Posted on 11/11/2007 5:02:18 AM PST by mreerm
Sneaky - must be all that lead in the paint.
Flucuations!
The chinese invented gunpowder but not much since then...unless you want to count the fortune cookie too.
That’s a little before the year 1800AD. And some dispute the claim that the chinese invented the use of gunpowder. They definitely invented the substance, but they only used it in firecrackers, small rockets, and small pottery “grenades”. These were bamboo tubes filled with gunpowder and broken bits of pottery shards. THese weapons(?) were used for the purpose of scaring horses to break up a cavalry charge. And for scaring troops that had never seen it before.
The first effective firearms were developed in europe. The first effective gunpowder was developed by europeans.
This is a facsinating topic for me and i know little about it. What are these “batteries” made of? ARe they giant lead-acid devices? In a nuke powered sub, is the propulsion done via steam directly? Or is the steam used to turn tubines that then turn electric generators? Are NASA-like fuel cells used anywhere in subs?
How about magnetic bearings? It seems to me these would be the quietest of all bearings. And ball bearings probaly the noisiest, followed by roller bearings and then plain bearings.
ibtz is “in before the zot”, which essentially means that you’ve posted to this thread before it was “zotted” or deleted, by the admin moderator.
The post above was meant for you!
I believe most commonly used batteries on modern electric subs are Li-ion cells (pretty much like the rechargable batteries in most power-tools and consumer electronics). Low maintenance, no environment impact (which is a huge issue since a sub is a closed environment) and high energy density.
Nowadays, electric subs are always constructed so that an electric motor, powered from either batteries or the generator, drives the propellers and you have some primary propulsion (diesel, AIP etc) driving the generator behind it. Main reason for this is that you really don’t want your noisy diesel engine connected to the propeller-shaft as that would transmit a lot of unnecessary noise into the water.
Its too bad there isn’t a device that can generate electricity directly from radioactive material without any moving parts.
The Germans are moving ahead with their Hydrogen fuel-cell subs, which is as close as you can get to a “no moving parts” electricity generation. You still have the electrical motor and the screws though.
Nuclear subs are actually by far noisier and leave a stronger signature (noise, heat, radiation) than conventional electrics. Especially the german fuel-cell driven ones or the Swedish AIP sterling models.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.