Misplaced Pages

#443556

29-509: La Fayette is a general purpose stealth frigate of the French Navy ( Marine Nationale ). She is the second French vessel named after the 18th century general Marquis de Lafayette . She is the lead ship of the class . La Fayette began a major life extension upgrade in October 2021. The upgrade is designed to permit the frigate to operate through the 2020s and into the 2030s and incorporates

58-452: A horizontal face are to be eliminated since they are very visible to radar. To bypass these limitations, many ships use features such as panels that cover reflective surfaces or use alternate designs of hardware. Additionally, efforts are made to minimize gaps on the ship. Hull shapes include tumblehome hull designs, which slope inward from the waterline, and small-waterplane-area twin hulls (SWATH), which allow for better stability when using

87-400: A ship. Another major element is signal emission control. Modern warships emit much electromagnetic radiation in the form of radar, radio, and bleed-off from the ship's electrical systems. These all can be used to track a ship, and thus modern stealth ships often have a mode that switches off many of the electronic emissions ( EMCON ), the downside being the ship has to rely on passive sensors and

116-479: A spokesman for Naval Sea Systems Command. The Swedish Navy 's Visby -class corvette is designed to elude visual detection , radar detection, acoustic detection, and infrared detection . The hull material is a sandwich construction comprising a PVC core with carbon fiber and vinyl laminate. Avoidance of right angles in the design results in a smaller radar signature, reducing the ship's detection range. The Royal Navy 's Type 45 destroyer has similarities to

145-546: A tumblehome hull. These RCS design principles were developed by several navies independently in the 1980s using work done on aircraft RCS reduction as the starting point. Sea Shadow , which utilizes both tumblehome and SWATH features, was an early US exploration of stealth ship technology. The currently-serving Zumwalt -class destroyer is a modern example of a stealth ship from the US Navy. Despite being 40% larger than an Arleigh Burke -class destroyer , its radar signature

174-431: A vessel's beam and creating a low center of gravity (by decreasing mass above the waterline), both tending to maximize stability. In the era of oared combat ships it was quite common, placing the oar ports as far abeam as possible, allowing maximum possible manpower to be brought to bear. Inward-sloping sides made it more difficult to board a vessel by force, as the ships would come to contact at their widest points, with

203-555: A warship, and so were cheaper to build and carried more than twice the cargo of a conventional vessel and could be handled by a much smaller crew. These factors resulted in a lower cost of transportation by Dutch merchants, giving them a major competitive advantage. Tumblehome has been used in proposals for several modern ship projects. The hull form in combination with choice of materials results in decreased radar reflection, which together with other signature (sound, heat etc.) damping measures makes stealth ships . This faceted appearance

232-409: Is flare . A small amount of tumblehome is normal in many naval architecture designs in order to allow any small projections at deck level to clear wharves . The term is also applied to automotive design, where a vehicle's sides taper inward as they go up. This includes a roof tapering in, and curved window glass. Tumblehome was common on wooden warships for centuries. It allowed for maximizing

261-539: Is a common application of the principles of stealth aircraft . Most designs feature tumblehome only above deck level; the US Navy 's Zumwalt -class destroyers demonstrate it above and below the waterline. Due to stability concerns, most warships with narrow wave-piercing hulls combine tumblehome with multi-hull designs, such as the Type 022 missile boat . The inward slope of a narrowboat's superstructure (from gunwales to roof)

290-406: Is a fairly new concept, many other forms of masking a ship have existed for centuries or even millennia. In designing a ship with a reduced radar signature, the main concerns are radar beams originating near or slightly above the horizon (as seen from the ship) coming from distant patrol aircraft, other ships, or sea-skimming anti-ship missiles with active radar seekers . Therefore, the shape of

319-464: Is also called the tumblehome. An example of a car with a pronounced tumblehome is the Lamborghini Countach . Less commonly, the inward curve of the body near the bottom may also be called a tumblehome. In 21st century automobile designs this turnunder is less pronounced or eliminated to reduce aerodynamic drag and to help keep the lower portions of the vehicle cleaner under wet conditions. It

SECTION 10

#1732892047444

348-404: Is known in bus body design as well. The S. A. Foster House and Stable were designed during an experimental period by Frank Lloyd Wright in 1900 and have some rare design features including Japanese-influenced upward roof flares at all of the roof peaks and on each dormer . The house and stable also incorporate an extremely rare tumblehome design throughout. The exterior walls slant inward from

377-543: Is more akin to a fishing boat, according to a spokesman for Naval Sea Systems Command ; sound levels are comparable to the Los Angeles -class submarine . The tumblehome hull and composite material deckhouse reduce radar return. Water sleeting along the sides, along with passive cool air induction in the mack , reduces infrared signature . Overall, the destroyer's angular build makes it "50 times harder to spot on radar than an ordinary destroyer", according to Chris Johnson,

406-411: Is referred to as tumblehome. The amount of tumblehome is one of the key design choices when specifying a narrowboat, because the widest part of a narrowboat is rarely more than 7 feet across, so even a modest change to the slope of the cabin sides makes a significant difference to the "full-height" width of the cabin interior. The inward slope of the " greenhouse " above the beltline of a motor vehicle

435-403: Is unable to easily send messages further than the line of sight. Also of importance are thermal emissions. A heat signature can make a ship stand out in the ocean, making it easier to spot. Because it is possible to see infrared emissions through features that would normally hide a ship such as fog, or a smoke screen, many detection platforms like patrol aircraft, UAVs, and satellites often have

