Buff upgrade

[chopper2004]

This is what the newly re engined buff may look like
https://www.airandspaceforces.com/new-image-shows-how-b-52h-will-look-after-engine-radar-replacement/?fbclid=IwAR2ba4AwHND7rasrznmpAeZXul_BGengDd-dK58N_TPYQKA9umkaIJ-hae8

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1280x376/image_9_f92739f0befea21f8d93a2dff94aa7185dcb0463.jpg

cheers

[H Peacock]

Hmm, nacelles look higher and further forward; guess they’ll borrow MCAS from the 73Max! 😳

[farsouth]

Incredible aircraft - first flight in 1952, less than 50 years after the Wright Brothers, last airframe produced 1962, and some of those airframes planned to still be in service in the 2050s, 100 years after the first flight!

[DaveReidUK]

German-designed engines on a B-52 - who'd have thought it ?

[Flugzeug A]

Pardon my ignorance , again it’s a real question: Does anyone know why they didn’t go for 1 , more powerful engine on each pylon?
I assume it’s simply that there isn’t an engine available with that much grunt but could someone enlighten me?

[ORAC]

That would mean a total pylon/ wing redesign along with hydraulics, electrics etc along with flight testing for engine out performance etc.

They opted for swap 8 for 8 to minimise the changes required.

https://theaviationist.com/2022/09/25/b-52-new-engine-nacelles-test/

https://www.airandspaceforces.com/article/new-power-for-the-b-52/

While USAF once considered four large-fan commercial engines instead, it stuck with eight to avoid substantial redesign of the wing, cockpit, and other components, and to minimize risk and delay.

[filejw]

Pardon my ignorance , again it’s a real question: Does anyone know why they didn’t go for 1 , more powerful engine on each pylon?
I assume it’s simply that there isn’t an engine available with that much grunt but could someone enlighten me?

Read it was a structural issue with the wing .

[tdracer]

According to KenV (who seems to have abandoned this forum), a big concern with one engine per pylon was it messing up the ability to load/drop munitions from the wings.
Back around the year 2000 I was on a team that was looking at just that - replacing each two engine pod with a single PW2000 or RB211-535 (e.g. 757 engines). The potential improvements were massive - the increased thrust and better fuel burn meant greatly increased range, payload, and massive fuel costs savings. Just the savings in fuel made it look like a no-brainer with the reduced fuel burn paying for the costs of the re-engine.
Allegedly the USAF nixed it because they feared making the BUFF more capable would hurt their case for buying more B-2s (which of course didn't happen).

[uxb99]

What sort of environment is the B52 meant to operate in these days? It's big and slow. A missile magnet?

[tdracer]

What sort of environment is the B52 meant to operate in these days? It's big and slow. A missile magnet?
It's a bomb truck. Most conflict areas don't have sophisticated air defenses and it can fly well above the range of ManPad type stuff. Plus it's a very good stand-off cruise missile platform.
No, it wouldn't last long against a proper air defense, but that's not where most of the action has been for the last 50 years.

[Freeman Lowell]

This is what the newly re engined buff may look like
https://www.airandspaceforces.com/new-image-shows-how-b-52h-will-look-after-engine-radar-replacement/?fbclid=IwAR2ba4AwHND7rasrznmpAeZXul_BGengDd-dK58N_TPYQKA9umkaIJ-hae8

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1280x376/image_9_f92739f0befea21f8d93a2dff94aa7185dcb0463.jpg

cheers
This looks very much as though PIXAR is involved in the re-design...
Freeman

[k3k3]

Pardon my ignorance , again it’s a real question: Does anyone know why they didn’t go for 1 , more powerful engine on each pylon?
I assume it’s simply that there isn’t an engine available with that much grunt but could someone enlighten me?

One of the main problems with the idea of four big fans, was the lack of rudder authority in the event of losing an outboard engine in a critical phase of flight .

[Flugzeug A]

Thanks all.
I did wonder re ‘just’ bolting on an RB211 etc , if only for the cost savings in maintaining 4 engines rather than 8.
How many are being converted & when’s it due in service?

[GlobalNav]

It's a bomb truck. Most conflict areas don't have sophisticated air defenses and it can fly well above the range of ManPad type stuff. Plus it's a very good stand-off cruise missile platform.
No, it wouldn't last long against a proper air defense, but that's not where most of the action has been for the last 50 years.

