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Channex757
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Re: Best Replacement Engines for the B52

Fri Sep 22, 2017 12:30 am

Interesting video report (annoying voiceover though)
https://www.youtube.com/watch?v=NrFk-H6Ai0M

Rolls is to bid with the BR725, or F130 as it's known locally, with a US finishing and test facility to be built.
 
SCAT15F
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Re: Best Replacement Engines for the B52

Tue Nov 07, 2017 3:10 am

That's strange, I thought earlier they were offering the BR715 which makes much more sense both in terms of fuel efficiency and thrust. The BR725 would actually offer less thrust than the TF-33 and higher fuel consumption than the BR715. The BR715's thrust margin would help with hot and hi too without pushing the engine so hard.
 
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Dutchy
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Re: Best Replacement Engines for the B52

Tue Nov 07, 2017 5:02 pm

Do they get a better fuel consumption with more trust? Seems like a no brainer for the BR715. Or doesn't the BR715 fit and the BR725 does? Or weight requirements etc.
Many happy landings, greetings from The Netherlands!
 
LightningZ71
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Re: Best Replacement Engines for the B52

Tue Nov 07, 2017 9:20 pm

The BR725 is within an inch smaller than the tf33p3 in fan diameter, 700 lbs lighter, is rates for within 100 lbs/ft of thrust and is the most modern variant of the br700 family. It is as close to a drop in fit as you will find for the application . Even that being the case, it's FAR from a simple project. The interior of the nacelle will still need to be heavily reworked, the wings will need to be opened to run plenty of wires, as will the interior of the forward fuselage. The cockpit will require extensive modifications both for the pilots and engineer. And, if you are ripping all of that up, you might as well do the fatigue life limited wing panels while you are at it. And, this will have to include work done on spare frames as well.

Not cheap at all.
 
jupiter2
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 2:36 am

LightningZ71 wrote:
The BR725 is within an inch smaller than the tf33p3 in fan diameter, 700 lbs lighter, is rates for within 100 lbs/ft of thrust and is the most modern variant of the br700 family. It is as close to a drop in fit as you will find for the application . Even that being the case, it's FAR from a simple project. The interior of the nacelle will still need to be heavily reworked, the wings will need to be opened to run plenty of wires, as will the interior of the forward fuselage. The cockpit will require extensive modifications both for the pilots and engineer. And, if you are ripping all of that up, you might as well do the fatigue life limited wing panels while you are at it. And, this will have to include work done on spare frames as well.

Not cheap at all.


Can they add a toilet while they're at it ?
 
DigitalSea
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 4:45 am

Would there be a problem with increasing the size & durability of the landing gear to allow it to sit higher off the ground to accommodate different engines?
 
LightningZ71
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 4:58 am

Yes, cost. Making any significant changes to the gears would involve a major tear-up of the belly and require a lot of internal rework to handle proper load distribution. At some point, it's cheaper to just build a new conventional bomber.
 
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AirlineCritic
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 7:08 am

Is there no toilet on the B52? If true, that's amazing...
 
mmo
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 1:09 pm

AirlineCritic wrote:
Is there no toilet on the B52? If true, that's amazing...


With over 2000 hours on the D/G/H. It is VERY TRUE!
If we weren't all crazy we'd all go insane!
 
angad84
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Re: Best Replacement Engines for the B52

Wed Nov 08, 2017 6:35 pm

mmo wrote:
AirlineCritic wrote:
Is there no toilet on the B52? If true, that's amazing...


With over 2000 hours on the D/G/H. It is VERY TRUE!

I'm going to have a word with the Bear pilots I know and tell them to STOP GRIPING ALREADY. Never realised the BUFF lacked a loo. Damn silly really.
 
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Revelation
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 1:55 am

Idlewildspotter wrote:
I believe the GE Passport BizJet Engine would be a wonderful replacement for the 8 Guzzling Tubes currently on the BUFF

SCAT15F wrote:
I never heard anything about the BR-725 being proposed.

Recent article at AvWeek: USAF Could Start Re-engining First Two B-52s By 2022 (free registration required) gives us lots of info from a recent conference at Barksdale:

• TF33 is not sustainable past 2030 due to obsolescence
• Another big issue is increased demands for electricity, up to 500 kVA
• Power demands come from modern weapons and fire control systems
• The aircraft will need an all-new power architecture too
• Program could cover 650 engines for the 72 aircraft fleet and for spares

and a lot more.

It ends with:

The leading candidates are Rolls-Royce’s 16,000 lb.-thrust BR725 and GE Aviation’s 18,000-lb.-thrust CF34-10.

Seems like the usual suspects smell blood and are circling the prey.

