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Whatever Happened To B-52 Reengine Program  
User currently offlineDAYflyer From United States of America, joined Sep 2004, 3807 posts, RR: 3
Posted (6 years 10 months 6 hours ago) and read 10873 times:

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??


One Nation Under God
31 replies: All unread, showing first 25:
 
User currently offlineDeltaDC9 From United States of America, joined Apr 2006, 2844 posts, RR: 4
Reply 1, posted (6 years 10 months 6 hours ago) and read 10872 times:

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.



Dont take life too seriously because you will never get out of it alive - Bugs Bunny
User currently offlineA342 From Germany, joined Jul 2005, 4679 posts, RR: 3
Reply 2, posted (6 years 10 months 5 hours ago) and read 10860 times:

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.
User currently offlineTexL1649 From United States of America, joined Aug 2007, 290 posts, RR: 0
Reply 3, posted (6 years 10 months 5 hours ago) and read 10862 times:

The CFM-56 would have been perfect (especially the upgraded models). Procurement needlessly complicated it (a la Arapaho). Typical.

User currently offlineRTFM From United Kingdom, joined Oct 2004, 413 posts, RR: 0
Reply 4, posted (6 years 10 months 5 hours ago) and read 10865 times:

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


User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 5, posted (6 years 10 months 2 hours ago) and read 10783 times:

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.


User currently offlineA342 From Germany, joined Jul 2005, 4679 posts, RR: 3
Reply 6, posted (6 years 9 months 4 weeks 1 day 11 hours ago) and read 10672 times:

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?



Exceptions confirm the rule.
User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 7, posted (6 years 9 months 4 weeks 1 day 10 hours ago) and read 10653 times:

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?


User currently offlineA342 From Germany, joined Jul 2005, 4679 posts, RR: 3
Reply 8, posted (6 years 9 months 4 weeks 1 day 7 hours ago) and read 10610 times:

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?



Exceptions confirm the rule.
User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 9, posted (6 years 9 months 4 weeks 1 day 6 hours ago) and read 10568 times:

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

It means that they are close enough to be considered the same.


User currently offlineRayChuang From United States of America, joined Jun 2000, 7965 posts, RR: 5
Reply 10, posted (6 years 9 months 4 weeks 12 hours ago) and read 10443 times:

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.

User currently offlineTexL1649 From United States of America, joined Aug 2007, 290 posts, RR: 0
Reply 11, posted (6 years 9 months 4 weeks 12 hours ago) and read 10439 times:

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;


User currently offlineA342 From Germany, joined Jul 2005, 4679 posts, RR: 3
Reply 12, posted (6 years 9 months 4 weeks 11 hours ago) and read 10424 times:

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.
User currently offlineLitz From United States of America, joined Dec 2003, 1753 posts, RR: 0
Reply 13, posted (6 years 9 months 3 weeks 5 days 5 hours ago) and read 10188 times:
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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


User currently offlineWaterpolodan From United States of America, joined Feb 2005, 1649 posts, RR: 5
Reply 14, posted (6 years 9 months 3 weeks 5 days 5 hours ago) and read 10180 times:

Are there any conceptual renderings of a 4 engined B52? I'd be curious to know what that would look like...

User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 15, posted (6 years 9 months 3 weeks 5 days 4 hours ago) and read 10170 times:

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.



User currently offlineWaterpolodan From United States of America, joined Feb 2005, 1649 posts, RR: 5
Reply 16, posted (6 years 9 months 3 weeks 5 days 2 hours ago) and read 10140 times:

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!

User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 17, posted (6 years 9 months 3 weeks 4 days 23 hours ago) and read 10111 times:

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.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6337 posts, RR: 3
Reply 18, posted (6 years 9 months 3 weeks 4 days 6 hours ago) and read 10003 times:

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.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineKC135TopBoom From United States of America, joined Jan 2005, 12128 posts, RR: 52
Reply 19, posted (6 years 9 months 3 weeks 4 days 5 hours ago) and read 9977 times:

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.


User currently offlineF14D4ever From United States of America, joined May 2005, 319 posts, RR: 4
Reply 20, posted (6 years 9 months 3 weeks 4 days 5 hours ago) and read 9968 times:

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.
Big version: Width: 437 Height: 380 File size: 156kb


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.



"He is risen, as He said."
User currently offlineKevinSmith From , joined Dec 1969, posts, RR:
Reply 21, posted (6 years 9 months 3 weeks 4 days 2 hours ago) and read 9933 times:

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



User currently offlineSCAT15F From United States of America, joined Feb 2007, 402 posts, RR: 0
Reply 22, posted (6 years 8 months 4 weeks 1 day 16 hours ago) and read 9620 times:

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)


User currently offlineRevelation From United States of America, joined Feb 2005, 12267 posts, RR: 25
Reply 23, posted (6 years 8 months 4 weeks 23 hours ago) and read 9478 times:

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.


Inspiration, move me brightly!
User currently offlinePADSpot From Germany, joined Jan 2005, 1676 posts, RR: 5
Reply 24, posted (6 years 8 months 4 weeks 21 hours ago) and read 9465 times:

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 


25 Post contains images SCAT15F : Hey, I just live here. All of my relatives came over from southern Germany.
26 OlegShv : 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 du
27 Post contains links KevinSmith : SECAF certified it for operational use. http://www.af.mil/news/story_print.asp?id=123063866
28 Post contains links and images N231YE : 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?
29 747400sp : 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.
30 Post contains images Srbmod : The CFM-56s (AKA GE F108) on the KC-135, C-40, and the P-8 are part French.... BAe is using the BR-710 on the Nimrod MRA4. The BR-715 is a little mor
31 Jwenting : 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 s
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