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  • #31
    Originally posted by Evan View Post
    Boeing didn't want to pay for that.
    It's funny how you keep using phrases like that. Are you aware that Boeing is not a charity? It would be much more correct to say "Boeing doesn't think their customers would want to pay for that."

    Oh and BTW, most of their customers aren't charities either. Ultimately the cost of all these engineering goodies will be borne by you and me and everyone else that buys airline tickets.
    Be alert! America needs more lerts.

    Eric Law

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    • #32
      Originally posted by Evan View Post
      Yes, everything is ultimately moved by a hydraulic ram. But the systems using the autonomous hydrostatic actuators are electrically controlled. They have no servo valve and no connection to the main hydraulic systems.
      I think that is not entirely correct because they share the same actuator with the same chambers. I think there are isolation valves to control wich system is in charge of this control surface.

      That has everything to do with FBW. There is nothing there for a cable to control.
      Why not? The same cable that moves the servo valve could simultaneously move a servo interruptor.

      The back-up systems for the hydraulic actuators with a servo valve (connected to the main hydraulics) is also an electrically controlled pump.
      Yes, that is a traditional design and nothing to do with FBW. You have engine-driven pump, electric pump, PTU, and APU and RAT (either driving an hydro pump or a generator that can run the electric pump).

      --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
      --- Defend what you say with arguments, not by imposing your credentials ---

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      • #33
        Originally posted by elaw View Post
        Heh... funny you should mention that... the company I work for actually has a patent on such a thing! http://www.freepatentsonline.com/6508439.html

        The really scary thing is it's not intended for use on the wing or tailplane of a fixed-wing aircraft... it's embedded in the rotor blades of a helicopter!
        I don't see the electric linear actuator (colloquially called electric piston) there.
        And I mean REAL linear motion, not devices where a rotation motion is converted in linear by some type of screw or gear.

        --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
        --- Defend what you say with arguments, not by imposing your credentials ---

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        • #34
          Gah... you're right!

          I'd never seen the patent before and didn't read the whole thing... I'd seen the work that led up to it. I'm not sure if the design evolved or what I saw is covered by a different patent, but at least initially the device included a linear actuator designed and built in-house along with an electronic control system... basically a linear stepper motor.
          Be alert! America needs more lerts.

          Eric Law

          Comment


          • #35
            Originally posted by Evan View Post
            ...I believe that the A320 is a safer airplane IF the crews are properly trained for standard, supplemental and unusual situations. The A320 requires a deeper systems-level understanding. We don't want pilots monkeying around with FCC CB's in midflight (that one still amazes me...)...
            ...the root of all of this is deeper, more insidious and, yes, GRAY

            In some ways, the Airbus control philosophy dumbs down the operation of the aircraft, and seemingly encourages someone to push buttons instead of be a pilot.

            Then we see accidents where pilots were seemingly dumb.

            Some of us wonder if there might be an association.

            You say the "Airbus is safer". Indeed, it might be- humans (you excluded) will have an occasional brain fart and a well-designed computer system can catch and reduce those.

            Then we have the eye rolling crashes where the pilots seem to lack really basic knowledge...Stuff where folks like Gabriel and I feel strongly that the passengers would have lived if we were the pilots (and believe me, we have NO business flying airliners!)

            That begs the question- does this dumbed down, "I don't act like a normal airplane" design system contribute to occasional crashes?

            Worse yet, the pilots know that the plane normally doesn't act like a plane, so something goes crazy- where the computer might make it act a couple of different ways, and guess whether it's trying to act like a plane or act like a vanilla X-box game, just what the hell IS going on? (Do you grasp that?)- The plane is acting abnormally- is everything OK...and the computer is simply in Alternate Law 1424.236A, where checklist 341.172M applies or do we have a serious structural problem or a serious computer problem, or just the pitot tubes are fouled up? (And we have "startle factor")

            With a Boeing design, it's supposed to act like a plane and if it starts acting other-than-how it's supposed to normally act, there's one less question as to what's wrong, and one less thing to be confused about during "startle factor).

