, carries way more than the BUFF, and would be just as survivable...

Edited to add:
Dan, check the dates, that was more than 40 years ago...

[West Coast]

Has the B-52 been in combat in the last 40 years?
Dropping bombs on designated targets, absolutely, but no combat.

Dropping bombs on guys who want to kill you is combat. That they didn’t get shot up/down likely speaks to tactics, counter measures and luck.

[TWT]

The Hanoi B-52 was shot down on December 27th, 1972

[George K Lee]

TDR - That's a concern of mine too. A bit like fitting a '58 Chevy with a 2018 Honda Civic engine.

The secondary concern is that someone's going to think it's easy or (if it's done competitively) underbid to get the work.

[sandiego89]

Has the B-52 been in combat in the last 40 years?
Dropping bombs on designated targets, absolutely, but no combat.


Have you ever heard of the Gulf War? Look it up.


I'll help...During Desert Storm, the B-52Gs completed approximately 1620 sorties. In fact, the B-52s managed to drop almost a third of the entire tonnage of bombs dropped by US aircraft. No B-52Gs were officially reported as having been lost as a result of enemy action during Desert Storm. However, several were damaged. One B-52G was damaged by a hit from an unknown type of missile, but was able to make it home safely. Another lost a couple of engines as a result of a near-miss by a SA-3 missile, whereas another was damaged by shrapnel from AAA fire. One B-52G (58-0248) was even damaged by a hit from an AGM-88A HARM missile fired by another US aircraft that was providing defense suppression support for the attacking force. The missile managed to home in on the tail-mounted gun-laying radar of the B-52G, and obliterated a sizeable chunk of the tail when it hit. Fortunately, the damaged B-52G was able to land safely at Jeddah and was sent to Guam for repair. One B-52G (59-2593) was lost on February 3, 1991. The cause of the loss was officially blamed on a catastrophic electrical system failure while returning to its base at Diego Garcia, but there are rumors going around that combat damage was actually responsible. Three of the crewmembers ejected safely before the aircraft crashed into the Indian Ocean, but three others ejected too late and were killed.


Service of Boeing B-52G Stratofortress (http://www.joebaugher.com/usaf_bombers/b52_16.html)


I would call that combat, and other conflicts since.

[TEEEJ]

Has the B-52 been in combat in the last 40 years?
Dropping bombs on designated targets, absolutely, but no combat.

B-52G low level info for Desert Storm.

Colonel Ramsay bio

In January 1991 he was the flight leader for the first night, low-level combat mission ever flown by a B-52G, leading 14 aircraft to strike five Iraqi airfields in the opening minutes of Operation Desert Storm.

http://www.151arw.ang.af.mil/resources/biographies/bio.asp?id=10878

On 17 January 1991, seven B-52Gs, known as the "Doom Flight", took off from Barksdale AFB in Louisiana to help kick off the air campaign. They performed a flight that lasted 35 hours and took them almost halfway around the world to launch 35 CALCMs and then go back home. The routes of the missiles were planned so that they would impact almost simultaneously, and 33 of them hit their assigned targets. That same day, the B-52G followed up this strike with the first low-level attacks conducted by the type after decades of training. Buffs swept into Iraqi airspace at an altitude of 90 meters (300 feet) to pound four airbases and a highway.

With Iraqi air defenses disabled, the B-52Gs then returned to high-altitude bombing, with three-ship formations pounding Iraqi troops concentrations in Iraq with 340 kilogram (750 pound) bombs and cluster bombs. The B-52 performed 1,600 sorties in the Gulf War and dropped 22,725 tonnes (25,000 tons) of munitions.

[2.0] B-52 At War (http://www.faqs.org/docs/air/avb52_2.html)

Video detailing a B-52G hit by two Iraqis SA-2s and returning with combat damage.

https://www.youtube.com/watch?v=k8XPnlk05gY

[KenV]

Ken - it's a shame that the Bone structural upgrades will be overly expensive. I'm not sure many folks appreciate the B-1's capabilities.USAF is well aware of the superiority of the Bone over the Buff. It basically has the performance of a fighter with the range and payload of a bomber. It's a remarkable airplane. That's why they've been working so hard for over 10 years to figure out how to keep it flying. It just can't be done in any kind of effective manner. It's not like they can just "re-skin" the wings and/or the fuselage like they've done on other aircraft.

Remember this is a swing-wing airplane. There are some massive, monolithic, fracture critical structural components that are flight critical. Even if they had saved the production tooling (which they didn't) repairing/replacing those structures is just not feasible. A lot of money has been spent and a whole bunch of very smart engineers have been working for over a decade to crack this nut. They've found that it would cost more to fix than it did to build, and even then, the final result is shaky at best.

[KenV]

Ken
I fear the USAF is going to find out just how expensive it is to retrofit modern FADEC engines onto an analog airplane and discover they would have better off fixing the B-1 structures.Actually, yes, they have looked at that. Modern FADEC engines are essentially self-contained. They're not dependent on aircraft systems (like air data computer outputs) for their operation. Obviously they need an electronic connection with the cockpit for throttle position, but that's about it. And that can be done on a databus. That same databus can provide the cockpit with engine operating parameters (EPR, N1, N2, TIT, fuel flow, etc). And the Buff has already received a fairly extensive avionics upgrade to make it GATM compliant, plus the fleet is now being upgraded with the Boeing CONECT digital communications upgrade which includes an extensive onboard high-bandwidth, rad-hard and EMP-hard digital databus. The Buff is by no means all analog. CONECT is open architecture, so expansions and upgrades were specifically designed to be (relatively) easy.

[GLIDER 90]

Hello All

The B-52 has been one of my favourite aircraft for a long time. With the different upgrades & modifications I hope they will be flying for another 30 years or so.

Cheers
Glider 90

[etudiant]

Have you ever heard of the Gulf War? Look it up.


I'll help...During Desert Storm, the B-52Gs completed approximately 1620 sorties. In fact, the B-52s managed to drop almost a third of the entire tonnage of bombs dropped by US aircraft. No B-52Gs were officially reported as having been lost as a result of enemy action during Desert Storm. However, several were damaged. One B-52G was damaged by a hit from an unknown type of missile, but was able to make it home safely. Another lost a couple of engines as a result of a near-miss by a SA-3 missile, whereas another was damaged by shrapnel from AAA fire. One B-52G (58-0248) was even damaged by a hit from an AGM-88A HARM missile fired by another US aircraft that was providing defense suppression support for the attacking force. The missile managed to home in on the tail-mounted gun-laying radar of the B-52G, and obliterated a sizeable chunk of the tail when it hit. Fortunately, the damaged B-52G was able to land safely at Jeddah and was sent to Guam for repair. One B-52G (59-2593) was lost on February 3, 1991. The cause of the loss was officially blamed on a catastrophic electrical system failure while returning to its base at Diego Garcia, but there are rumors going around that combat damage was actually responsible. Three of the crewmembers ejected safely before the aircraft crashed into the Indian Ocean, but three others ejected too late and were killed.


Service of Boeing B-52G Stratofortress (http://www.joebaugher.com/usaf_bombers/b52_16.html)


I would call that combat, and other conflicts since.

I accept the characterization of the initial Desert Storm engagements as combat and correct my statement to 35 years.

[tdracer]

Actually, yes, they have looked at that. Modern FADEC engines are essentially self-contained. They're not dependent on aircraft systems (like air data computer outputs) for their operation.
Ken, modern FADECs can operate 'self contained', but far from optimized (commonly referred to as 'failsafe' or 'get home' mode). I've been involved in integrating FADECs into the aircraft systems from 1986 until I retired a little over a year ago, and it's horrendously complex. That anyone in the USAF thinks it'll be simple or that modern FADECs are 'self contained' simply validates my concerns...

[GreenKnight121]

I accept the characterization of the initial Desert Storm engagements as combat and correct my statement to 35 years.

Ummm... 2018 - 1991 = 27 years.

35 would be 1983.

[BEagle]

Having seen the B-52 contrails heading north, I used to wonder what the Republican Guard thought. They knew that they would most likely soon be desert hamburger and there wasn't a thing they could do to stop it - except to surrender.

[Heathrow Harry]

Not much you can do - hope they're going to hit someone else, hope they miss...

But it always astounds me how many people seem to have survived a carpet bombing attack over the last 80 years

[Pontius Navigator]

Not much you can do - hope they're going to hit someone else, hope they miss...

But it always astounds me how many people seem to have survived a carpet bombing attack over the last 80 yearsSurvive, yes. Unit cohesion, combat effectiveness, morale? Questionable.

[Heathrow Harry]

yes but if they'rre trained and bloody minded they can still stop an advance - rather like the episodes in WW1 and the US Civil War when people exploded bloody great mines under the opposition front line.

In most cases someone (normally an NCO) rallied the survivors and reoccupied the devastated area in time to slow or stop the oncoming attackers... Also several occurrences in Normandy in '44.... and we won't mention Casino ................

[esscee]

"Don't mention the war". "It's OK Major, I think I got away with it", said Basil.

[KenV]

yes but if they'rre trained and bloody minded they can still stop an advance.Apparently the carpet bombed Iraqi troops weren't so trained and/or so minded, because they surrendered in droves to coalition forces as soon as they showed up.

