oldcrowcv63
Tech Sergeant
More on allied RADAR: [4.0] Microwave Radar At War (1)
"For the moment, the US had no operational airborne radars of their own, but the NRL, no doubt holding their nose at having to use British gear, (what? you didn't know that british gear smells bad?) (That's the quote! I swear I didn't make it up!) put ASV Mark II into production as "ASE" or, in Army service, the "SCR-521". The British had already put ASV Mark II on their Consolidated Catalina flying-boat patrol aircraft, and so it was straightforward to mount it on US Navy Catalinas as well, making the type the first US aircraft to carry radar in operational service.
Since ASE was too big to fit on smaller aircraft, the NRL built their own longwave set, the 58 cm (515 MHz) "ASB", originally "XAT", which was fitted to the Grumman TBF Avenger torpedo bomber. Like ASE, it featured a Yagi antenna fitted under each wing, skewed 7.5 degrees from the centerline, and presumably used lobe-switching. Peak power was 200 kW and pulse width was 2 microseconds. It was the first operational US carrier-based aircraft to be fitted with radar. The ASB was very popular, with 26,000 units built. First operational use was at the Battle of Santa Cruz Island, October 26, 1942. Unfortunately the TBF-1 so equipped was shot down in a famous post launch engagement with 'rogue' A6M escorts.
The British had proven that ASV radar was an important weapon against the U-boats, and now the Americans went through the same painful learning curve. The longwave ASV Mark II / ASE fitted to Catalinas and ASB fitted to Avengers were useful, but not completely adequate. Development of centimetric ASV now became the Rad Lab's top priority. The initial ASV was a fast modification of the Western Electric SCR-520 AI, the "SCR-517", which was installed on USAAF Liberators for ocean patrol beginning in the spring of 1942.
Of course, centimetric radar was a big help in the war against the U-boats. The early SCR-517 centimetric ASV radar had a number of obvious limitations, particularly in that it only swept forward of the aircraft, limiting the radar's field of view over the ocean, and lacked a PPI display, meaning that it could only really observe one target at a time.
It was accordingly followed by the improved Philco-built "ASG" or "AN/APS-2", known as "George" to its users, which scanned full-circle, displaying echoes on a PPI display, and had a longer range of 24 kilometers (13 nautical miles). Reliability and operator training were poor at first, but as spring came it helped the Allies gained the upper hand in the Battle of the Atlantic.
The USAAF built their own version of the ASG, the "SCR-717", which differed in using a "B-scope" display and not a PPI display. A B-scope display gives a view somewhat like that of some early video games, with the operator staring down on top of a rectangular area, with the target tracked left or right and forward or back. The SCR-717 supplanted the SCR-517 in USAAF service.
The next step after ASG was to build a 3 cm (10 GHz) X-band ASV, which emerged as the "ASD", or simply "Dog", and was produced as the "AN/APS-3" by Philco. It could be mounted in a pod under the wing of an Avenger torpedo-bomber, and proved much more effective than the Avenger's earlier longwave ASB radar."
Too good to leave out:
"Centimetric ASV had greater maximum and shorter minimum range than longwave ASV, was much more accurate, and Metox (German passive radar detection) couldn't detect it. U-boats were hit without warning on the surface at night and in low visibility. Escort vessels were also fitted with centimetric ASV, allowing them to hunt down U-boats at night. Doenitz and his senior officers were baffled, suspecting at first that the sinkings of their submarines were due to the work of spies. They were further confused when a RAF Coastal Command prisoner told his captors that RAF planes were homing in on emissions from Metox, leading to an order for the removal of Metox from all U-boats."
Of course you can't home on a passive system! It's not emitting anything! removing Metox made the U boats vulnerable to the most primitive forms of ASV which it had formerly defeated.
another good source: http://www.history.navy.mil/library/online/radar-10.htm
"For the moment, the US had no operational airborne radars of their own, but the NRL, no doubt holding their nose at having to use British gear, (what? you didn't know that british gear smells bad?) (That's the quote! I swear I didn't make it up!) put ASV Mark II into production as "ASE" or, in Army service, the "SCR-521". The British had already put ASV Mark II on their Consolidated Catalina flying-boat patrol aircraft, and so it was straightforward to mount it on US Navy Catalinas as well, making the type the first US aircraft to carry radar in operational service.
Since ASE was too big to fit on smaller aircraft, the NRL built their own longwave set, the 58 cm (515 MHz) "ASB", originally "XAT", which was fitted to the Grumman TBF Avenger torpedo bomber. Like ASE, it featured a Yagi antenna fitted under each wing, skewed 7.5 degrees from the centerline, and presumably used lobe-switching. Peak power was 200 kW and pulse width was 2 microseconds. It was the first operational US carrier-based aircraft to be fitted with radar. The ASB was very popular, with 26,000 units built. First operational use was at the Battle of Santa Cruz Island, October 26, 1942. Unfortunately the TBF-1 so equipped was shot down in a famous post launch engagement with 'rogue' A6M escorts.
The British had proven that ASV radar was an important weapon against the U-boats, and now the Americans went through the same painful learning curve. The longwave ASV Mark II / ASE fitted to Catalinas and ASB fitted to Avengers were useful, but not completely adequate. Development of centimetric ASV now became the Rad Lab's top priority. The initial ASV was a fast modification of the Western Electric SCR-520 AI, the "SCR-517", which was installed on USAAF Liberators for ocean patrol beginning in the spring of 1942.
Of course, centimetric radar was a big help in the war against the U-boats. The early SCR-517 centimetric ASV radar had a number of obvious limitations, particularly in that it only swept forward of the aircraft, limiting the radar's field of view over the ocean, and lacked a PPI display, meaning that it could only really observe one target at a time.
It was accordingly followed by the improved Philco-built "ASG" or "AN/APS-2", known as "George" to its users, which scanned full-circle, displaying echoes on a PPI display, and had a longer range of 24 kilometers (13 nautical miles). Reliability and operator training were poor at first, but as spring came it helped the Allies gained the upper hand in the Battle of the Atlantic.
The USAAF built their own version of the ASG, the "SCR-717", which differed in using a "B-scope" display and not a PPI display. A B-scope display gives a view somewhat like that of some early video games, with the operator staring down on top of a rectangular area, with the target tracked left or right and forward or back. The SCR-717 supplanted the SCR-517 in USAAF service.
The next step after ASG was to build a 3 cm (10 GHz) X-band ASV, which emerged as the "ASD", or simply "Dog", and was produced as the "AN/APS-3" by Philco. It could be mounted in a pod under the wing of an Avenger torpedo-bomber, and proved much more effective than the Avenger's earlier longwave ASB radar."
Too good to leave out:
"Centimetric ASV had greater maximum and shorter minimum range than longwave ASV, was much more accurate, and Metox (German passive radar detection) couldn't detect it. U-boats were hit without warning on the surface at night and in low visibility. Escort vessels were also fitted with centimetric ASV, allowing them to hunt down U-boats at night. Doenitz and his senior officers were baffled, suspecting at first that the sinkings of their submarines were due to the work of spies. They were further confused when a RAF Coastal Command prisoner told his captors that RAF planes were homing in on emissions from Metox, leading to an order for the removal of Metox from all U-boats."
Of course you can't home on a passive system! It's not emitting anything! removing Metox made the U boats vulnerable to the most primitive forms of ASV which it had formerly defeated.
another good source: http://www.history.navy.mil/library/online/radar-10.htm
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