DAYflyer
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Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 4:27 am

I recently attended the airshow at DAY and a B-52 pilot told me that at one time the USAF had talked about re-engining the B-52 with the CFM56 (like they did on a limited number of KC-135) but the program never materialized. Does anyone have any information on it??
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deltadc9
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 4:42 am

Quoting DAYflyer (Thread starter):
I recently attended the airshow at DAY and a B-52 pilot told me that at one time the USAF had talked about re-engining the B-52 with the CFM56

I had heard they were looking into something much bigger and swapping 8 for 4.
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A342
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 5:15 am

IMO, four CFM56-5C4s are enough. The combined thrust is the same as that of the eight TF33s, which are not rated at full power anyway.
Exceptions confirm the rule.
 
texl1649
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 5:20 am

The CFM-56 would have been perfect (especially the upgraded models). Procurement needlessly complicated it (a la Arapaho). Typical.
 
rtfm
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 5:53 am

Quoting DAYflyer (Thread starter):
re-engining the B-52 with the CFM56

Actually there was a proposal to re-engine them with RR RB211s; there is some more info on the B52 entry on Wikipedia on this; seems like the cost/benefits did not work out (tho' the entry goes on to state that these figures have been disputed...)

Link is here: http://en.wikipedia.org/wiki/B52
 
KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 8:57 am

See I no kidding had heard that they were thinking about re-engining them with 8 CF34s, not unlike what is on the ERJ-190s. It seems to me that the 8 for 8 would be ideal because you wouldn't have to rewire and re-plumb for four engines. Then again I am sure that there are other costs. One CFM56 might be cheaper than two CF34s. Four engines means 50% less engine maintenance.

Quoting A342 (Reply 2):
which are not rated at full power anyway.

What does that mean? That the TF-33s are capable more than 17K lbs of thrust a piece?

Quoting A342 (Reply 2):
four CFM56-5C4s

That'd work alright  Wink I'd be afraid of them scrapping the ground though.
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A342
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RE: Whatever Happened To B-52 Reengine Program

Sat Sep 15, 2007 11:27 pm

Quoting KevinSmith (Reply 5):
What does that mean? That the TF-33s are capable more than 17K lbs of thrust a piece?

Bingo! On the E-3 Sentry AWACS aircraft they're rated at 21K lbf each.

Quoting KevinSmith (Reply 5):
That'd work alright  wink  I'd be afraid of them scrapping the ground though.

Yes, one CFM56-5C4 provides 34K lbf each. Regarding ground clearance: If the CFM56 doesn't work, how would the RR RB.211?
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KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 12:23 am

Quoting A342 (Reply 6):
RR RB.211?

I don't think they would work either.

Quoting A342 (Reply 6):
On the E-3 Sentry AWACS aircraft they're rated at 21K lbf each.

Ah ok I see. In fairness though the E-3 has PW-100As and the 52 P-3/103s. Close enough for government work though, right?
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A342
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 3:13 am

Quoting KevinSmith (Reply 7):
I don't think they would work either.

It was extensively studied, so I think it could have worked. Only the bean counters prevented it.

Quoting KevinSmith (Reply 7):
Close enough for government work though, right?

How do you mean that?
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KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 5:09 am

Quoting A342 (Reply 8):
How do you mean that?

It means that they are close enough to be considered the same.
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 10:23 pm

I think the most likely upgrade could be what Pratt & Whitney proposed in the early 1980's: replace eight TF-33's with four militarized versions of the PW2040 engine found on later-production 757's. This would allow the B-52H fleet to remain operational to the 2040 retirement date the USAF has talked about for many years.
 
texl1649
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 10:44 pm

Boeing pushed the RB211, had lot's of notional drawings, and projected long-term savings in the billions I think if the AF had re-engined about 5-10 yrs ago.

"Boeing is proposing to change the B-52 from an eight-engine configuration to four, saying the new configuration would give a number of advantages:

• A savings of $6 billion during the remaining life of the B-52 fleet, which could be extended by about 30 years.

• Boosting aircraft performance by increasing take-off thrust from 136,000 pounds to 172,000 pounds and also decreasing required runway distance. "

http://www.bizjournals.com/wichita/stories/1996/07/08/story1.html

Boeing looked at a lot of options;
 
A342
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RE: Whatever Happened To B-52 Reengine Program

Sun Sep 16, 2007 11:28 pm

Quoting KevinSmith (Reply 9):
It means that they are close enough to be considered the same.

Well, they might be the very same engine, only with different ratings. But I don't know for sure.
Exceptions confirm the rule.
 
