Monica was a range-only

tail warning radar A tail warning radar, sometimes TW for short, was a short-lived class of aircraft-mounted radar systems used to provide warning of another aircraft approaching from the rear. They were mostly used on World War II bombers, starting with the Monic ...

for

bombers A bomber is a military combat aircraft that utilizes air-to-ground weaponry to drop bombs, launch torpedoes, or deploy air-launched cruise missiles. There are two major classifications of bomber: strategic and tactical. Strategic bombing is ...

, introduced by the RAF in June 1942. Officially known as ARI 5664, it operated at

frequencies Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

of around 300

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), often described as being equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose formal expression in terms of SI base u ...

(on the boundary between VHF and

UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ...

). The system was also used by the

US Army Air Forces The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

, under the name AN/APS-13, and the nickname Archie.

History

Monica was developed at the Bomber Support Development Unit (BSDU) in

Worcestershire Worcestershire ( , ; written abbreviation: Worcs) is a Ceremonial counties of England, ceremonial county in the West Midlands (region), West Midlands of England. It is bordered by Shropshire, Staffordshire, and the West Midlands (county), West ...

. After the ''

Luftwaffe The Luftwaffe () was the aerial warfare, aerial-warfare branch of the before and during World War II. German Empire, Germany's military air arms during World War I, the of the Imperial German Army, Imperial Army and the of the Imperial Ge ...

'' became aware of Monica from a crashed bomber, German scientists developed a passive radar receiver, named Flensburg (FuG 227). From early 1944, FuG 227 was used by

nightfighter A night fighter (later known as all-weather fighter or all-weather interceptor post-Second World War) is a largely historical term for a fighter or interceptor aircraft adapted or designed for effective use at night, during periods of adverse ...

crews to home in on Allied bombers using Monica. However, on the morning of 13 July 1944, a 7.''Staffel''/

NJG 2 ''Nachtjagdgeschwader'' 2 (NJG 2) was a German Luftwaffe night fighter and night intruder wing during World War II. Background Night fighter operations did form part of Wehrmacht war games during 1935 and 1936. Luftwaffe Service Regulation No. 1 ...

-flown

Junkers Ju 88 The Junkers Ju 88 is a twin-engined multirole combat aircraft designed and produced by the German aircraft manufacturer Junkers Aircraft and Motor Works. It was used extensively during the Second World War by the ''Luftwaffe'' and became one o ...

G-1 nightfighter equipped with Flensburg mistakenly landed at

RAF Woodbridge Royal Air Force Woodbridge, or more simply RAF Woodbridge, is a former Royal Air Force station located east of Woodbridge and around 7 miles north-east of Ipswich, in the county of Suffolk, England. Constructed in 1943 as a RAF military airfi ...

. After examining the Flensburg equipment, the RAF ordered Monica withdrawn from all

Bomber Command Bomber Command is an organisational military unit, generally subordinate to the air force of a country. The best known were in Britain and the United States. A Bomber Command is generally used for strategic bombing (although at times, e.g. during t ...

aircraft.Price, p. 154. An AN/APS-13 was used as a

radar altimeter A radar altimeter (RA), also called a radio altimeter (RALT), electronic altimeter, reflection altimeter, or low-range radio altimeter (LRRA), measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it t ...

during the

Atomic bombings of Hiroshima and Nagasaki On 6 and 9 August 1945, the United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki, respectively, during World War II. The aerial bombings killed between 150,000 and 246,000 people, most of whom were civili ...

by the

509th Composite Group The 509th Composite Group (509 CG) was a unit of the United States Army Air Forces created during World War II and tasked with the operational deployment of nuclear weapons. It conducted the atomic bombings of Hiroshima and Nagasaki, Japan, in ...

, USAAF.

References

External links

Oral History of Defence Electronics

History

See also

References

External links

Further reading