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Originally Posted by Deathblow
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Originally Posted by compressioncut
No, the "caterpillar" was a magnetic drive that didn't have any moving parts as I recall - pulled water in one end and pushed it out the other in some sort of perstaltic movement.
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Sounds weird. One thing I do remember about THFRO when I read that part was that it didn't seem to make any sense at all  though I don't remeber what kind of imagined techno-babble they tried.
My understanding is that a pumpjet is a more efficieny propellor because less of the energy off the propellor is lost to rotational swirl of the wake and with a pumpjet the energy lost to swirl is decreased, as well as the fact that the pumpjet blade ends see higher pressures than they otherwise would, decreasing cavitation tendencies.
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Last year some defense contractor put out a press release about a new kind of propulsor they were developing - basically and advanced shrouded prop driven by an electric motor, so that none of the propulsion machinery penetrates the sub's hull. It sounded pretty neat.
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Sweet, I've been fancinated by the possible performance of high power electric drives for a while now. Mainly how fast they would be compared to traditional drives. |
Well, the Brits have been using pumpjets since the early/mid 70s (Swiftsure), while the Russians and Americans have been essentially happy to use normal, albeit highly engineered, propellers until very recently. I suspect that the fact they are massive has been the main drawback - if you look at that Kilo with it's propulsor disassembled, the stator section alone probably weighs as much as four or five normal props.