Posted on 04/13/2011 8:09:12 PM PDT by sukhoi-30mki
EB: Submarines can be ''stretched'' to boost firepower
By Jennifer McDermott
Publication: The Day
Electric Boat says it can add more missile tubes to Virginia-class submarines without compromising speed or stealth.
EB has been working on a concept for a "stretch Virginia" to boost firepower. The task was to figure out whether the subs could be lengthened by about 90 feet to accommodate triple the number of Tomahawk missiles they now carry, and to launch the weapons of the future, including unmanned undersea vehicles.
Preliminary estimates say the modification could cost up to $500 million per ship, adding roughly 20 percent to the cost of an attack submarine.
Two years ago the Navy asked EB to work on the project, which is not an official Navy program at this point.
After completing the initial engineering work the company found that it can be done, according to John Holmander, the vice president who manages the Virginia-class program. Company officials are discussing the concept at the Navy League's three-day Sea-Air-Space Exposition that began Monday in Maryland.
U.S. Rep. Joe Courtney, D-2nd District, plans to advocate for research and design money for the Navy in the fiscal 2012 budget, some of which could be used to further develop the concept. But fully funding a new program would be an uphill battle, given the federal government's fiscal woes.
The Navy's Submarine Force will lose about 60 percent of its undersea firepower in the late 2020s with the retirement of its four guided-missile subs, capable of carrying up to 154 Tomahawk missiles. This is happening at the same time that the number of attack submarines in the fleet is dropping because of the retiring of the aging members of the Los Angeles-class subs.
The first "stretch" Virginia could be the sub that EB starts building in 2019, which would be commissioned close to the time that the first guided-missile sub retires.
On the most recent Virginia-class subs, two large-diameter missile tubes located forward of the sail can launch six Tomahawk cruise missiles each. The subs also carry torpedoes.
Extending the submarine to 471 feet would make room for a module near the middle with four additional tubes capable of launching seven missiles each. That would be a 230 percent jump in the number of Tomahawks that can be launched quickly, from 12 to 40.
These stretched subs would still fit in the docks at EB, which at one time held Ohio-class submarines 560 feet long.
The four new missile tubes would be more than 7 feet in diameter.
"This opens the door to many, many other game-changing applications," Rear Adm. Richard P. Breckenridge, deputy director of the Submarine Warfare Division, said in an interview.
The stretch Virginia ranks third in the Submarine Force's priorities, Breckenridge said. Topping the list is the program to replace the current fleet of Ohio-class, or Trident, submarines, followed by finding ways to mitigate the dip in the number of attack submarines as the aging subs of the Los Angeles class retire.
If the Navy had a more robust budget, it would pay for the capability "without hesitation," he said. The Navy is looking to the Defense Department to see if funds could be available to proceed with the stretch Virginia concept, Breckenridge said.
Peter W. Singer, director of the 21st Century Defense Initiative and a senior fellow in foreign policy at the Brookings Institution, said the stretch Virginia seeks to answer a key problem that the Navy faces, the crunch in the number of submarines overall and the limits in the number of missiles they can deploy. Both problems look to be worsening in the future, he added.
"The Navy is going to face a series of tough decisions budgetwise. But all things being equal, it's a program we have to give serious consideration towards," Singer said Tuesday.
The USS Florida was one of the three U.S. submarines that launched Tomahawk missiles into Libya last month to support a no-fly zone. One of the fleet's four guided-missile submarines, the Florida launched a majority of its Tomahawk missiles, Breckenridge said. Typically guided-missile submarines deploy with 105 missiles, he added.
"The Navy would've needed eight other attack subs in theater to do what that one ship, Florida, did," he said.
While the economy and the budget "will not tolerate" building a new class of guided-missile submarines, Breckenridge said the stretch Virginia solution offers a more affordable way for the Navy to get a "strategically important capability." It gives the Navy flexibility to distribute more missiles on submarines in more locations, rather than concentrating them on the guided-missile submarines, he added.
Courtney said the fact that Congress still plans to pay for two Virginia-class submarines this year instead of one, despite immense pressure for spending cuts, bodes well for the future of the stretch Virginia concept.
"If you're going to make that investment, you obviously want to concentrate the return to the greatest extent possible," he said Tuesday. "And stretching the missile capacity, I think, makes sense."
j.mcdermott@theday.com
Those were the days when the Soviet Union had already beaten the US to space with the Sputnik, and the Cold War seemed very hot.
Once the US developed the Polaris missile, there was a great sense of urgency to get it to sea as soon as possible. The keel for Scorpion had already been laid, and was used for the Washington. I’m sure that the FBM program raided many other boats under construction to get the first five boomers to sea. I was also on the Roosevelt, which ended up with many parts originally meant for Scamp.
“A boat’s hull speed increases with waterline length.”
Which is of no benefit to a sub trying to stay stealthy at low power levels.
JC
Quantifying resistance of floating objects is generally credited to William Froude, who used a series of scale models to measure the resistance each model offered when towed at a given speed. Froude's observations led him to derive the Wave-Line Theory which first described the resistance of a shape as being a function of the waves caused by varying pressures around the hull as it moves through the water. The naval constructor Ferdinand Reech had put forward the concept in 1832 but had not demonstrated how it could be applied to practical problems in ship resistance. Speed/length ratio was originally defined by Froude in his Law of Comparison in 1868 in dimensional terms as: \mathrm{Speed\ Length\ Ratio} =\frac {V}{\sqrt \mathrm{LWL} } where: v = speed in knots LWL = length of waterline in feet
http://en.wikipedia.org/wiki/Froude_number
I’m not interested in long-winded tech discussions but, in general, “hull speed” characteristics relate to positive displacement surface vessels. Submarine hydrodynamics are much more complex and suggest that a length-to-beam ratio of approx. 7.5 to 7.7 offer the least hull drag resistance. The existing Virginia class attack sub (L=377ft, W=34ft) has a 11.1 ratio while a 90 ft extension yields a 13.7 ratio that is less efficient meaning more power is required to attain a given speed through the water. Higher power means higher RPM, increasing the risk of blade cavitation which is a catasprophe for stealthy submariners!
JC
Well, I guess General Dynamics - Electric Boat are bunch of idiots.
“Well, I guess General Dynamics - Electric Boat are bunch of idiots.”
Not at all; they are competing for additional business, and if I had to guess, I would say that at slow, on station, operational speeds, the additional power requirements would be negligible. The blanket statement that speed would not be sacrificed is kinda like one of those Obama promises - “it all depends on the details”!
JC
I was under the impression that the USS Scorpion went down with all hands in 1968
I was under the impression that the USS Scorpion went down with all hands in 1968You are correct. The original keel for the Scorpion had been laid, but it was renamed George Washington. Afterwards, the Navy started over with a new USS Scorpion, which was the boat that sank.
And when they're done with them, they cut them back out, and make prototype school trainers for NNPTC.
I have to wonder if we’re looking at increasing the number of launchers for conventional-warhead munitions because Obama took the use of tactical nukes off the table.
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