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Once Again The USAF Is Looking To Re-Engine Its B-52 Fleet

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  • MadRat
    Rank 5 Registered User
    • Aug 2006
    • 5032

    #41
    Water AFAIK hasn't been used on the B-52's since J57's.

    They do not have to do anything structurally anytime soon. The AF and Boeing have clearly said so. With the average hours on the B-52 fleet around 20,000 hours per frame, that makes perfect sense. Boeing had programs for rebuilding the wings, but the problem is the wings have always been overbuilt. The CF6-80C2 (aka F138-GE-100) would probably work fine. The C-5M fleet plus the upcoming KC-46 fleet are using that engine type. My next choice would be F108-CF-100 (CFM56-2B) because they already have enough of them in retired KC-135R's to do the work. And there were 4,000 more built for the civilian world. If I was being unrealistic then I'd be asking for engines that offer far bigger fuel savings using engines not even fully tested.



    Every solution requires changes to the datalinks, electrical, hydraulic, bleed air, and fuel systems. It boils down to do you rip open the internal wing channels or leave the old tubes and cables in place? IMHO you open them up and remove the old stuff to save weight. Kerosene rot is eating the fuel lines and storage tanks. I don't think they have much choice, but to put every B-52H through modernization. http://www.af.mil/News/ArticleDispla...e-head-on.aspx

    Another realistic suggestion is adding a dedicated APU or two. The B-52H never had any and uses six engines to generate electrical power.

    Just to show the CF6-80C2 isn't a giant leap in size...

    The 747 is carrying the CF34-8, smaller sibling of the CF34-10E that Boeing wants to use.
    Last edited by MadRat; 2nd March 2015, 14:48.
    Go Huskers!

    Comment

    • LowObservable
      Rank 5 Registered User
      • Jul 2007
      • 960

      #42
      The usual economic argument for fewer engines does not apply here because whatever engine you choose will not require scheduled overhaul for the life of the aircraft, and if it performs according to its commercial service record will seldom if ever come off the wing at all.

      Comment

      • MadRat
        Rank 5 Registered User
        • Aug 2006
        • 5032

        #43
        Commercial CF34-10 follows a 7/10 Program. 7,000 hours or 10 years, whichever comes first.

        Commercial CF6-80C2 with the FADEC has been reaching 20,000 to 24,000 on new engines and 16,000 to 18,000 hours after one overhaul.

        The CF6-80C2 is a big leap in efficiency when it comes to lifetime costs for a 20-year to 25-year period.
        Last edited by MadRat; 2nd March 2015, 15:57.
        Go Huskers!

        Comment

        • RpR
          RpR
          Rank 5 Registered User
          • Jan 2013
          • 1128

          #44
          Originally posted by MadRat View Post
          Commercial CF34-10 follows a 7/10 Program. 7,000 hours or 10 years, whichever comes first.

          Commercial CF6-80C2 with the FADEC has been reaching 20,000 to 24,000 on new engines and 16,000 to 18,000 hours after one overhaul.

          The CF6-80C2 is a big leap in efficiency when it comes to lifetime costs for a 20-year to 25-year period.
          Commercial engines do not experience anything near that of military engines so the commercial stats are irrelevant.

          Comment

          • djcross
            Rank 5 Registered User
            • Jan 2000
            • 5464

            #45
            Originally posted by RpR View Post
            Commercial engines do not experience anything near that of military engines so the commercial stats are irrelevant.
            Commercial engines are worked much harder than bomber engines. Bombers no longer fly NOE because look down radars can pick them out of ground clutter. A B-52 flies once a week. Typically on a 5 hour training sortie. A commercial airliner will fly twice a day (or more) six days a week and will rack up an average of 60 flight hours.

            But wishing for commercial maintenance on bomber engines will be dead on arrival if the government depot at Tinker has anything to say about it. They have their jobs to protect and B-52s continuing to fly with ancient TF33s protects their jobs.

            Comment

            • TomcatViP
              Rank 5 Registered User
              • Nov 2011
              • 6122

              #46
              Originally posted by djcross View Post
              [...]
              But wishing for commercial maintenance on bomber engines will be dead on arrival if the government depot at Tinker has anything to say about it. They have their jobs to protect and B-52s continuing to fly with ancient TF33s protects their jobs.
              This is quite disrespectful for the people that have managed to keep the BUFF in operation during all those years.

              It's an old bird. There is a plentiful of problems that can arise without a proper notice (see the inner tank coating pealing after the move from JP4 to 8 for ex. ). The synergistic impact of one problem to another push to a cautious stepping into any novel solution.

