The Automatic Gun-Laying Turret (AGLT), also known as the Frazer-Nash FN121, was a

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...

-directed, rear

gun turret A gun turret (or simply turret) is a mounting platform from which weapons can be fired that affords protection, visibility and ability to turn and aim. A modern gun turret is generally a rotatable weapon mount that houses the crew or mechani ...

fitted to some

British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English ...

bomber A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching aerial torpedo, torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped ...

s from 1944. AGLT incorporated both a low-power

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 ...

and

fire-control system A fire-control system (FCS) is a number of components working together, usually a gun data computer, a Director (military), director, and radar, which is designed to assist a ranged weapon system to target, track, and hit a target. It performs ...

, which could detect approaching enemy fighters, aim and automatically trigger machine guns – in total

darkness Darkness, the direct opposite of lightness, is defined as a lack of illumination, an absence of visible light, or a surface that absorbs light, such as black or brown. Human vision is unable to distinguish colors in conditions of very low ...

or cloud cover if necessary. The radar warning and fire-control system itself was commonly known by the code names Village Inn and "Z Equipment",Stephen Flower, ''The Dam Busters: An Operational History of Barnes Wallis' Bombs''. Stroud, Glouc.; Amberley Publishing, p. 393. as well as the serial number TR3548. It was intended that all

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

bombers, and other Allied aircraft attached to

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 ...

would have an

IFF In logic and related fields such as mathematics and philosophy, "if and only if" (shortened as "iff") is a biconditional logical connective between statements, where either both statements are true or both are false. The connective is bicondi ...

infra-red Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

nose lamp, which would allow rear gunners to avoid

friendly fire In military terminology, friendly fire or fratricide is an attack by belligerent or neutral forces on friendly troops while attempting to attack enemy/hostile targets. Examples include misidentifying the target as hostile, cross-fire while e ...

. In practice, however, Allied aircraft without lamps often crossed paths with AGLT aircraft and, even when they were fitted and operational, the lamps were not always visible to gunners, for various reasons. As a result, Village Inn was generally used purely as an

early warning system An early warning system is a warning system that can be implemented as a chain of information communication systems and comprises sensors, event detection and decision subsystems for early identification of hazards. They work together to for ...

. According to the official history of the

RCAF The Royal Canadian Air Force (RCAF; french: Aviation royale canadienne, ARC) is the air and space force of Canada. Its role is to "provide the Canadian Forces with relevant, responsive and effective airpower". The RCAF is one of three environ ...

during World War II, fully automated "blind-firing" was used by gunners in only four out of every 1,000

sortie A sortie (from the French word meaning ''exit'' or from Latin root ''surgere'' meaning to "rise up") is a deployment or dispatch of one military unit, be it an aircraft, ship, or troops, from a strongpoint. The term originated in siege warf ...

Development

The system was devised by a team led by

Philip Dee Philip Ivor Dee CBE FRS FRSE (8 April 1904, Stroud – 17 April 1983, Glasgow) was a British nuclear physicist. He was responsible for the development of airborne radar during the Second World War. Glasgow University named the Philip Ivor Dee Me ...

and designed under the aegis of chief designer

Alan Hodgkin Sir Alan Lloyd Hodgkin (5 February 1914 – 20 December 1998) was an English physiologist and biophysicist who shared the 1963 Nobel Prize in Physiology or Medicine with Andrew Huxley and John Eccles. Early life and education Hodgkin was bo ...

, after receiving a request from the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

for such a system in early 1943. Village Inn was evaluated and tested by the

Telecommunications Research Establishment The Telecommunications Research Establishment (TRE) was the main United Kingdom research and development organization for radio navigation, radar, infra-red detection for heat seeking missiles, and related work for the Royal Air Force (RAF) d ...

(TRE) at

RAF Defford Royal Air Force Defford or more simply RAF Defford is a former Royal Air Force station located northwest of Defford, Worcestershire, England. History Second World War At the outbreak of the Second World War, Croome Court and its surrounding ...

using the Lancaster Mark I serial number ''ND712'' Lancaster Mark III ''JB705'' and Mk II ''LL736'' and ''LL737'' and subsequently put into production. The system consisted of a

transmitter In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to ...

/ receiver unit mounted in the navigator's compartment, operating through a

conical scanning Conical scanning is a system used in early radar units to improve their accuracy, as well as making it easier to steer the antenna properly to point at a target. Conical scanning is similar in concept to the earlier lobe switching concept used ...

parabolic aerial attached to rear turrets. It worked on a

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

of 9.1 cm (3

GHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one ...

