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Boeing Launches 737 New Engine Family

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  • Vega ECM
    Rank 5 Registered User
    • Oct 2005
    • 493

    #21
    Originally posted by Amiga500 View Post
    You don't need separation of the frontal projection of the nacelle/wing to guarantee lift.

    [/IMG]
    Amiga - Please advise, for a cruise mach number, the percentage cord for an Engine Nacelle where flow transition occurs which leads to turbulent flow separation.

    Also please advise the CL max that can be expected for a supercritical aerofoil within a separated turbulent air flow.

    To make such a bold statement as this you should be able to answer these questions.

    As for the twaddle about Boeing being the only manf to "hire people to make aeroplanes" it really show zero understanding of the industry.

    As for US subsidisation of Boeing;- The podded jet engine was developed for the Boeing B47 paid for by DoD then gifted to its civil business, the CFRP fuselage was developed for the Boeing Osprey paid for by DoD then gifted to its civil business and there are numerous other small examples of gifting;- a typical unseen example is the analysis package used for Birdstrike Cert known as "Dyna3d" originally paid for DoD to model underground nuclear tests.

    Upon investigation at Boeing's request, the WTO decided there was no case to answer.
    Last edited by Vega ECM; 2nd September 2011, 08:46.

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    • Amiga500
      Rank 5 Registered User
      • Feb 2010
      • 2166

      #22
      Originally posted by Vega ECM View Post
      Amiga - Please advise, for a cruise mach number, the percentage cord for an Engine Nacelle where flow transition occurs which leads to turbulent flow separation.
      Turbulent flow separation?

      Are you getting confused between boundary layer transition and separation. There is no separation on the nacelle, however there is transition.

      Off the top of my head: On a conventional nacelle, in cruise, transition would be expected to occur before 5% chord length. The DLR did quite a bit of work on laminar nacelles in the early to mid 90s - with some patchy results, good BL flow over 50% chord length on some bits of the nacelle, and much less impressive on others.


      Originally posted by Vega ECM View Post
      Also please advise the CL max that can be expected for a supercritical aerofoil within a separated turbulent air flow.
      Erm? (on the separated flow)

      Assuming you mean turbulent boundary layer.

      CL max is not important for cruise. L/D is.

      Also, with the nacelle shroud lowering as it approaches the wing leading edge, the turbulent boundary layer - which remains attached* - this turbulent sheet passes below the wing.

      Simplified: the main aspects of nacelle-pylon integration are:
      • minimising excrescence drag from the pylon-wing interface
      • ensuring the design stagnation point (line) on the wing is unaffected by the presence of the nacelle
      • minimise the change in pressure distribution on the wing pressure surface due to the presence of the nacelle (or, if possible, modify it advantageously)




      *There is no shock-induced BL separation on any competently designed nacelle.

      Comment

      • MattGarner
        Rank 5 Registered User
        • Jun 2008
        • 103

        #23
        In regards of the cockpit, I remember reading that the airlines asked Boeing not to change it so I believe it may be the same. Although there could be some slight differences I suppose?

        Edit: Just found the site from where I read the above.

        "Albaugh also said Boeing plans no changes to the 737 Max's flight deck: "The one thing we do want to make sure we have with this airplane is compatibility with the NG, compatibility with airplanes we've already delivered. What customers have told us is don't touch the cockpit, and our plans are not to do that."
        http://www.flightglobal.com/articles...x-changes.html
        Last edited by MattGarner; 2nd September 2011, 09:03.

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        • Vega ECM
          Rank 5 Registered User
          • Oct 2005
          • 493

          #24
          Originally posted by Amiga500 View Post
          Turbulent flow separation?

          CL max is not important for cruise. L/D is.

          Also, with the nacelle shroud lowering as it approaches the wing leading edge, the turbulent boundary layer - which remains attached* - this turbulent sheet passes below the wing.

          Simplified: the main aspects of nacelle-pylon integration are:
          • minimising excrescence drag from the pylon-wing interface
          • ensuring the design stagnation point (line) on the wing is unaffected by the presence of the nacelle
          • minimise the change in pressure distribution on the wing pressure surface due to the presence of the nacelle (or, if possible, modify it advantageously)




          *There is no shock-induced BL separation on any competently designed nacelle.
          Cruise L/D will be evitable lost if a section of the wing is exposed to poor Nacelle integration QED.

          I agree with your Nacelle/Wing optimisation objectives, but to me the top lip of the Nacelle seems to be above the wing leading edge meaning point 2/3 are significantly compromised (the 787 & 737 pictures are at different viewing angles but you can just about see it.......). As the impact is on area the loss of wing efficiency for the impacted section will be exponential.

          Also as the cord line of the engine gets closer to the wing cord achiving zeroshock-induced BL separation becomes somewhere between very difficult and impossible.

          Just 18 months ago Boeing were talking about the 737 being at the end of it possible development due to problems around the integration of a larger fan engine. Now, under pressure from NEO sales, the same guys that brought you the 787 programme disaster have decided that its now all possible again. As I said before I was expecting a longer MLG with a shortening mech.

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          • Arthur Pewtey
            Rank 5 Registered User
            • Sep 2006
            • 1000

            #25
            What a shame the flight deck isn't going to change. Boeing have an opportunity to bring the 737 cockpit into the 1980s but it seems they aren't going to take it. The overhead panel and centre pedestal are ergonomic nightmares from nearly 50 years ago.

            I've used both A320 and 737 flightdecks and the Airbus is streets ahead in terms of almost every parameter you can think of.
            So much for Pathos

            Comment

            • Ship 741
              Rank 5 Registered User
              • Oct 2006
              • 805

              #26
              Agree Arthur. I have no doubt that Southwest is driving the bus on the stupid cockpit to supposedly save pilot re-training costs. Darn them! How can one customer ruin a design for the whole industry?