            So the question (and the reason this debate may never die) is: Would the airbus be even saferer if it wasn't designed with the "dumb-it-down" philosophy?

            Right or wrong, the Blind Cowboy Boeing Lovers do indeed lean towards a system where pilots are pilots, with no real objection to a computer/FBW system that assists with the process and calls out the Evan-All-Pervasive-Pilot-Idiocy when needed.
            Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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            • #36
              Originally posted by Gabriel View Post
              I think that is not entirely correct because they share the same actuator with the same chambers. I think there are isolation valves to control wich system is in charge of this control surface.
              (Sorry 3WE, I have to roll out the acronyms here). Gabriel, there are basically three types of actuators on the A380/A350 and each critical flight control surface can be moved by a any one of these. Like the A320, they are distributed on three channels, but in this case one channel is electric. This not only saves weight by eliminating the third hydraulic channel, it provides added safety due to the dissimilarity of the actuators. Even in the event of a total hydraulics loss, the self contained actuators on the electrical channel are fully operational.

              The actuators are:

              • [*=1]EHA: Electro-Hydraulic Actuators - these are self contained, they have no connection to a hydraulic power channel. They use a small reservior for hydraulics and are electrically controlled and powered. They are all about FBW.
                [*=1]EBHA: Electrical Back-up Hydraulic Actuators - these are essentially traditional hydraulic actuators that contain an electric pump back-up with an accumulator for self-contained operation if the main hydraulic system fails. They are connected to the green and yellow systems and the electrical channel.
                [*=1]Traditional Hydraulic Actuators - connected to the green and yellow systems.


              The next technological leap might be EMA's - Electrical-Mechanical Actuators, which, as you have mentioned, are not currently used on transport category airplanes.

              So, it's plain to see that, in the interests of efficiency, lower operating costs and safety, FBW is essential to current and future aircraft design. Boeing would not argue with that. If they built a clean-sheet replacement for the B737, it would be FBW and probably involve some of this 'power-by-wire' control surface actuation.

              It seems to me that both Boeing and Airbus followed the same path (the "lazy" path if you will) and that all things that you criticize from Boeing you should be also doing with Airbus. It would not surprise me if Boeing and Airbus held secret (and illegal) meetings to agree which path to go. If one of them had launched a clean-sheet design, the other would have had to follow through.
              I agree that they are both taking the "lazy path" here; neither wanted to retool an entire production line, but there is a key difference between extending the A320 and extending the B737. The A320 was well ahead of its time in 1987 and still very modern today. Some aspects are becoming antiquated but the path for modernization is still quite open. For example, since it is already FBW, losing the blue hydraulics and outfitting the aircraft with an A350 level of EHA/EBHA actuators would be possible. (Airbus didn't want to pay for that). Just one example but the key difference is that the A320 IS a 21st century airframe and if they wanted to, they could keep modern variants in service for another half-century. The B737 can be upgraded in certain ways (the FBW spoilers seem like an obvious crutch to me), but it is NOT a 21st century airframe. It is a 20th century airframe on life support. That's a bit lazier.

              So we have the issue of industry leadership here. Boeing seems to be conceding it to Airbus for practical business reasons... and to get to the core of it, I think those 'practical' decisions are driven by immediate shareholder value rather than long-term vision. It's a widespread problem in American industry and I'm afraid the days of American technological leadership may be ending as a result.

              Comment


              • #37
                Originally posted by Evan View Post
                EHA: Electro-Hydraulic Actuators - these are self contained, they have no connection to a hydraulic power channel. They use a small reservior for hydraulics and are electrically controlled and powered. They are all about FBW.
                Why?