[ORAC]

USAF likely to issue B-52 engine replacement request for proposals in early 2019 (https://www.flightglobal.com/news/articles/usaf-likely-to-issue-b-52-engine-replacement-reques-446745/)

The US Air Force is likely to issue a request for proposal for its Boeing B-52H Stratofortress bomber engine replacement programme close to the first quarter of 2019, according to an Air Force document released on 13 March.

The contract for re-engining the USAF’s 76 Boeing B-52H bombers would likely be granted some four to six months after final proposals are submitted, according to the document. The department is looking to acquire at least 608 new, commercially available turbofan engines to replace the eight Pratt & Whitney TF33s each bomber carries.......

[pr00ne]

Does each B-52 really need 608 new engines? That's a lotta new engines...

[Davef68]

The B52 these days is really a big PGM truck rather than a carpet bomber

[Lynxman]

They’re obviously very small engines, one TF33 being equivalent to 76 of the new engines.

[sandiego89]

So 76 B-52H models going forward? I seem to recall around 42 being combat coded, a few dozen more with various reserve/attrition coding, and about 90+ H still intact, with 12 still at AMARC in 1000/inviolate storage (with GhostRider escaping a few years ago, the only B-52 to date to do so). I note the pondered order is for at least 608 engines, but would imagine another 10-20% for spares? An impressive order indeed.

[Heathrow Harry]

Apparently the carpet bombed Iraqi troops weren't so trained and/or so minded, because they surrendered in droves to coalition forces as soon as they showed up.


But they were still alive Ken... which is my original point... carpet bombing (or mining) doesn't wipe out all opposition.... I doubt the Wermacht or the Confederacy would have surrendered in droves...

[KenV]

But they were still alive Ken... which is my original point... carpet bombing (or mining) doesn't wipe out all opposition.... I doubt the Wermacht or the Confederacy would have surrendered in droves...I had no idea the point of carpet bombing was to "wipe out all opposition." Indeed its doubtful anything short of a nuke could do so, and even then there will likely be survivors. I believe there is a vast difference between the existence of survivors and the existence of an effective fighting force, and its neutralizing the latter that is the point of carpet bombing. So yes, plenty of Iraqi survivors, but no, no longer an effective fighting force. And that just applies to tactical use of carpet bombing. Carpet bombing is also effective at destroying manufacturing, transportation, governmental, and other strategic targets.

[cornish-stormrider]

I seem to recall A British company did a total nuts and bolts repair of a wing and marry it to a new fuselage then found that each one was a bit different..... In the end it cost an absolute fortune and the pollies scrapped the whole shebang just when it was about to come good....

I think there is a market in becoming the " official government aviation tooling scrapper" and buying it all then mothballing it and preserving the lot and showing the inspectors a pile of similar scrap

Then twenty years down the line when it's needed I " find the tooling " which had been mislabelled due to an admin error...... Lessons learned etc and you see where I'm going with this don't you??

Every engineer knows you never ever ever throw away a jig or a special tool, just in case

[KenV]

I seem to recall A British company did a total nuts and bolts repair of a wing and marry it to a new fuselage then found that each one was a bit different..... In the end it cost an absolute fortune and the pollies scrapped the whole shebang just when it was about to come good....True enough. But replacing engines and replacing wings are two very different things, with the former being much much lower risk than the latter.

[cornish-stormrider]

True enough. But replacing engines and replacing wings are two very different things, with the former being much much lower risk than the latter.

Ok....

But don't say we didn't warn you.....
Someone put the popcorn on, I'll get the pizza in the oven.
This will make an entertaining saga.


The book is..... Will it come in on.....??

1. Cost
2. Spec
3. Time
4. Without a significant political scandal

My twenty quid ( donating to RAFA if I lose ) says this won't achieve any of those four aims - but the closest to the mark will be spec

[George K Lee]

You might think that making a tanker version of a commercial airplane would be low-risk, particularly when it's your third go on the same type.

[KenV]

Ok....

But don't say we didn't warn you.....
Someone put the popcorn on, I'll get the pizza in the oven.
This will make an entertaining saga.

The book is..... Will it come in on.....??

1. Cost
2. Spec
3. Time
4. Without a significant political scandal

My twenty quid ( donating to RAFA if I lose ) says this won't achieve any of those four aims - but the closest to the mark will be spec
Hmmmm. The C-5 RERP project (Re-engine and Reliability Program) successfully replaced four mechanical turbofans with four FADEC turbofans on 52 C-5 airframes. Airframes that were designed and built with 100% mechanical and analog systems. First fllight of the C-5 was 1968. Delivery of the last B-52 was in 1962, so they are roughly the same vintage technology wise, but with the B-52 receiving many more upgrades during its service life than the C-5.

Before C-5 RERP USAF successfully undertook the KC-135 re-engine program, replacing the old J-57 turbo jets with modern CFM-56 turbofans. And before that industry (in this case GammaCorp with Douglas doing the actual engineering) very successfully undertook the re-engining of DC-8 airliners with CFM-56 turbofans. 707s (similar to but not the same as KC-135) have also been successfully re-engined with CFM-56 engines, with the last 10 years or so of production (all military derivatives of the 707) being equipped with CFM-56s. And then there are the many re-engining programs that fitted JT-8D low bypass turbofans to several different aircraft.

And finally, do not forget that the B-52 itself has already undergone an engine change over its lifetime, replacing J-57 turbojets with TF-33 turbo fans.

So what's the bottom line? This kind of project is not something new to either industry nor USAF, and has been completed very successfully multiple times on multiple different airframes. Is caution warranted? Certainly. Is the deep skepticism and even cynicism displayed here warranted? NOT.

[KenV]

You might think that making a tanker version of a commercial airplane would be low-risk, particularly when it's your third go on the same type.Anyone who thinks that does not understand the complexity of such an undertaking. It is a complexity orders of magnitude greater than an engine change.

[George K Lee]

I think you're making my point, Kenneth old chap.

Boeing certainly should have understood the complexities of the KC-46 and, accordingly, submitted a proposal with realistic costs and schedule - and stuck to it. Instead, they submitted a risky bid and then changed the manufacturing strategy in an attempt to reduce cost. The guy who announced that change - let's just say that he didn't face any negative consequences.

And as for C-5 RERP... "successfully"? It blew through Nunn-McCurdy and delivered 49 modded aircraft rather than the 108 originally planned.

https://fas.org/sgp/crs/weapons/RL34264.pdf

[KenV]

Boeing certainly should have understood the complexities of the KC-46 and, accordingly, submitted a proposal with realistic costs and schedule - and stuck to it. Shoulda woulda coulda. The point is Boeing's proposal was VERY aggressive on cost and schedule to ensure they won. They succeeded. And Airbus succeeded in suckering Boeing into making such an aggressive bid (indeed, Airbus's bid was non-conforming as they proposed a tanker based on the passenger version rather than the freighter version of the A330 when a freighter door and freighter floor were spec requirements.) Actually delivering to the proposed price and schedule is an entirely different matter, but all on Boeing as it is a fixed price contract with penalties for late delivery.

The further point is that KC-46 has less than nothing to do with re-engining B-52s and why I did not include KC-46 in my post. You mentioning it here is a total red herring and yet another example of the butwhataboutery that is common in these sorts of threads.


And as for C-5 RERP... "successfully"? It blew through Nunn-McCurdy and delivered 49 modded aircraft rather than the 108 originally planned.
https://fas.org/sgp/crs/weapons/RL34264.pdfDid you actually read the report you cited? RERP included 70 initiatives to improve C-5 reliability, with the re-engine the centerpiece. The numbers of aircraft to be RERPed went down because the A model, which made up the majority of the fleet, were simply too far gone to warrant making such a major investment. Nunn-McCurdy was breached not because the estimated re-engine costs went up, but because as the actual condition of the C-5A fleet became known and the estimated cost of repairing them to make the re-engine investment worth it went way up. Once the C-5As were withdrawn as RERP candidates estimated costs went back down. Indeed, the actual costs of re-engining the B and C model aircraft (not the estimates which triggered Nunn-McCurdy) were slightly below estimates.

You also completely failed to understand the complex political dance that was going on when RERP was in the proposal stages and which is reflected in this old report. The MCS (Mobility Capability Study) and various other political moves of that period made retiring any C-5As impossible. Once the C-5A was taken off the table as a RERP candidate, almost everything changed. And the actual outcome of RERP proved the re-engine to be a success

So other than getting essentially all the facts wrong, nice rebuttal.

[George K Lee]

To begin with: "Aggressive pricing" is another word for "underestimated costs and time". And the costs are not all on Boeing, as Boeing does not pay for unplanned life extensions for inventory tankers. And this is a serious business, so dismissing such a comment with a blase "shoulda coulda woulda" is a mite sophomorish.

And, clearly, C-5M and KC-46 have one important common feature: underestimated cost and time. The A models had been flying for 30 years and their condition should not have been a mystery; if there were internal issues that might not be found until teardown, margin should be included. We've been finding nasties in old airplanes for decades.

There was one difference: the KC-46 bid was low in order to win, and the C-5M bid was low in order to get the program started.