              This is not conservatism. Nor it is a sign of corporatism. This is a scientific and cost effective approach toward any solution.
              Last edited by TomcatViP; 3rd March 2015, 03:22.

              Comment

              • RpR
                RpR
                Rank 5 Registered User
                • Jan 2013
                • 1128

                #47
                Originally posted by djcross View Post
                Commercial engines are worked much harder than bomber engines. Bombers no longer fly NOE because look down radars can pick them out of ground clutter. A B-52 flies once a week. Typically on a 5 hour training sortie. A commercial airliner will fly twice a day (or more) six days a week and will rack up an average of 60 flight hours.
                Thank God your opinion and reality are totally different.
                One hundred commercial hours are not even close to the pounding military engines take in fifty hours.

                http://www.mcconnell.af.mil/news/story.asp?id=123406214

                http://http://theaviationist.com/2014/06/04/b-52-deployed-to-fairford/

                From 2014:

                The B-1 averaged a 53.7% ready rate and the Northrop Grumman B-2 Spirit achieved 30.3%, while the B-52 averaged 80.5% during the 2000–2001 period. The B-52's $72,000 cost per hour of flight is more than the B-1B's $63,000 cost per hour, but less than the B-2's $135,000 per hour.
                Last edited by RpR; 3rd March 2015, 16:01.

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                • djcross
                  Rank 5 Registered User
                  • Jan 2000
                  • 5464

                  #48
                  News stories because extended training flights are rare these days. USAF doesn't fly Chrome Dome like the 1960s. And a bomber doesn't get abused like a fighter
                  Last edited by djcross; 3rd March 2015, 12:34.

                  Comment

                  • swerve
                    Rank 5 Registered User
                    • Jun 2005
                    • 13612

                    #49
                    Originally posted by RpR View Post
                    Thank God your opinion and reality are totally different.
                    One hundred commercial hours are not even close to the pounding military engines take in fifty hours.

                    http://www.mcconnell.af.mil/news/story.asp?id=123406214

                    http://http://theaviationist.com/201...d-to-fairford/

                    From 2014:
                    Really? Where was the pounding in those bomber flights? Cruising altitude & speed, with AAR in the middle, pounds engines how?

                    Commercial airliners don't do AAR, but flights of that length, with a refuelling stop en route, are routine in commercial operations. Try flying to Australia. There are no news stories about them exactly because they're routine, normal, operations. Airliners on long haul routes will fly half that time, land, be cleaned (for new passengers) & refuelled, then fly back the same day - & do that day after day. That's not what bombers do.

                    When the A380 reached its 5th anniversary in service, average fleet utilisation was over 13 hours per day. Almost 5000 hours per year. If B-52s had achieved that, the fleet would have an average of over half a million hours in the air. But by 1999, the average utilisation across the fleet had reached 14700 hours. Usage was less per year than an A380 per month - & most of those were on high-level flights, no more taxing than a standard airline flight. The Boeing 777-200LR achieved even higher utilisation up to 2011, averaging 14.3 hours per day.
                    Last edited by swerve; 3rd March 2015, 14:00.
                    Juris praecepta sunt haec: honeste vivere, alterum non laedere, suum cuique tribuere.
                    Justinian

                    Comment

                    • RpR
                      RpR
                      Rank 5 Registered User
                      • Jan 2013
                      • 1128

                      #50
                      Originally posted by swerve View Post
                      Really? Where was the pounding in those bomber flights? Cruising altitude & speed, with AAR in the middle, pounds engines how?

                      Commercial airliners don't do AAR, but flights of that length, with a refuelling stop en route, are routine in commercial operations. Try flying to Australia. There are no news stories about them exactly because they're routine, normal, operations. Airliners on long haul routes will fly half that time, land, be cleaned (for new passengers) & refuelled, then fly back the same day - & do that day after day. That's not what bombers do. -- No they flew 20 hours non-stop two way trip. No ground check on plane or crew.

                      When the A380 reached its 5th anniversary in service, average fleet utilisation was over 13 hours per day. Almost 5000 hours per year. If B-52s had achieved that, the fleet would have an average of over half a million hours in the air. But by 1999, the average utilisation across the fleet had reached 14700 hours. Usage was less per year than an A380 per month - & most of those were on high-level flights, no more taxing than a standard airline flight. 00 Your proof for this U.S. Air Force operations standard is where? Hmm, you expect the Air Force to take their aircraft and take long slow flights such as airlines do for the sake of flying, BRILLIANT~
                      The Boeing 777-200LR achieved even higher utilisation up to 2011, averaging 14.3 hours per day. -- -- Yep nice easy on the passenger cruise flights, really tough. If you think commercial flights are as demanding as military flights then you live in NeverLand.
                      It is obvious you did not read the one paste, partly becasue I had to fix it to read it myself, but any way.