Somebody must must have written a book about how the operating assumptions for the B-52 have evolved over the last 65 years. First it was a long range, high altitude nuclear deterrent. Then it became a long range low altitude nuclear deterrent, to avoid enemy radars. Remember the wrinkled skins that resulted from the low level turbulence? Then, it’s use in south Viet Nam was a huge change, high altitude conventional “dumb bomb” carpet bomber. When used over North Viet Nam, of course, it was high altitude again, but now in a highly defended airspace, and they took severe losses due to obsolete tactics (in spite of the excellent advise offered by the Thud and Phantom tactics shops). The next major combat use I can think of is the Gulf Wars (were they used over Bosnia?). They became high-altitude close air support (CAS) of all things, employing precision-bombs. Most of this time, perhaps still?, the Buff remained part of the nuclear deterrent triad, though I suppose in the latter years this depended on long range standoff munitions. How many times over the years were long range B-52 operational demonstrations used to send a warning to mischievous dictators?

General LeMay would be proud of what the Boeing Company of yesteryear was cable of building and it stood the test of time. It’s had a major role in Cold War for which it was built, and a much broader utility than imagined at first, for which the free world should be grateful.

[Not Long Here]

Somebody must must have written a book about how the operating assumptions for the B-52 have evolved over the last 65 years. First it was a long range, high altitude nuclear deterrent. Then it became a long range low altitude nuclear deterrent, to avoid enemy radars. Remember the wrinkled skins that resulted from the low level turbulence? Then, it’s use in south Viet Nam was a huge change, high altitude conventional “dumb bomb” carpet bomber. When used over North Viet Nam, of course, it was high altitude again, but now in a highly defended airspace, and they took severe losses due to obsolete tactics (in spite of the excellent advise offered by the Thud and Phantom tactics shops). The next major combat use I can think of is the Gulf Wars (were they used over Bosnia?). They became high-altitude close air support (CAS) of all things, employing precision-bombs. Most of this time, perhaps still?, the Buff remained part of the nuclear deterrent triad, though I suppose in the latter years this depended on long range standoff munitions. How many times over the years were long range B-52 operational demonstrations used to send a warning to mischievous dictators?

General LeMay would be proud of what the Boeing Company of yesteryear was cable of building and it stood the test of time. It’s had a major role in Cold War for which it was built, and a much broader utility than imagined at first, for which the free world should be grateful.
Also for a time some were assigned to NATO for N.Atlantic Anti-shipping with Harpoon.

[treadigraph]

Delighted to see one come in across Sarf London during the recent deployment, sounded great even though it was throttled back during the descent...

[Chu Chu]

If I ever made a movie, it would start with a few seconds of the opening sequence of Dr. Strangelove, then the camera would pull back and show that it was someone watching Dr. Strangelove on an iPad, and then further to show the he (or better she) was in the cockpit of a B-52 refueling from a KC-135. (I guess I'd have to work out how to explain movie watching during refueling.)

[DaveReidUK]

I did wonder re ‘just’ bolting on an RB211 etc , if only for the cost savings in maintaining 4 engines rather than 8.

Many reasons why not, some alluded to above.

You could start by simply comparing the fan diameter of the F130/BR700 with that of any of the current big fans.

[Asturias56]

It's also highly symbolic - you send a B1 or a B2 no-one notices but a B-52... everyone knows what they are and what they represent.

[SASless]

The B-52 a Bomb Truck.....yes indeed for sure....it rains bombs...lots of bombs....and when you run them over a target in Three's.....it is very impressive.

During the Vietnam War those Strikes known as "Arc Light" Strikes....were announced by radio several ways so that other aircraft could avoid the target areas.

We would plot the coordinates on our paper maps (the only kind we had) with a start point and an end point then we knew where not to be.

Mis-plotting due to a transcription error could sometimes have rather interesting results.....like really startling results as the jungle in front of your erupted into smoke, flame, and airborne debris along with some interesting turbulence.

Landing ground troops to do a BDA and movement to contact with NVA troops that had been the target afforded some interesting sights and accounts of the devastation that could be wrought by the Arc Light.

Lots of nice trees got turned into splinters....and huge craters became cat fish ponds as a result too.

Probably the best example of the B-52 in those days as a Tactical Bomber was in its role in the breaking of the seige of Khe Sanh Marine Base.

Long video....the Buff's appear at Ten Minutes into the film.

https://www.youtube.com/watch?v=dE-FRuOnW_M

[dixi188]

Globalnav:
Yes they were used over Bosnia, 1998/99.
I remember seeing 5 going SW over my house in Somerset one morning and also hearing them calling London one evening when inbound to Fairford while we were inbound to Stansted.

