I reckon that shot must be showing it after one of the crosswoven interlayers has been added to the spiral windings, but yeah, why is it all lumpy bumpy like that? That can’t be great.
The only time I’ve ever seen a one-horse-shay reference in the wild! Thank you for that!
Only, then, the parson was sitting upon a rock, at half-past-something by the meeting-house clock, and not a mound, as if he had been to the mill and ground.
Never having heard of a “one horse shay” I looked it up. The reference was a bit obscure until I found this “poem” by Oliver Wendell Holmes. It’s pretty lengthy but here are two parts relevant to the subject of this thread:
Now in building of chaises, I tell you what,
There is always somewhere a weakest spot,—
In hub, tire, felloe, in spring or thill,
In panel, or crossbar, or floor, or sill,
In screw, bolt, thoroughbrace,—lurking still
Find it somewhere you must and will,—
Above or below, or within or without,—
And that’s the reason, beyond a doubt,
A chaise breaks down, but doesn’t wear out.—What do you think the parson found,
When he got up and stared around?
The poor old chaise in a heap or mound,
As if it had been to the mill and ground!
You see, of course, if you’re not a dunce,
How it went to pieces all at once,—
All at once, and nothing first,—
Just as bubbles do when they burst.
End of the wonderful one-hoss shay.
Logic is logic. That’s all I say.
I don’t recall where I first saw a reference to it. It may have been in school, or it may have been in science fiction. (After all, considering it applies a bit in this situation, it’s a good analogy of design) Basically, it was designed for maximum life, but when it failed, every part failed catastrophically at the same time. The idea of the rider ending up suddenly sitting in a pile of rubble is … interesting.
There are various joking references in auto racing to the same idea.
The ideal race car disintegrates into a cloud of high speed dust about 4" beyond the finish line. But not 1" before the finish line. Any other outcome means the car was overbuilt.
A similar joking design rubric applies to individual parts:
Toss the part into the air. If it comes back down, it’s too heavy.
Never let go of a part made of Unobtanium, it will immediate rise into space.
I imagine similar thinking goes into the design of handcycles. As Vince Lombardi almost said
Light weight isn’t quite “the only thing”, but it’s darn close to “everything.”
It would be cool if you could make one light enough to fly, so you’d have a personal sorta-blimp but without all the air drag and windage of a bulky envelope. Building a rigid machine to weigh negative ~75 to negative ~100kg is a right bitch though.
From a quick search, it looks like 27-34 lbs for the commercial ones.
Mine is 46 lbs bare (grain of salt not included). I have no idea what it weighs with the rack, grab bars and fenders I added.
Then there’s the lights, bags, tools/tubes, hydration, etc that are always on board.
I think you mean upsidaisium.
Unobtanium is unique in that it’s properties match the needs of the application. If you need ultimate lightness, it’s weightless. If you need strength, it’s unbreakable. No projectile can pierce it, no knife can cut it, it will never freeze and is unmeltable, yet it’s easy to form any part you want.
True, but upsidaisium comes with fond memories of moose and squirrel.
If only we had enough thiotimoline, we might be able to bring Titan up before it was launched.
For those interested the YouTube channel Real Engineering explores some of the issues with this sub’s construction (and the narrator has some expertise on the subject):
Interesting. They had “Acoustic Monitoring” so they could hear it failing.
The “snap buckling failure” is pretty much exactly what I had in mind. Good to find out that the mode has a specific term of art. Time to search for some research papers with that phrase…
Unless the inrushing water traveled faster than the alert klaxon… which seems pretty likely.
I think the notion was they would hear minor failures happening and then do something to rectify the problems on the surface.
But, as the video notes, failure is a cliff. There is no “slow” mode to this. When it fails, it fails completely and instantly. It seems the owner was cavalier about this and had no interest in spending money to ensure safety.
I found it interesting that the video indicates that the failure would occur on the inside of the tube, for reasons which are not yet understood. That seems counter-intuitive to me, but unlike Stockton Rush, I trust what engineers are saying.
I’m sure there are all kinds of interesting dynamics going on. But I don’t think that failure mode should be too surprising. If you consider just a small radial segment of the tube, you have a piece that’s essentially flat, with layers that are parallel to each other. If you apply force along the same line, it’s likely that the layers will separate and buckle in opposite directions. Imagine taking a ream of paper, putting a paperclip somewhere in the stack as a “defect”, and pushing on the ends. It’s likely that the stacks to either side of the paperclip will buckle apart, and as the separation gets larger, it gets even easier to push the ends together. So it’s a fast, runaway process.
There’s a curve in this case, which makes it so that the inward-facing buckle will tend to make a large bubble, while the outward-facing part might bulge just a little bit (since it’s already curving in that direction).
Predicting when and where this happens seems to be poorly understood, though.
Something that struck me when watching the video was the illustration of the way that the interior delaminates first.
The pressure on the outer layers would surely compress them more than the interior. If the skin was solid metal, it would stretch and shrink to contain the internal movement, but a laminate cannot do that, so would it not be surprising to find that different layers would deform at different rates.
I heard a clip in which he states, “As General MacArthur said, you’re only remembered for the rules you break.”
I mean, he’s not wrong…