Under standard conditions, pure water density is 1000 kg/m3 and air density is 1.29 kg/m3. Therefore, the resistance of moving in the water of the object is much greater than that of moving in the air. When an object moves in water, the total resistance is the vector sum of frictional force, viscous resistance and xingbo resistance. At low speeds, the resistance to the object is mainly the frictional force and viscous resistance with water. At high speeds, the main resistance to an object is the Xingbo resistance. In order to increase the speed, the hull can be allowed to get out of the water as much as possible, one of the methods is to use the air cushion effect or lift the hull part (sidewall) or all (full cushion lift) out of the water, because the surface area of the hull that generates drag in the water is greatly reduced, and the speed can reach up to 90 knots (166.68 km/h). The Norwegian and Soviet navies of the world built and equipped side-walled air-cushioned combat ships, which, in addition to speed, had the advantage of navigating in extremely shallow waters, which were very suitable for activity in coastal waters.
Sidewall (Surface Effect Ship) and full-cushion lift hovercraft (Hovercraft) working principle, the sidewall ship left and right side rigid hull is still in the water, the bow, tail through the flexible apron (orange part in the picture) contact with the water surface, left and right side rigid hull and bow, tail flexible apron to form a relatively closed space, in which compressed air is injected to form an air cushion to lift the hull support out of the water, thereby reducing the hull contact with the water to very little The full-cushioned lifting gasket has a flexible apron (orange part in the picture) at the bottom, in which compressed air is injected to form an air cushion to lift the hull out of the water
In 1999, the Norwegian Navy built the first "Shield" (P 960) stealth sidewall missile boat that took advantage of the air cushion effect and entered service with the Royal Norwegian Navy, the hull surface adopted a sloping flat design, the structure was heavily made of composite materials, with a very low radar reflection signal, in order to take advantage of Norwegian bays and fjords to hide, the hull surface was painted with digital camouflage, reducing visibility in the visible light band.
Until 2009, the Royal Norwegian Navy classified the Skjold-class stealth side-wall missile boats as motorized torpedo boats (MTBs). Due to its seaworthiness comparable to corvettes and the absence of torpedoes, the Royal Norwegian Navy reclassified them as corvettes starting in 2009.
The P 960 stealth side-wall guided-missile boat, later classified as a corvette, is currently one of the most advanced stealth corvettes in the world
The Skjold-class stealth corvettes are of the side-walled hovercraft type:
(1) The rigid hull on the left and starboard sides is immersed in the water to support the hull to maintain stability, and forms a relatively sealed space with the flexible skirt brace of the bow and tail, which accommodates the compressed air injected into the hull to lift the hull support out of the water surface and reduce the navigation resistance; the waterjet thrusters located at the tail end of the left and right side hulls that are immersed in the water are used to achieve heading control and turning by using the speed difference between the water spray.
(2) The direction of the opening of the seam at the joint of the flexible skirt of the bow and tail is inconsistent, the stern is a horizontal seam, and the bow is a vertical direct seam.
(3) It can sail at low speed in the drainage state, or it can sail at high speed in the air cushion state.
(4) The hull, turret, superstructure and mast adopt an oblique design, which deviates the incident radar wave from the direction of incidence and cannot return to the antenna that emits the radar wave, and the surface of the hull is coated with radar absorbing paint, digital camouflage and other stealth technical measures.
"Shield" class stealth side-wall corvette tri-line view, length 47.50m, width 13.50m, draft depth of 2.5m (drainage state), 1m (air cushion state), full load displacement of 274t, speed of 64 knots / 118.6km / h (calm sea surface), 48 knots / 89km / h (five levels of sea conditions waves), range of 1500km (speed of 74km / h), crew of 16 people (4 officers, 12 soldiers), self-sustainability of 7 days COmbined Gas And Gas (COGAG) with a power of 12,000 kW/16092hp – 2 units each of pratt & Whitney ST18M and ST40M, with 2 propellers of Ola-Ro Kamewa waterjet thrusters
The rigid hull on the left and starboard sides is immersed in water to support the hull to remain stable, and the flexible skirt support of the bow and tail forms a relatively sealed space to accommodate the compressed air injected into it
Details of the bow flexible skirt support
The two waterjet thrusters are located at the tail end of the left and right side of the hull immersed in the water
The scene of the stealth side-walled corvettes of the Skjold class sailing at low speeds in a drained state with no obvious trails at the tail
The Skjold class sails at high speed in an air cushion state, with a clear track at the rear and water mist atomized by compressed air leakage on the side of the hull
Weapons of the Skjold class stealth side-wall corvettes:
(1) The bow A gun position is equipped with an Otto-Breta 76mm/62 caliber ultra-fast gun, which has anti-ship, air defense, and ground attack capabilities, and is used to deal with small and medium-sized targets.
(2) Behind the superstructure, two Consburg "Sea Protector" 12.7mm remote control weapons stations, or two Browning 12.7mm heavy machine guns, are installed to deal with small targets at sea surface and in the air.
(3) Carry 2×4 naval strike missiles (NSMs) for dealing with large and medium targets, the basic tactics are to use the bay and fjords to covertly approach the enemy's large and medium-sized ships, use radar or photoelectric systems to detect and lock the target, enter the anti-ship missile range and launch anti-ship missiles (Figures 11, 12), missiles "after launch", after launching corvettes will withdraw from the battlefield; in addition, after equipping ground-attack naval strike missiles, When operating in coastal areas, it has the ability to carry out precision strikes against targets at a distance of 100 km from the shore.
