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US Air Force upgrading B-52s

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  • #46
    Originally posted by Monash View Post
    Yes, but how long can they keep "upgrading" these old airframes? I note the apparent success of the P-8 as a replacement for the PC-3. Could they modify a commercial design as a stopgap standoff "heavy" bomber pending final development of any new supersonic manned/unmanned replacement for the B-52 mid this century?
    One of the guys who worked for me on the Joint Staff was a B-52H navigator. We'd talk about this stuff now and then during down time and he was of the opinion that the only thing that threatens those air frames was bad pilots. Like the U-2, A-4, and probably a whole lot of other aircraft I've crossed paths with, and I'm a shipboard AAW guy and not an aviator of any stripe, a good design and production run sort of speaks for itself in the number of aircraft available in the fleet, and the particular service's trust in it's capability. The Buff just keeps reinventing itself, and in many ways, just keeps getting better.

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    • #47
      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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      • #48
        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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        • #49
          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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          • #50
            TF-39 on JB-52E
            Attached Files

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            • #51
              Originally posted by JA Boomer View Post
              TF-39 on JB-52E
              Man, it makes those J-57's look like a glorified hair dryer!
              "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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              • #52
                That's kind of funny, since the TF39 is a direct ancestor of the CFM56.

                Edit: VVV Good catch lol
                Last edited by Jimmy; 30 Aug 13,, 17:50.

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                • #53
                  Originally posted by Jimmy View Post
                  That's kind of funny, since the TF39 is a direct descendant of the CFM56.
                  Other way around isn't it?

                  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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