Tag Archives: design

What Does 40 Years of Design Get You?

AU0E1641.jpgThe Boeing 747-8 has not been a terribly successful program.  Boeing decided to update the 747 family with new engines and revisions to the wing along with a stretch to the fuselage.  The resulting jet was delayed by its own and other program issues and it came around at a time when there were few passenger airlines interested and the freighter market was taking a kicking.  The result has been anemic sales and a production rate that has steadily reduced as a result of the low demand.  However, from a technical point of view, it is a nice upgrade.

C59F2632.jpgThe wing came in for a lot of attention and was significantly redesigned.  The most conspicuous change is the introduction of the swept tips common to many Boeing designs these days.  Less obvious is that the flap system was completely redesigned.  The original 747 flaps, carried through on the 747-400 are very complex.  Sections are triple slotted.  The Boeing aerodynamicists came up with a single slot design to replace this which apparently has good performance but I imagine is a lot simpler to make and maintain.  Only from the rear on approach can you see the difference.  These shots compare a 747-400 from Air New Zealand with a Korean Air 747-8 and you can see for yourself how much simpler the new design is.

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The Less Subtle Bits of Dreamliner Design

AU0E2346.jpgAirliner design is a complex task with many compromises. It is not a surprise that some aspects of the design that results aren’t exactly what you would like. Today I am picking on one particular type – the Boeing 787 Dreamliner. This is almost as new as it gets in the airliner design world so you would expect it to be better than what came before.   However, having seen a number of them recently, I have been focused on two areas of the design that are rather disappointing. One is the wing root fairing area and the other is the cargo doors.

AU0E3642.jpgA nice smooth design is what the old aero guy in me likes to see and the inlets and fairings around the transition from the fuselage into the wing root are pretty ugly. They are obviously there as a result of functionality requirements but it does not look good and I imagine it comes with a drag penalty that has had to be accepted.

AU0E2336.jpgThe other area is the cargo doors. I am not sure whether this is a function of the load transfer requirements from composite to metal in the hinges but this area looks rather chunky and draggy. I know from previous projects that the nature of composites versus metals means that you can end up with some large joining fixtures to redistribute the loads but there may be other reasons I haven’t thought about. Given how smooth some metallic fuselage cargo doors are, these jumped out at me. Perhaps I have never looked closely enough at other types. Whatever the fairness of it, I just don’t like what they have done here.