5 ms·

The 737 is a great example of a Ship of Theseus, years of small changes have left barely anything of the original besides the name... and the type certificate.

bunderbunder 8y ago
And, apparently, sitting very low on the tarmac. What I haven't seen yet, and would love to see, is an explanation of why they went for this cascade of apparent band-aid solutions, instead of just adjusting the landing gear to give them more options for where to put the engines. I'm sure everything I'm reading is an oversimplification, but, from what I have read, it sure sounds like the crux of the problem here is that they put the moment of thrust in the wrong spot.
- WalterBright 8y ago
  Lengthening the main landing gear would require a near total redesign of the wing, as the gear would have to be moved further outboard.
  - burfog 8y ago
    That was but one of many options, all with pros and cons. It does appear that there is a bit of room to move the gear attachment point outward. Internal stuff might need to be relocated. A very nice solution is to fold the landing gear as the B52 bomber does, asymmetrically with one in front of the other. Internal stuff almost certainly would need to be moved around, and then doors would be required. The doors would probably fit, unlike on the original, so that would be a nice upgrade. Boeing did add some fancy stuff (on the 737MAX-10 only) to lengthen the gear right before lifting into the air and then unlengthen it as it gets retracted. The nice thing about this choice is that there need not be any changes to the height of airport equipment unless the fancy mechanism wasn't used for the nose gear. So that helps: food/maid truck, fuel truck, baggage truck, jetway or airstairs, etc. Another option is to keep the aircraft low. This of course makes it much harder to increase the frontal area of the engines while keeping the aircraft with a pair of under-wing podded engines. We can imagine playing with the definition of "engine", installing units that have pairs of side-by-side turbines that can only be operated or maintained as a complete unit. We can imagine a much higher engine mounting, with some of the bypass air flowing over the top of the wing. We can imagine moving the engines outward to give more clearance due to wing shape, at the cost of being less-capable of crosswind landings and being more difficult to fly straight when an engine is out. Or they could just do a clean new design.
- JorgeGT 8y ago
  Here's Gary Hamatani, chief project engineer for Boeing's 737 MAX program, explaining that they needed the main landing gear to fit the existing wheel wells: https://www.youtube.com/watch?v=F4IGl4OizM4 https://www.youtube.com/watch?v=F4IGl4OizM4 I find it very illustrative, as it contains the keywords that are at issue here: "we wanted to preserve commonality", "from a pilot's perspective there's absolutely nothing different", etc.
growlist 8y ago
Or Trigger's Broom (for those of us in the UK): https://www.youtube.com/watch?v=56yN2zHtofM https://www.youtube.com/watch?v=56yN2zHtofM

bunderbunder 8y ago

And, apparently, sitting very low on the tarmac. What I haven't seen yet, and would love to see, is an explanation of why they went for this cascade of apparent band-aid solutions, instead of just adjusting the landing gear to give them more options for where to put the engines. I'm sure everything I'm reading is an oversimplification, but, from what I have read, it sure sounds like the crux of the problem here is that they put the moment of thrust in the wrong spot.

WalterBright 8y ago
Lengthening the main landing gear would require a near total redesign of the wing, as the gear would have to be moved further outboard.
- burfog 8y ago
  That was but one of many options, all with pros and cons. It does appear that there is a bit of room to move the gear attachment point outward. Internal stuff might need to be relocated. A very nice solution is to fold the landing gear as the B52 bomber does, asymmetrically with one in front of the other. Internal stuff almost certainly would need to be moved around, and then doors would be required. The doors would probably fit, unlike on the original, so that would be a nice upgrade. Boeing did add some fancy stuff (on the 737MAX-10 only) to lengthen the gear right before lifting into the air and then unlengthen it as it gets retracted. The nice thing about this choice is that there need not be any changes to the height of airport equipment unless the fancy mechanism wasn't used for the nose gear. So that helps: food/maid truck, fuel truck, baggage truck, jetway or airstairs, etc. Another option is to keep the aircraft low. This of course makes it much harder to increase the frontal area of the engines while keeping the aircraft with a pair of under-wing podded engines. We can imagine playing with the definition of "engine", installing units that have pairs of side-by-side turbines that can only be operated or maintained as a complete unit. We can imagine a much higher engine mounting, with some of the bypass air flowing over the top of the wing. We can imagine moving the engines outward to give more clearance due to wing shape, at the cost of being less-capable of crosswind landings and being more difficult to fly straight when an engine is out. Or they could just do a clean new design.
JorgeGT 8y ago
Here's Gary Hamatani, chief project engineer for Boeing's 737 MAX program, explaining that they needed the main landing gear to fit the existing wheel wells: https://www.youtube.com/watch?v=F4IGl4OizM4 https://www.youtube.com/watch?v=F4IGl4OizM4 I find it very illustrative, as it contains the keywords that are at issue here: "we wanted to preserve commonality", "from a pilot's perspective there's absolutely nothing different", etc.

growlist 8y ago

Or Trigger's Broom (for those of us in the UK): https://www.youtube.com/watch?v=56yN2zHtofM https://www.youtube.com/watch?v=56yN2zHtofM