AN/APS-4 search radar

Last updated
AN/APS-4 search radar
APS-4.jpg
Front-oblique view of the AN/APS-4 radar pod without its external shell
Country of originUK
Introduced1943 (1943)
Type Surface-search radar
Frequency3300 ±50 MHz (S-band)
PRF 660 pps
Beamwidth ~10º horizontal,
~15º vertical
Pulsewidth1 μs
RPM60 rpm
Range1 to 100 mi (1.6–160.9 km)
Diameter28 in (0.71 m)
Azimuth 320º
Precision~5º
Power40 kW
Other NamesASH
RelatedAN/APS-5, AN/APS-6
Side view of an AN/APS-4 radar pod without its shell An-APS-4 side view.jpg
Side view of an AN/APS-4 radar pod without its shell

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.

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.

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, and Curtiss SC Seahawk.

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

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]

Related Research Articles

<span class="mw-page-title-main">Airborne early warning and control</span> Airborne system of surveillance radar plus command and control functions

An airborne early warning and control (AEW&C) system is an airborne radar early warning system designed to detect aircraft, ships, vehicles, missiles and other incoming projectiles at long ranges, as well as performing command and control of the battlespace in aerial engagements by informing and directing friendly fighter and attack aircraft. AEW&C units are also used to carry out aerial surveillance over ground and maritime targets, and frequently perform battle management command and control (BMC2). When used at altitude, the radar system on AEW&C aircraft allows the operators to detect, track and prioritize targets and identify friendly aircraft from hostile ones in real-time and from much farther away than ground-based radars. Like ground-based radars, AEW&C systems can be detected and targeted by opposing forces, but due to aircraft mobility and extended sensor range, they are much less vulnerable to counter-attacks than ground systems.

<span class="mw-page-title-main">Active electronically scanned array</span> Type of phased array radar

An active electronically scanned array (AESA) is a type of phased array antenna, which is a computer-controlled antenna array in which the beam of radio waves can be electronically steered to point in different directions without moving the antenna. In the AESA, each antenna element is connected to a small solid-state transmit/receive module (TRM) under the control of a computer, which performs the functions of a transmitter and/or receiver for the antenna. This contrasts with a passive electronically scanned array (PESA), in which all the antenna elements are connected to a single transmitter and/or receiver through phase shifters under the control of the computer. AESA's main use is in radar, and these are known as active phased array radar (APAR).

<span class="mw-page-title-main">Pulse-Doppler radar</span> Type of radar system

A pulse-Doppler radar is a radar system that determines the range to a target using pulse-timing techniques, and uses the Doppler effect of the returned signal to determine the target object's velocity. It combines the features of pulse radars and continuous-wave radars, which were formerly separate due to the complexity of the electronics.

<span class="mw-page-title-main">AN/APG-68</span> Radar system

The AN/APG-68 radar is a long range Pulse-doppler radar designed by Westinghouse to replace AN/APG-66 radar in the F-16 Fighting Falcon. After years of Service, AN/APG-68 radar currently being replaced on US Air Force F-16C/D Block 40/42 and 50/52 by the latest generation AN/APG-83 AESA radar.

<span class="mw-page-title-main">Airport surveillance radar</span> Radar system

An airport surveillance radar (ASR) is a radar system used at airports to detect and display the presence and position of aircraft in the terminal area, the airspace around airports. It is the main air traffic control system for the airspace around airports. At large airports it typically controls traffic within a radius of 60 miles (96 km) of the airport below an elevation of 25,000 feet. The sophisticated systems at large airports consist of two different radar systems, the primary and secondary surveillance radar. The primary radar typically consists of a large rotating parabolic antenna dish that sweeps a vertical fan-shaped beam of microwaves around the airspace surrounding the airport. It detects the position and range of aircraft by microwaves reflected back to the antenna from the aircraft's surface. The secondary surveillance radar consists of a second rotating antenna, often mounted on the primary antenna, which interrogates the transponders of aircraft, which transmits a radio signal back containing the aircraft's identification, barometric altitude, and an emergency status code, which is displayed on the radar screen next to the return from the primary radar.

The AN/APG-76 radar is a pulse Doppler Ku band multi-mode radar developed and manufactured by Northrop Grumman.

<span class="mw-page-title-main">Passive electronically scanned array</span> Type of antenna

A passive electronically scanned array (PESA), also known as passive phased array, is an antenna in which the beam of radio waves can be electronically steered to point in different directions, in which all the antenna elements are connected to a single transmitter and/or receiver. The largest use of phased arrays is in radars. Most phased array radars in the world are PESA. The civilian microwave landing system uses PESA transmit-only arrays.

<span class="mw-page-title-main">Bars radar</span> Russian radars

The Bars (Leopard) is a family of Russian all-weather multimode airborne radars developed by the Tikhomirov Scientific Research Institute of Instrument Design for multi-role combat aircraft such as the Su-27, Su-30 and the MiG-29.

<span class="mw-page-title-main">Irbis-E</span> Russian fighter jet radar

Irbis-E is a Russian multi-mode, hybrid passive electronically scanned array radar system developed by Tikhomirov NIIP for the Sukhoi Su-35 multi-purpose fighter aircraft. NIIP developed the Irbis-E radar from the N011M Bars radar system used on Sukhoi Su-30MKI aircraft.