                So we have the issue of industry leadership here. Boeing seems to be conceding it to Airbus for practical business reasons... and to get to the core of it, I think those 'practical' decisions are driven by immediate shareholder value rather than long-term vision. It's a widespread problem in American industry and I'm afraid the days of American technological leadership may be ending as a result.
                It is evident that Boeing is prioritizing the leadership in the wide cabin segment, which is more profitable for airplanes manufacturers. They can't apply all the resources to all zones at the same time.

                --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                --- Defend what you say with arguments, not by imposing your credentials ---

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                • #38
                  Originally posted by Gabriel View Post
                  Why?
                  Because with EHA, the command is carried from the cockpit to the actuator by wires, not mechanics. Fly By Wire.

                  It is evident that Boeing is prioritizing the leadership in the wide cabin segment, which is more profitable for airplanes manufacturers. They can't apply all the resources to all zones at the same time.
                  Why can't they? This is the company that developed the 707, 727, 737 and 747 all in less than two decades, then developed the 757 and 767 simultaneously. The decision to scrap the Y1 was not due to a lack of resources, it was due to a reluctance to devote funding of those resources. It was the first part of the Yellowstone Project. Y1 was cancelled, Y2 was built as the 787. And Y3...?

                  Comment


                  • #39
                    Originally posted by Evan View Post
                    Because with EHA, the command is carried from the cockpit to the actuator by wires, not mechanics. Fly By Wire.
                    But that's an implementation, not a requisite. As I said, the same cable that moves the servo-valve can simultaneously move a servo-interruptor that is located next to the EHA. The wires only carry signal from the cockpit to the EHA, not power. That means that there is an electric control right there in the EHA.

                    --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                    --- Defend what you say with arguments, not by imposing your credentials ---

                    Comment


                    • #40
                      Originally posted by Gabriel View Post
                      But that's an implementation, not a requisite. As I said, the same cable that moves the servo-valve can simultaneously move a servo-interruptor that is located next to the EHA. The wires only carry signal from the cockpit to the EHA, not power. That means that there is an electric control right there in the EHA.
                      Hmm... I think you are arguing just to argue now. Are you seriously going to provide cockpit input to a remote electronic actuator module via a heavy and stretch-prone steel control cable? The EHA / EBHA architecture is strictly a back-up provision; the benefit is significant weight and maintenance reduction. In normal flight all surfaces are moved by main-system hydraulics. But when they are needed, they are electrically powered and electronically controlled. EHA / EBHA has no servovalve for a cable to control (what is a "servo-interruptor"?). EHA has no main-system hydraulic connection (there is a centralized reservior refill circuit that can only be used on the ground).

                      Bottom line here Gabriel, No FBW = No EHA/EBHA, so three hydraulic systems necessary for safe operation and more weight to fly around simply as a back up provision. In other words, inefficiency. In other words, the past. EHA/EBHA is obvious progress and EMA is coming. It is all based on FBW. Meanwhile, the 737 limps into the future when it should have been enjoying its retirement by now.

                      Comment


                      • #41
                        Originally posted by Evan View Post
                        ...Pages upon pages of arguments with Gabriel...Sorry 3WE, I have to roll out the acronyms here......pages upon pages of arguments with Gabriel.
                        It's unfortunate that you can't simply admit that you have OCOTOATS (Obsessive Compulsive Objection to Older Aircraft Types).
                        Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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                        • #42
                          Originally posted by 3WE View Post
                          It's unfortunate that you can't simply admit that you have OCOTOATS (Obsessive Compulsive Objection to Older Aircraft Types).
                          Not true. I love the older planes. I love the older cars. I love the older ships. I hope they keep flying/rolling/sailing for a long time to come.

                          I also like progress and innovation, especially when it benefits safety, the environment and reduced consumption of natural resources.

                          I just don't like it when cynical short-term business economics stifle progress and innovation.

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                          • #43
                            737 NG: 0.27 hull losses every million take-offs
                            A320: 0.24 hull losses every million take-offs

                            Boeing claims that the operating cost of the 373 MAX will be lower than that of the A320 neo.