[Dunhovrin]

Great reads:

https://www.amazon.co.uk/We-Were-Crewdogs-Vietnam-Collection-ebook/dp/B002XITJMM/ref=sr_1_4?crid=3COA5JHH3SKSR&keywords=Crewdogs&qid=1666380677&qu=eyJxc2MiOiIwLjAwIiwicXNhIjoiMC4wMCIsInFzcCI6IjAuMDAifQ%3D %3D&sprefix=crewdogs%2Caps%2C98&sr=8-4

[Asturias56]

Of course they should have been re-engined years ago - they could be on their 3rd or 4th set of engines if the investment has been made - but all the cash goes on designing shiny new toys - some of which even make it into production - and then fade away whilst the B-52's just keep going

[punkalouver]

One of the main problems with the idea of four big fans, was the lack of rudder authority in the event of losing an outboard engine in a critical phase of flight .
Take a look at the size of the rudder in terms of chord as compared to the vertical stab. It is amazingly small. Same with the elevator. Compare it with the 4-engine KC-135.

It is no wonder the B-52 has crosswind landing gear……it needs it.

https://aviation.stackexchange.com/questions/59630/why-does-the-b-52-have-such-a-tiny-rudder

[ORAC]

https://youtu.be/BkzdK-V4JK0

[Asturias56]

its blank ORAC

[ORAC]

Working perfectly for me - absolutely standard youtube link.

https://youtu.be/BkzdK-V4JK0

[Ninthace]

Working perfectly for me - absolutely standard youtube link.
Blank for me too, you forgot to put the link in quotes

[treadigraph]

Works for me...

[ORAC]

You don’t have to put youtube links in quotes, they usually work with just a straight paste.

[Herod]

Click on "quote". You should find it in there.

[SASless]

I did not use Quotation Marks for the YouTube video I posted.....just a copy of the highlighted information in the address bar and paste in the Message Block here.

Perhaps there is a bit of delay in the linked video appearing?

[Ninthace]

You don’t have to put youtube links in quotes, they usually work with just a straight paste.
Fact remains, I can see your quoted Youtube link but not the original which is still a blank.

[dixi188]

I wonder if it is still true that "The father of the last B52 pilot is yet to be born"?
I heard that about 30 years ago.

[DaveReidUK]

You don’t have to put youtube links in quotes, they usually work with just a straight paste.

PPRuNe has its own (Youtube) tag, which tends to work more reliably than simply using a (URL) tag. Using square brackets, obviously:

BkzdK-V4JK0

(quote this post to see the code)

[NicolaJayne]

One of the main problems with the idea of four big fans, was the lack of rudder authority in the event of losing an outboard engine in a critical phase of flight .
that is my understanding of the issue as well.

[anson harris]

Many reasons why not, some alluded to above.

You could start by simply comparing the fan diameter of the F130/BR700 with that of any of the current big fans.

The main issue is that if you lose an engine (with a quarter of the thrust, rather than an eighth), the rudder would need to be larger to counteract the swing. I imagine that might also require the fuselage to be rebuilt for greater strength to accommodate the greater forces that a new rudder would bring. Additionally if the engines have to be moved forward like on the 737 debacle, then you'd also possibly need better elevators too and a stronger tailplane. At that point probably easier to go for a clean sheet design. Don't quote me on this but I imagine these are the main considerations.

[DaveReidUK]

Additionally if the engines have to be moved forward like on the 737 debacle, then you'd also possibly need better elevators too and a stronger tailplane.

The difference in diameter between the big fans and the F130 is much greater than that between the 737NG's CFM56 and the Max's LEAP, so I don't think any pylon configuration would allow a 4-engine option.

Unless they stuck them on top of the wing à la HondaJet/VFW614. :O

[GlobalNav]

Globalnav:
Yes they were used over Bosnia, 1998/99.
I remember seeing 5 going SW over my house in Somerset one morning and also hearing them calling London one evening when inbound to Fairford while we were inbound to Stansted.

Thank you, I supposed so. I remember thinking how lame USAF A&D was during the 70’s and 80’s not to come up with a suitable replacement for the venerable BUFF. But now I’m just grateful for the skill and hard-nosed leadership and engineering that wrought it. The KC135 too has been a capable and faithful work horse, even relatively primitive as it is compared to the alternatives. Nothing seems to beat quality and robust design.

I don’t want to forget, either, the sacrifices in peacetime and combat of the heroic crews who flew them, nor all the skilled ground support that kept them flying. I’m so proud to have served in the USAF during those years, proud of what I belonged to.

[megan]

From the flight manual.