The bow A gun is equipped with an Otto-Breta stealth 76mm/62 caliber super-fast gun, the stern can be lifted by 2× and 4 naval strike missiles tilt storage-launch box
The direction of the opening of the seam at the joint of the flexible skirt support of the bow and tail is inconsistent, and the stern is a horizontal seam, but the bow is a vertical direct seam
The "Shield" (Skjold) class stealth side-wall corvette adopts the stealth Otto-Breta 76mm/62 caliber ultra-fast gun, and the rear superstructure is equipped with a radar/TV with fire control system, which can engage sea surface ships, aircraft, shore targets, and can fire high-explosive bombs, high-explosive armor-piercing shells, etc., with a maximum effective range of 8000m, a rate of fire of 120 rounds per minute, 85 rounds of spare ammunition, and 85 rounds of carrying
The rear superstructure of the 76mm ultrafast gun is a radar/photoelectric sensor for its fire control system
It has the ability to automatically aim at moving targets in the air or at sea for accurate shooting; behind the superstructure, 2-seater/Browning 12.7mm heavy machine guns are installed for shooting small targets in the air or at sea
Mounted behind the superstructure of the Skjold-class stealthy side-walled corvette, Consburg's two Sea Protector 12.7mm remote-controlled weapon stations remotely control the firing of targets at sea and in the air in the combat fire control room
Behind the superstructure was installed two man-operated Browning 12.7mm heavy machine guns, which were used to deal with complex small targets on the sea surface, etc
Under the aft deck, a liftable 2×4 Naval Strike Missile Launch Box is installed, and a rectangular opening for the tail flame to be removed during missile launches is opened on the vertical stern
The launch box of the Navy's strike missile is a 2×2 quad structure
Launch of naval strike missiles instantly
The Navy attack missile is launched instantly, the booster pushes it out of the launch box and then separates and falls off, the missile's miniature turbofan engine works to maintain the missile cruise flight, the missile adopts GNSS/INS mid-section guidance + infrared imaging terminal guidance, with the combat capability of "no matter after launch", the length is 3960mm, the weight is 407kg, the flight speed is 0.7 ~ 0.9 Mach, and the range is more than 185km
The Skjold-class stealth side-wall corvettes are equipped with a comprehensive range of sensors:
(1) The use of Thales MRR-3D-NG multi-purpose active phased array single-sided array radar, through mechanical rotation to achieve 360 ° scanning search, can effectively suppress interference and sea clutter, patrol boats sea surface target detection distance of 180 km (97.1 nautical miles), can track 128 targets at the same time and has the ability to detect and track sea-skimming anti-ship missiles.
(2) Crack navigation radar is used for navigation navigation.
(3) Saab Ceros 200 fire control radar/photoelectric sensor for fire control of the bow 76mm ultrafast gun.
(4) Adopt the "Condor" CS-3701 advanced integrated electronic warfare kit, including radar/radio detection system (ESM) - can detect enemy radar at 125% of the enemy radar detection distance, located behind the bow A gun position Rheinmetall TKWA/MASS multimunition soft kill system, soft kill decoy launch against incoming anti-ship missiles, for large-scale interference or centralized interference of multiple targets.
(5) The Sagem Vigy 20 photoelectric turret is adopted, which contains a TV, infrared imager, laser rangefinder, which can be used for 360° scanning search, auxiliary navigation, 76mm ultrafast gun fire control and so on when the radio is silent.
The Skjold class stealth side-wall corvette superstructure and the A-shaped three-step mast are arranged on the Rheinmetall TKWA/MASS multimunition soft kill system transmitter, saab Ceros 200 fire control radar/photoelectric sensor, satellite navigation receiving antenna, Thales MRR-3D-NG multipurpose active phased array single-sided array radar and satellite communication antenna (mast first step), respectively. Crack navigation radar (mast second step) and electronic warfare antenna, Sagem Vigy 20 optical turret and electronic warfare antenna
The single-sided array antenna of the MRR-3D-NG multipurpose active phased array radar enables 360° scanning and search through mechanical rotation
The Saab Ceros 200 fire control radar/photoelectric sensor is located at the top of the superstructure for fire control of the bow 76mm ultrafast gun
The Rheinmetall TKWA/MASS multimunition soft kill system is located in front of the superstructure and is used to fire decoys to jam incoming anti-ship missiles
Located on the third step of the mast, the Sagem Vigy 20 optical turret contains a TELEVISION, infrared imager, laser rangefinder for 360° scan searches, assisted navigation, 76mm ultrafast gun fire control and more during radio silence
The level of informatization and "glassization" of the "Shield" class stealth side-wall corvettes is very high:
In the steering seat, the observation, navigation and operation are integrated, which improves the reaction speed of the ship and reduces the crew, so that 2 crew members can complete the ship.
In the combat fire control room, the operation of all sensors, the aiming and shooting of weapons can be completed, which is convenient for combatants to handle information and engage with targets in a coordinated manner.
Observation, navigation and operation are integrated in the steering seat, and two crew members can complete the operation of the ship
In the combat fire control room, you can complete the operation of all sensors, weapon aiming, shooting, etc
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