                      "In such exercises as well as in real operations, the B-52s always play an important role: all weather nuclear deterrence aside, the Stratofortress can perform a wide variety of conventional missions ranging from the BAI (Battlefield Area Interdiction) to CAS (Close Air Support), to TASMO (Tactical Air Support to Maritime Operations), to SAR (Search And Rescue)… using GPS and Laser-guided bombs, cruise missiles and aerial mines."

                      Gee and you are saying they have the capability to perform these missions without practice, WOW, they are even better prepared than I though, MARVELOUS!

                      They are not being flown as much now as they were five to ten years ago because they do not fly for the sake of flying but the fact they want to re-engine them means they intend to use them when ever necessary or possible.
                      Anyone who thinks all they need is a few commercial engines is as ignorant about military requirements as Obama is about handling the Islamists.

                      Couple more just to show what B-52s can do, if need be in a war zone, that airliners or their engines are not made to do.
                      Sadly the second one shows what happens when you push too hard on your retirement flight.

                      https://www.youtube.com/watch?v=7VGf6p-fp9g

                      https://www.youtube.com/watch?v=YQa4PpIkOZU
                      Last edited by RpR; 3rd March 2015, 17:02.

                      Comment

                      • MadRat
                        Rank 5 Registered User
                        • Aug 2006
                        • 5032

                        #51
                        I'd be more comfortable with swerve's logic and experience at this point. Silly how the military uses so many civilian engines. And with so few changes to their maintenance schedules. Silly, them military folks.
                        Go Huskers!

                        Comment

                        • RpR
                          RpR
                          Rank 5 Registered User
                          • Jan 2013
                          • 1128

                          #52
                          Originally posted by MadRat View Post
                          Silly how the military uses so many civilian engines. And with so few changes to their maintenance schedules. Silly, them military folks.
                          Withe the rationalizing you are using for logic that would be normal.
                          Which combat aircraft are you speaking of?

                          There have often been civilian versions of military engines, so it is not the matter of engine source as much as it is type.
                          They want eight engines, which means to be down to only two or three engines, five to six would have to fail, with four engine it would only take one or two.
                          Fortunately "all we gotta do" is usually not accepted on military aircraft.

                          The type of rationalizing you use is what created the F-111B and F-35.
                          Last edited by RpR; 4th March 2015, 05:33.

                          Comment

                          • MadRat
                            Rank 5 Registered User
                            • Aug 2006
                            • 5032

                            #53
                            I use the educated and disciplined rationalizing. Really, bringing in F-111 and F-35 into this? Surely you jest.

                            I already stated plainly in English the Commercial CF34-10 follows a 7/10 Program. 7,000 hours or 10 years, whichever comes first.

                            Silly manufacturer. They really don't want engines coming off the wing any sooner than a decade. But they have to come off in a decade. Many larger engines like FADEC versions of CF6-80C2's push this out to two decades.
                            Go Huskers!

                            Comment

                            • swerve
                              Rank 5 Registered User
                              • Jun 2005
                              • 13612

                              #54
                              Originally posted by RpR View Post
                              It is obvious you did not read the one paste, partly becasue I had to fix it to read it myself, but any way.

                              "In such exercises as well as in real operations, the B-52s always play an important role: all weather nuclear deterrence aside, the Stratofortress can perform a wide variety of conventional missions ranging from the BAI (Battlefield Area Interdiction) to CAS (Close Air Support), to TASMO (Tactical Air Support to Maritime Operations), to SAR (Search And Rescue)… using GPS and Laser-guided bombs, cruise missiles and aerial mines."

                              Gee and you are saying they have the capability to perform these missions without practice, WOW, they are even better prepared than I though, MARVELOUS!
                              Please think about what is actually involved in those missions, & how often they're flown. And stop making false claims about what I'm saying. I most certainly did NOT say that they do anything without practice. You made that up.

                              It is true that B-52s fly, on average, no more in a year than airliners fly in a month. The figures I quoted are not disputed. They are from manufacturers & US government agencies. You gave an example of an unusually long flight as an example of the 'pounding' that a B-52s engines get - but this is (1) an uncommon event, & (2) not greatly dissimilar to normal running for an engine in airline service. It runs continuously in such a very long flight for longer than an airline engine, but an airline long haul engine would do a landing & take-off & quick turnround in that many hours (& I've done that on airline flights, a few times), & I wouldn't want to say that a long flight at cruising speed imposes more stress on an engine than the same hours flying with a landing & take-off in the middle. Airliners have cycle life limits on the airframes, as well as airframe hours - & so do military aircraft.