As for the so-called nonconforming Airbus bid...

Since the two rival tankers had already satisfied 372 mandatory performance requirements, price determined the outcome and Boeing emerged victorious.

And that's according to Boeing's own consultant. (https://www.forbes.com/sites/beltway/2011/02/28/how-boeing-won-the-tanker-war/#136b21bf3d49)

[ORAC]

And Airbus succeeded in suckering Boeing into making such an aggressive bid Really? And there was me thinking they were grown-ups capable of making rational commercial decisions on their own.

And of course they would have had no signs or idea about the Airbus bid. Allegedly.....

[KenV]

To begin with: "Aggressive pricing" is another word for "underestimated costs and time". That's one way to look at it. Another way is to look at the risk of losing vs the risk of underbidding and choose the latter. Boeing had already lost twice. They were determined not to lose again. And yeah, I like quips like "shoulda, woulda, coulda" and "butwhataboutery." You call them sophomorish. I think they add a touch of panache.

And "unplanned life extensions for inventory tankers"? You actually think that USAF is going to invest millions to extend the life of existing tankers because the KC-46 is late? Let's talk abut "sophomorish" some more.

And, clearly, C-5M and KC-46 have one important common feature: underestimated cost and time. The A models had been flying for 30 years and their condition should not have been a mysteryThere it is again. "should"? Really? You have the authority to tell USAF what they "should" do and "should" know? The actual condition of the A fleet was not fully known until the first one was torn down and RERPed. That was the point of that exercise. It was a mess. Based on that experience and additional data gathering, the A's were not only not candidates for RERP, they became candidates for the bone yard. Indeed that's where they all are.

The B-52 is undergoing something similar right now. Having made the decision to retire B-1 and B-2 and keep B-52 flying, USAF has sent one B-52 to the San Antonio depot to figure out what it's going to take to keep the fleet going. More decisions, including the re-engining, will be made based on the data gathered there.

And about that "Boeing consultant"? He predicted, literally days before the award, that EADS (now Airbus) would surely win the award. He was dead wrong. He still is.

[KenV]

Really? And there was me thinking they were grown-ups capable of making rational commercial decisions on their own.Grown-ups everywhere make lousy business decisions all the time. Edison went with DC while Tesla/Westinghouse went with with AC. We all know how that went. Ford tried to keep the Model T going long after it was no longer viable, and later came out with the Edsel. Yet they're going gangbusters. GM went bankrupt. As did Chrysler. Microsoft failed to go after the mobile market and have not a prayer of catching up. Aerospatiale/BAC decided to develop and build a supersonic airliner in the age of jumbo jets. Airbus decided to develop and build a giant four-engine airliner in the age of twin-jets. Airbus decided to develop and build a military transport with the worlds largest single disk turbo prop and its dragging down the ENTIRE enterprise. Do I even need to mention the Nimrod MRA4? The list of failed aircraft projects is nearly endless.

But here's the thing. The KC-46 has not failed and almost certainly will not fail, although, yes, it will be late. Maybe a year or more late. But was the risk of late deliveries and development cost over runs worth it? Almost certainly yes. You guys are thinking short term. Boeing is thinking long term. Does anyone seriously doubt that Boeing will be unable to generate some profit from this venture, low bid and all? REALLY??!!

And finally, comparing KC-46 to the proposed B-52 re-engine project is classic butwhataboutery run amok. You may as well compare Edison's choice of DC powerplants with Apple's choice of smartphone feature sets.

[NWSRG]

But here's the thing. The KC-46 has not failed and almost certainly will not fail, although, yes, it will be late. Maybe a year or more late. But was the risk of late deliveries and development cost over runs worth it? Almost certainly yes. You guys are thinking short term. Boeing is thinking long term. Does anyone seriously doubt that Boeing will be unable to generate some profit from this venture, low bid and all? REALLY??!!


Agree with you here Ken. KC-46 will fly for 50 years...that's a lot of support services pretty much guaranteed. Not to mention, there seems to be chat now that KC-Y will be a KC-46 follow-on order.

[George K Lee]

But was the risk of late deliveries and development cost over runs worth it? Almost certainly yes.

Most likely you're right, if you're Boeing. The customer may have a different perspective. And is there any reason why the same won't apply to B-52RE, a few years down the road? Because we know where the guy who set up the KC-46 deal is sitting today, do we not?

And of course that consultant still cashes Boeing checks. And of course (it's your MO) you're deflecting my question about your assertion that EADS submitted a grossly noncompliant bid. How about some evidence for that?

[George K Lee]

Damn, the USAF is really cracking down on Boeing's personnel management...

L'US Air Force ne veut plus de retards pour ses KC-46A - Air&Cosmos (http://www.air-cosmos.com/l-us-air-force-ne-veut-plus-de-retards-pour-ses-kc-46a-108827?utm_source=Sociallymap&utm_medium=Sociallymap&utm_campaign=Sociallymap)

I thought we were supposed to call them "specially gifted program managers" now?

[ORAC]

KenV, my comment was in responsible to the remark about Airbus “suckering” Boeing into pitching their bid where they did. Now you are saying it was a good long term commercial decision.

Make up your mind, you can’t have it both ways. The6bwere either suckered is they weren’t. My point was tha5 they weren’t.

[KenV]

But was the risk of late deliveries and development cost over runs worth it? Almost certainly yes.

Most likely you're right, if you're Boeing. The customer may have a different perspective. Different perspective? Why? Boeing is covering the extra costs and is paying penalties for the late deliveries. After this batch, each new batch of tankers will require a new negotiation. It's up to the customer on how to handle that negotiation.

Because we know where the guy who set up the KC-46 deal is sitting today, do we not?Loren Thompson?!! Set up the KC-46 deal? Really?!!! That's delusional.

And of course that consultant still cashes Boeing checks. You appear to have a fixation on Loren Thompson being a "Boeing Consultant". He is not. Yes Boeing pays the Lexington Institute, but the Lexington Institute is a lobbying firm who's mission is to "inform, educate, and shape the public debate of national priorities in those areas that are of surpassing importance to the future success of democracy, such as national security, education reform, tax reform, immigration and federal policy concerning science and technology." Yes, they do influence Congress to support a wide range of defense and technology programs, which is clearly in Boeing's interest. But no, they have zero influence on specific defense programs, and no special insights into what and how EADS/Airbus (or any other contractor) is bidding.

And of course (it's your MO) you're deflecting my question about your assertion that EADS submitted a grossly noncompliant bid. How about some evidence for that?
My MO? Really? On what do you base this specious claim? In any event, this was well covered in another thread well over a year ago. EADS (now Airbus) bid a tanker based on the passenger version of the A330 because at first there was no requirement to base the tanker on a freighter. (Remember that the original KC-X competition was in 2007. The A330F did not fly till 2009). But the final RFP did require a freighter aircraft, and EADS would not offer the freighter version. Why? Hard to say, but my understanding is that the freighter is a converted passenger airplane. Converting a passenger plane to a freighter and then converting that to a tanker was too big a bite to chew. It's one reason why Northrop pulled out of the partnership. Several guys on this forum justified EAD's decision to not base their offer on a freighter by stating that because the A330 is bigger than the 767, it "did not need" a cargo door nor cargo floor nor under floor fuel tanks. That may or may not be true but is totally beside the point that unlike the first RFP, the final RFP mandated a cargo door and floor.

[KenV]

KenV, my comment was in responsible to the remark about Airbus “suckering” Boeing into pitching their bid where they did. Now you are saying it was a good long term commercial decision.

Make up your mind, you can’t have it both ways. The6bwere either suckered is they weren’t. My point was tha5 they weren’t.Northrop/EADS had already won the first competition and Boeing was determined to beat EADS in the new competition and willing to bid very aggressively on both price and schedule. Northrop had already pulled out of the final bid and had EADS pulled out Boeing would have been much less aggressive on both cost and schedule. Further, Boeing would not have included their advanced refueling boom. The KC-767 and the original KC-46 booms were both based on the KC-135 boom. But that boom had a much smaller envelope than the Airbus boom, so Boeing switched to a modified KC-10 boom. A change that was neither easy not cheap. But EADS decided to go it alone with what was essentially their original bid, which was based on the passenger aircraft and non compliant to the new RFP. Northrop pulled out because a new proposal would be expensive and bidding the old proposal would result in nothing in it for them. But bidding with the old proposal was very smart strategically for Airbus as it caused Boeing to not only offer a much better boom, but to be very aggressive on price and schedule. It was a good long term business decision for Boeing to beat Airbus with a low bid, but Boeing could have bid much less aggressively on both cost and schedule and still won, and done so with much less risk exposure.

[Heathrow Harry]

"at any price"...

Not sure about that Ken - costs them cash, reputation and diversion of men, materials and management I'm sure they'd be better off using elsewhere - such as on the 757/767 replacement

[KenV]

Not sure about that Ken - costs them cash, reputation and diversion of men, materials and management I'm sure they'd be better off using elsewhere - such as on the 757/767 replacementYour ignorance of aircraft engineering is showing. The Middle of Market Aircaft (MMA) is still in the configuration development phase and well staffed with configuration design engineers. The KC-46 is staffed with detail design engineers. Big difference. By the time the MMA gets launched, the configuration is frozen, and the detail design engineering begins, the KC-46 effort will be finished and the engineers supporting KC-46 will be able to be moved to MMA. And BTW, much more near term than MMA is 777X detail design engineering. Currently that effort is sufficiently staffed and tracking on schedule.

