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Zumwalt Follies (?)


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http://www.military.com/daily-news/2015/11/30/navys-new-destroyers-seaworthiness-stability-questioned.html?ESRC=eb.nl

Navy's New Destroyer's Seaworthiness, Stability Questioned

"BATH, Maine -- The largest destroyer built for the U.S. Navy cuts an imposing figure: massive, with an angular shape, hidden weapons and antennas, and electric-drive propulsion. But underneath the stealthy exterior resides a style of hull that fell out of favor a century ago in part because it can be unstable."

 

Polmar approves, though:

"Norman Polmar, a naval historian, analyst and author who is sometimes critical of the Navy's decisions, said he has no qualms about the Zumwalt's seaworthiness after a large-scale model was built to prove the concept."

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I'm not a naval engineer, but it seems foolish to criticize a design because its configuration was declared unstable in decades past. As an example from the aerospace world, the B-2 shares its basic configuration with the YB-49, yet it FCS and other technologies allow it to avoid the stability issues of the older design.

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The YB-49's issues were control problems solved by computers and fly-by-wire technologies. Boyancy is pretty fundamental. At least we'll only have three (humungously expensive) white elephants if the boyancy issues come back to bite us.

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I wonder whether they've ever tried a semi-sub concept. Cruise the high seas in a normal configuration. Then be able to semi submerge in firing configuration or calmer seas to protect itself from ASM.

The Zumwalt class has the ability to "ballast down," but a full semi-submersible has most of the cost problems of a fully-submersible while a much less pronounced benefit. It's not a terrible idea, it's just on the wrong side of the cost-benefit curve.

Edited by Halidon
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The Zumwalt class has the ability to "ballast down," but a full semi-submersible has most of the cost problems of a fully-submersible while a much less pronounced benefit. It's not a terrible idea, it's just on the wrong side of the cost-benefit curve.

 

Just put a fusion reactor, railgun, hypersonic missiles and supercavitating torpedos on a ship, and the semi-submersible capabilty no longer makes a dent into that curve.

 

Dreadnought 2050: Is This the Battleship of the Future?

The Royal Navy came up with a sleek concept for a future warship.
By Franz-Stefan Gady
September 07, 2015
Locally 3-D printed drones, a 3-D holographic command table, “supercavitating” torpedoes evaporating the water around them, laser weapons and an electro-magnetic railgun are just a few of the features of the battleship of the future, according to a team of young British engineers.
Designed as part of an informal challenge by the U.K. Ministry of Defense (MOD) and Royal Navy, the concept ship — dubbed the Dreadnought 2050 (the original HMS Dreadnought was a Royal Naval battleship commissioned in 1906, “which represented such an advance that all other major warships were rendered obsolete” according to a press release — is a trimaran made of ultra-strong acrylic see-thru composites and powered by a fusion reactor or highly efficient turbines rendering it an extremely silent and quite deadly stealth vessel.
The main objective of the MOD tech challenge was to come up with the most modern surface warship design possible, given current budgetary limitations. According to Startpoint, an organization of the Royal Navy tasked with managing the Dreadnought 2050 project, “the mission is to tackle parallel challenges of providing advanced technology set against the backdrop of funding constraints.” And “while some of these technologies push today’s boundaries in science and engineering, there is no reason why elements could not be incorporated into future designs,” according to Muir Macdonald, a senior executive at Startpoint.
The Dreadnought 2050 would be submersible “to present a lower profile which would make the ship more stealthy and even harder to detect.” Instead of a mast the vessel would sport a tethered quad-copter. “This tether would be made of carbon nanotubes and cryogenically cooled in order to transmit significant power to the quad-copter for multi-spectral sensors and act as a high-power (i.e. laser) weapon to knock down enemy missiles or aircraft,” the press release states.
The ship’s crew would consist of around 50 to a 100 sailors, rather than the 200 strong crew found on today’s warships, with the vessel’s nerve center, the Operations Room, staffed by five rather than 25 people.
“There would be an electro-magnetic railgun at the bow, capable of firing projectiles the same distance as today’s long-range cruise missiles; and at the stern there would be a ‘moon pool’ or floodable dock area to deploy Royal Marines and other troops on amphibious raiding missions, or unmanned underwater vehicles (UUVs) to detect mines,” according to the press release.
“Above the floodable dock would be a large, extendable flight deck and hangar for multiple remotely piloted air systems (RPAS/UAVs), many equipped with weapons, which could target the enemy without putting the crew in harm’s way,” it continues.
The Dreadnought 2050 would also be equipped with “missile tubes for defensive hypersonic (i.e. Mach 5 plus) missiles, directed energy weapons to stop small enemy craft loaded with explosives; and in the armas (the outrigger hulls) would be torpedo tubes to fire super-cavitating torpedoes capable of 300+ knots.”

 

http://thediplomat.com/2015/09/dreadnought-2050-is-this-the-battleship-of-the-future/

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To me, the biggest problem with the Zumwalt isn't its hull shape or other design features, rather the fact that budget constraints caused it to be built without a volume search radar, meaning it has to be paired with a Burke to provide those capabilities, which makes you wonder if going that route, if it wouldn't just be easier to just use another, modified Burke hull. Apparently, the navy has also come to that conclusion.

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There she sails. As the ship was passing by on her way to her first sea trials, she was heard to whisper, "Take that all you Zumwalt skeptics!"