                              According to the USAF & Boeing, the remaining B-52 fleet was just under half way through its airframe life by 1999, at 14700 hours. Life was estimated at 30-35000 hours. IIRC it had been adjusted upwards a bit to allow for a cut back in low-flying. That's very much more than the airframe life of a fighter. There's no single military standard. It depends on the aircraft & its role.

                              I have no idea where you get 'long slow flights' from. What speed do you think airliners fly at? Their efficient cruising speed is close to their maximum speed - & that's deliberate, designed in. A Boeing 777, for example, typically cruises at ca 490 knots, 96% of its top speed. That's over 85% of the top speed of a B-52, & is actually a little more than the reported cruise speed of the B-52, not less.

                              Please explain what exactly puts such terrible strain on the engines of a B-52 in the roles you listed. Is it performing aerobatics, sudden changes of thrust, extended low flying, etc.? Or does it do all those roles from pretty high altitude, flying steadily?

                              The sad case of the crashing B-52 doesn't prove anything, except that it shouldn't be flown like that. Didn't you understand that? You confuse what it can do, when pushed to its absolute limits & in that case, beyond them, with what it actually does most of the time when it's flying. If B-52s were routinely flown like that, how many would still be in service? How many more dead crews would there be, in the wreckage of their aircraft?

                              Note that one or two airliners have been rolled (empty) - but these days, I'm sure it'd be a career-ending move, though not necessarily a life-ending one, as those B-52 manouevres were. There's no point to doing it, so it isn't done.
                              Last edited by swerve; 4th March 2015, 11:59.
                              Juris praecepta sunt haec: honeste vivere, alterum non laedere, suum cuique tribuere.
                              Justinian

                              Comment

                              • Cherry Ripe
                                Rank 5 Registered User
                                • Jul 2009
                                • 564

                                #55
                                Originally posted by eagle View Post
                                8 engines is the only sensible option.
                                4 bigger engines come with a lot of problems as you mentioned. One engine out is another problem with the B-52's tiny rudder. To sort out all these issues would require major design work and thus is a no-go imho.

                                You should tell Boeing and the USAF that, they thought they had the aerodynamics and process worked-out for the four-RB211 proposal; auto-rudder responding to any engine-out yaw.

                                And if there wasn't money for that, well just make the pilot earn his salary:

                                The task force suggested in the event differential thrust becomes an issue,
                                instituting a standard operational practice of taking off with engine throttles set at the
                                single engine failure power setting would mitigate the problem, as well as save engine
                                life, provide additional power for climb after gear and flap retraction, and make engine
                                failure a non-event
                                .
                                Will you be correcting them?

                                Comment

                                • TR1
                                  TR1
                                  http://tiny.cc/tp8kd
                                  • Oct 2010
                                  • 9826

                                  #56
                                  Originally posted by RpR View Post
                                  Thank God your opinion and reality are totally different.
                                  One hundred commercial hours are not even close to the pounding military engines take in fifty hours.

                                  http://www.mcconnell.af.mil/news/story.asp?id=123406214

                                  http://http://theaviationist.com/2014/06/04/b-52-deployed-to-fairford/

                                  From 2014:

                                  The B-1 averaged a 53.7% ready rate and the Northrop Grumman B-2 Spirit achieved 30.3%, while the B-52 averaged 80.5% during the 2000–2001 period. The B-52's $72,000 cost per hour of flight is more than the B-1B's $63,000 cost per hour, but less than the B-2's $135,000 per hour.
                                  Never realized the availability rate was that low for the B-1 and B-2.
                                  sigpic

                                  Comment

                                  • djcross
                                    Rank 5 Registered User
                                    • Jan 2000
                                    • 5464

                                    #57
                                    Originally posted by TR1 View Post
                                    Never realized the availability rate was that low for the B-1 and B-2.
                                    The availability of spare parts drives non-availability. AFMC's budget is often shorted by the Penatgon. But the availability of the few jets standing nuclear alert is always close to 100% because parts from non-alert jets are robbed to keep the alert jets up.

                                    Comment

                                    • TR1
                                      TR1
                                      http://tiny.cc/tp8kd
                                      • Oct 2010
                                      • 9826

                                      #58
                                      Originally posted by djcross View Post
                                      The availability of spare parts drives non-availability. AFMC's budget is often shorted by the Penatgon. But the availability of the few jets standing nuclear alert is always close to 100% because parts from non-alert jets are robbed to keep the alert jets up.
                                      Gotcha, ty.
                                      sigpic

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