) with a

pulse repetition frequency The pulse repetition frequency (PRF) is the number of pulses of a repeating signal in a specific time unit. The term is used within a number of technical disciplines, notably radar. In radar, a radio signal of a particular carrier frequency is tu ...

of 660 Hertz. The

magnetron The cavity magnetron is a high-power vacuum tube used in early radar systems and currently in microwave ovens and linear particle accelerators. It generates microwaves using the interaction of a stream of electrons with a magnetic field whil ...

used was the CV186 of approx 35 kW. The electronics sent a signal back to the turret, where it was displayed on a cathode ray tube (CRT) display screen positioned adjacent to the gun sight, the image of which was projected on to the Mark IIC

gyro gunsight A gyro gunsight (G.G.S.) is a modification of the non-magnifying reflector sight in which target lead (the amount of aim-off in front of a moving target) and bullet drop are calculated automatically. The first examples were developed in Britain ...

via a semi-transparent mirror. Initially, ranging information was provided only at the transmitter situated in the navigator's compartment and was read off to the gunner over the

intercom An intercom, also called an intercommunication device, intercommunicator, or interphone, is a stand-alone voice communications system for use within a building or small collection of buildings which functions independently of the public telepho ...

, the gunner using foot pedals to set the target range on the sight. In production equipment the process was made automatic, the range information being fed electronically directly into the gunsight, with the navigator's "running commentary" only being retained for the benefit of the rest of the crew. The gunner simply maneuvered his guns to place the "blip" in the centre of the gunsight's reticle and opened fire when the range was appropriate. Windage, bullet drop, and other factors were already calculated by the gunsight. The first squadron to use Village Inn operationally was No. 101 Squadron RAF, based at Ludford Magna, in the autumn of 1944, followed soon afterwards by No. 49 in the attack on

Darmstadt Darmstadt () is a city in the States of Germany, state of Hesse in Germany, located in the southern part of the Frankfurt Rhine Main Area, Rhine-Main-Area (Frankfurt Metropolitan Region). Darmstadt has around 160,000 inhabitants, making it th ...

on September 11/12,

156 Year 156 ( CLVI) was a leap year starting on Wednesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Silvanus and Augurinus (or, less frequently, year 909 '' Ab urbe co ...

and 635 Squadrons. Village Inn was eventually produced in four Marks: * AGLT Mark I — initial design — Airborne Radio Installation (ARI) 5559. * AGLT Mark II — modified, improved, Mark I — soon discontinued — ARI 5561. * AGLT Mark III — scanning aerial mounted remotely from turret. Scan independent of turret's movements — ARI 5562. * AGLT Mark IV — ARI 5632 The system was also fitted to the Rose turret on at least one

Avro Lincoln The Avro Type 694 Lincoln is a British four-engined heavy bomber, which maiden flight, first flew on 9 June 1944. Developed from the Avro Lancaster, the first Lincoln variants were initially known as the Lancaster IV and V; these were renamed L ...

B.Mk II, although how many is not known. Some Lincolns fitted with the Boulton Paul Type D tail turret also incorporated the equipment. A similar type of system was produced in the US by the

Emerson Electric Company Emerson Electric Co. is an American multinational corporation headquartered in Ferguson, Missouri. The ''Fortune'' 500 company manufactures products and provides engineering services for industrial, commercial, and consumer markets.

St. Louis, Missouri St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, whic ...

when an Emerson Model III tail turret was equipped with the Emerson APG8 Blind Tracking Radar and fitted to the

Canadian Canadians (french: Canadiens) are people identified with the country of Canada. This connection may be residential, legal, historical or cultural. For most Canadians, many (or all) of these connections exist and are collectively the source of ...

-built Lancaster ''KB805''. The system was found to have no advantages over the British system and the project was subsequently dropped.

References

External links

{{Commons category, Village Inn (codename)
A photograph of a Village Inn-equipped 635 Sqn Lancaster

Illustration of a 460 Sqn Lancaster I/III fitted with Village Inn

A photograph of a Village Inn-equipped Rose Rice turret on an Avro Lincoln

A photograph of a Village Inn-equipped twin .5 in turret on a Handley Page Halifax

Village Inn
(PDF)
Eyewitness account of Village Inn testing on 460 Squadron
Aircraft radars World War II British electronics World War II radars Military radars of the United Kingdom

Development

See also

References

External links