The AN/APS-4, originally known as ASH (air-surface, model H) is an early military air to air and air to surfaceradar used by American and British warplanes during World War II.
AN/APS-4 search radar
Front-oblique view of the AN/APS-4 radar pod without its external shell
Side view of an AN/APS-4 radar pod without its shell
APS-4 operated in the X band at 3 cm, compared to the 10 cm S band used by most radars of the era. This allowed the antenna to be greatly reduced in size and the unit as a whole to fit into a single streamlined fairing that could be mounted to many aircraft.
The APS-4 radar is a lightweight air-to-air and air-to-surface radar with a detection range for large ships of about 15 miles (24 km), and about 5 miles (8.0 km) against aircraft. It could also detect coastline at approximately 75 miles (121 km).[1]
Physically, the APS-4 consists of a control box, one or two indicators, the same number of indicator-amplifiers, an antenna, a transmitter-receiver, and a cable junction box.[2] The antenna and transmitter-receiver were typically housed externally below one wing, in a fiberglass shape that was similar to a Mk 17 500-pound (230 kg) bomb.[3] These displays could be set for ranges of 4, 20, 50, and 100 nautical miles (6, 30, 80, and 160 km).[4] The radar weighed 180 pounds (82 kg).[4]
The APS-4 broadcast in the X-band with a wavelength of 3 cm.[4][2] Peak broadcast power varied from 40 to 70 kW according to radar version. Pulse repetition frequency was adjustable by the operator to either 600 or 1000 pulses per second.[5]
The APS-4 emitted a radio beam in the form of a 6° cone. The beam could be directed in three modes, manual, search and intercept. In manual mode the beam was aimed by operator control from 10° above, to 30° below the longitudinal axis of the aircraft. In search mode, the radar beam scans through 150° in azimuth, and while doing so would run two lines scans, each separated by 4°. This caused the beam to cover 10° in a vertical plane. In intercept mode, the beam executes a four-line scan, with 6° between lines, to cover a vertical plane of 24°.[3] Results were displayed on one or two 3-inch displays.[2]
An improved version was called the AN/APS-5. A simplified version for single-seat fighters was called the APS-6.[6]
^ abc"HyperWar: Tactical Uses of Radar in Aircraft (RADTWOA) [Part II]". www.ibiblio.org.
^ abThe tactical use of radar in aircraft aef.se Retrieved 15 April 2023
^ abcBudge, Kent G. "The Pacific War Online Encyclopedia: ASH Airborne Radar". pwencycl.kgbudge.com.
^"Duxford Radio Society: Restoration: Radar APS-4". www.duxfordradiosociety.org.
^Budge, Kent G. "The Pacific War Online Encyclopedia: APS-6 Airborne Radar". pwencycl.kgbudge.com.
October 21, 2023
search, radar, originally, known, surface, model, early, military, surface, radar, used, american, british, warplanes, during, world, front, oblique, view, radar, without, external, shellcountry, originukintroduced1943, 1943, typesurface, search, radarfrequenc. The AN APS 4 originally known as ASH air surface model H is an early military air to air and air to surface radar used by American and British warplanes during World War II AN APS 4 search radarFront oblique view of the AN APS 4 radar pod without its external shellCountry of originUKIntroduced1943 1943 TypeSurface search radarFrequency3300 50 MHz S band PRF660 ppsBeamwidth 10º horizontal 15º verticalPulsewidth1 msRPM60 rpmRange1 to 100 mi 1 6 160 9 km Diameter28 in 0 71 m Azimuth320ºPrecision 5ºPower40 kWOther NamesASHRelatedAN APS 5 AN APS 6Side view of an AN APS 4 radar pod without its shellAPS 4 operated in the X band at 3 cm compared to the 10 cm S band used by most radars of the era This allowed the antenna to be greatly reduced in size and the unit as a whole to fit into a single streamlined fairing that could be mounted to many aircraft In American service it was used on many aircraft including the Douglas C 47 Skytrain North American P 82D F H Twin Mustang Vought F4U 2 5N Corsair Grumman F6F 3 5 Hellcat Curtiss SB2C 5 Helldiver and Grumman TBF 3 and TBM 3S Avenger In Fleet Air Arm and RAF service it was known as ASV Mark IX and equipped a number of aircraft including the Fairey Firefly Fairey Barracuda de Havilland Mosquito and a small number of Grumman Avengers Design EditThe APS 4 radar is a lightweight air to air and air to surface radar with a detection range for large ships of about 15 miles 24 km and about 5 miles 8 0 km against aircraft It could also detect coastline at approximately 75 miles 121 km 1 Physically the APS 4 consists of a control box one or two indicators the same number of indicator amplifiers an antenna a transmitter receiver and a cable junction box 2 The antenna and transmitter receiver were typically housed externally below one wing in a fiberglass shape that was similar to a Mk 17 500 pound 230 kg bomb 3 These displays could be set for ranges of 4 20 50 and 100 nautical miles 6 30 80 and 160 km 4 The radar weighed 180 pounds 82 kg 4 The APS 4 broadcast in the X band with a wavelength of 3 cm 4 2 Peak broadcast power varied from 40 to 70 kW according to radar version Pulse repetition frequency was adjustable by the operator to either 600 or 1000 pulses per second 5 The APS 4 emitted a radio beam in the form of a 6 cone The beam could be directed in three modes manual search and intercept In manual mode the beam was aimed by operator control from 10 above to 30 below the longitudinal axis of the aircraft In search mode the radar beam scans through 150 in azimuth and while doing so would run two lines scans each separated by 4 This caused the beam to cover 10 in a vertical plane In intercept mode the beam executes a four line scan with 6 between lines to cover a vertical plane of 24 3 Results were displayed on one or two 3 inch displays 2 An improved version was called the AN APS 5 A simplified version for single seat fighters was called the APS 6 6 References Edit ASH airborne radar kgbudge com a b c HyperWar Tactical Uses of Radar in Aircraft RADTWOA Part II www ibiblio org a b The tactical use of radar in aircraft aef se Retrieved 15 April 2023 a b c Budge Kent G The Pacific War Online Encyclopedia ASH Airborne Radar pwencycl kgbudge com Duxford Radio Society Restoration Radar APS 4 www duxfordradiosociety org Budge Kent G The Pacific War Online Encyclopedia APS 6 Airborne Radar pwencycl kgbudge com Retrieved from https en wikipedia org w index php title AN APS 4 search radar amp oldid 1149993142, wikipedia, wiki, book, books, library,