 

There has been talk that some factions inside the Navy want to cancel the third ship. I think it is reasonable to predict that regardless of what is discovered while the DDG-1000's upcoming sea trials are underway, Congress will force completion of the third ship and will allocate some level of funding every year to keep the Zumwalt program alive, even if no further hulls are constructed beyond the first three.

 

Once IOC for the Zumwalt Class has been declared, it is also likely the Navy will then issue a memorandum that the USMC's near-term and mid-term Naval Surface Fire Support requirements have been met, and that research on railguns will continue as the Navy's preferred solution to the USMC's far term NSFS requirements.

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If the role of the Zumwalt is supposed to be supporting troops, isn't the double 155mm a little "small" and "light?" Maybe they need more "guns" on that ship and leave the cruise missile duties to the Burkes.

Missiles are easier to add, turrets are bulky. But not all 155mm are created equal, the AGS has a pretty long range and high rate of fire.

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If the role of the Zumwalt is supposed to be supporting troops, isn't the double 155mm a little "small" and "light?" Maybe they need more "guns" on that ship and leave the cruise missile duties to the Burkes.

 

"WE WANT EIGHT! WE CAN'T WAIT!" - screams narcissistic fucktards on the beach hehehehe ;) :lol:

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Guest Jason L

The YB-49's issues were control problems solved by computers and fly-by-wire technologies. Boyancy is pretty fundamental. At least we'll only have three (humungously expensive) white elephants if the boyancy issues come back to bite us.

 

There is a bit more to ship hydrodynamics than buoyancy. :rolleyes:

 

Tumblehome and inverted bows are hardly unique/high risk features. The Ulstein design performs extremely well for instance.

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But that's just a improved whale back and you note that her buoyancy will increase dramatically as the bow digs in and that buoyant area is upfront to counter the plunging effect. Basically they got rid of the flare to soften the ride into the seas. Also resupply ships work off the aft deck, so the bow can be optimized for sea going.

If you looked at the zommie and seen the construction pictures of just how thin the bow section is and note as she digs into a sea the amount of buoyant area being submerged is reducing , not increasing as you would with a flared bow. Up to a certain sea state the hull design will work quite well, but after that, her entire forward section will become mission incapable and that state will happen sooner with a raising sea state than a traditional hull design of the same tonnage. I suspect also her bow section is going to suffer whacking and flexing stresses, from trying to shed the seas on top of her deck, particularly around the section holding the bulbous bow. also not sure how this design will handle battle damage and subsequent partial flooding.

 

Edited by Colin
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Guest Jason L

But that's just a improved whale back and you note that her buoyancy will increase dramatically as the bow digs in and that buoyant area is upfront to counter the plunging effect. Basically they got rid of the flare to soften the ride into the seas. Also resupply ships work off the aft deck, so the bow can be optimized for sea going.

If you looked at the zommie and seen the construction pictures of just how thin the bow section is and note as she digs into a sea the amount of buoyant area being submerged is reducing , not increasing as you would with a flared bow. Up to a certain sea state the hull design will work quite well, but after that, her entire forward section will become mission incapable and that state will happen sooner with a raising sea state than a traditional hull design of the same tonnage. I suspect also her bow section is going to suffer whacking and flexing stresses, from trying to shed the seas on top of her deck, particularly around the section holding the bulbous bow. also not sure how this design will handle battle damage and subsequent partial flooding.

 

 

Without knowing the weight distribution and details of the ballisting system you've got no way of knowing how well she'll handle or how prone she is to plunging.

 

The fact that the ship gets skinnier vertically doesn't really mean much, what matters is the location center of buoyancy relative to the center of mass, as well as their lateral positions. We know neither of those compared to a similar conventional hull design.

 

You make it sound like engineers haven't thought through the design.

 

Also, on the x-bow design boyant area doesn't increase

Edited by Jason L
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New designs often have a lot of problems, the Island class cutters suffered from cracking because the designers did not anticipate the sea states they would be working in. that just one example. Every ship is a series of trade off, throw in accountants looking to save money, things go sideways.

 

Actually buoyant area does increase as the bow submerges. In the X bow the increase only diminishes slight as the bow digs in, on the Zummie that increase of buoyant area rapidly decreases.

 

Lets say the ship has 3 decks under water in the forward section, for argument sake roughly a triangle 30m base going to a point 50m forward. In a traditional design, the next deck to submerge is 32mx50m, the deck after that is 34mx50m, then 36mx50. So the amount of buoyant area increases. dramatically. On the tumblehome, the opposite happens, you go 30mx50m, to 28x50, 26x50 and 24x50.

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To me, the biggest problem with the Zumwalt isn't its hull shape or other design features, rather the fact that budget constraints caused it to be built without a volume search radar, meaning it has to be paired with a Burke to provide those capabilities, which makes you wonder if going that route, if it wouldn't just be easier to just use another, modified Burke hull. Apparently, the navy has also come to that conclusion.

IIRC the radar system would not fit an Arleigh Burke hull in a reasonable compromise with other subsystems.

 

I question whether the extra reduction of radar cross section is worth all that effort.

Many missiles have or will have IR sensors and see the ship easily, and the ship will be visible to radars at high altitudes simply because of wakes, different echo than the sea etc.

 

Moreover, whatever capability these ships add to the fleet won't be available to the majority of CVBGs.

There will at most one of these "destroyers" be forward deployed on given time on average.

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