Radar in World War II greatly influenced many important aspects of the conflict. This revolutionary new technology of radio-based detection and tracking was used by both the Allies and Axis powers in World War II, which had evolved independently in a number of nations during the mid 1930s. At the outbreak of war in September 1939, both the United Kingdom and Germany had functioning radar systems. In the UK, it was called RDF, Range and Direction Finding, while in Germany the name Funkmeß (radio-measuring) was used, with apparatuses called Funkmessgerät . By the time of the Battle of Britain in mid-1940, the Royal Air Force (RAF) had fully integrated RDF as part of the national air defence.

The AN/APY-10 is an American multifunction radar developed for the U.S. Navy's Boeing P-8 Poseidon maritime patrol and surveillance aircraft. AN/APY-10 is the latest descendant of a radar family originally developed by Texas Instruments, and now Raytheon after it acquired the radar business of TI, for Lockheed P-3 Orion, the predecessor of P-8.

<span class="mw-page-title-main">Aircraft interception radar</span>

Aircraft interception radar, or AI radar for short, is a British term for radar systems used to equip aircraft with the means to find and track other flying aircraft. These radars are used primarily by Royal Air Force (RAF) and Fleet Air Arm night fighters and interceptors for locating and tracking other aircraft, although most AI radars could also be used in a number of secondary roles as well. The term was sometimes used generically for similar radars used in other countries, notably the US.

<span class="mw-page-title-main">AMES Type 82</span> Cold War-era British medium-range 3D radar

The AMES Type 82, also widely known by its rainbow codename Orange Yeoman, was an S-band 3D radar built by the Marconi Company and used by the Royal Air Force (RAF), initially for tactical control and later for air traffic control (ATC).

<span class="mw-page-title-main">ASV Mark II radar</span> Type of aircraft radar

Radar, Air-to-Surface Vessel, Mark II, or ASV Mk. II for short, was an airborne sea-surface search radar developed by the UK's Air Ministry immediately prior to the start of World War II. It was the first aircraft mounted radar of any sort to be used operationally. It was widely used by aircraft of the RAF Coastal Command, Fleet Air Arm and similar groups in the United States and Canada. A version was also developed for small ships, the Royal Navy's Type 286.

Radar, Air-to-Surface Vessel, or ASV radar for short, is a classification used by the Royal Air Force (RAF) to refer to a series of aircraft-mounted radar systems used to scan the surface of the ocean to locate ships and surfaced submarines. The first examples were developed just before the opening of World War II and they have remained a major instrument on patrol aircraft since that time. It is part of the wider surface search radar classification, which includes similar radars in ground and ship mountings.

<span class="mw-page-title-main">AN/APS-20</span> Airborne search radar

The AN/APS-20 was an airborne early warning, anti-submarine, maritime surveillance and weather radar developed in the United States in the 1940s. Entering service in 1945, it served for nearly half a century, finally being retired in 1991. Initially developed at Massachusetts Institute of Technology (MIT) under Project Cadillac, the radar was developed to be carried by aircraft to extend the sensor range of ships by placing a radar at altitude. Although developed for carrier-borne operation, first being installed in the single-engined General Motors TBM-3W Avenger, it was also used in larger four-engined airframes, the last being a fleet of Avro Shackleton AEW.2 which were converted from maritime patrol aircraft. Similarly, although developed for detecting aircraft, it saw extensive service in anti-submarine and maritime patrol roles and was one of the first radars to be used in researching extreme weather like hurricanes by agencies like the Environmental Science Services Administration (ESSA). As well as the United States, the radar was used by a large number of services in other countries, including the French Navy, Japan Maritime Self-Defense Force (JMSDF), Royal Air Force (RAF) and Royal Canadian Air Force (RCAF). Early versions of the radar could see a low-flying aircraft at 65 nautical miles and a ship at 200 nautical miles. This was improved, so that later versions had a range against aerial targets of 115 nautical miles.

<span class="mw-page-title-main">Multi-role Electronically Scanned Array</span> Type of aircraft radar

The Multi-role Electronically Scanned Array (MESA) is an active electronically scanned array surveillance radar system for the Boeing E-7 Wedgetail airborne early warning and control aircraft. The radar is produced by Northrop Grumman.

<span class="mw-page-title-main">SCR-720</span> Type of aircraft radar

The SCR-720 was a World War II aircraft interception radar designed by the Radiation Laboratory (RadLab) at MIT in the United States. It was used by US Army Air Force night fighters as well as the Royal Air Force (RAF) in a slightly modified version known as Radar, Aircraft Interception, Mark X, or AI Mk. X for short.

References

  1. ASH airborne radar kgbudge.com
  2. 1 2 3 "HyperWar: Tactical Uses of Radar in Aircraft (RADTWOA) [Part II]". www.ibiblio.org.
  3. 1 2 The tactical use of radar in aircraft aef.se Retrieved 15 April 2023
  4. 1 2 3 Budge, Kent G. "The Pacific War Online Encyclopedia: ASH Airborne Radar". pwencycl.kgbudge.com.
  5. "Duxford Radio Society: Restoration: Radar APS-4". www.duxfordradiosociety.org.
  6. Budge, Kent G. "The Pacific War Online Encyclopedia: APS-6 Airborne Radar". pwencycl.kgbudge.com.