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RE: Whatever Happened To B-52 Reengine Program

Wed Sep 19, 2007 5:52 am

Quoting TexL1649 (Reply 11):
A savings of $6 billion during the remaining life of the B-52 fleet, which could be extended by about 30 years.

Only one reaction possible to that .... wow ... that is just one amazing airplane.

- litz
 
waterpolodan
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RE: Whatever Happened To B-52 Reengine Program

Wed Sep 19, 2007 6:09 am

Are there any conceptual renderings of a 4 engined B52? I'd be curious to know what that would look like...
 
KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Wed Sep 19, 2007 6:41 am

Quoting Waterpolodan (Reply 14):
Are there any conceptual renderings of a 4 engined B52? I'd be curious to know what that would look like...

Not exactly what you were looking for but it can give you an idea.

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waterpolodan
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RE: Whatever Happened To B-52 Reengine Program

Wed Sep 19, 2007 8:54 am

That's a hell of a big engine, what is it? Early 747 powerplant? The photo looks old, and though I'm no expert it looks like the outer engines are still turbojets, so it's suprising to see such a modern looking high bypass turbofan on that plane... Cool!
 
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RE: Whatever Happened To B-52 Reengine Program

Wed Sep 19, 2007 12:08 pm

Quoting Waterpolodan (Reply 16):
outer engines are still turbojets

They are.

The engine in question according to the website is a TF-39, what they used on the C-5.
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KELPkid
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RE: Whatever Happened To B-52 Reengine Program

Thu Sep 20, 2007 4:20 am

Quoting Waterpolodan (Reply 16):
That's a hell of a big engine, what is it? Early 747 powerplant? The photo looks old, and though I'm no expert it looks like the outer engines are still turbojets, so it's suprising to see such a modern looking high bypass turbofan on that plane... Cool!

It might very well be the JT9D. IIRC, the B-52 was the only aircraft that was not experimental that was available (and able!) to flight test the P&W JT9D...nothing else had the on-wing clearance to do the test.
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RE: Whatever Happened To B-52 Reengine Program

Thu Sep 20, 2007 5:49 am

Quoting A342 (Reply 2):
IMO, four CFM56-5C4s are enough. The combined thrust is the same as that of the eight TF33s, which are not rated at full power anyway.



Quoting KevinSmith (Reply 5):
What does that mean? That the TF-33s are capable more than 17K lbs of thrust a piece?



Quoting A342 (Reply 6):
Bingo! On the E-3 Sentry AWACS aircraft they're rated at 21K lbf each.

There are two different versions (and generations) of the TF-33 used on the B-52H and the E-3A/B/C. The B-52H TF-33P7 engines could be uprated to only 18,000lbs, but why do that? The E-3A has the TF-33-P100 engine.

There was a Boeing proposal in the 1980s to reengine all B-52G & H aircraft with 6 CFM-56-B4 engines, the same engine in the KC-135R reengine program. The engines would be mounted like the configueration on the old B-47. Later came the proposal for 4 PW-2042 C-17 engines (for the B-52G/H), and finally 4 RR RB-211 engines for the B-52H only.

All 3 proposals have been rejected as not being worth the costs of the engineering and reengining.
 
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RE: Whatever Happened To B-52 Reengine Program

Thu Sep 20, 2007 6:11 am

Quoting KevinSmith (Reply 17):
The engine in question according to the website is a TF-39, what they used on the C-5.

The TF39 was indeed test flown on a B-52, but the turbofan in your photo is not a TF39, as the cowl is much too long to be a TF39, and the TF39 first fan stage is half-span, very recognizable.
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Quoting KELPkid (Reply 18):
It might very well be the JT9D.

Could be, but also could be a CF6. The GE photo archive has photos of a CF6 undergoing flight test.
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KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Thu Sep 20, 2007 8:17 am

Quoting F14D4ever (Reply 20):
The GE photo archive has photos of a CF6 undergoing flight test

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SCAT15F
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RE: Whatever Happened To B-52 Reengine Program

Mon Oct 15, 2007 7:04 pm

Quoting KC135TopBoom (Reply 19):
There was a Boeing proposal in the 1980s to reengine all B-52G & H aircraft with 6 CFM-56-B4 engines, the same engine in the KC-135R reengine program. The engines would be mounted like the configueration on the old B-47. Later came the proposal for 4 PW-2042 C-17 engines (for the B-52G/H), and finally 4 RR RB-211 engines for the B-52H only.

All 3 proposals have been rejected as not being worth the costs of the engineering and reengining.