LightningZ71 wrote:
The BR725 is within an inch smaller than the tf33p3 in fan diameter, 700 lbs lighter, is rates for within 100 lbs/ft of thrust and is the most modern variant of the br700 family. It is as close to a drop in fit as you will find for the application . Even that being the case, it's FAR from a simple project. The interior of the nacelle will still need to be heavily reworked, the wings will need to be opened to run plenty of wires, as will the interior of the forward fuselage. The cockpit will require extensive modifications both for the pilots and engineer. And, if you are ripping all of that up, you might as well do the fatigue life limited wing panels while you are at it. And, this will have to include work done on spare frames as well.

Not cheap at all.

Indeed. As above, add to your list an all new power architecture, new fire control system and weaponry, etc.

Then ask where the money comes for this, B-22, F-35, KC-46A, etc.
The gun is NOT a precious symbol of freedom
It is a deadly cancer on American society
Those who believe otherwise are consumed by an ideology
That is impervious to evidence
 
mmo
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 7:30 am

Revelation....

Since you seem to be so pedantic, just wanted to clarify, there is HO fire control system on the H models. The vulcan cannon was removed several years ago. Also, could you tell us what the B-22 is? I must have missed that one. Do you mean the B-2 or the B-21?
If we weren't all crazy we'd all go insane!
 
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flyingturtle
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 10:19 am

AirlineCritic wrote:
Is there no toilet on the B52? If true, that's amazing...


Yes, they still have a simple bucket. This was also featured in http://www.bbc.com/news/magazine-33766644 .

In a Swiss bunker (built after 1950, to repel a possible Soviet invasion) I've seen a toilet seat mounted above a trash bag holder. I hope it was +/- airtight.............


LightningZ71 wrote:
the wings will need to be opened to run plenty of wires, as will the interior of the forward fuselage. The cockpit will require extensive modifications both for the pilots and engineer.


Wait - couldn't they put a little computer between cockpit and each engine, so that the computer translates all commands and signals in such a way that the modern engine is presented to the cockpit as an old TF-33?

David
Keeping calm is terrorism against those who want to live in fear.
 
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Revelation
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 1:07 pm

mmo wrote:
Revelation....

Since you seem to be so pedantic, just wanted to clarify, there is HO fire control system on the H models. The vulcan cannon was removed several years ago. Also, could you tell us what the B-22 is? I must have missed that one. Do you mean the B-2 or the B-21?

The fire control requirement is mentioned in the AvWeek article, and I too didn't understand why that was on the table.

The B-22 is a typo. I meant B-21 which is a program that one would think would be demanding a lot of funds at the same time this proposal would also need funding.

Thanks for your questions.
The gun is NOT a precious symbol of freedom
It is a deadly cancer on American society
Those who believe otherwise are consumed by an ideology
That is impervious to evidence
 
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Revelation
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 1:12 pm

flyingturtle wrote:
Wait - couldn't they put a little computer between cockpit and each engine, so that the computer translates all commands and signals in such a way that the modern engine is presented to the cockpit as an old TF-33?

I think developing, certifying, manufacturing and maintaining that translation interface is going to be more costly than just installing the new technology end to end.

As an engineer, pretty much every time I've taken the approach you are suggesting I've regretted it.

For instance, there's going to be a spamload of very useful information that a modern engine will generate, yet that info can't be passed via the TF-33's control mechanism.

You might as well just use the modern mechanism that's already ready to go, at the cost of having to redo the cockpit, which you'll want to do anyway to take advantage of the additional information.

Things are going to have to be torn down due to the uprated power production anyway so running the control paths for the engines should be relatively minor.
The gun is NOT a precious symbol of freedom
It is a deadly cancer on American society
Those who believe otherwise are consumed by an ideology
That is impervious to evidence
 
morrisond
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 8:12 pm

The B21 should be in production well before 2030 - just use the funds to build more of them or speed up production and stop putting more money into the B-52.

The TF-33 may not be sustainable for the full fleet after 2030 - but they should have enough parts or canabalize other planes to gradually retire them after 2030 - giving more time to build more B-21's.
 
mmo
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 8:49 pm

morrisond wrote:
The B21 should be in production well before 2030 - just use the funds to build more of them or speed up production and stop putting more money into the B-52.

The TF-33 may not be sustainable for the full fleet after 2030 - but they should have enough parts or canabalize other planes to gradually retire them after 2030 - giving more time to build more B-21's.



The problem is the decision to keep the BUFF in the inventory until the mid 2050s. The TF-33 will be unsustainable sometime after early 2020, which means there would be no more engines to cannibalize.
If we weren't all crazy we'd all go insane!
 
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flyingturtle
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Re: Best Replacement Engines for the B52

Thu Dec 28, 2017 9:48 pm

Revelation wrote:
For instance, there's going to be a spamload of very useful information that a modern engine will generate, yet that info can't be passed via the TF-33's control mechanism.


Well, can't they just use Wifi? :bouncy:

...anyway, re-engining those old and trusty bomb trucks isn't the most expensive thing for the USAF.


David
Keeping calm is terrorism against those who want to live in fear.

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