B-52 Re-engining?

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shingen

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Unread post21 Jan 2012, 23:12

What would be the best way to improve the B-52's engines?

Is it likely that the reduced consumption of fuel would pay for new engines?

Would going to 4 engines reduce fuel and maintenance costs more?

What would be the ideal engine for the B-52 if they were to be replaced and why?
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sferrin

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Unread post21 Jan 2012, 23:28

Is there a reason they couldn't swap the TF-33s for the F118s used in the B-2?
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Unread post21 Jan 2012, 23:35

Ge-90115B. Would require significantly new pylons but you would only need two of them and they are the 2nd (?) most efficient jet engines in that class (I think the GeNX is more efficient, but at half the thrust) Maintenance drops from 8 engines to 2. High wing design so clearance should not be an issue.

8x TF33 (current motors)
Thrust: 8x17,000 = 136,000 lbs
Weight: 8x4,790 = 38,320 lbs
TSFC: .56

2x Ge90-115B (from 777-300ER)
Thrust: 2x115,000 = 230,000 lbs
Weight 2X18,260 = 36,520 lbs
TSFC: ~.3-.35

2x GeNX (from 787)
Thrust: 2x72,300 = 144,600 lbs
Weight: 2x12,822 = 25,644
TSFC: ??
Last edited by sprstdlyscottsmn on 21 Jan 2012, 23:40, edited 1 time in total.
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sprstdlyscottsmn

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Unread post21 Jan 2012, 23:37

f118s have less thrust

edit: double checked numbers, used wrong specs for TF33 in above post. But the re-engineing should drop the engines to 4 or 2 for maintenance
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Unread post22 Jan 2012, 00:05

A proposal to re-engine the B-52 with 4 high-bypass turbofans (for better low altitude performance) was made in 1953. LeMay, never a fan of low-level penetration, shot the plan down.
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Unread post22 Jan 2012, 00:48

Well, boys, we got three engines out, we got more holes in us than a horse trader's mule, the radio is gone and...


Two GE-90's and future generations won't appreciate this. :cry:

The envisioned sequel: "Well boys, we got two engines out, I guess the movie is over."

We'll also lose the signature, timeless SAC bomber phrase:

"Grab some throttles, we're going around."

:D

(What will they do with the extra throttles?)
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Unread post22 Jan 2012, 01:11

Two engines has never been an option. The same issue arose with the KC-135 upgrade. It would cost too much to re-engineer the wings, pylons, flight controls, and systems. Hence the KC-135 retained 4 motors on 4 pylons. The B-52 upgrade studies of the past did the same; kept 4 motors on the 4 available pylons.

With that; in the interest of saving the USAF money and capitalizing on existing contracts and infrastructure; I'd opt for the F117 of the C-17 @ 40.4K thrust. We can call it the F117-PW-200. There are over 1000 F117 engines currently in use with the USAF. Logistics are in place and much experience has been gained with this military version of the PW2000 commercial engine. Many common parts would be available worldwide.

The F108 of the KC-135 could be an option as well; many 'used motors' would be available as the new KC-46 comes online and the KC-135s are sent to the bone yard. Downfall to this is only 27K thrust which equal to combined twin J57-P-43WB of the older B-52G, but lower than the combined twin TF33-P-103 power.

The Allison/Rolls commercial RB-211-535 has been considered,.

Others including the PW2040 (Which could be our F117-PW-200)

Read for the savings and thoughts on the topic; http://www.acq.osd.mil/dsb/reports/ADA428790.pdf

Keep 'em flyin' :thumb:
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(Edit - added clarification of my F108 statement)
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Unread post22 Jan 2012, 01:50

TEG, thanks for telling us that there was such an issue with twin engine conversions. The F117 is a logical choice for logistics. And looking at preliminary TSFC data (drag characteristics would change a little, but not a lot, its a big plane) there would be something on the order of a 50%+ increase in range. That would be a combat radius of ~5,800 nm or a ferry range of ~13,000nm. For ferry ops it would need less than full fuel to get to any point on the planet, full fuel would allow for HUGE detours. Oh yeah, and the 18% increase in thrust would allow for shorter runways for takeoff and better climb out. Okay TEG, start a petition.
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Unread post22 Jan 2012, 02:32

outlaw162 wrote:
Well, boys, we got three engines out, we got more holes in us than a horse trader's mule, the radio is gone and...


