The Taming of the Screw (2000)

http://www.americanhistory.si.edu/subs/anglesdangles/taming.html

by thicknavyrain • 8 years ago

61 23 8 years ago

americanhistory.si.edu

jstanley• 8 years ago

I thought the most interesting part of this was the part about the internal structure being classified.

Naively I assumed that they were cast solid and then the surface machined to the exact shape, but it sounds like they either have internal passages or they're made of some sort of honeycomb to reduce weight? What else could be inside?

ars• 8 years ago

Some sort of sound deadening? Like how an empty and full can sound different?

Retra• 8 years ago

It could also just be material layering for stability, shaping, cavitation protection, noise reduction, strength, etc..

petee2• 8 years ago

It could have been done like some jet engine blades, where a thin skin 'pocket' is pressured or vacuumed into shape during forging. Or perhaps simply, they are not made of metal anymore, albeit unlikely.

You're probably closest with the internal passages though; if one of the primary issues is cavitation, there must be some solution to relieve that vacuum pressure from becoming too great, or absorbing the shock when it does

dsfyu404ed• 8 years ago

I would suspect that there's some internal structure made of a different material (steel, air, silly putty, whatever) that is tuned to act as a damper or allows the screw to flex in a certain way that changes its acoustic signature allowing it to be quiet at higher speeds like those crappy flex fans for car radiators.

Casting in an internal pocket with sufficient accuracy(!) in a part so massive would have been very, very, very difficult/expensive if not impossible with the kinds of industrial process control that were available in the 1960s.

starbeast• 8 years ago

Could it be a bureaucratic reason where technically they have only declassified the shape, so therefore the inside could be said to still be classified and the Navy could waive it, but finds it funny to force civilians to lug the complete thing around for a while?

trhway• 8 years ago

reminded the 198x scandal of Toshiba CNC used to machine USSR submarine screws https://en.wikipedia.org/wiki/Toshiba-Kongsberg_scandal

The high precision allowed for very quiet screws and that caused all that such a screaming noise back then :)

https://www.nytimes.com/1987/06/22/opinion/submarined-by-jap...

gregschlom• 8 years ago

I believe that story is actually mentioned in the article.

gwern• 8 years ago

Ah, so that's what that bit about the TV was alluding to.

petee2• 8 years ago

Yes, page 2, second paragraph

userbinator• 8 years ago

I am reminded of the blade shape of quiet computer fans --- although designed to work in a different fluid, I bet a lot of what applies to making a quiet fan blade also applies to propellers in water.

bediger4000• 8 years ago

I don't think air cavitates. There's a fairly gradual transition from incompressible to compressible flow for air, but I don't think that's true for water.

adrianN• 8 years ago

How would air cavitate if it is already a gas?

nigrioid• 8 years ago

Cool old-style website! Look at the source; there's no CSS.

agumonkey2• 8 years ago

wow, that website design.. much memories

lokopodium• 8 years ago

Remember how Bing Maps had a picture of a classified screw? https://ogleearth.com/2007/08/microsofts-birds-eye-view-catc...

grendelt• 8 years ago

It's not perfect, by I made a more legible single-page layout here:

http://n5dux.com/taming/

agumonkey2• 8 years ago

Very nice

White-• 8 years ago

thanks

jacobush2• 8 years ago

There is something even more silent prowling (occasionally) the high seas:

lukego• 8 years ago

Sounds a lot like trying to get computer hardware interfaces published so that people can write their own drivers for them!

The Taming of the Screw (2000)

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