Stealth ship
Under a stealth ship ( English stealth ship ), a ship meant in which with the aid of stealth technology is attempted to impede its location or prevent. Both the location by radar and other sensors such as z. B. infrared sensors meant.
History of the stealth ships
As early as the First World War , British and American warships tried to deceive German submarines by using camouflage . This should deceive the submarines in terms of size, direction of travel and speed. This technology, along with deceptive superstructures, was also used in combat under surface ships.
When the first functioning radar systems were developed and built in the late 1930s , new questions arose for camouflaging ships. It was now possible to locate ships over long distances. Guided missiles, controlled by radar, infrared detectors and magnetic field detection systems, were added later. Even countries without their own warships were now able to sink warships.
It was therefore necessary to construct ships that are difficult for the radar to detect and that can also fool other sensors. Experience from aircraft construction has confirmed the techniques relating to shaping and radar-absorbing coatings. In the German submarine -construction of the Second World War were such as snorkels used to drive less frequently surfaced and need it to disclose less the Allied radar. With the improvement of the radar, which made it possible to locate the snorkel, work was also carried out on camouflage measures for the snorkels themselves, including using radar-absorbing coatings. An undisguised snorkel reduced the echo effect to around 20% of a submarine and lowered the detection range to around 25% of a submarine. With the development of camouflaged snorkels, the residual reflection was reduced to approx. 10% and the detection range was reduced by up to 65%.
In addition to the attenuation of intrinsic noises, measures were also used to make localization by the enemy ASDIC (forerunner of sonar ) more difficult. For example, an opanine cover, an approx. 4 mm thick rubber coating, dampens the sound reflection in the frequency band between 10 and 18 kHz up to 15%. The effect of the protective agent is strongly dependent on the salt content, air content and temperature of the water. This technique was first used in 1943 on the German U 480 , which is considered to be the world's first stealth submarine.
Basic features of camouflage
A key feature of camouflage is the minimization of the radar cross-sectional area , i.e. H. minimizing the radar signature . So as little energy as possible should be reflected back to the transmitter, which is achieved by avoiding right angles on the deck of the ship. The electromagnetic waves hitting the ship are thereby radiated in other directions. Also cylindrical forms are to be avoided because they reflect incident transmit pulses from any direction directly. In many stealth ships there are therefore no conventional round superstructures (masts, chimneys, etc.). Radar-absorbing coatings and building materials are also used.
In order to reduce the heat signature, attempts are made on many ships to minimize the radiated infrared radiation. For example, the exhaust gases are cooled or diverted into the water, and special, infrared-absorbing coatings are used. The active measure Magnetic Self- Protection (MES) is used to reduce the magnetic signature of a ship . In the case of submarines, non-magnetizable submarine steel is also used as a passive measure .
The noise signature is kept as low as possible through quiet drive systems. In addition, attempts are made to minimize the noises caused by the propellers and the bubbles formed ( cavitation ), e.g. B. with techniques such as the prairie masker system. In submarine construction, low-noise propulsion technologies such as external air-independent propulsion on fuel cells of the German-Italian submarine class 212 A are also used.
In order to minimize the ship's wake , the area of the ship that cuts through the water on the surface is kept as small as possible. This is achieved by separating the hull into a permanently above water and a permanently under water part. Both parts are only connected by narrow webs that are the only ones cutting through the water surface ( SWATH hull ).
Optical camouflage such as camouflage painting or fogging options still play a role.
List of stealth ships and ship classes
The following list contains stealth ships that, like stealth aircraft, are completely coated with radar-absorbing material (full stealth) and also have radiation-absorbing properties in terms of shape:
_1.jpg)
In addition, most modern warship types strive at least through the design to reduce the radar reflective surface and thus certain stealth properties. In the German Navy, for example, the corvette K130 and the F124 were designed in the so-called X-shape, with all side surfaces of the hull and the superstructure inclined towards each other in order to largely deflect incident radar beams in other directions.
literature
- Christopher R. Lavers: Stealth warship technology. Adlard Coles Nautical, London 2012, ISBN 978-1-408-17525-5 .
