5 ms·

Yes, clearly it's not just "dump motors in room, get results", but rather that it's usually very doable to generate failures. There are only so many reasons th

Yes, clearly it's not just "dump motors in room, get results", but rather that it's usually very doable to generate failures. There are only so many reasons that they can fail and it shouldn't be too difficult to generate the circumstances that cause those failures. Obviously figuring out which circumstances are the ones that are actually responsible for failures will be more difficult. But it's not too hard to do some sensitivity analysis to get some clues. If they're highly sensitive to having too much current drawn then that might make you suspect that somehow, somewhere the system's power demands are overwhelming the generator and that's what is causing the failure. The point behind "it's not rocket science" is that rockets are very, very expensive to make and so you can't just test as many of them as you'd like, for as long as you'd like, until you through trial and error reproduce the conditions that caused the failure. You also don't get the rocket back when it either succeeds or fails. But in this case the starter/generators are cheap, and they are able to in many cases sort through the debris of the crash. So that does make it qualitatively and quantitatively different than rocket science.

TallGuyShort 11y ago
Sounds exactly like why people tell me it shouldn't take so long to get bug-free software.
- msandford 11y ago
  You can't see software. You can't touch it. It can spontaneously change shape, form and function in dramatic ways if a single memory bit gets corrupted. That's very, very different than physical objects.
  - irishcoffee 11y ago
    Not when software controls hardware, which it does in this case.
    - msandford 11y ago
      Please point me to the software that controls the alternator/generator/starter motor. I'm not talking about the whole thing, just the part whose failure is causing the larger failure. When software controls hardware, yes things can get weirder. But the software can't cause magical things to happen; the atoms don't rearrange themselves. Bit flips tend to be much more like magic, if applied to the real world. A wrench doesn't stop working because you swap out a single atom. But software can, if you flip the wrong bit.
  - TallGuyShort 11y ago
    On the other hand, I can relatively (meaning compared to physical aircraft) easily and inexpensively replicate thousands of copies of my prototypes and automate exhaustive testing. Complex systems are just complex - very few things are actually as trivial as a bystander may think.
  - thaumasiotes 11y ago
    > It can spontaneously change shape, form and function in dramatic ways if a single memory bit gets corrupted. > That's very, very different than physical objects. True... spontaneous changes to the structure of physical objects are quite a bit more likely. One of software's greatest features is that it's not subject to the physical wear that physical tools experience.
- lmm 11y ago
  Once you can consistently reproduce a particular bug it's a small step to fixing it.
  - jacquesm 11y ago
    Could we please have a 'usually' in that sentence. I've had one or two where even though reproduction was easy fixing it was not a small step by any accounting method. In one case the fix required a total overhaul of the system. Several months turnaround on that one between the reproduction and the eventual fix.
pc86 11y ago
> Obviously figuring out which circumstances are the ones that are actually responsible for failures will be more difficult. Actually if the components catch on fire or something finding out which one shit the bed is by far the easiest part of the entire ordeal, assuming it's not spread over the face of a mountain.
mturmon 11y ago
It's not rocket science, but it is aeronautics, and duplicating the failure conditions (temperature, airspeed, altitude, vibration, load) for such a suite of "100-1000" generators could be challenging. It strikes me as presumptuous to assume the engineers on the project are incompetent.

TallGuyShort 11y ago

Sounds exactly like why people tell me it shouldn't take so long to get bug-free software.

msandford 11y ago
You can't see software. You can't touch it. It can spontaneously change shape, form and function in dramatic ways if a single memory bit gets corrupted. That's very, very different than physical objects.
- irishcoffee 11y ago
  Not when software controls hardware, which it does in this case.
  - msandford 11y ago
    Please point me to the software that controls the alternator/generator/starter motor. I'm not talking about the whole thing, just the part whose failure is causing the larger failure. When software controls hardware, yes things can get weirder. But the software can't cause magical things to happen; the atoms don't rearrange themselves. Bit flips tend to be much more like magic, if applied to the real world. A wrench doesn't stop working because you swap out a single atom. But software can, if you flip the wrong bit.
- TallGuyShort 11y ago
  On the other hand, I can relatively (meaning compared to physical aircraft) easily and inexpensively replicate thousands of copies of my prototypes and automate exhaustive testing. Complex systems are just complex - very few things are actually as trivial as a bystander may think.
- thaumasiotes 11y ago
  > It can spontaneously change shape, form and function in dramatic ways if a single memory bit gets corrupted. > That's very, very different than physical objects. True... spontaneous changes to the structure of physical objects are quite a bit more likely. One of software's greatest features is that it's not subject to the physical wear that physical tools experience.
lmm 11y ago
Once you can consistently reproduce a particular bug it's a small step to fixing it.
- jacquesm 11y ago
  Could we please have a 'usually' in that sentence. I've had one or two where even though reproduction was easy fixing it was not a small step by any accounting method. In one case the fix required a total overhaul of the system. Several months turnaround on that one between the reproduction and the eventual fix.

pc86 11y ago

> Obviously figuring out which circumstances are the ones that are actually responsible for failures will be more difficult. Actually if the components catch on fire or something finding out which one shit the bed is by far the easiest part of the entire ordeal, assuming it's not spread over the face of a mountain.

mturmon 11y ago

It's not rocket science, but it is aeronautics, and duplicating the failure conditions (temperature, airspeed, altitude, vibration, load) for such a suite of "100-1000" generators could be challenging. It strikes me as presumptuous to assume the engineers on the project are incompetent.