                            --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                            --- Defend what you say with arguments, not by imposing your credentials ---

                            Comment


                            • #44
                              Originally posted by Gabriel View Post
                              737 NG: 0.27 hull losses every million take-offs
                              A320: 0.24 hull losses every million take-offs

                              Boeing claims that the operating cost of the 373 MAX will be lower than that of the A320 neo.
                              Ok...

                              1) Those hull loss statistics are of little relevance. As I said, both airframes are very safe. How many of those hull losses are attributed to airframe design or flight control methodology? Almost all are due to poor pilot training and gross pilot error. The only distinction we could use here are the number of accidents avoided by design features and, while we don't have that data, I would bet on FBW there.

                              2) Boeing claims... Airbus claims... There is the usual marketplace noise going on. Both claim better efficiency, but in most areas of cost and efficiency, the differences are small. Boeing is crippled by two form-factor limitations: fan diameter and total fuel capacity. Airbus is getting thousands of pounds more thrust out of virtually the same engine core (with some drag penalty) so they have the GTOW and payload advantage. Boeing might have a slight advantage on range with the B738 over the A320 but loses this in the B737 and B739 categories, and moreover, if an operator is really looking for a LR single-aisle performer, the A321LR will be the clear winner; Boeing cannot extend fuel capacity on the 739.

                              But the only efficiency number that really matters to operators is CASM, and Airbus is winning there. Cost-per-seat-mile is even lower on the Space Flex configured aircraft, though it is arguably an evil affront to passenger comfort (which operators could care less about).

                              Here is a blurb off airwaysnews.com that pretty much sums it up:
                              Meanwhile, the A321neo sustains a tangible CASM advantage of 3.5-4% over the 737 MAX 9 regardless of fuel. This sustained advantage, coupled with the performance deficits of the 737 MAX 9 and a few other factors (to be discussed in Part III) create the stunning advantage in orders for the A321neo that is the driver behind Airbus’ lead in market share.
                              3) Last I checked, Airbus has 60% of this market and Boeing had 40%. Also, Boeing had fallen a year behind Airbus. Lufthanse already has the A320NEO in service.

                              4) I'm not trying to make this a Boeing vs Airbus argument. I'm trying to make this an argument for innovation over stagnation. I'm making a B737MAX vs Y1 argument here. Would the Y1 be more efficient than the B737MAX. Yes! Would it be more resistant to pilot error? Yes! Would it be more comfortable to passengers? Yes! Would it be obsolete in twenty years? No! Would it beat Airbus on CASM and own 60% of the narrowbody market? Quite possibly.

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                              • #45
                                I know that these claims are... well... just claims. As you said, they are very close in everything

                                One things that they are close, and this is data, not claims, is:

                                The 737 NG has better dispatch reliability than the A320.
                                The 737 NG has a lower (better) empty weight / MTOW (it's structurally more efficient, despite being a design 20 years older and the A320 having a much more extensive use of composite materials).
                                These 2 things help in the business equation: With the same useful on board, the 737 is lighter what helps reduce the fuel burn (which compensates for smaller fan diameter). And the better dispatch reliability means not only better customer (passenger) satisfaction but also lower cost in terms of hotels, crews, etc...

                                The A320 is a good plane, as good as the 737, and each of them has their stronger and weaker points when compared one to the other.
                                But both of them still have too much value as to trash it, ans neither of them is willing to do it.

                                None of them would be able to price a clean-sheet single aisle replacement at the same prices that they are selling the 737 and A320. The investment is huge, and not only in the product development but also in the factories and tooling (all along the supply chain). And none of them is willing to do it by now, because, again, they both have a product that still has a lot of value. Would a clean sheet design be better? Sure! Nobody argues that. Not me at least. But that is not enough for a business case.

                                --- Judge what is said by the merits of what is said, not by the credentials of who said it. ---
                                --- Defend what you say with arguments, not by imposing your credentials ---

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