FLIGHT CHARACTERISTICS WITH ENGINE FAILURE

SINGLE ENGINE FAILURE

The loss of an engine at any time during takeoff or while in flight is considered an emergency, regardless of the amount of thrust still available, since some emergency procedure must be executed. The loss of an engine during takeoff can be controlled easily by correct application of rudder pedal force and a slight amount of lateral control force. The rudder pedal force required in the event of an outboard engine failure is about 40 pounds at speeds below takeoff speed with zero trim. The force increases to about 80 pounds at the recommended climbout speed. All of this rudder correction usually can be removed by application of rudder trim. The rudder trim limits should be observed. See "Airspeed Limitations, " Section V.

MULTI-ENGINE FAILURE ON ONE SIDE
During inflight emergencies involving multi-engine failures on one side, applications of large amounts of rudder and lateral control are necessary in order to maintain control when extreme amounts of asymmetrical thrust exist or are applied, Application of this control creates severe loads on the aircraft structure. These loads vary in magnitude in accordance with the degree of thrust dissymmetry, degree of deflection of corrective rudder. rate of rudder application, amount of yaw/roll displacement that has taken place prior to rudder application, abruptness with which engine thrust is removed, indicated airspeed, gross weight, center oi‘ gravity, fuel distribution, amount oi air turbulence present, aircraft configuration including flaps and landing gear positions, missile loading, external tank loading, etc. If these variables occur in certain combinations, critical structural loads can result. In view of the difficulty in controlling these variables, close observance of the following procedure will minimize the possibility of structural overload.

1. If asymmetrical thrust develops abruptly, the resulting yaw/roll tendency should be counteracted with lateral control followed by steady rudder application. Trim as required to balance control forces.
2. If thrust requirements permit, readjust the power on the remaining engines to minimize control surface deflections‘ Power adjustments should be applied slowly and simultaneously with control surface movement.
3. Avoid turbulent air and limit bank angle to 20° maximum.

PERFORMANCE - WARNING - Nonzero lateral trim resulting from inoperative engines must not be compensated for by fuel manipulation because an uncontrollable roll may occur when power is reduced on approach for landing.

This aircraft is unique in its ability to handle asymmetrical thrust conditions provided the prescribed procedures are followed. See "Multi-Engine Failure on One Side, " this section. The takeoff and climbout performance of the aircraft with inoperative engines is shown in Parts 2, 3, and 4 of the Appendix, In each case, the inoperative engines are assumed to be in the most outboard positions and all on the same side. This is the most adverse condition from the stand point of trim drag which is associated with control surface deflections. Advancing the throttles to full travel in an emergency situation will give maximum thrust. This may exceed normal engine limits. Overthrusting the engines will accentuate the aircraft control problems and reduce engine life. All instances of overthrust. as indicated by excessive EGT and/or rpm will be recorded can Form 781. See "Engine Limitations," Section V.

[Ascend Charlie]

Another reason for keeping 8 engines was the design of the systems to get multiple redundancy from several sources for hydraulics, electrics, air etc.

Losing 1/2 of the electrics for an application is better than losing it all.

[henra]

That would mean a total pylon/ wing redesign along with hydraulics, electrics etc along with flight testing for engine out performance etc.
They opted for swap 8 for 8 to minimise the changes required.

https://theaviationist.com/2022/09/25/b-52-new-engine-nacelles-test/

https://www.airandspaceforces.com/article/new-power-for-the-b-52/

While USAF once considered four large-fan commercial engines instead, it stuck with eight to avoid substantial redesign of the wing, cockpit, and other components, and to minimize risk and delay.

At the end of the day it is always cost vs. benefit. The advantage of 4 bigger modern engine compared to 8 modern Business Jet engines won't be terribly big. And for this little extra advantage you have to redesign A LOT of systems and validate structure and aeroelasticity of the wing and in the worst case make structural changes to the wing structure. And have less redundancy plus potential directional control problems in case of engine failure of the outer engines. And all this for <5% less fuel burn (0.657 vs 0.627 lb/lb/h cruise sfc RR725 vs CFM56-7).

[Bahrd]

At the end of the day it is always cost vs. benefit.

Looking just at the thrust numbers of the new B-52's and the B-2's engines (and assuming the latter will be similar in B-21) I wonder why they decided not to use the Raider's engines as replacements.

[ORAC]

Still speculation as to whether the B-21 has 2 or 4 engines, let alone which type they are.

[Asturias56]

"I wonder why they decided not to use the Raider's engines as replacements."

