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from the may-return-home-under-its-own-power-one-day dept.
El Reg reports:
The US Navy's most advanced ship yet, the $4.4bn stealth destroyer USS Zumwalt, has had to be ignominiously towed through the Panama Canal after its engines failed yet again.
While cruising down the intercontinental waterway, the crew spotted water leaking from two of the four bearings that link the destroyer's advanced electric engines to its propeller drive shafts. Both engines locked up shortly afterwards, and the ship hit the side of the canal, causing some cosmetic damage.
[...] Repairs are expected to take at least ten days and may mean the ship doesn't get into its home port until next year.
This is the latest in a long litany of failures for the USS Zumwalt that have raised questions over the efficacy of the new class of ships. Originally the US planned a fleet of 32 of the advanced destroyers, but the eye-watering cost of the craft has since seen that cut to just three vessels.
[...] It's natural to get teething problems with a new design, particularly something as revolutionary as the USS Zumwalt. But the Navy has already decided to revert to an older class of destroyer for its fleet upgrade. It seems someone on the general staff actually read Arthur C Clarke's warning tale Superiority .
Previously: USS Zumwalt Breaks Down During Sea Trials
[Ed note. Superiority, linked above, is a science fiction classic; well worth reading.]
(Score: 5, Interesting) by VLM on Monday November 28 2016, @01:52PM
advanced electric engines
The advanced part is the controllers and systems integration, not the electric drive itself. The idea has been tried on and off since WWI (one not two)
https://en.wikipedia.org/wiki/Turbo-electric_transmission [wikipedia.org]
It would work fine for the Z, but you know how engineers love to optimize things, so the Navy invested in a lot of programs to F around with advanced motor control stuff and various wild optimizations leading to impressive performance but unreliable performance.
The best computer analogy I can come up with is its quite easy to build a desktop PC that's utterly reliable and usefully productive although perhaps heavy and not terribly fast. Meanwhile there exist people trying to build ever smaller boxes with ever more fans and they try to overclock such that they can make a $50 CPU do the job of a $60 CPU although it'll take $300 in fans and crazy water cooling and the result will crash every 3 hours.
What the Z is doing is unusual, but its an ancient idea thats had varying levels of success historically and they're running up to and far beyond realistic levels of operation, and finding those limits the hard way. Well, technically better this way, than in combat.
Unclassified sources claim the Z has 80 MW of electrical generators (probably more) hooked up to two 40 MW electric motors (probably more) on a 15 kiloton hull. I'm just saying that a century ago our own navy had excellent results with electric drives using 20 MW of on board generators and 5 MW per prop on a 40 kiloton hull. The ability to build a motor controller that digitally synthesizes 3-ph power at 40 MW out is very impressive but it smells like fundamentally the problem with pushing 40+ MW per shaft isn't the drive electronics (although I imagine they've created some impressive fireworks LOL).
Its not useless in that the Z must go like a bat out of hell, classified of course, when its working at all of course, if you have 80 MW on a 15 kiloton hull and a century ago a mere 20 MW on a 40 kiloton hull got "eh 20 sumthin knots unclassified". I would imagine the only limit to acceleration is cavitation.
Here's a puzzler to think over. A century ago a electric drive FREAKING BATTLESHIP was the same length as the Z and only about twice as fat. So they're trying to BS this stealth ship as a 2010s destroyer LOL. The Z is a skinny battleship not a mere destroyer. Probably some political or treaty or legislation bullshit requires us to pretend its not a battleship, but its a battleship. There was a classic plot device in Asimovs Foundation series where he fictionally made the point that dying empires always supersize the F out of everything before they collapse. A battleship sized destroyer is very bad news for the American Empire. Of course its not isolated in that burgerland supersizes food, people, car/SUV, and houses. Not looking good, USA.
Another fascinating analogy is the Z has a tenth the (wo)manpower of the Tennessee. Remember those old WWII pictures of the entire crew on desk and its shoulder to shoulder like 5 ranks deep? Well the entire crew of the Z on one side of the ship would be like one sea(wo)man for every six or so feet. They could almost lay down on desk head to foot in a row from bow to stern if they allow a little wiggling and maybe stretch around the ends a bit. This is insane because in a battle they might lose ten men if a shell hits and on the Tennessee that really sucked for those ten men of course, but at least the ship isn't gonna sink because theres 1390 other men to save the ship and put out the fire or WTF and keep on fighting. On the Z losing 10 men is at least 10% of total combat effectiveness, and that kind of loss might end a mission completely depending on who got hit. We're kinda going back to wooden ships and iron men in that the modern navy is all about the crew because there's so dang few of them they become hyper critical to mission success. The T had 25 five inch guns and if one gun crew got hit, they lost 4% combat effectiveness and carried on with the other 24 guns, not to mention the main guns of course. The Z has two, repeat, two, 155mm arty for ground support and if "the crewman", as in singular, who knows 155mm gunnery gets hit the ship is no longer combat effective for ground support. Of course the thing is mostly a VLS missile launcher but its interesting to think that it carries 80 missiles which is very near one per crew.
(Score: 2) by art guerrilla on Monday November 28 2016, @04:16PM
useful info imparted, as per usual...
thank you for your ongoing contributions, dont always agree, but you are almost always informative and evenhanded...
thank you
(Score: 3, Interesting) by bob_super on Monday November 28 2016, @07:17PM
I think their point is that they don't expect to get hit.
The Battleships were like working trucks designed to take major abuse during visual range bombardment, but dish more than they took before finding a quiet place to bend the plates back the right way. This is a fancy sports car. It will lose most of its advantages if hit, but thanks to progress in automatic sprinklers, plus airtight compartments, it won't necessarily sink easily even with major flooding.
As someone pointed out, it's a lot harder not to get hit if you don't have your almost-million-dollars shells to shoot from far BVR. And I'm curious what modern radars and having waves over the top do to the advertised stealth. We know the Serbs had found that a small frequency tweak could negate the F-117's stealth, I'm curious how wideband the Z's stealth really is.
A first-gen concept is always expensive, and at least this one won't sink with 1400 lives...