Originally posted by Monash
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US Air Force upgrading B-52s
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There's frequently been talk of converting 747's into bombers or cruise missile carriers. The problem is that structurally these civilian aircraft are much different than a B-52. They would handle much differently than a purpose built bomber when loaded with a heavy bomb load and then suddenly dropping it. When you figure in the structural changes and ruggedization plus the avionics, you are not saving so much money. Then there is the problem of using something that is recognized as an airliner the world over as a weapon- do you make a target of all airliners now? Best to just use the civilian stuff for freight and personnel transport and use bombers for bombers. Why mess with a successful design?
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I understand that the availability of spare engines would inhibit the buff's engine swap. But consider these numbers...
The typical cruise fuel flow on a JT8D is ~ 3,000 pph/engine: X 8 = 24,000 pounds/hour
JT8D TO thrust - varies between models, but call it 15,000 lb each, total 120,000 lb
If the engine pods were replaced with 4 ea CFM56 engines, the cruise fuel flow would be approximately 2,800 pph/engine; total fuel flow 11,200 lb - less than half the fuel flow. Imagine the range improvement! And it doesn't take long at that savings to pay for the engines with reduced fuel burn alone.
The BUFF can carry 312,000 lb of fuel. Ignoring climb fuel for a moment, 300,000 lb equates to 26 hours of flight. Also, fewer engines generally equates to superior maintenance and readiness.
The thrust using 4 ea. CFM56 engines may not be adequate. One option would be to hang 2 larger engines inboard, and use CFM-56's outboard. Another option which I'm sure has been tossed out is some sort of aerodynamic fairing that would allow the crew to shut engines down without an immense drag penalty. That would be complex, probably not practical, but in terms of range - another enormous boost.
Just thinking out loud.
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There are several variants of the CFM56 that produce 30k+. But there would be other options as well, such as removing or replacing the external tanks with smaller ones, thanks to the vastly improved efficiency. I've never read the B-52 TO, but if its engines have the same limitations as the E-3s a 26-hr mission isn't even possible. Even without physically modifying the fuel tank system, it's unlikely a BUFF would ever need to take off with a full fuel load anyway.
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TF-39 on JB-52E
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Originally posted by JA Boomer View PostTF-39 on JB-52E"There is never enough time to do or say all the things that we would wish. The thing is to try to do as much as you can in the time that you have. Remember Scrooge, time is short, and suddenly, you're not there any more." -Ghost of Christmas Present, Scrooge
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Originally posted by Jimmy View PostThat's kind of funny, since the TF39 is a direct descendant of the CFM56.
Anyways I guess that B-52E was used as the testbed platform for the TF39, which was to be installed on the C-5A Galaxy that was in production, and was the first high bypass turbofan put into production.
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