Recent from talks
Searchlight Control radar
Knowledge base stats:
Talk channels stats:
Members stats:
Searchlight Control radar
Searchlight Control, SLC for short but nicknamed "Elsie", was a British Army VHF-band radar system that provided aiming guidance to an attached searchlight. By combining a searchlight with a radar, the radar did not have to be particularly accurate, it only had to be good enough to get the searchlight beam on the target. Once the target was lit, normal optical instruments could be used to guide the associated anti-aircraft artillery. This allowed the radar to be much smaller, simpler and less expensive than a system with enough accuracy to directly aim the guns, like the large and complex GL Mk. II radar. In 1943 the system was officially designated Radar, AA, No. 2, although this name is rarely used.
The sight of searchlights swinging about wildly during the Blitz led a group of British Army engineers to begin development of SLC in early 1940. It was built using the electronics from the 1.5 m wavelength ASV Mark I connected to new antennas and a unique lobe switching system. The American SCR-268 and German Würzburg were generally similar in concept, but the SLC was small enough to be mounted directly to the light, as opposed to requiring a separate carriage. This made the overall operation much easier. There were several Marks of the system, differing in their mounting system, not the electronics.
The effect of using SLC was dramatic; aided by sound locators, in 1939 a searchlight had about a 1% chance of tracking a target, while with SLC this improved to 90%. SLC's greatest success was during Operation Steinbock in early 1944; SLC was involved in the vast majority of interceptions of German bombers, helping guide the night fighters without the need to use their own radars. They proved less useful against the V-1 flying bomb attacks later that year, but by this time improved radars like the SCR-584 were rendering the SLC concept obsolete. The US made a largely identical copy as the SCR-768 while an all-new design based on the same concepts was SCR-668.
SLC also proved useful to the enemy; in early 1942 an SLC and GL Mk. II were captured by Japanese forces at Singapore, along with the US SCR-268 in the Philippines. The SLC's Yagi antennas were unknown to the crews that discovered them, and they were surprised to find they were a Japanese invention. NEC produced a slightly modified version known as Ta-Chi 3, but it did not enter service.
Before WWII, searchlights generally had two settings. One produced a wider beam a few degrees wide that was used for searching while the second narrowed the beam as much as possible in order to illuminate a single target. At the altitudes flown during World War I, the wider beam still produced enough illumination to detect a target, which the crews would do by swinging around the expected location. This was often aided with a Mark IX sound locator, which could help narrow the search area. When a target was seen, the beam would be narrowed to provide more illumination.
By the opening of WWII, such systems were effectively useless. As combat altitudes moved over 15,000 feet (4,600 m), the illumination provided by the wide setting was no longer enough to see a target, but searching for a target using the narrow setting was very difficult. The greatly increased speeds, roughly double that of WWI aircraft, made the speed of sound a major problem for the sound locators. Offsetting these problems was the high quality of pre-war training, and the crews were still able to find their targets at a high enough rate that there did not seem to be a problem.
Things changed when the number of searchlights in service began to increase with the start of the war in 1939. The rapid enlargement of the force by newly trained crewmen had the effect of diluting the competence level. Another problem was that as the lights were moved from their training areas inland to various coastal deployments, they were invariably placed near the guns they would work with. This made the sound locators useless once the guns started firing. At the beginning of the war, searchlights had about a 1% chance of locating a target.
The British Army was the first group in Britain to suggest the use of radar; a 1931 report by W. A. S. Butement and P. E. Pollard of the Army's Signals Experimental Establishment proposed using it for detecting ships in the English Channel. The Army proved uninterested in their proposal and the matter was forgotten. In 1935, the Air Ministry independently took up the radar concept and began rapid development of Chain Home. The Army was suddenly very interested, and sent Butement and Pollard to set up a lab at the Air Ministry's research site at Bawdsey Manor in 1936.
Hub AI
Searchlight Control radar AI simulator
(@Searchlight Control radar_simulator)
Searchlight Control radar
Searchlight Control, SLC for short but nicknamed "Elsie", was a British Army VHF-band radar system that provided aiming guidance to an attached searchlight. By combining a searchlight with a radar, the radar did not have to be particularly accurate, it only had to be good enough to get the searchlight beam on the target. Once the target was lit, normal optical instruments could be used to guide the associated anti-aircraft artillery. This allowed the radar to be much smaller, simpler and less expensive than a system with enough accuracy to directly aim the guns, like the large and complex GL Mk. II radar. In 1943 the system was officially designated Radar, AA, No. 2, although this name is rarely used.
The sight of searchlights swinging about wildly during the Blitz led a group of British Army engineers to begin development of SLC in early 1940. It was built using the electronics from the 1.5 m wavelength ASV Mark I connected to new antennas and a unique lobe switching system. The American SCR-268 and German Würzburg were generally similar in concept, but the SLC was small enough to be mounted directly to the light, as opposed to requiring a separate carriage. This made the overall operation much easier. There were several Marks of the system, differing in their mounting system, not the electronics.
The effect of using SLC was dramatic; aided by sound locators, in 1939 a searchlight had about a 1% chance of tracking a target, while with SLC this improved to 90%. SLC's greatest success was during Operation Steinbock in early 1944; SLC was involved in the vast majority of interceptions of German bombers, helping guide the night fighters without the need to use their own radars. They proved less useful against the V-1 flying bomb attacks later that year, but by this time improved radars like the SCR-584 were rendering the SLC concept obsolete. The US made a largely identical copy as the SCR-768 while an all-new design based on the same concepts was SCR-668.
SLC also proved useful to the enemy; in early 1942 an SLC and GL Mk. II were captured by Japanese forces at Singapore, along with the US SCR-268 in the Philippines. The SLC's Yagi antennas were unknown to the crews that discovered them, and they were surprised to find they were a Japanese invention. NEC produced a slightly modified version known as Ta-Chi 3, but it did not enter service.
Before WWII, searchlights generally had two settings. One produced a wider beam a few degrees wide that was used for searching while the second narrowed the beam as much as possible in order to illuminate a single target. At the altitudes flown during World War I, the wider beam still produced enough illumination to detect a target, which the crews would do by swinging around the expected location. This was often aided with a Mark IX sound locator, which could help narrow the search area. When a target was seen, the beam would be narrowed to provide more illumination.
By the opening of WWII, such systems were effectively useless. As combat altitudes moved over 15,000 feet (4,600 m), the illumination provided by the wide setting was no longer enough to see a target, but searching for a target using the narrow setting was very difficult. The greatly increased speeds, roughly double that of WWI aircraft, made the speed of sound a major problem for the sound locators. Offsetting these problems was the high quality of pre-war training, and the crews were still able to find their targets at a high enough rate that there did not seem to be a problem.
Things changed when the number of searchlights in service began to increase with the start of the war in 1939. The rapid enlargement of the force by newly trained crewmen had the effect of diluting the competence level. Another problem was that as the lights were moved from their training areas inland to various coastal deployments, they were invariably placed near the guns they would work with. This made the sound locators useless once the guns started firing. At the beginning of the war, searchlights had about a 1% chance of locating a target.
The British Army was the first group in Britain to suggest the use of radar; a 1931 report by W. A. S. Butement and P. E. Pollard of the Army's Signals Experimental Establishment proposed using it for detecting ships in the English Channel. The Army proved uninterested in their proposal and the matter was forgotten. In 1935, the Air Ministry independently took up the radar concept and began rapid development of Chain Home. The Army was suddenly very interested, and sent Butement and Pollard to set up a lab at the Air Ministry's research site at Bawdsey Manor in 1936.
Recent media