[George K Lee]

Ken...

Please produce credible evidence that the EADS bid was noncompliant. If the RFP called for a freight floor and cargo door, and EADS did not offer this, that would be a matter of public record. But as far as I know, the deal came down to price.

I'm asking for linked independent evidence. This is (mostly) a forum where standards prevail.

And please don't imagine I think Thompson set up the tanker deal for Boeing. That's absurd. And, yes, Thompson is a consultant to many defense contractors, including Boeing.

[Heathrow Harry]

"the KC-46 effort will be finished"

is that a promise???

[KenV]

Ken...

Please produce credible evidence that the EADS bid was noncompliant. If the RFP called for a freight floor and cargo door, and EADS did not offer this, that would be a matter of public record. But as far as I know, the deal came down to price.

I'm asking for linked independent evidence. This is (mostly) a forum where standards prevail.

And please don't imagine I think Thompson set up the tanker deal for Boeing. That's absurd. And, yes, Thompson is a consultant to many defense contractors, including Boeing.It is a matter of public record that EADS offered the passenger version of the A330 and not the
freighter. (Ref: https://en.wikipedia.org/wiki/KC-X).

The detailed specifications of the final RFP are not in the public domain.

Ref: "sauce for goose is sauce for gander."
On the subject of this forum being "where standards prevail", what "linked independent evidence" do you offer to:
1. Support your contention that EADS' offer was fully compliant with the RFP.
2. Support your claim that Boeing paid a consultant to "set up the tanker deal".
3. Support your charge that it is my MO to deflect

Yeah, I thought so.

[KenV]

"the KC-46 effort will be finished"
is that a promise???A promise? Heck, if that's what you want, I'll swear to it on a stack of bibles and sign the contract in blood.

And what will that mean?

This is yet more specious butwhataboutery.

[George K Lee]

Ken...

It is a matter of public record that EADS offered the passenger version of the A330 and not the freighter.

The Wikipedia entry shows nothing of the sort. It shows no discontinuity between the EADS/NGC bid, based on the KC-30 MRTT, and the EADS solo bid. Proof or hold your peace.

And I don't have to prove anything, certainly not the negatives of your fantasies. Particularly nothing about a consultant setting up the deal, because that's not what I said.

As for your MO, recall your long and tedious ranting about how the JSF GenIV HMDS included eyeball-movement tracking, when the GenIV didn't actually exist.

[KenV]

Ken...

It is a matter of public record that EADS offered the passenger version of the A330 and not the freighter.

The Wikipedia entry shows nothing of the sort. It shows no discontinuity between the EADS/NGC bid, based on the KC-30 MRTT, and the EADS solo bid. Proof or hold your peace.

Oh my. The EADS/NGC offer was for the passenger version of the A330. At that time there was no requirement for a freighter and further, the A330F did not yet exist and could not be offered. And as you yourself just stated, the final EADS solo bid was the same as that earlier team bid.

Ken...
I don't have to prove anything, certainly not the negatives of your fantasies. Particularly nothing about a consultant setting up the deal, because that's not what I said.Hmmmm. You "don't have to prove anything?" So sauce for the goose is NOT sauce for the gander? Hmmmmm.

Now about that consultant. This is what you said in post #57:

Because we know where the guy who set up the KC-46 deal is sitting today, do we not?
And of course that consultant still cashes Boeing checks.

Sounds to me that "that consultant" who "still cashes Boeing checks" also "set up the KC-46 deal". Or are you talking about two different people here? If so who are the two different people because that is not at all clear.

As for your MO, recall your long and tedious ranting about how the JSF GenIV HMDS included eyeball-movement tracking, when the GenIV didn't actually existBack to that are we? I very clearly and emphatically admitted that I erred when I talked about eyeball-movement tracking because I had attributed features in the lab helmet that was demonstrated to me with features in the production helmet. Further, a SINGLE misstatement made nearly three years ago does not remotely constitute an "MO." Nor does a misstatement of this kind remotely constitute a "deflection", which was your claim. So I call total BS on your entire assertion.

And finally, you demanded "linked independent evidence." Your recollection of an exchange that happened nearly three years ago does not remotely constitute "linked independent evidence." So while demanding "linked independent evidence" from others, you exempt yourself from that requirement. So is this really a case of sauce for the goose is not sauce for the gander or just plain old fashioned hypocrisy?

BTW, holding a grudge for going on three years is not healthy. You might want to consider that.

[George K Lee]

Ken...

https://news.northropgrumman.com/news/releases/northrop-grumman-kc-45:-why-we-won-key-selection-criteria

https://leehamnews.com/2015/09/24/bjorns-corner-usaf-tanker-program/

A company source and a respected independent source, both mentioning pallet counts. So there was a cargo door and a floor. Without it, the proposal would have been rejected outright, and it was not. As for your evidence, you have presented a Wikipedia entry that doesn't mention pallets or cargo.

And then you add another completely false claim, which is that the A330F "did not yet exist and could not be offered" at the time of the EADS/Boeing contest. Source selection was in 2011. The A330F was launched in 2007, flew in 2009 and entered commercial service in 2010.

By the way, you are the one making a claim that appears to be new (that the Airbus proposal was noncompliant) so it's really up to you to prove it.

Thompson and the person who set up the deal are separate. English is not always a precise instrument, but I already explained the difference to you, and on you still bang about it.

I don't know what your game is, apart from schoolboyish trolling. And I had quite forgotten about your similar behavior from years back until you started firing insults left and right about people's "ignorance".

[KenV]

Ken...I don't know what your game is, apart from schoolboyish trolling. And I had quite forgotten about your similar behavior from years back until you started firing insults left and right about people's "ignorance".Oh my. First, you directly accused me of having an "MO of deflection" in post #55 dated 22 March. I suggested HH was ignorant of modern aircraft engineering in post #61, dated 26 March. If the math is difficult, that's four days later. So unless you have a time machine that enabled you to travel four days into the future, your claim that my "ignorance insult" reminded you of that single years ago event is utterly false on its face. And second, one of the sure signs of a troll is accusing others of being a troll.

Adios. I'm done with you here.

[Buster15]

I have just read most of the above inputs and (fairly normal for PPRUNE) non relate to the subject of the post - B52 replacement engine.
Instead it has degenerated to childish personal insults.
The mods really ought to remove these should they not???

[George K Lee]

I agree to a point... I think the discussion turned on the relative difficulty of B-52RE versus other programs & Boeing's performance on things that should have been straightforward.

I spent many years in a field where you could very easily find yourself being spanked severely for making unsourced claims and such behavior on a reputable forum consequently :mad:es me off.

So, let the discussion resume, about the myriad ways in which the apparently sensible idea of putting new motors on the B-52 can get gooned up.

[KenV]

I have just read most of the above inputs and (fairly normal for PPRUNE) non relate to the subject of the post - B52 replacement engine.I made the exact same point multiple times and attempted multiple times to steer the conversation back to the topic. I failed. Certain folks here just cannot resist the opportunity to slag Mr B and mock USAF even if its totally unrelated to the topic at hand.

[Heathrow Harry]

Given the issues reported by the three major engine providers right now it is a brave man who'd belie any promises TBH....

[ORAC]

One the other hand fuel efficiency since 1960 has increased by about 60% - of which engine improvements have provided about 40% whilst aerodynamics and airframe materials has provided about 20%. And from what I read that trend is ongoing - so I’d extend the engine manufacturers some slack.

[tdracer]

Given the issues reported by the three major engine providers right now it is a brave man who'd belie any promises TBH....

Having dealt with all three on a regular basis (prior to my retirement), we had a saying:
"The worst engine manufacturer in the world is the one you're dealing with today"
That being said, based on the last ten years, I'd say GE is less likely to screw the pooch than the other two.
ORAC, it's not just fuel efficiency - the maintenance/reliability/shutdown rates/time on wing have all gotten much, much better.

[George K Lee]

There are certainly a number of suitable engines, and with luck, military requirements will not require too many modifications (= cost and risk). I would just hope that the REP would include an early demonstrator with a pair of new engines in an installation that traces directly to production.

[KenV]

Given the issues reported by the three major engine providers right now it is a brave man who'd belie any promises TBH....The engine change decision has VERY little to do with promises from engine manufacturers. The point is that the current engines will be non supportable in less than a decade, and the plans are to keep the airframes going for another two or three decades. Without new engines the airframes will simply stop flying long before the airframe life has been reached.

It is HOPED that the engine change will pay for itself in operating savings, but this is not what is driving the decision. And the savings include reduced fuel burn AND reduced maintenance. For example, it is estimated that on average the new engines will require at most one removal during the remaining life of the airframe. And a significant number of engines will likely NEVER require an engine removal during the life of the airframe. Yes, the new engines are that much more reliable/durable.