464-535: The Visby class, but is much more conventional, employing traditional steel instead of carbon fiber. Like Visby , its design reduces the use of right angles. The ROC Navy 's Tuo Chiang -class corvette is a class of fast stealth multi-mission corvettes currently in service with the Republic of China (Taiwan) Navy . The ships are designed to have a low radar cross-section and evade radar detection making it difficult to detect

493-487: The Atlantic to fill a gap resulting from the retirement of the patrol vessel Premier-Maître L'Her and a delay in the commissioning of the new frigate Amiral Ronarc'h . Stealth ship These techniques borrow from stealth aircraft technology, although some aspects such as wake and acoustic signature reduction ( acoustic quieting ) are unique to stealth ships' design. Although radar cross-section (RCS) reduction

522-429: The ability to see multiple bands in the infrared spectrum. This necessitates the control of thermal emissions. The most common method is to mix any hot gasses emitted by the main source of heat—the engines' exhaust—with cold air to dilute the signature and make it harder to pick out the ship from the background warmth. Another method vents the exhaust into the water, although this increases the ship's acoustic signature. For

551-596: The addition of hull-mounted sonar, improved point air defence systems, the CANTO anti-torpedo countermeasures system, as well as the capacity to deploy the latest variant of the Exocet anti-ship missile. The frigate returned to sea for testing of her new systems in May 2022 and was declared fully operational again in November 2022. She is to remain active until 2031. In February 2023, the frigate

580-462: The advent of long-range radar. Just like choices in shaping, the choice of materials affects the RCS of a ship. Composites like fiberglass and carbon fiber are effective blockers of radar and give smaller vessels an advantage in further RCS reductions. However, composites are fragile and often unsuited to larger ships or ships that expect to take fire, although new laminates can partially negate some of

609-438: The decks some distance apart. With the advent of gunpowder, extreme tumblehome also increased the effective thickness of the hull versus flat horizontal trajectory gunfire (as any given width material grows effectively "thicker" as it is tilted towards the horizontal) and increased the likelihood of a shell striking the hull being deflected—much the same reasons that later tank armour became sloped . Steel warships especially of

SECTION 20

#1732892047444

638-518: The early 1880s frequently demonstrate tumblehome, though it has been an influential factor in their design ever since their beginnings. One of the first ironclad warships , the CSS ; Virginia of 1862, could be considered an early example of this integral trend. However, the French Navy in particular promoted the design, advocating it to reduce the weight of the superstructure and increase seaworthiness by creating greater freeboard . A French yard

667-414: The hull, cool water can be actively distributed across the hull of the ship. Another less crucial but still relevant part of a stealth ship is visual camouflage . This area is probably the oldest form of stealth, with records going back almost as far as the writing of ancient mariners using visual tricks to make their ships harder to spot. Although still relevant, this area has taken on lesser importance with

696-471: The ship avoids vertical surfaces, which are effective at reflecting such beams directly back to the emitter. Retro-reflective right angles are eliminated to avoid the cat's eye effect . A stealthy ship shape can be achieved by constructing the hull and superstructure with a series of slightly protruding and retruding surfaces. Furthermore, round shapes on the ship are eliminated or covered up, examples being smokestacks and gun turrets. Also, cavities that present

725-405: The ship when operating closer to the coastline. Stealth technology represents more than just a low RCS ; noise reduction plays a role in naval stealth because sound is conducted better in water than air. Some of the techniques used include muffled exhaust systems, modified propeller shapes, and pump-jets . The shape of the hull can also have a great effect on the reduction of the noise from

754-423: The weaknesses. This restricts larger ships to metals like steel and aluminum alloys. To compensate, a ship may include a coating of a radar-absorbing material, although this can be expensive and may not stand up to the corrosive effects of salt water. (Year of commission) Tumblehome Tumblehome is a term describing a hull which grows narrower above the waterline than its beam . The opposite of tumblehome

783-724: Was breached. Four tumblehome Borodino -class battleships, which had been built in Russian yards to Tsesarevich ' s basic design, fought on 27 May 1905 at Tsushima . The fact that three of the four were lost in this battle resulted in the discontinuing of the tumblehome design in future warships for most of the 20th century. Another example of tumblehome hull design were the Dutch fluyt , 17th century cargo sailing vessels. Fluyt ships were designed to facilitate transoceanic delivery of cargo with maximum of cargospace and crew efficiency. Unlike rivals, they were not built for conversion in wartime to

812-636: Was contracted to construct the pre-dreadnought battleship Tsesarevich along the lines of France's Jauréguiberry . Tsesarevich was delivered to the Russian Imperial Navy in time for it to fight as Admiral Wilgelm Vitgeft 's flagship at the Battle of the Yellow Sea on 10 August 1904. The Russo-Japanese War proved that the tumblehome battleship design was excellent for long-distance navigation, but could be dangerously unstable when watertight integrity

841-601: Was tasked to initiate an around the world deployment accompanying the helicopter assault ship Dixmude . The deployment was to involve a series of exercises and port calls enroute. According to the commander of the mission, Captain Emmanuel Mocard, La Fayette possesses improved sea-keeping and endurance following her upgrade and the scope of the planned deployment would not have been feasible prior to her refit. The frigate returned to Toulon in July. In 2024, La Fayette deployed to

#443556