IF they are different its probably because the B21 engines have to fit in a stealth airframe and environment

The B-52 is so unstealthy you just fit the ones that are the best deal on cost, maintainability, economy etc as it makes no effective difference to the radar signature

[Bahrd]

Still speculation as to whether the B-21 has 2 or 4 engines, let alone which type they are.
I think four engines in B-21 are more likely (B-2 has four, and one of the reason B-52 has (and will have) eight engines is the redundancy (both are strategic bombers) and "rudder authority" issues (in case of an engine failure)).
IF they are different its probably because the B21 engines have to fit in a stealth airframe and environment
From the available sources (like e.g. Northrop Grumman B-21 Unveiling May Answer Lingering Mysteries | Aviation Week Network (https://aviationweek.com/defense-space/aircraft-propulsion/northrop-grumman-b-21-unveiling-may-answer-lingering-mysteries) and Air Force Unveils New B-21 Stealth Bomber After Seven Years in the Making - Defense One (https://www.defenseone.com/technology/2022/12/air-force-unveils-new-b-21-stealth-bomber/380435/)) one can learn that B-21 has been designed with modularity in mind and with the help of as many off-the-shelf components as possible.

I am sure US AF, together with Northrop Grumman and Boeing, have examined the single engine type option in both bombers and just wondered what the reason would be not to choose it.

[unmanned_droid]

There are references to F135 derived engines in B-21 that would suggest only 2 are required.

I believe ground clearance is a major issue with a 4-engined B-52.

[KiloB]

If the B21, which has no fin and no rudder, is a twin, the single engine handling case must have been a significant design challenge!

[ORAC]

Not sure why, two centrally mounted engines with a centreline exhaust shouldn’t prove a major issue with a single engine failure.

Might need a titanium divider between them though - as in the F-111.

[Asturias56]

""one of the reason B-52 has (and will have) eight engines is the redundancy"

no - when it was designed/built (70 years ago) they needed 8 engines of the time to make it work

[tdracer]

I believe ground clearance is a major issue with a 4-engined B-52.

When I was involved in a B-52 re-engine exercise in the early 2000's, the leading contenders were the PW2000 and RB211-535 (i.e. 757 engines) - one per pod. While ground clearance was a concern, we had ways of dealing with it (one idea was getting rid of the outrigger gear on the wingtip and incorporating something into the outboard engine nacelles).
According to 'former' poster Ken V, the big issue with going with four engines was messing up the ability to carry wing mounted weapons.
Engine maintenance was not considered to be much of a concern. The time-on-wing between overhauls is so high on modern engines (15-20,000 hours between overhauls being pretty common) that the airframe would wear out before the engines...

[rigpiggy]

That would mean a total pylon/ wing redesign along with hydraulics, electrics etc along with flight testing for engine out performance etc.

They opted for swap 8 for 8 to minimise the changes required.

https://theaviationist.com/2022/09/25/b-52-new-engine-nacelles-test/

https://www.airandspaceforces.com/article/new-power-for-the-b-52/

While USAF once considered four large-fan commercial engines instead, it stuck with eight to avoid substantial redesign of the wing, cockpit, and other components, and to minimize risk and delay.
believe many eons ago they were offered jt8-219s for reengine. Too expensive, gas is cheap.

[unmanned_droid]

Yeah, I'd say having to incorporate landing gear into nacelles represents a ground clearance issue and extensive engineering effort in the solution. It sounds like a bad solution to me.

You are correct, weapons carriage on wing was another issue that was mentioned.

[tdracer]

Yeah, I'd say having to incorporate landing gear into nacelles represents a ground clearance issue and extensive engineering effort in the solution. It sounds like a bad solution to me.


The outrigger gear on the BUFF wingtips are not intended to carry significant load - they are basically there just to support the wing statically - the main body gear are intended to take all the landing loads (they don't even touch the ground unless the wing is carrying lots of fuel). So in short, the structural requirements were not that big of deal - the mass and thrust of the engines was a far more significant design consideration (for example, the gyroscopic loads of a rapidly spinning turbofan engine at rotation are massive).

[RAFEngO74to09]

Testing Underway for New B-52 Engines | Air & Space Forces Magazine (airandspaceforces.com) (https://www.airandspaceforces.com/testing-underway-for-new-b-52-engines/#.ZABhrTx3JGU.twitter)Testing is underway of two Rolls-Royce F130 engines to confirm how they perform close together and to test new digital engine controls. Rolls is conducting the tests at NASA’s Stennis Space Center, Miss., the company said.

“We want to be wrapped up by the middle of the year with this testing … because confirming that we’ve got the right inlet paces a lot of things, in terms of finalizing what the nacelle is going to look like,” Rolls-Royce B-52/F130 program director Scott Ames said in an interview.

The program is “marching toward” a critical design review in early 2024, he said. These tests will ensure “we’re ready to go with the next phase of the development program, [and] flight testing, etc.,” Ames said. “We want to make sure we get this locked in.”