[KenV]

There are certainly a number of suitable engines, and with luck, military requirements will not require too many modifications (= cost and risk). I would just hope that the REP would include an early demonstrator with a pair of new engines in an installation that traces directly to production.Current plans (which are very much still in flux) are to replace all 8 engines on a single "pathfinder" airframe that will also do a lot of flight testing to ensure the flight envelope (and more importantly, the weapons release envelope) is not affected by the new engines and engine installation. Swapping out only a single pair of engines will not enable the level of testing that is needed.

[k3k3]

Does this mean that the E3 (TF33) engines will also become unsupportable?

[George K Lee]

Good point, k3k3, since the TF33-AWACS in USAF and NATO is supposed to run to 2035. And AWACS has tended to run at higher utilization rates then the B-52.

[KenV]

Does this mean that the E3 (TF33) engines will also become unsupportable?The answer is a bit more complex than that, but in a nutshell, yes. However in the case of AWACS there is an existing thoroughly tested, in production solution: CFM engines. The B-52 does not have that option and the solution is not only not yet developed, but the engine swap is more complicated. And much much more complicated than the engine swap itself is the possible impact on the B-52's weapons release envelopes caused by an engine swap, which AWACS does not have to contend with. That's why it's being addressed now on the B-52, many years before the actual need. Further, since an engine swap MUST be done on the B-52, the earlier it is done the more money will be saved AFTER the swap, potentially paying for itself in savings.

And FWIW, the most difficult part of an engine swap on AWACS will be deciding to go with the older standard CFM-56 engines, or the LEAP versions which cost more, but are more efficient. Are the savings worth the expense when the airframes may not have that many more years left in them? Or do the AWACS users commit early to a life extension program so that the potential savings can be realized?

[George K Lee]

Except that the engine used on the E-3 went out of production when the E-3 did, more than 25 years ago. The generation that succeeded it is also going OOP, replaced by the LEAP.

[seafury45]

KenV,

Could you briefly explain how the engine swap affects weapons release envelopes please?

[ORAC]

https://www.flightglobal.com/news/articles/usaf-details-scope-and-schedule-for-b-52-re-engining-444327/

“A new US Air Force document released last week outlines the details, timeline and likely competitors for a plan to acquire at least 608 new turbofan engines to replace the eight Pratt & Whitney TF33s on each of 76 Boeing B-52H bombers in the US Air Force fleet........

The new engines must not alter the aircraft’s take-off performance and the weapon release envelope, the document says.“.....

[Heathrow Harry]

KenV,

Could you briefly explain how the engine swap affects weapons release envelopes please?


The top secret toss bombing manoeuvre?????

[George K Lee]

If I had to take a guess, the weapon-release issue would involve the airflow between the new and larger nacelle and the body side and its effects on the pylon and stores.

[BobbyHowie]

I saw a photo of a B52 in flight with 4 engines. Can't remember the make I'm afraid. Was the early 80's I think.

[sandiego89]

I saw a photo of a B52 in flight with 4 engines. Can't remember the make I'm afraid. Was the early 80's I think.

Bobby, there have been several proposals to put 4 engines on the B-52 over the decades, but that has now been shelved. Two B-52F's were used to test a single large fan (in place of an inner engine pair) for the C-5 and 747 program, but I do not believe one ever flew with 4 large fans other than in artists renderings.


If all these TF-33's get freed up coming off B-52's and the remaining K/E-135's that still have them + spares, I do wonder if that would be enough to keep the smaller E-3 fleet running?

[KenV]

KenV,
Could you briefly explain how the engine swap affects weapons release envelopes please?


The top secret toss bombing manoeuvre?????

If I had to take a guess, the weapon-release issue would involve the airflow between the new and larger nacelle and the body side and its effects on the pylon and stores.

Everyone please remember that the B-52 does not carry weapons only internally. It has very large EXTERNAL weapons pylons that carry a VERY wide variety of weapons. Significantly altering the airflow under the wings would necessitate recertifying not just all those weapons, but also the very large variety of weapon combinations over multiple flight conditions. That is a HUGE deal potentially much more difficult and time consuming to test for than the engine swap. This was one of the drivers that drove the eight small engine solution vs the four large engine solution.

[KenV]

If all these TF-33's get freed up coming off B-52's and the remaining K/E-135's that still have them + spares, I do wonder if that would be enough to keep the smaller E-3 fleet running?Maybe, but doubtful. The engines become unsupportable not because of a dearth of numbers, but because the materials and manufacturing methods required to produce the necessary parts simply become unavailable.

Talk to the hobbyists that try to keep steam locomotives running. Not only are the parts no longer available, no one knows how to build those parts anymore. Heck no one can even figure out how to build the F-1 engines that powered the Saturn V moon rockets and they are of more recent vintage than the TF-33. It's a lost art. The problem is even more acute when we're talking about electronics. A lot of the chips that power 10 or even just 5 year old avionics are no longer being made and there is no equipment around anymore to make them. Obsolescence is a HUGE deal and must be carefully planned for.

[KenV]

I saw a photo of a B52 in flight with 4 engines. Can't remember the make I'm afraid. Was the early 80's I think.Nope, not a photo. Artist's rendering. Both the Rolls RB211 and the P&W2040 were considered as possibilities. Nothing came of the ideas, largely because the USAF was agin it. USAF was convinced that the B-52's days were numbered and they would be replaced by the B-70, then the B-1A, then the B-1B, then the B-2, and so on. They thought any money directed at the B-52 would be money competing with those shiny new bombers. But now that they've decided to retire both the B-1 and B-2 and keep the B-52 for multiple more decades, they're finally taking a serious look at re-engining because they have to. And once again, contrary to the various skeptics and cynics, this is a top down idea from USAF trying to solve a real problem, not a bottom up idea from engine manufacturers wishing to sell more engines.

[Rhino power]

Talk to the hobbyists that try to keep steam locomotives running. Not only are the parts no longer available, no one knows how to build those parts anymore...

Try telling that to the A1 Steam Locomotive Trust! ;)

-RP

[Heathrow Harry]

Ken

given the continued apparent usefulness of the B-52 do you think they'd ever go for a replacement - a striaght sub-sonic, BIG, bomb truck that can carry just about anything you can think of?????

Or is it a bit like the fabled DC-3 replacement - so many built and available you could never get the price low enough to build a replacement??

[etudiant]

This seems like excess money chasing spending opportunities to me.
The US's large engagement in Afghanistan is supported via a 1000 mile truck based logistics chain maintained over less than spectacular Pakistani highways. The true cost per gallon of fuel there is surely several times the norm, yet no one complains. So I don't buy the idea that economics are a factor here either.
The minimal usage of the B-52s, even lower than that of corporate jets, make any economic return on a multi billion re-engining deeply implausible.
Meanwhile, to claim that parts for a 70 year old design cannot be efficiently made any more is just silly. Maybe they would not be made as badly as before, because metallurgy has progressed, but there is no conceivable reason that TF-33s could not be replicated today, at much lower cost than re-certifying the B-52 for a whole new propulsion system.

[tdracer]

Etudiant, it's not that simple.
Some of the manufacturing processes and alloys used 70 years ago have been effectively banned due to EPA and OSHA regulations. Newer processes and alloys result in parts that have different mass characteristics - which affects other parts in the engine - which in turn affect other parts, and pretty soon you need to remake the entire engine. So what you end up with is an very expensive re-development of a 70 year old engine design. All the costs of a new, modern engine with the crappy performance of the original.
When we looked at the RB211-535 re-engine ~20 years ago, they were looking at a lease arrangement. The savings in fuel and engine maintenance alone would have paid the lease costs (and that was without factoring in the fact that aerial refueling fuel costs several times more than stuff uploaded on the ground. Plus, a ~30% reduction in fuel burn means a corresponding improvement in range and/or greater payload capabilities.
HH - I doubt the USAF would ever go for a replacement 'bomb truck' - the Air Force brass want their new stuff to be fancy - they just can't help themselves. If they started out with a RFP for a new bomb truck, they'd add so much crap to it before they were done that it would end up costing more than a B-2 (I'm not even remotely optimistic that the new B-21 will come in at anything less than a $Billion per copy and will be less than 10 years late).
George, you are correct that the CMF56-2 that was used to re-engine the KC-135 (and DC-8) is long OOP, but the CFM56-7 on the 737NG isn't going OOP anytime soon (and even when it does, figure it'll be in commercial service at least another 30 years). While I can see some major obstacles to using the LEAP on the P-3 (among other things, it's significantly heavier than the CFM), I don't think a re-engine with the CFM56-7 would be too much worse than the -2. Plus the -7 is already in the US inventory on the P-8. That being said, I suspect the USAF will spring for new AWACs aircraft rather than re-engine.

[BobbyHowie]

Bobby, there have been several proposals to put 4 engines on the B-52 over the decades, but that has now been shelved. Two B-52F's were used to test a single large fan (in place of an inner engine pair) for the C-5 and 747 program, but I do not believe one ever flew with 4 large fans other than in artists renderings.


If all these TF-33's get freed up coming off B-52's and the remaining K/E-135's that still have them + spares, I do wonder if that would be enough to keep the smaller E-3 fleet running?

Thanks sandiego89. Was a while ago but it did look real.

