4 ms·

I would still expect the `maximum theoretical load` to be well above the `designed limit load`.

by rtomanek 7y ago

ChuckMcM 7y ago
And it is, it is 154% or slightly more than 2.5x the 'design limit load'.
- tempestn 7y ago
  Slightly more than 1.5x you mean. And yeah, since the design limit load is already going to have a safety margin over the max anticipated load, as long as the test performs some amount beyond that design level, it's good. Edit: This is assuming the 'design level' is the level it was designed to withstand, which is how I would normally understand the term. Having watched the full video now though, it sounds like it actually exceeded the expected max force that could be expected in the real world by 1.54 times, and that the design anticipated about 1.5x. So indeed, it hit dead-on the design expectation, rather than vastly exceeding it—but that's fine, because the design included a 50% margin of error (and one would hope, a conservative worst-case estimate).
  - ChuckMcM 7y ago
    This is the way I see it, you get to the design limit, that is 1x the design limit, then you up that by 100% so now you are at 2x the design limit, and then you go 54% more so you are at 2.54x the design limit.
    - skosch 7y ago
      It's 154% of the design load, not 154% more than the design load. So 1.54×.
- kortilla 7y ago
  90% of $100 is not $190
  - ChuckMcM 7y ago
    Interestingly the 154% number seems to be gone from the article now The language is tricky, if you interpret it as I did, or 154% "more" than the design limit, then it is the design limit plus 1.54 more design limits. Like saying you salary is $100 and we're paying you 90% beyond your salary. Then you would expect to get $190. If you interpret it to be 154% "of" the design limit, then I would agree it would be 1.54x the design limit. Since other publications from Boeing, and Boeing staff at the "Future of Flight" museum in Everett have said that the planes are safer because they can withstand over twice their design limit, I read the 154% number as the amount "over" the limit. Since folks from Boeing read Hackernews, it would be great for one of them to chime in here with some clarification :-).
    - dmix 7y ago
      It’s in the above Boeing video not the article.
    - mkl 7y ago
      It's not a matter of interpretation or tricky language. The video says "of" [1] so it's 1.54 times the design limit. [1] https://youtu.be/Ai2HmvAXcU0?t=45 https://youtu.be/Ai2HmvAXcU0?t=45
    - kortilla 7y ago
      The video was clear and left no room for interpretation. Planes are safer because “they can withstand twice their design limit” is senseless. The 2x factor you are thinking of is the design limit. The design limit has all of the huge safety margins built in for the normal load limits. The planes are designed to take at least 2x the max normal loads.

I would still expect the `maximum theoretical load` to be well above the `designed limit load`.

ChuckMcM 7y ago

And it is, it is 154% or slightly more than 2.5x the 'design limit load'.

tempestn 7y ago
Slightly more than 1.5x you mean. And yeah, since the design limit load is already going to have a safety margin over the max anticipated load, as long as the test performs some amount beyond that design level, it's good. Edit: This is assuming the 'design level' is the level it was designed to withstand, which is how I would normally understand the term. Having watched the full video now though, it sounds like it actually exceeded the expected max force that could be expected in the real world by 1.54 times, and that the design anticipated about 1.5x. So indeed, it hit dead-on the design expectation, rather than vastly exceeding it—but that's fine, because the design included a 50% margin of error (and one would hope, a conservative worst-case estimate).
- ChuckMcM 7y ago
  This is the way I see it, you get to the design limit, that is 1x the design limit, then you up that by 100% so now you are at 2x the design limit, and then you go 54% more so you are at 2.54x the design limit.
  - skosch 7y ago
    It's 154% of the design load, not 154% more than the design load. So 1.54×.
kortilla 7y ago
90% of $100 is not $190
- ChuckMcM 7y ago
  Interestingly the 154% number seems to be gone from the article now The language is tricky, if you interpret it as I did, or 154% "more" than the design limit, then it is the design limit plus 1.54 more design limits. Like saying you salary is $100 and we're paying you 90% beyond your salary. Then you would expect to get $190. If you interpret it to be 154% "of" the design limit, then I would agree it would be 1.54x the design limit. Since other publications from Boeing, and Boeing staff at the "Future of Flight" museum in Everett have said that the planes are safer because they can withstand over twice their design limit, I read the 154% number as the amount "over" the limit. Since folks from Boeing read Hackernews, it would be great for one of them to chime in here with some clarification :-).
  - dmix 7y ago
    It’s in the above Boeing video not the article.
  - mkl 7y ago
    It's not a matter of interpretation or tricky language. The video says "of" [1] so it's 1.54 times the design limit. [1] https://youtu.be/Ai2HmvAXcU0?t=45 https://youtu.be/Ai2HmvAXcU0?t=45
  - kortilla 7y ago
    The video was clear and left no room for interpretation. Planes are safer because “they can withstand twice their design limit” is senseless. The 2x factor you are thinking of is the design limit. The design limit has all of the huge safety margins built in for the normal load limits. The planes are designed to take at least 2x the max normal loads.