The two-engine nacelle test was “a part of the Rolls-Royce proposal from the get-go,” he said. “Coming to a decision finalizing what the inlet mold lines look like for the nacelle by the middle of the year is our overarching objective.”

[fdr]

From the flight manual.

FLIGHT CHARACTERISTICS WITH ENGINE FAILURE



MULTI-ENGINE FAILURE ON ONE SIDE
During inflight emergencies involving multi-engine failures on one side, applications of large amounts of rudder and lateral control are necessary in order to maintain control when extreme amounts of asymmetrical thrust exist or are applied, Application of this control creates severe loads on the aircraft structure. These loads vary in magnitude in accordance with the degree of thrust dissymmetry, degree of deflection of corrective rudder. rate of rudder application, amount of yaw/roll displacement that has taken place prior to rudder application, abruptness with which engine thrust is removed, indicated airspeed, gross weight, center oi‘ gravity, fuel distribution, amount oi air turbulence present, aircraft configuration including flaps and landing gear positions, missile loading, external tank loading, etc. If these variables occur in certain combinations, critical structural loads can result. In view of the difficulty in controlling these variables, close observance of the following procedure will minimize the possibility of structural overload.

1. If asymmetrical thrust develops abruptly, the resulting yaw/roll tendency should be counteracted with lateral control followed by steady rudder application. Trim as required to balance control forces.
2. If thrust requirements permit, readjust the power on the remaining engines to minimize control surface deflections‘ Power adjustments should be applied slowly and simultaneously with control surface movement.
3. Avoid turbulent air and limit bank angle to 20° maximum.

PERFORMANCE - WARNING - Nonzero lateral trim resulting from inoperative engines must not be compensated for by fuel manipulation because an uncontrollable roll may occur when power is reduced on approach for landing.

This aircraft is unique in its ability to handle asymmetrical thrust conditions provided the prescribed procedures are followed. See "Multi-Engine Failure on One Side, " this section. The takeoff and climbout performance of the aircraft with inoperative engines is shown in Parts 2, 3, and 4 of the Appendix, In each case, the inoperative engines are assumed to be in the most outboard positions and all on the same side. This is the most adverse condition from the stand point of trim drag which is associated with control surface deflections. Advancing the throttles to full travel in an emergency situation will give maximum thrust. This may exceed normal engine limits. Overthrusting the engines will accentuate the aircraft control problems and reduce engine life. All instances of overthrust. as indicated by excessive EGT and/or rpm will be recorded can Form 781. See "Engine Limitations," Section V.

I'm kind of hazy on that, from only having 13,000 out of 28,000 hrs on 4 engine aircraft, but pretty sure that above VMCa2 they all would cope to an extent with a multiple engine failure on the same side. Between Vmca1 and 2, there was a bit of a choice as to what your preference was, and the outcome was dependent on having adequate clear air between the plane and the planet in order to accelerate with limited thrust on what could be controlled. (once upon a time we used to actually practice that in the plane, and that finally went to doing it in a sim, much more comfortable).

The oddity with the Buff is they had a marginal structure at the rear end, and a rudder that was designed to give excessive torsion for the amount of lateral force that may be needed. Couple that all with the design decision to go with spoilers for roll control, and you are endowing the plane with the qualities of being a bit of a beast, and not just to the other team, but to the poor schmucks that are cocooned in the plane. Design constraints in the late 40s led to the configuration that was chosen, and they have lasted some time with only a modest loss of personnel.

How bad the inherent handling of the B52 is is exhibited in the Fairchild practice disaster. While the driver and the command system got beaten up for the event, it is interesting to note that the spoiler response was being saturated quite early in the left turn that Holland entered. The speed and the bank resulted in exceeding the authority of the spoiler system, and the rudder, well, we have just commented on the rudder's authority. Occasionally, limits are there for very good reasons, bank limits on the Buff were rational, and needed to be respected. Asymmetric thrust was the last resort remaining to come out of the steepening bank, and that has not been indicated as having been attempted by the crew. Pity, McGeehan died ensuring that no other pilot in his squadron had to fly with a pilot who has a known history of operational violations.

[havoc]

https://www.airandspaceforces.com/re-engined-b-52-b-52j/?fbclid=IwAR3eCpwOjr8BErkecDUVk9NcnAb-N8S_mdYbnINTajKe-tvXFHXztAGmvqE&mibextid=Zxz2cZ

[MPN11]

Good news. Just don't do aerobatic displays with it, eh? It's not a Vulcan!

[ORAC]

https://www.airandspaceforces.com/re-engined-b-52-b-52j/

It’s Official: The Re-Engined B-52 Will be the B-52J

Once they receive their new Rolls Royce F130 engines, B-52Hs will become B-52Js, according to the Air Force’s fiscal 2024 budget documents.