Two GE-90's and future generations won't appreciate this. :cry:

The envisioned sequel: "Well boys, we got two engines out, I guess the movie is over."

We'll also lose the signature, timeless SAC bomber phrase:

"Grab some throttles, we're going around."

:D

(What will they do with the extra throttles?)


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http://www.youtube.com/watch?v=JlSQAZEp ... re=related
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southernphantom

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Unread post22 Jan 2012, 21:20

If the TF33s were replaced with former KC-135 CFM-56 engines, it would need to be a one-for-one replacement to avoid LOSING overall thrust. One CFM-56/F108-CF-100 does not have anywhere the thrust of two TF-33s.
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That_Engine_Guy

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Unread post22 Jan 2012, 22:27

southernphantom wrote:If the TF33s were replaced with former KC-135 CFM-56 engines, it would need to be a one-for-one replacement to avoid LOSING overall thrust. One CFM-56/F108-CF-100 does not have anywhere the thrust of two TF-33s.


The F108 wouldn't add thrust, but would increase efficiency and reduce weight.

Everyone should remember, the B-52 re-engine studies weren't based on 'increasing thrust' but reducing fuel burn, and reducing logistics costs on the Buff's remaining life cycle.

TEG
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Unread post22 Jan 2012, 22:32

Here yo go, a B-52 with 4 RB-211s

Image

http://homepage.ntlworld.com/rez.manzoo ... /fakes.htm

Here is a B-52 testing a C-17 engine

Image
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Unread post22 Jan 2012, 22:59

SpudmanWP wrote:Here yo go, a B-52 with 4 RB-211s

Very cool fake, only thing I would say it lacks is a shortened #1/#4 (outboard) pylons.

If you look at the second photo, a large BPR engine on the outboard pylons would require a very short profile.

Otherwise they'd drag due to the Buff's pronounced wing-droop.

Maybe a wheel in the bottom of the cowling? :lol:

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Unread post22 Jan 2012, 23:40

SpudmanWP wrote:Here is a B-52 testing a C-17 engine

Image


Actually that was a TF39 for the C-5A. They were testing the engine for the C-5 program, not as an option for the B-52. There was a second B-52 used to test the JT9D for the 747 program.

USAF Museum wrote:Two B-52Es were modified for use as engine test beds. One aircraft (B-52E-55-BW, S/N 57-0119) was used to test the General Electric TF-39 for the Lockheed C-5A Galaxy program. The TF-39 was mounted on the right inboard engine pylon in place of the two J57s normally installed. The single TF-39 turbofan, rated at about 40,000 pounds, had as much thrust as four J57 turbojets on a standard production B-52E.

Another aircraft (B-52E-85-BO, S/N 56-0636) was similarly modified to test the JT9D turbofan engine for the Boeing 747 program.


http://www.nationalmuseum.af.mil/factsh ... sp?id=2628

Here are the other photos of JB-52E (S/N 57-0119)

Image
Image
Image

Until recently PW used two old Boeing 720 to test a variety of their motors.

Photo credits to the appropriate people but lots of images and test motor installations can be seen here.
http://www.airliners.net/search/photo.s ... entry=true

Or do a google image search for "C-FETB"

Less photographed was N720PW, but she was cannibalized for parts to keep sister C-FETB in the air; N720PW was to be scrapped in 2008 or 2009.

It's said on the internet that PW Canada retired C-FETB in Sep of 2010.

Edit - PW now uses 747SP - N747UT to test engines.
Video of her here: http://www.youtube.com/watch?v=acMduTBOhtY

Keep 'em flyin' :thumb:
TEG
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Unread post23 Jan 2012, 01:58

Good catch (re C-5/C-17 mixup), my bad.
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