[Carbon Bootprint]

That being said, I suspect the USAF will spring for new AWACs aircraft rather than re-engine.The JDF is already using the E-767 (https://en.wikipedia.org/wiki/Boeing_E-767). Wouldn't that make a suitable replacement platform, especially since Boeing is allegedly planning to continue 767 production?

[ORAC]

The current trend is to replace such platforms with large business jets with satellite comms and do the vast majority of both the processing and control from the ground. Or even data fusion from all the other airborne sensors - and perhaps reflections from ground emitters to build a multi-polar passive picture.

https://www.flightglobal.com/news/articles/jstars-replacement-cancelled-in-new-usaf-budget-plan-445844/

https://rusi.org/sites/default/files/20170605_air_c2_proof_3_jm.pdf

[etudiant]

Etudiant, it's not that simple.
Some of the manufacturing processes and alloys used 70 years ago have been effectively banned due to EPA and OSHA regulations. Newer processes and alloys result in parts that have different mass characteristics - which affects other parts in the engine - which in turn affect other parts, and pretty soon you need to remake the entire engine. So what you end up with is an very expensive re-development of a 70 year old engine design. All the costs of a new, modern engine with the crappy performance of the original.

.

That seems just implausible to me.
I don't know of an engine parts process that has been outlawed and I'm unaware of an relevant alloy that has become unavailable due to EPA and/or OSHA regs. We're not talking beryllium here, just simple nickel alloys, at least afaik.
Happy to be corrected, but thus far I remain convinced it is just a case of too much money chasing limited spending opportunities.

[tdracer]

That seems just implausible to me.
I don't know of an engine parts process that has been outlawed and I'm unaware of an relevant alloy that has become unavailable due to EPA and/or OSHA regs. We're not talking beryllium here, just simple nickel alloys, at least afaik.
Happy to be corrected, but thus far I remain convinced it is just a case of too much money chasing limited spending opportunities.

You can remain the skeptic, but I've seen it. For example, around 1990, GE ran into a big problem with voids in the turbine blades for their new engines - and many of the suspect parts had made it into service before the problem was discovered. Long story, but what they finally discovered was that - due to EPA regulations - the formulation for the stuff they used for the blade molds had changed. The new formulation eliminated a 'trace contaminant' which, it turns out, wasn't really a contaminant - it had acted to prevent the voids from forming in the blades. It costs GE million$ to develop a new process that didn't result in voids, and million$ more in inspections and warrantee costs. This on an engine that had been certified barely two years prior. GE also traced part of the problem with uncontained turbine disc failures on the CF6 engine to 'aftermarket' PMA turbine blades (Parts Manufacturing Authority) - the PMA blades were slightly heavier that the OEM blades which increased the stresses on the turbine disc. Sure, you can re-engineer and re-analyze everything that isn't exactly the same as it was 70 years ago (which would be pretty much the whole engine), but that takes a lot of time, and a lot of money.
You're talking components spinning very rapidly, the failure of which can be catastrophic to the aircraft and crew. There is no such thing as a 'simple' change...

[etudiant]

Thank you for that informative post, tdracer. It does underline the unforeseen risks of process changes.
Nevertheless, I remain unconvinced that maintaining TF-33s for another 50 years is anywhere nearly challenging enough to justify the huge cost of engine replacement.

[Turbine D]

tdracer,
Some of the manufacturing processes and alloys used 70 years ago have been effectively banned due to EPA and OSHA regulations.
Check your pm...

TD

[seafury45]

KenV,


a belated thank you for the explanation for weapon release envelope. I had forgotten just how much ironmongery can hang under a B-52.

[sandiego89]

The JDF is already using the E-767 (https://en.wikipedia.org/wiki/Boeing_E-767). Wouldn't that make a suitable replacement platform, especially since Boeing is allegedly planning to continue 767 production?


I would imagine a KC-46 variant (767 based) will be the preferred platform to offer over a civil based 767 as it is already hardened, miles of extra wiring....

[ORAC]

Too big. Even if they didn’t go for a business jet they’d go for a P-3 variant - it already has a radar and it has already for provision f9r the appropriate consoles and comms etc.

In fact, that’s what Boeing has already selected and proposed.......

http://www.defensenews.com/air/2016/09/13/boeing-sees-promising-defense-outlook-for-737-airliner/

[tdracer]

737 'Wedgetail' already exists for the AWACS mission.
No need to re-invent the wheel - not that it would stop them from trying...

[KenV]

Ken

given the continued apparent usefulness of the B-52 do you think they'd ever go for a replacement - a striaght sub-sonic, BIG, bomb truck that can carry just about anything you can think of?????

Or is it a bit like the fabled DC-3 replacement - so many built and available you could never get the price low enough to build a replacement??Unlike the DC-3 the B-52 cannot fly forever. It WILL run out of service life. Once the B-21 (really? 21 because its the first 21st century design?!) ) gets into service and goes into full production, USAF will almost certainly have to start getting serious about replacing the B-52. Depending on the source, the B-21 might not have true strategic range, which if true will mean a true long range bomber will be needed to replace the B-52. And it will very likely have at least some stealth, so it won't look at all like the B-52. But it likely will not have the extreme level of stealth the B-21 has, which (reportedly) includes stealth against lower frequency radars (VHF and UHF) which the B-2 lacks, especially from the rear. But a lot can change in the meantime, so who knows? For all we know that new bomber might be optimized as a directed energy weapon platform, with the B-21 doing duty as the bomb truck. Who knows?

[KenV]

Except that the engine used on the E-3 went out of production when the E-3 did, more than 25 years ago. The generation that succeeded it is also going OOP, replaced by the LEAP.Ummm, no. Not completely true. The -2s on the AWACS and E-6s are OOP, but the -7s on the NG 737 (thousands built) are not and will be flying for quite some time. Further, the C-40 fleet, the Wedgetail, and the P-8 fleet all are equipped with -7s and thus will be around for quite some time, with the production line likely continuing for some time. Going from -2 to -7 would be a rather small generational jump. Putting LEAP engines on the AWACS aircraft will require significantly more of a development effort with not that much return on that additional investment.

That being said, will it make sense to keep those airframes going, or just replace them with something new? Like a 767 AWACS? Or more likely a 737 based Wedgetail? Or maybe even something based on a large biz-jet. It'll depend a lot on how much processing they want to do on-board vs how much raw radar data they want to datalink and then process off-board. If they're willing to do very high bandwidth datalinking of raw radar data with off-board processing, then something un manned might do the job. But there's only so much available real-time bandwidth. The last thing they want to do is use up the bandwidth and end up constraining everything else that needs robust comms. So my guess is that they'll opt for on-board processing. Which likely also means on-board decision makers. Which would seem to favor something a bit bigger than the biz jets. Maybe a 100 seat airliner, like the Embraer E-195 and Bombardier CS-100? Boeing's betting that the bottom end of the 737 range is just right. Who knows?

[ORAC]

737 'Wedgetail' already exists for the AWACS mission.
No need to re-invent the wheel - not that it would stop them from trying... Different generations. Airframe is different, role is increasingly different, Radar is incredibly different - and would undoubtedly be multi-mode and underslung - and the vast majority of the processing and use would be distributed elsewhere.

We get back to the fact that even the 737 airframe is to big and a business jet would be more suitable.

[tdracer]

We get back to the fact that even the 737 airframe is to big and a business jet would be more suitable.
It's not as dramatic as it used to be, but if you're going to fly it a lot (1,000 hrs./year) most bus jets cost more/hr. to operate than a 737. That's one thing that has really boosted the 737 BBJ.
The problem with distributed sensors/processing is it has to be 100% jam proof - and needs to stay that way indefinitely. If it's 99% jam proof you can be sure the 1% will happen at the worst possible time.

[KenV]

We get back to the fact that even the 737 airframe is to big and a business jet would be more suitable.But is it? If processing is on board (and there are LOTS of arguments against off-board processing) then besides the processor operators, it also makes sense to put the decision makers on board. That generally requires more volume than most biz jets provide. Further, once you go over about 1000 FH/yr, airliners are actually cheaper to operate than biz jets. So any cost advantage of a biz jet goes out the window if you actually fly the airplane.

But the really big issue is power generation. Biz jet engines and accessory gear box systems just are not designed to generate lots of power, and with active jamming, laser defense, laser offense, high power sensors, big on board processing systems, a robust comms suite, etc etc, the host aircraft needs to be able to generate LOTS of power. And finally, mission sets tend to creep upward, not downward. A bizjet based aircraft will likely not have a lot of growth margin. That's not to say that biz jets never make sense. Depending on the mission set and implementation, a biz jet may be ideal. But for the mission set of the current AWACS, you just couldn't cram all of the capability of that aircraft into a biz jet sized platform.

To put all this in perspective consider that the P-8 is based on the longer -800 airframe, not the shorter -700 airframe. And that's because the extra volume is needed. And the engines and nacelles of the P-8 have been modified with 180KVA generators. 360 kilowatts is a LOT of power. And when (not if) directed energy weapons start being fielded, they'll likely need to triple that power and get in the megawatt range.