There has also been a more recent proposal to reengine the B-52 with 8 Rolls Royce BR-715 engines at 21,000 lb thrust each. The advantage being that the B-52 is already set up for 8 engines. (and of course, the BR-715 is a very efficient engine)
 
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 16, 2007 11:45 am

I thought one reason the re-engine programs did not make financial sense was that the government had already bought large stockpiles of TF-33s.
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 16, 2007 1:31 pm

Quoting SCAT15F (Reply 22):
The advantage being that the B-52 is already set up for 8 engines. (and of course, the BR-715 is a very efficient engine)

Sure but, civil aviation has shown that few larger engines are more economical than many smaller ones. And as the BR-715 is a German made engine I can imagine people expressing their fear again that infidel ally Germany could use that to blackmail the US in case of an unwanted war.  duck   stirthepot 
 
SCAT15F
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 16, 2007 5:00 pm

Quoting PADSpot (Reply 24):
And as the BR-715 is a German made engine I can imagine people expressing their fear again that infidel ally Germany could use that to blackmail the US in case of an unwanted war.

Hey, I just live here. All of my relatives came over from southern Germany.

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OlegShv
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 16, 2007 8:44 pm

Quoting DAYflyer (Thread starter):
Does anyone have any information on it??

I've seen a talk by the head of AFRL Propulsion directorate a couple weeks ago. It seems like the Air Force abandoned this B-52 reengining program due costs involved. The latest and greatest thing they are looking at right now to save money on fuel is to use 50/50 mix of regular jet-a with synthetic coal-based fuel. They already have a B-52 demonstrator flying with the new fuel system. This program is supposed to be cost effective as long as the crude stays above $50-60/barrel.
 
KevinSmith
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 16, 2007 8:58 pm

Quoting OlegShv (Reply 26):

I've seen a talk by the head of AFRL Propulsion directorate a couple weeks ago. It seems like the Air Force abandoned this B-52 reengining program due costs involved. The latest and greatest thing they are looking at right now to save money on fuel is to use 50/50 mix of regular jet-a with synthetic coal-based fuel. They already have a B-52 demonstrator flying with the new fuel system. This program is supposed to be cost effective as long as the crude stays above $50-60/barrel.

SECAF certified it for operational use.

http://www.af.mil/news/story_print.asp?id=123063866
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N231YE
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RE: Whatever Happened To B-52 Reengine Program

Fri Oct 26, 2007 11:34 pm

Out of curiosity, why is the B-52 re-enginement program deemed a waste of money, yet there is a current C-5 re-enginement program going on right now? Is the C-5 a worse fuel hog, or utilized more, or even planned to be around longer?

Quoting KELPkid (Reply 18):
Quoting Waterpolodan (Reply 16):That's a hell of a big engine, what is it? Early 747 powerplant? The photo looks old, and though I'm no expert it looks like the outer engines are still turbojets, so it's suprising to see such a modern looking high bypass turbofan on that plane... Cool!
It might very well be the JT9D. IIRC, the B-52 was the only aircraft that was not experimental that was available (and able!) to flight test the P&W JT9D...nothing else had the on-wing clearance to do the test.

From the USAF website:

http://i127.photobucket.com/albums/p152/N231YE/061127-F-1234S-026.jpg
 
747400sp
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RE: Whatever Happened To B-52 Reengine Program

Tue Oct 30, 2007 10:37 pm

It was supposed to be six CFM 56-2. If this project was a success, the B-52 would have had the most CFM 56 on one a/c.
 
srbmod
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RE: Whatever Happened To B-52 Reengine Program

Sat Nov 17, 2007 8:54 pm



Quoting PADSpot (Reply 24):

Sure but, civil aviation has shown that few larger engines are more economical than many smaller ones. And as the BR-715 is a German made engine I can imagine people expressing their fear again that infidel ally Germany could use that to blackmail the US in case of an unwanted war.

The CFM-56s (AKA GE F108) on the KC-135, C-40, and the P-8 are part French....  duck 

BAe is using the BR-710 on the Nimrod MRA4.

The BR-715 is a little more powerful engine than the TF-33s, so they would be an ideal candidate as a replacement engine on the B-52s. I'm sure Rolls Royce would like to see some more orders for the BR-715s since now that the 717 is no longer in production, the number of engines they'll be selling down the road is not as great.
 
jwenting
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RE: Whatever Happened To B-52 Reengine Program

Sun Nov 18, 2007 5:05 pm

interesting isn't it, how this topic comes up here with such regularity while the rest of the world has decided it's a non-issue because the BUFF is soldiering on nicely on its existing engines.
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