BUFFs heading in for new upgrades

[PR19_Kit]

I wonder how soon it will be before the first grand-child of an original B-52 pilot flies one?   

IIRC they already are. I seem to recall that being mentioned in a magazine article a year or so back.

I of all people here are only too aware that a R-R built item helps fly the F-35 as I installed and maintained the monster friction welder that makes the lift fans. If they had decided to re-engine the Buffs with an RB211 variant they would have to have been built in Derby as it's the only R-R or Allison plant large enough to assemble them.

[Dizzyfugu]

There was a proposal a few years back to re-engine them with CFM fans as well. 

I remember reading about this topic in the early 90ies, when the idea of four more modern and fuel-economic turbofans (by the time, Boeing introduced the 757 and 767 with two engines each) on the B-52 was already around. Now, more than 20 years later, no progress, but the BUFF is still in service...

[Spey_Phantom]

indeed, i would recommend replacing the 8 TF-33's (17.000lbs of thrust) with 4 new CFM56-5C4 turbofans (34.000lbs of thrust) witch also powers the Airbus A340.

or if you want something more with lower maintainance costs, 2 or 4 PW4000's (74.000 to 98.000lbs of thrust)

they would not only make the B-52 less thursty, but it would also provide some extra power 

[Weaver]

Thinking about the economics of it some more, one issue might be that military aircraft fly far fewer hours than civil ones, so it would take far longer for a more fuel-efficient engine to pay for itself on a B-52 than on an airliner. Of course, this all depends on the fuel price, and you might still make an argument that, given the length of the B-52's projected life, it was short-sighted not to re-engine them in advance of a fuel-price hike rather than in reaction to it.

[Talos]

If I remember correctly, the ultimate reason the USAF didn't go with the RB or any other reengining for the B-52 was that they had enough spare TF33s and parts in maintenance stockpiles to last for the entire expected service life of the plane.

[famvburg]

ISTR reading that a major reason for not going with 4 large engines instead of the 8 smaller ones is that the airframe's aerodynamics was designed for failure of one of 4 engines at take-off, not 1 of 2, the assymetric thrust being too much apparently.

[Gondor]

ISTR reading that a major reason for not going with 4 large engines instead of the 8 smaller ones is that the airframe's aerodynamics was designed for failure of one of 4 engines at take-off, not 1 of 2, the assymetric thrust being too much apparently.

Then surely they can replace the TF33's with something about the same physical size and quantities which being modern would be more fuel efficient and would also have probably more thrust.

Gondor

[jcf]

So the TF33 has a length of 142", max diameter of ~54", fan is 51+; the CFM56-7B series as used on
the 737NG have a length of 98.7", fan diameter of 61". The power ratings go from 19,500 to 27,000 lbs,
depending on sub-type. The most powerful -27B is used on the 737-800/900/BBJ and P-8.
http://www.cfmaeroengines.com/engines/cfm56-7b

Slight increase in nacelle diameter, big increase in performance, without the possible negative effects
of a 6 foot or more diameter fan.

Two -27B on each inboard pylon, one on the outer for a Super B-47 look. 


BTW the TF33-P-100A as used on the E-3 are 21,000lb thrust engines, so I wonder if the BUFF engines
could be upgraded to that standard?

[KJ_Lesnick]

Why not just get GE to acquire through CFM a license from RR to build the RB-211-535: Sure they'd have to pay royalties but it's an off the shelf engine which we can build on US soil with US workers as it should be.

[PR19_Kit]

GE to buy an R-R engine licence? Yeah, right....

Ask them if they'd do it the other way round and see what they say, they're competing with each other in the big fan market!!!

[Howard of Effingham]

i always wonder if even with these upgrades and more modern techniques, the B-52 fleet will eventually just
run out of airframe hours.

[Rheged]

There's a perfectly good American  company called The Allison Engine Company*  who could  build  Rolls Royce engines in the USA.   I can't see  Rolls Royce Group PLC  objecting!







*Allison is also known as "Rolls-Royce Corporation, part of Rolls-Royce North America".

[PR19_Kit]

There's a perfectly good American  company called The Allison Engine Company*  who could  build  Rolls Royce engines in the USA.   I can't see  Rolls Royce Group PLC  objecting!

KCF pointed that out already, but would it make commercial sense to build a complete new plant just to build a small number of RB211s? The size of the assembly hall in Derby where they build them is IMMENSE, and I can't see R-R wanting to invest in a copy of it over in the US unless there was the prospect of a longer production run there.

[scooter]

There's a perfectly good American  company called The Allison Engine Company*  who could  build  Rolls Royce engines in the USA.   I can't see  Rolls Royce Group PLC  objecting!

KCF pointed that out already, but would it make commercial sense to build a complete new plant just to build a small number of RB211s? The size of the assembly hall in Derby where they build them is IMMENSE, and I can't see R-R wanting to invest in a copy of it over in the US unless there was the prospect of a longer production run there.

It would make supply stream logistics easier for the airlines in the US that have RB211-equipped airframes.  Use it to not only build new, but also rebuild as a depot-level maintenance facility.

And while we're at it, why not re-engine the E-3/E-8 fleet with 211s?

[PR19_Kit]

There's a perfectly good American  company called The Allison Engine Company*  who could  build  Rolls Royce engines in the USA.   I can't see  Rolls Royce Group PLC  objecting!

KCF pointed that out already, but would it make commercial sense to build a complete new plant just to build a small number of RB211s? The size of the assembly hall in Derby where they build them is IMMENSE, and I can't see R-R wanting to invest in a copy of it over in the US unless there was the prospect of a longer production run there.

It would make supply stream logistics easier for the airlines in the US that have RB211-equipped airframes.  Use it to not only build new, but also rebuild as a depot-level maintenance facility.

And while we're at it, why not re-engine the E-3/E-8 fleet with 211s?

Is there enough room under the wings of anE-3/E-8 for even the smallest 211?

The 757 uses a 'little' 211 with around 40000 lbs thrust and it's a LONG way off the ground. One reason why the 707 was never stretched like the DC8s were was because it had shorter legs and couldn't rotate a longer fuselage. Stretching the legs to get a big turbo-fan clear of the ground would require a complete re-design of the inner wings, fuselage and landing gear, anything BUT economic, even if it was actually practical.