[sandiego89]

While a 737/P-8 airframe size does seem to be what Boeing wants to pitch as the next AWACS, I do wonder if range/endurance wise something a KC-46/767, or even 787, sized airframe would be tempting especially for the USAF. 6,000 miles or 9+ hours endurance or so would be significant, especially when considering the Pacific basin. Yes I do realize there can be air-to-air refueling, but when you want endurance, internal space for racks and warm bodies (and spare crew), power, and external space for a large array, size does have a certain quality.


While Wedgetail, E-2, and bizjets work for many users the USAF might want to stay big.

[KenV]

While a 737/P-8 airframe size does seem to be what Boeing wants to pitch as the next AWACS, I do wonder if range/endurance wise something a KC-46/767, or even 787, sized airframe would be tempting especially for the USAF. 6,000 miles or 9+ hours endurance or so would be significant, especially when considering the Pacific basin.FYI, the 737 based P-8 has 10.5 hours endurance at 300NM on station, without inflight refueling. That's pretty much the limit of endurance for the crew. Add inflight refueling and the crew may expire before the aircraft landed.

As an aside, I see that this thread has once again wandered far afield and no one is discussing B-52 engine replacement any more. So to bring things back, while the B-52 engine replacement will involve the installation of engines designed for biz-jets, the B-52 installation will include more and bigger generators. Today, only the lefthand engine of each two-engine pair has a generator. The new installation will include one generator for each engine (thus eight total generators) and each generator will be larger than the 45KVA generators now on the B-52.

[KenV]

In a decision announced May 10, Boeing has been selected to serve as integrator for a program to install new commercial engines on the B-52 bomber. The Commercial Engine Replacement Program (CERP) is the latest in a series of modernizations that will ensure the aircraft remains mission-ready through at least 2050. “The (U.S.) Air Force has long recognized that new engines are the right choice to carry the B-52 into the future,” said James Kroening, B-52 program manager. “The aircraft is structurally viable for years to come, and it’s the only large, heavy bomber of its type in the current and future fleet. We are very proud to have been selected as integrator and excited to partner with the Air Force as the CERP gets under way.”

It looks like USAF is genuinely serious about this engine replacement program for B-52 and putting the infrastructure in place to make it happen. The only thing lacking at this point is the funding. And if I read the tea leaves right Congress supports the program and will find and authorize the funds.

[sandiego89]

It looks like USAF is genuinely serious about this engine replacement program for B-52 and putting the infrastructure in place to make it happen. The only thing lacking at this point is the funding. And if I read the tea leaves right Congress supports the program and will find and authorize the funds.

Agree that the timing seems right- congress and the administration do not seem to be at all concerned about deficit spending at this time, and plenty of talk about the need to "improve" the military.

I do get that B-1 and B-2 bed down/phase out are part of the long term plans, but think the USAF and congress will need to get serious about that for funding and credibility sake. It will take some time to ensure the B-21's are up and running, but it looks like there will be period where FOUR bomber programs are up and running. That does get expensive.

I note here that Ellsworth, Dyess and Whiteman are likely slated to be the three B-21 bases, which seems like a natural transition of the types at those bases. Minot and Barksdale remain with the B-52. Air Force picks 3 bases for new B-21 Raider bomber - Business Insider (http://www.businessinsider.com/air-force-picks-3-bases-for-new-b-21-raider-bomber-2018-5) The magic will be in the timing, and if/how many upgrades the B-1 and B-2 will need to keep them going. A slip is B-21 fielding could be costly in many ways, and doubt anyone wants a bomber gap at their base.

[RAFEngO74to09]

Program proceeding apace - final RFP end-March to Summer - selection by end-2020 - contract early-2021.

Interviews with P&W and G-E:

P&W would save 5,400 lbs on 8 x engines - in similar dimensions - and offer 40% range increase.

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

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

[RAFEngO74to09]

Original Boeing video from 2017 explaining the benefits of the re-engine program to keep in service beyond 2050:

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

TF33 overhaul cost in 1996 per engine was $230K - $2M by 2017.
New engines will not require a depot level overhaul at all during the projected life to 2050.
Overall savings of $10 Billion in engine operating costs to 2050.

[ORAC]

https://www.flightglobal.com/fixed-wing/us-air-force-issues-draft-request-for-proposal-to-replace-b-52-engines/138099.article

US Air Force issues draft request for proposal to replace B-52 engines

[ORAC]

https://www.airforcemag.com/usaf-releases-b-52-engine-replacement-rfp-award-expected-july-2021/

USAF Releases B-52 Engine Replacement RFP, Award Expected July 2021

[Asturias56]

It should have been done years ago

[tdracer]

Looks like it's really going to happen this time:

Later this year, the 76 remaining B-52 Stratofortresses will start to get new engines that just might keep the venerable bomber flying through its 100th birthday.
But “the bones of it are still a 60-year-old airplane,” Gebara said. Each of the remaining 76 bombers was built between 1961 and 1962. The engine overhaul won’t change that—the $11.1 billion CERP, or commercial engine replacement program, is expected to replace only about 10 percent of the bomber’s overall components, Air Force officials said.

https://www.defenseone.com/technology/2021/06/engine-replacement-could-keep-venerable-b-52-flying-through-its-100th-birthday/182687/

[sandiego89]

Looks like it's really going to happen this time:




https://www.defenseone.com/technology/2021/06/engine-replacement-could-keep-venerable-b-52-flying-through-its-100th-birthday/182687/

And at 76X8, plus spares, quite a nice engine order for someone.

[ORAC]

A one off mind you - with the expected flying hours and engine life, once mounted they’re expected to stay on the aircraft wings until they leave service.

[treadigraph]

100th birthday. The equivalent of the Vickers Vimy retiring about now...

[etudiant]

A one off mind you - with the expected flying hours and engine life, once mounted they’re expected to stay on the aircraft wings until they leave service.

So very true.
The fleet averages about 200 hours/year/aircraft, so assuming a 20,000hr TBO, they should be able to avoid any major overhaul until 2120.
I've heard of the concept of 'blister pack' weapons, but this is really in another league.

[tdracer]

A one off mind you - with the expected flying hours and engine life, once mounted they’re expected to stay on the aircraft wings until they leave service.

No doubt that will be taken into account in the bid prices. In the commercial world, it's pretty common that the engine companies sell the engines for new aircraft at (or very near) cost - or even at a slight loss. The profit is in the maintenance and parts - engines will fly 3,000 to 4,000 hrs./year and do that for ~ 60,000 to 100,000 hrs. That's a lot of maintenance and spare parts.
So the per engine prices for the B-52 re-engine would be correspondingly higher than the commercial market.
No doubt some congressional critics will see the difference in prices and make a big stink about how the company is ripping off the government...

[Mr N Nimrod]

It should have been done years ago
says the B52 engineering, operations and engines expert

[Mr N Nimrod]

100th birthday. The equivalent of the Vickers Vimy retiring about now...
only if you think engineering advancements have been linear

[tdracer]

says the B52 engineering, operations and engines expert
We were seriously looking at a B-52 re-engine program over 20 years ago - math said the savings in fuel burn alone would pay for it. But apparently the USAF thought that giving the B-52 new life would limit their B-2 buy, so they fudged the numbers to say it didn't make economic sense by pricing aerial refueling fuel the same as depot fuel (when in reality it's ~3x the cost). Then of course the B-2 buy got limited anyway so their bluff got called...

[Asturias56]

"says the B52 engineering, operations and engines expert"

Not just me - see td racers post and many many US Govt studies

[Crash alot]

"says the B52 engineering, operations and engines expert"

Not just me - see td racers post and many many US Govt studies

Or anyone with a sliver of intelligence. However seems Mr Nimrod has a axe to grind.

[etudiant]

No doubt that will be taken into account in the bid prices. In the commercial world, it's pretty common that the engine companies sell the engines for new aircraft at (or very near) cost - or even at a slight loss. The profit is in the maintenance and parts - engines will fly 3,000 to 4,000 hrs./year and do that for ~ 60,000 to 100,000 hrs. That's a lot of maintenance and spare parts.
So the per engine prices for the B-52 re-engine would be correspondingly higher than the commercial market.
No doubt some congressional critics will see the difference in prices and make a big stink about how the company is ripping off the government...

In this instance, perhaps the desire for corporate prestige will override the normal profit maximizing impulse.
We have a clear cut 3 way competition, all entrants are technically qualified, winner take all, so it comes down to 'best value'.
I'd think RR would dearly love to be the supplier to the USAF strategic bomber force....

[tdracer]

In this instance, perhaps the desire for corporate prestige will override the normal profit maximizing impulse.
We have a clear cut 3 way competition, all entrants are technically qualified, winner take all, so it comes down to 'best value'.
I'd think RR would dearly love to be the supplier to the USAF strategic bomber force....
Not too sure how much corporate prestige there is in the re-engine of a 1950's bomber - heck most people don't know who makes the engines in the F-22 or B-2.
That being said, the RB211-535 (from the 757) was the leading contender when we were looking at this in the late 1990's - the plan being to replace each two engine pod with a single RB211. Being basically an analog engine (no FADEC) with throttle cables would have made the integration into an analog aircraft somewhat easier.

[Asturias56]

The problem will be to stop every other upgrade idea being piggy-backed onto an engine upgrade................

