Skip to comments.Changing Needs Influence Warship Design
Posted on 05/09/2011 8:19:13 PM PDT by sukhoi-30mki
Changing Needs Influence Warship Design
May 9, 2011
By Bill Sweetman, Andy Nativi, Francis Tusa, David Eshel
Washington, Genoa, London, Tel Aviv
Warship design in much of the world may be entering a new era, with requirements driven less by peer-on-peer sea battles and more by lessons of the past decade, combined with economic constraints. Brazil, Canada, Israel and the U.K. are among the nations looking at new surface combatant programs. The first three represent markets for Europes shipbuilders (and possibly South Korea) while the U.K. is trying to break back into the global warship business.
Success will involve anticipating changes in user requirementsincluding an increased emphasis on multirole platforms that can survive in combat, but also participate in long patrols against low-tech threats or support humanitarian operations. That capability is important at political levels because the ability to participate in international operations is a big factor in a countrys standing. Different suppliers approach the challenge in different ways.
Germanys Blohm & Voss shipyard, part of the Thyssen Krupp Marine Systems (TKMS) group, is bringing experience from two recent programs to bear on future requirements. Already in service are the South African Navys four Valour-class frigates, based on the Meko A200 design, with a number of TKMS-unique features. The ships have an X‑type cross-section above water, with hull sides canted inward and the superstructure flared outward at the same angle to reduce radar cross-section, and the engine exhausts are at the waterline and water-cooled to reduce infrared signature.
They have a new propulsion system, with diesel-powered propellers for cruise and turbine-powered waterjetsa first on a warship of this sizefor speed and maneuvering. The waterjets have thrust reversers for rapid deceleration, which is valuable for intercepting small craft. The A200 attains 23 kt. on diesel/propeller power and will often cruise on one of two diesels. The A200 is on offer to a number of customers, including Algeria, but as a craft designed for South Africa, TKMS notes, it is built for open-ocean operations.
The companys other major program is Germanys F125 frigate, a larger ship at 7,000 tons, with controllable-pitch propellers and a combination of diesel-electric and turbine power. For reliability and flexibility the ships have four 2.9MW MTU diesels that provide propulsion and secondary power, with a single GE LM2500 turbine for high speed.
The biggest and most challenging innovation, in requirements, is that the ships are intended to operate for two years in foreign waters, with crews rotating in friendly ports, without requiring more than routine dockside repairs. German experience in deployed operations has proven the cost and difficulty of transiting ships back and forth for maintenance. The requirement puts a premium on reliability of all systems (active array radars, for instance, are a necessity).
The U.K., meanwhile, is trying to expand into the export market from which it retreated 40 years ago, with the Type 26/Global Combat Ship. The GCS is set to enter service at the end of the decade, and will progressively replace Type 22 and 23 frigates. The reason it is such a challenge is that in the past, the requirements of the Royal Navy led to over-optimized platforms that suited only the U.K.
We tend to speak about flexibility and modularity in the GCS design, comments Brian Johnson, BAE Systems business development director for surface ships. What we are trying to doand I think the Royal Navy has got itis to show that if you make a bespoke [custom] product, you end up optimizing every space on the ship, and that costs.
This has seen tradeoffs conducted by BAE Systems and the Royal Navy to eliminate customized requirements and opt for modular sub-systems, such as storage and accommodation units.
This cuts down on complexity [and cost] although it does make the ship a little bigger, Johnson says. He indicates that modularity adds 5-10% of the overall ship size, which is now in the 5,500-metric-ton range.
With major backing from the government, the GCS is aiming at a number of possible export targets, such as Australia, Brazil, India and Japan. We are looking at whats likely to get put on GCS by export customers, Johnson explains. The U.K. will put the Artisan radar on it, but we would be crazy not to make it capable of taking the [Thales] Smart S radar. The U.K. is still talking about putting a 4.5-in. gun on its ships, but wed be equally stupid to do a design and not be able to take a U.S. or Italian 5-in. gun.
Other weapons, such as the Raytheon Standard Missile system, will also be provided, even though the U.K. will use the MBDA Common Anti-Air Missile. Another design aspect to retain flexibility is crew size. With standardized cabin spaces, you can fit them for as few as 120-130 people, or make them denser-packed for over 200, Johnson says, explaining that there are some major differences in crew requirements between target customers.
The most interesting tradeoff has been over the propulsion system, Johnson says. If you back off the speed requirement by 2-3 kt., you could use diesel rather than gas turbines, and save money through life. Diesel technology has improved since the Type 23 frigate was designed. So you are right on the edge of the capability curve here. But, he adds, some navies are reluctant to step away from gas turbines, which they see as trading away capability.
The Italian navy is dealing with the challenge of multirole ships. They require multirole crews, which means that many skills have to be trained and practiced. The same trends affect other navies. South Africa has increased the A200 crew size to 120 from 100, to support a wider range of skills. The F125 is sized to accommodate a 50-member special operations team and four rigid-hull inflatable boats, two NH90 medium helicopters plus two 20-ft. ISO containers for specialized mission equipment.
One concept being explored in Italy calls for tailoring crew size and composition to specific missions. If the navy is sending a corvette to conduct an antipiracy mission, it can leave antisubmarine and antiaircraft specialists, adding instead a boarding party. The result is a basic crew to which specific mission-related personnel will be attached.
But sometimes the opposite happens and a complex command staff can be embarked. This requires extra berthing and mess spaces that can be used for other purposes, such as embarking a special forces detachment. To exploit the higher availability levels of the new vessels, the navy may follow the example of the U.S. Navys SSBN fleet, with Gold and Blue crews alternating on the same ship.
TKMS invented the modular ship concept in the early 1970s with the original Meko class, and others have adapted the idea. In Denmark, the Standard Flex concept was developed by the Danish naval materiel command jointly with Promecon Co., and has been applied on a class of 14 offshore patrol vessels/corvettes with a mere 450 tons displacementthe Flyvefisken class, which entered service between 1989 and 1996. These ships share 101 modules of 11 types.
The Danish modules are smaller and lighter than the Meko ones and can be changed faster. The modular approach has been extended, first with the Thetis-class patrol frigates, then with five modular vessels, two Absalon Flexible Combat Support Ships and followed by three patrol frigates (destroyers) of the Huitfeldt class.
A different challenge is faced in Israel, where the navy wants to acquire a fleet of Saar V Mk II multirole ships, equipped with the Barak 8 area-defense missile and its EL/M-2248-MF-STAR radar. Behind the program is a strategic issue: Israel is preparing to protect its newfound resource, a natural gas bonanza discovered in the eastern Mediterranean, parts of which Lebanon and the Palestinians also claim.
Threats to the gas fields include sabotage by swimmers, ballistic threats from shore or small vessels, as well as attack by antiship missiles. Hezbollah possesses Iranian-modified Chinese C-802 antiship cruise missiles with a 180-km (110-mi.) range.
One result will be a renewed push to get more capability on the new ships. Already, potential bidders have noted that the Israeli philosophy is to arm the ships for any contingency, resulting in small ships with limited endurance and habitability. This is expected to carry over to whatever design forms the basis of the new Israeli class.
With Francis Tusa in London, Andy Nativi in Genoa and David Eshel in Tel Aviv.
South African Valour class frigate
They makin’ any ships that won’t hesitate to sink pirates? We need some of those. ‘Cause a lot of people on ‘em now ain’t up to it.
The builders of the Bismark.
That is good looking a target (submarine meat).
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.