The designation resolves a question that had been debated for several years (https://www.airandspaceforces.com/b-52h-may-become-b-52j/), as the B-52 undergoes some of the most significant improvements in the H model’s 61-year service life.

“Any B-52H aircraft modified with the new commercial engines and associated subsystems are designated as B-52J,” the Air Force said in justification documents for its 2024 budget request.

The service had been considering various designations for the improved Stratofortress, because in addition to new engines, the B-52 will also be receiving a new radar (https://www.airandspaceforces.com/new-image-shows-how-b-52h-will-look-after-engine-radar-replacement/), as well as new communications and navigation equipment (https://www.airandspaceforces.com/image-of-new-b-52-cockpit-shows-a-cleaner-layout/) and weapons, among other improvements intended to keep it credible and capable through the 2050s.

Given the number of major changes, Global Strike Command had considered using interim designations—“J” model aircraft would have then become B-52Ks.…

[havoc]

https://cimg1.ibsrv.net/gimg/pprune.org-vbulletin/1080x1658/img_3965_09142b0a46df20537fd01a803fb05e4dc1dcf45b.jpeg

[Winemaker]

While the driver and the command system got beaten up for the event, it is interesting to note that the spoiler response was being saturated quite early in the left turn that Holland entered. The speed and the bank resulted in exceeding the authority of the spoiler system, and the rudder, well, we have just commented on the rudder's authority. Occasionally, limits are there for very good reasons, bank limits on the Buff were rational, and needed to be respected.
Holland was a hotdog pilot who exceeded the limits and should justifiably be blamed for the crash. I well remember this event - this was not an aircraft issue, it was a driver issue. Watching video of that crash all I can think is how did the pilot imagine any lift would be generated at that bank angle; at his altitude there was no escape. This was not a crop duster; spoiler response did not cause this crash.

[Asturias56]

somewhere on here there's a thread about that crash

[ORAC]

somewhere on here there's a thread about that crash


​​​​​​​https://www.pprune.org/military-aviation/283175-bud-holland-s-low-pass-yakima-range.html#post3400550

[ORAC]

https://ukdefencejournal.org.uk/rolls-royce-on-track-for-b-52-engine-tests-by-year-end

Rolls-Royce on track for B-52 engine tests by year end

Rolls-Royce is finalising initial testing of the F130 engine for the United States Air Force B-52J Stratofortress by the conclusion of this year.

[dead_pan]

Was chatting to one of the B52 crew at RIAT about the upgrade - he said that apart from the reliability & endurance benefits, the engine pods would throw off a lot more electrical power which could have all manner of benefits (EW, comms, etc).

[ORAC]

And DEW…

[rattman]

Was chatting to one of the B52 crew at RIAT about the upgrade - he said that apart from the reliability & endurance benefits, the engine pods would throw off a lot more electrical power which could have all manner of benefits (EW, comms, etc).

yes which why they are going to be able to power an F-18 radar thats getting installed

[ORAC]

https://x.com/airpowernew1/status/1738740698705211544?s=61&t=rmEeUn68HhlFHGKbTPQr_A


A recent Office of the Under Secretary of Defense solicitation provides the best insight yet into range requirements from the USAF's high-speed Cruise Missile dev. efforts. According to the notice, USAF is looking at the Air-Breathing Cruise Missile to exceed 1000 miles.

As per the notice, AF Global Strike Command is developing a new conventional High Speed, ABCM capable of range >1K miles to be carried by the B52 that is expected to exceed the capacity of the existing conventional W pylon & Heavy Stores Adapter Beam thus requiring a redesign.

One option the Air Force is considering is repurposing the existing SUU-67/A Aircraft Pylon for conventional use. The SUU-67/A is currently used to carry the AGM-86/B Air Launched Cruise Missile (ALCM).

https://cimg3.ibsrv.net/gimg/pprune.org-vbulletin/1213x314/image_7981c9a17ffd8e795e9d487c7cfd9b4e80a560bf.png
The success criteria for this effort as per the solicitation will be the delivery of an modified SUU-67/A prototype. The modified SUU-67/A prototype will be delivered as an ready-to-integrate & ready-to-flight demonstrate asset as per the notice.

https://www.sbir.gov/node/2479843

Potential conflicts in the Pacific region will need dozens of cruise missiles in mass attacks against hostile forces. B-52 would carry 8 missiles internal and 12 on external underwing pylons. Without the modified pylon, capacity would see a 60% reduction as per the notice.