[cavuman1]

I see this advertisement in The Air Force Times. It runs almost every day:

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/680x265/b52_pratt_and_whitney_9cfa0542633ed31f49d624fa56b4e19ce79bb9 b1.jpg
GE also has an ad running with some frequency. I have not seen any submissions from Rolls-Royce. What is the status of the bidding and/or contract award?

- Ed

[etudiant]

The problem will be to stop every other upgrade idea being piggy-backed onto an engine upgrade................

The award was scheduled to be made this July, but thus far the only news is that acting AF Secretary Roth said that the projected cost was up 9% to $11 billion.
TDRacer could give real insight into the attractive 'mission creep' opportunities this program offers. Certainly lots of wiring will need to be repurposed/modified.
There are already rumors of a 50% cost increase circulating, so perhaps some mission creep is happening.even before the award.

[sandiego89]

Not too sure how much corporate prestige there is in the re-engine of a 1950's bomber - heck most people don't know who makes the engines in the F-22 or B-2.
That being said, the RB211-535 (from the 757) was the leading contender when we were looking at this in the late 1990's - the plan being to replace each two engine pod with a single RB211. Being basically an analog engine (no FADEC) with throttle cables would have made the integration into an analog aircraft somewhat easier.

Looks like the 4 engine option is dead. Program calling for a 8 for 8 replacement. I do think the 4 big fan option would have been the way to go decades ago.

[Davef68]

Looks like the 4 engine option is dead. Program calling for a 8 for 8 replacement. I do think the 4 big fan option would have been the way to go decades ago.

Presumably the theory is that it's easier to incorporate smaller engines into the existing nacelles than looking at changing the nacelles as well.

[Bing]

Presumably the theory is that it's easier to incorporate smaller engines into the existing nacelles than looking at changing the nacelles as well.

From what I read a while back the issue is to do with changing the centres of thrust and mass of the engines, which affects the relief from aero-elastic bending, fatigue life, etc. So a 'like for like' swap keeps things simple, even if they do need new nacelles.

[NWSRG]

Looks like the 4 engine option is dead. Program calling for a 8 for 8 replacement. I do think the 4 big fan option would have been the way to go decades ago.

Was there not problems with engine-out performance? 1 lost out of 4 being very different from 1 lost out of 8? Think it was to do with assymetric thrust and control authority? But that could be my imagination!

[tdracer]

Presumably the theory is that it's easier to incorporate smaller engines into the existing nacelles than looking at changing the nacelles as well.
The nacelles are going to be all new (and most probably the struts). Modern fan-jet engines are much larger in diameter and tend to be significantly heavier due to the big fans and improved engine failure containment criteria.
As I understand it, there were two major issues with going with 4 big(ger) engines - ground clearance and (this from Ken V way back in this thread) maintaining the ability to carry/drop munitions from the wings.
Regarding ground clearance, back when we were looking at the RB211 replacement, I suggested perhaps they could get rid of those outrigger gear on the wing tips and incorporated something into the outboard engine nacelles.

[ORAC]

Risk reduction…

https://www.forbes.com/sites/lorenthompson/2020/07/13/hanging-new-engines-on-60-year-old-b-52-bombers-is-not-easy-here-are-some-risks/

https://www.defensedaily.com/reducing-development-risk-key-b-52-re-engining-program/air-force/

[iranu]

Not too sure how much corporate prestige there is in the re-engine of a 1950's bomber - heck most people don't know who makes the engines in the F-22 or B-2.
That being said, the RB211-535 (from the 757) was the leading contender when we were looking at this in the late 1990's - the plan being to replace each two engine pod with a single RB211. Being basically an analog engine (no FADEC) with throttle cables would have made the integration into an analog aircraft somewhat easier.I believe extensive studies were performed at the time and the complications were more significant than first realised. The reduction in fuel burn over the rest of the life-time of the fleet wasn't enough to justify the risk, even though, as now, the fuel cost savings would essentially, in theory, pay for the upgrade. A non-US solution was also an issue, as usual.

[sandiego89]

Was there not problems with engine-out performance? 1 lost out of 4 being very different from 1 lost out of 8? Think it was to do with assymetric thrust and control authority? But that could be my imagination!

You are remembering correctly, engine out performance and control authority in such a state was a concern, as were the other issues mentioned above. The 4 big fans did look neat in the renderings and fuel burn calcs however, and seemed "simple" in theory, then came the actual hard work...

[ORAC]

Pending the inevitable protests of course…..

https://www.airforcemag.com/rolls-royce-wins-b-52-re-engining-program-worth-2-6-billion/

Rolls-Royce Wins B-52 Re-Engining Program Worth $2.6 Billion

The Air Force has selected Rolls-Royce North America as its contractor for the B-52 Commercial Engine Replacement Program, or CERP, which will supply new F130 powerplants for all 76 of Air Force Global Strike Command’s B-52H bombers, the Pentagon announced Sep. 24. If all options are exercised, the work is worth $2.6 billion.

The F130 engine is flying on the C-37 transport and E-11 BACN (Battlefield Airborne Communications Node) aircraft. The first part of the indefinite quantity-indefinite delivery contract is worth $500.9 million. The contract calls for Rolls to supply 608 engines, to equip 76 B-52s with eight engines each, with manufacture and installation to be completed by Sept. 23, 2038. Rolls said the actual number of powerplants, including spares, is 650.

The Air Force did not say when the installs will begin. The engines will be built at Rolls’s Indianapolis, Ind., facilities, where the company said it has invested $600 million in an “advanced manufacturing campus.” The work will require 150 new hires, the company said. The contract value is substantially below initial estimates, which ran as much as $10 billion for the CERP……

[tdracer]

The Air Force did not say when the installs will begin. The engines will be built at Rolls’s Indianapolis, Ind., facilities, where the company said it has invested $600 million in an “advanced manufacturing campus.” The work will require 150 new hires, the company said. The contract value is substantially below initial estimates, which ran as much as $10 billion for the CERP……

Rolls Indy was formerly Allison (they offered me a job way back when) - so while the parent company is now British, they are still "American" engines.

[Asturias56]

"Not too sure how much corporate prestige there is in the re-engine of a 1950's bomber"

Its the income that is important - especially in the current economic climate for aerospace

[ORAC]

Same engine as selected for the MRA-4 Nimrod......

[henra]

Same engine as selected for the MRA-4 Nimrod......
Are you sure? I thought Nimrod was to get RR715!? This one is getting RR725. Same as Gulf 650. Not a bad choice prolly.

[ORAC]

Happy to be proved wrong, but I believe it’s just a modified version of the same 710 series, Nimrod just had a modified exhaust.

http://all-aero.com/index.php/component/content/article/64-engines-power/13522-rolls-royce-br700-rolls-royce-br710-rolls-royce-br715-rolls-royce-br725

[dixi188]

Not a very quick program, "compteted by 23 Sept 2038". Thats less than 5 aircraft a year, and a very precise date.

[NutLoose]

If this it it, it seems to fit well.

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

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/1920x1080/rolls_royce_f130_b52_e24469b2b6b2a50932a3d244d5c24bf8c0300cd d.jpg

[NutLoose]

Not a very quick program, "compteted by 23 Sept 2038". Thats less than 5 aircraft a year, and a very precise date.

That’s still 40 engines per year though.

[West Coast]

There might be an operational component to the rate as well. How many B-52s can the USAF have down and still meet commitments? Doubt anyone on here can answer that, but have to think it plays into the decision. I know it does at the airlines for equipment change.

[NutLoose]

Are you sure? I thought Nimrod was to get RR715!? This one is getting RR725. Same as Gulf 650. Not a bad choice prolly.

The problem with it in the Nimrod installation was it was never designed to be installed in a long intake duct and that caused problems, or so i am told by a RR guy.

[Ascend Charlie]

The article also explains that it is easier to slot new engines into the 8 pods than to re-design the 8 distribution systems for hydraulics, air, electrics etc into four.

[Jhieminga]

Changing to four engines would require increased rudder authority to deal with the OEI case.

[ORAC]

Still have to be redesigned.

IIRC an earlier article covers the fact that each of the new engines will have a generator so, even if the total power isn’t vastly greater, there is more redundancy. However that does mean the entire electric system needs a rethink. The same may hold true for the hydraulics etc.

[Just This Once...]

Could be more than that ORAC. The new engine and nacelle was designed with compact VFGs in mind - up to 2 per engine - and managed via an ACPC to regular aircraft power levels. Sentinel had 2 VFGs per engine, for example. So if you predict a future with directed energy weapons an option for 16 generators might have you covered!

[Flap Track 6]

Nimrod just had a modified exhaust.

BR710N for MRA4 was a marinised version of the engine with significant material changes for the environment and an integrated compressor wash facility. All the magnesium alloy components had to be changed.

[DCThumb]

Could be more than that ORAC. The new engine and nacelle was designed with compact VFGs in mind - up to 2 per engine - and managed via an ACPC to regular aircraft power levels. Sentinel had 2 VFGs per engine, for example. So if you predict a future with directed energy weapons an option for 16 generators might have you covered!

The engine can be configured with an accessory gearbox for 1 or 2 Gens - BR710 in Global has 2, but in the 550 it has just 1. The F130 is a BR725 as used on the G650 - same core, just a larger N1 Fan. On the 650 it has only 1 Gen.