              Comment

              • Amiga500
                Rank 5 Registered User
                • Feb 2010
                • 2166

                #27
                Originally posted by Vega ECM View Post
                but to me the top lip of the Nacelle seems to be above the wing leading edge
                That in itself doesn't necessarily matter.

                Originally posted by Vega ECM View Post
                meaning point 2/3 are significantly compromised
                No - meaning point 2/3 may be significantly compromised if appropriate steps are not taken to handle the potential problem.

                Originally posted by Vega ECM View Post
                Also as the cord line of the engine gets closer to the wing cord achiving zeroshock-induced BL separation becomes somewhere between very difficult and impossible.
                Sorry - but what?

                I assume you are talking about the reduced pylon length between wing and nacelle?

                'Back in the day' it was assumed that the gap would have to be of the order of 1 nacelle diameter. That quickly reduced to 0.5 diameters.

                Recent times, its under 0.1 without any significant problems. NASA have previously done work on much closer integration (late 90s if memory serves - check the ntrs). You need to consider lateral curvature of the pylon to control this, but its well understood and not a big deal for Airbus/Boeing.

                A supercritical aerofoil pressure surface may, indeed usually will, have a weak shock on its lower surface, but this is usually 3/4 or later chord length. Due to the weak nature of this shockwave, there is no BL separation on the pressure surface of any well designed (i.e. any Boeing/Airbus) wing.

                The nacelle bypass shroud has long since terminated by that point, and your into the flow downstream of the nozzle, which is underexpanded anyway with a very complex shock structure. But this is normally separate from the small transonic pocket on the wing pressure surface.

                Originally posted by Vega ECM View Post
                Just 18 months ago Boeing were talking about the 737 being at the end of it possible development due to problems around the integration of a larger fan engine.
                It is the same PR bullsh!tters that tried to disparage the NEO now trying to maximise everything to do with the 737 re-engine. They are best treated without outright contempt, or, at least completely ignored.

                I'm fairly certain the engineers would have completely backed a re-engine. They know fine well propfans are absolutely key to the next generation single aisle, and that any new frame built before that is on a hiding to nothing. But that doesn't stop bullsh!tters like Albaugh coming out with complete p!sh - he's a project manager - never designed a f**king aircraft part or system in his life.

                Comment

                • Trident
                  Rank 5 Registered User
                  • May 2004
                  • 3970

                  #28
                  Originally posted by J Boyle View Post
                  As an side, years ago I remember reading that Boeing gave Ilyushin data on how to hand engines underwings for their IL-96. In return the USSR gave Boeing sokme data on how to machine titanium. Anyone else remember that or am I mistaken ?
                  Interesting... I searched Flight's online archive but drew a blank, however you might just be onto something there. I've frequently wondered about the remarkable (if superficial) resemblance between the PS-90A nacelle and some aspects of NASA's Energy Efficient Engine (E) programme from the late 1970s. The time frame fits perfectly as well.

                  Do you have any more specific memory of where you heard about this exchange? Are you positive that you are not confusing it with the more well-known talks about exporting RB.211 or CF6 turbofans to the USSR around the same time? Thanks in advance!

                  Originally posted by J Boyle View Post
                  Boeing gets some state tax brakes...and some R&D from NASA. Do they compare? Depends on who you ask.
                  Between that, cross-pollination from lavishly funded military projects and non-accountable black project money, I would be surprised if they don't at least compare. This is not a question of the 737 in particular either as you imply above, that's a bit of a deflection on your part.
                  sigpic

                  Comment

                  • Cking
                    Rank 5 Registered User
                    • Oct 2004
                    • 1000

                    #29
                    Originally posted by ThreeSpool View Post
                    http://www.newairplane.com/737/737Max/

                    Looks like the have changed the design of section 48, and got rid of that awful APU inlet.
                    Let's hope they have sorted out the whole of the APU bay and got rid of the bl***y shroud! I had to top the oil up on one last night, so the shroud is top of my hate list at the moment!

                    Rgds Cking

                    Comment

                    • J31/32
                      Rank 5 Registered User
                      • Jan 2005
                      • 560

                      #30
                      They got rid of the shroud on the NG.

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                      • longshot
                        Rank 5 Registered User
                        • Aug 2008
                        • 1676

                        #31
                        [QUOTE=Amiga500;1795801]


                        They know fine well propfans are absolutely key to the next generation single aisle, and that any new frame built before that is on a hiding to nothing. (unquote)

                        I remember reading an article about 20 years ago in Air&Space that Boeing thought that whilst designing the 737-300 and that it might sell a few hundred before the prop-fans came in!!!!!

                        Comment

                        • Cking
                          Rank 5 Registered User
                          • Oct 2004
                          • 1000

                          #32
                          Originally posted by J31/32 View Post
                          They got rid of the shroud on the NG.
                          I didn't know that, thanks.
                          I don't have anything to do with the NG's but I've been working the -200's and -3/4/500's for years. When ever they say they are going to "Warm over" the 737 I think of the poor bits, the APU shroud, eye brow windows and the brake attachment bolts to name a few.
                          Now you tell me the shroud has gone that's three of my pet dislikes gone!
                          I always think that the aircraft manufacturers should go down to the shop floor and ask the engineers about the bits that they hate on their previous designs before thay start to design a new aircraft. Every engineer has loads of them.

                          Rgds Cking

                          Comment

                          • J31/32
                            Rank 5 Registered User
                            • Jan 2005
                            • 560

                            #33
                            Eye brow windows are now gone as well on production aircraft with a retrofit mod to fit blanks to Classics as well. 2 out of 3 now!

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