Warrior Maven Video Above - What Are the Navy's Plans for the New Columbia-Class subs?
By Kris Osborn - Warrior Maven
The US Navy is planning its first strategic patrol of the emerging nuclear-armed Columbia-class ballistic missile submarine in 2031 -- launching a new generation of technically advanced submarines intended to quietly patrol the undersea domain to ensure second-strike ability should the US be hit with a catastrophic nuclear attack.
As of last Summer, the Navy had issued at least one-fourth of the designs and made major advances in work on systems such as a stealthy "electric drive" propulsion, a new variant of the nuclear-armed Trident II D5 modernization and early missile-tube prototyping for the boats.
“Construction start for Columbia remains on schedule to begin in 2021, with delivery in 2027 and a first strategic patrol by 2031. As stated by Navy leadership, we continue to look for opportunities to increase the margin for timeliness in construction, test and delivery,” William Couch, spokesman for Naval Sea Systems Command, told Warrior Maven.
Knowledge that a Chinese submarine-launched, nuclear armed JL-3 missile is capable of striking portions of the US has naturally sustained, if not heightened, focus on US strategic deterrence efforts. The emerging Chinese JL-3 attracted international attention when it was test launched in November of last year.
Therefore, the Columbia is being engineered with the hope of bringing unprecedented levels of quieting technology, weapons, sonar and propulsion, among other things - in part to meet threats such as this.
The Columbia class is to be equipped with an electric drive propulsion train, as opposed to the mechanical-drive propulsion train used on other Navy submarines.
In today’s Ohio-class submarines, a reactor plant generates heat which creates steam, Navy officials explained. The steam then turns turbines which produce electricity and also propel the ship forward through “reduction gears” which are able to translate the high-speed energy from a turbine into the shaft RPMs needed to move a boat propeller, Navy weapons developers have explained.
“The electric drive system is expected to be quieter (i.e., stealthier) than a mechanical drive system,” a Congressional Research Service report on Columbia-class submarines from last year states.
Quieter propulsion is increasingly taking on importance as the US strives to sustain its undersea technical advantage. It is an edge in jeopardy of decreasing as potential adversaries acquire advanced sonar and other new methods of detecting submarines.
Designed to be 560-feet– long and house 16 Trident II D5 missiles fired from 44-foot-long missile tubes, Columbia-class submarines will use a quieting X-shaped stern configuration.
The “X”-shaped stern will restore maneuverability to submarines; as submarine designs progressed from using a propeller to using a propulsor to improve quieting, submarines lost some surface maneuverability, Navy officials explained.
Navy developers say that electric drive propulsion technology still relies on a nuclear reactor to generate heat and create steam to power turbines. However, the electricity produced is transferred to an electric motor rather than reduction gears to spin the boat's propellers.
The use of an electric motor brings other advantages as well, according to an MIT essay written years ago when electric drive was being evaluated for submarine propulsion.
Using an electric motor optimizes use of installed reactor power in a more efficient way compared with mechanical drive submarines, making more on-board power available for other uses, according to an essay called “Evaluation and Comparison of Electric Propulsion Motors for Submarines." Author Joel Harbour says that on mechanical drive submarine, 80-percent of the total reactor power is used exclusively for propulsion.
“With an electric drive submarine, the installed reactor power of the submarine is first converted into electrical power and then delivered to an electric propulsion motor. The now available electrical potential not being used for propulsion could easily be tapped into for other uses,” he writes.
Research, prototyping, science and technology work and initial missile tube construction on Columbia-class submarines have been underway for several years. One key exercise, called tube-and-hull forging, involves building four-packs of missile tubes to assess welding and construction methods. These structures are intended to load into the boat’s modules as construction advances.
While the Columbia-class is intended to replace the existing fleet of Ohio-class ballistic missile submarines, the new boats include a number of not-yet-seen technologies as well as different configurations when compared with the Ohio-class.
The Columbia-class will have 16 launch tubes rather than the 24 tubes current on Ohio boats, yet the Columbias will also be about 2-tons larger, according to Navy information. The new submarines are expected to serve all the way into the 2080s and beyond.
General Dynamics Electric Boat is acquiring long-lead items in anticipation of beginning construction; the process involves acquiring metals, electronics, sonar arrays and other key components.
Columbia-class to Fire Trident II D5 Nuclear-Armed Missiles
While the Navy may ultimately engineer a replacement for its 1980s era Trident II D5, the missile is being modernized to fire from the Columbia-class. The Navy has been working with Lockheed on a Trident II D5 life-extension program aimed at ensuring the weapon can serve well into the 2040s.
A new, life-extended variant, called the Trident II D5LE, was first installed in 2017, arming the fleet with an upgraded weapon, according to a Navy fact sheet.
The three-stage ballistic missile can travel a nominal range of 4,000 nautical miles and carry multiple independently targeted reentry bodies, according to Navy and Lockheed information.
In recent years, the Navy as been working with Lockheed on a number of key technical upgrades to both modernize and sustain the nuclear weapon. Some of these are ongoing, and others have made sufficient progress, laying the foundation for next-stage sustainment efforts, Navy officials told Warrior.
This has included work on the missile's Mk-6 guidance system, with a specific focus on the weapon's electronic modules, Navy developers have said.
“D5LE is using two stars for stellar navigation, which apparently provides more flexibility with regard to the submarine’s precise position,” Hans Kristensen, Nuclear Information Project at the Federation of American Scientists, told Warrior Maven.
As part of the technical improvements to the missile, the Navy has also been upgrading what’s called the Mk-4 reentry body, the part of the missile that houses a thermonuclear warhead. The life-extension for the Mk-4 reentry body includes replacing components such as the firing circuit, Navy officials explained. A new Mk-4A variant, according to Kristensen, has an enhanced fuzing and firing unit bringing improved targeting.
Navy and industry engineers have also been modernizing the guidance system by replacing two key components due to obsolescence – the inertial measurement unit and the electronics assembly, developers said.
The Navy has also, in recent years, been working with the Air Force on refurbishing the Mk-5 reentry body. Navy officials say the Mk-5 reentry body has more yield than an Mk-4 reentry body, adding that more detail on the differences was not publicly available.
The missile also has a larger structure called a release assembly which houses and releases the reentry bodies. There has been an ongoing effort to engineer a new release assembly that will work with either the Mk-4 or Mk-5 reentry body.
Within the last several years, the Navy has acquired more than 100 Trident II D5 missiles in order to strengthen the inventory for testing and further technological development.
The 130,000-pound Trident II D5 missile can travel 20,000-feet per second, according to Navy figures. The missiles cost $30 million each.
The "Bulletin of the Atomic Scientists" further describes the weapon -- "The Trident D5s carry three types of warheads: the W76/Mk-4, the 100-kiloton W76-1/Mk-4A, and the W88/Mk-5 warhead, the highest-yield ballistic missile warhead in the U.S. arsenal."
“By now, we estimate that all the deployed W76 warheads are of the new W76-1 type. The National Nuclear Security Administration just announced that it has completed production of the last W76-1,” Kristensen added.
--- Kris Osborn is a Senior Fellow at The Lexington Institute - The Lexington Institute
Osborn previously served at the Pentagon as a Highly Qualified Expert with the Office of the Assistant Secretary of the Army - Acquisition, Logistics & Technology. Osborn has also worked as an anchor and on-air military specialist at national TV networks. He has a Masters in Comparative Literature from Columbia University.
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