[fdr]

Holland was a hotdog pilot who exceeded the limits and should justifiably be blamed for the crash. I well remember this event - this was not an aircraft issue, it was a driver issue. Watching video of that crash all I can think is how did the pilot imagine any lift would be generated at that bank angle; at his altitude there was no escape. This was not a crop duster; spoiler response did not cause this crash.

No argument that the. Fairchild event was directly caused by violation of the Dash 1. However, command had repeatedly failed to act in response to deliberate violations. The comment on the lateral direction stability is that the assumption that exceeding limits is merely a violation of a boiler plate standard limit is not always the case. Many aircraft can exceed the envelope of the certification without a catastrophic consequence. Some cannot. The loss of control had occurred well before the nose starts to drop at Fairchild, The attitude limits on the Buff are not just empty words, exceeding them can lead to loss of control. Holland routinely breached the Dash 1, command looked the other way, and some good people died needlessly due to the whole sorry disregard of regulations, obligation and common sense.

[Commander Taco]

No argument that the. Fairchild event was directly caused by violation of the Dash 1. However, command had repeatedly failed to act in response to deliberate violations. The comment on the lateral direction stability is that the assumption that exceeding limits is merely a violation of a boiler plate standard limit is not always the case. Many aircraft can exceed the envelope of the certification without a catastrophic consequence. Some cannot. The loss of control had occurred well before the nose starts to drop at Fairchild, The attitude limits on the Buff are not just empty words, exceeding them can lead to loss of control. Holland routinely breached the Dash 1, command looked the other way, and some good people died needlessly due to the whole sorry disregard of regulations, obligation and common sense.

Most tragically, and IIRC, the poor chap in the right seat was there that day with the express purpose of pulling Holland from flying duties. It still is a shocking video to watch all these years later. The last 15 seconds or so must have been absolutely terrifying. Did/does the B52 carry a CVR?

[havoc]

Most tragically, and IIRC, the poor chap in the right seat was there that day with the express purpose of pulling Holland from flying duties. It still is a shocking video to watch all these years later. The last 15 seconds or so must have been absolutely terrifying. Did/does the B52 carry a CVR?


It did not have a CVR at that time.

[ORAC]

7 years to integrate a proven commercial engine onto a proven jet that’s been in service for over 60 years…..

https://www.defensenews.com/air/2024/02/20/tinker-air-force-base-readies-for-b-52-upgrades-as-engines-tested/

Tinker Air Force base readies for B-52 upgrades as engines tested

The Air Force expects to finish qualification testing of the new engines planned for the B-52 Stratofortress (https://www.defensenews.com/air/2024/02/12/the-new-b-52-how-the-air-force-is-prepping-to-fly-century-old-bombers/) by the end of 2024.

And the service plans to make a Milestone B decision on the Commercial Engine Replacement Program by the end of the summer, which would allow it to move into its engineering and manufacturing development phase, officials said in an interview with Defense News.….

The Air Force knows the F130 engine works, Cleaver said, since a version of it has powered the Gulfstream G650 business jet for years. But the F130s will be mounted differently on the B-52, and the Air Force needs to make sure there aren’t any surprises with the bomber’s twin-pod, under-wing configuration.

Rolls-Royce last year completed much of the initial twin-pod testing of the F130 engines at NASA’s Stennis Space Center in Mississippi, Cleaver said, and the last six-week test cycle there is expected to start in early March. Those tests will involve exposing the engine pods to cross-wind blowers, and seeing what happens if one engine in the pod has to operate at reduced power or is even inoperative.

More tests will follow, Foreman said. In April, the F130 will start sea-level performance testing on a stand at a Rolls-Royce facility in Indianapolis. Another engine will undergo durability testing through 2025, Cleaver said. And this fall, F130 testing will move to the Arnold Engineering Development Complex in Tennessee, where it will be subjected to simulated altitudes to produce more data on how it might behave in flight.

Once that round is done, they said, the F130 will have finished its qualification testing that ensures it would be safe to fly, and pave the way for test modifications to begin.

The first two test B-52s will be modified at Boeing’s San Antonio, Texas facility beginning in 2026. It will take a few years to upgrade these bombers for the first time, Cleaver said, and ground and flight tests will go from late 2028 to 2031.

After this year’s testing, Boeing will set up four systems integration laboratories to ensure adding the new engines onto the B-52 will go smoothly, Cleaver said. Three will be in Oklahoma City, near Tinker Air Force Base, and the fourth — focusing on the engines’ electrical systems — will be at a Boeing facility near Seattle.

“We have a mix of simulated functions and hardware … functions to make sure that our systems are working with each other, and that we’re not using the test aircraft as our place to find problems,” Cleaver said. The labs “will really prove out the design before we even cut into a jet.”….