Fog Investigation and Dispersal Operation (FIDO)

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Fog Investigation and Dispersal Operation (FIDO) (which was sometimes referred to as "Fog Intense Dispersal Operation" or "Fog Intense Dispersal Of") was a system used for dispersing fog from an airfield so that aircraft could land safely.

The invention of FIDO is formally attributed to Dr John David Main-Smith PhD, BSc, an ex-Birmingham resident & Principal Scientific Officer of the Chemistry Dept of the Royal Aircraft Establishment at Farnborough, Hants, and as a courtesy the joint-patent held by the Ministry of Supply was shared by the department head Dr Ramsbottom as was normal practice at that date. This formal government recognition is enshrined in an Air Ministry postwar letter to the late inventor's late widow and held by the son Bruce Main-Smith (February 2008). It also deals with the lesser role of those developing support equipment, notably the FIDO burner. It is my memory (writes BMS) that much of the airfield installation was pioneered at Hartford Bridge Flats airfield (aka Blackbushe near Yately, Surrey) a convenient few miles from the RAE's Farnborough aerodrome. Though JDMS co-owned the FIDO patent no royalties accrued from any UK civilian usage after WW2 as there was none, it being too petrol-hungry. At an attempt to quantify the saving of aircrew life BMS suggests possibly 11,000 airmen but nor all would be fit to fly again....

It is difficult for the modern (2008) UK resident to comprehend what WW2 fogs were like. It was not uncommon for a person to be unable to see the hand at the end of an outstretched arm. The post-war Clean Air Act hugely ameliorated UK fogs, comments BMS.

The FIDO system was developed at the University of Birmingham, United Kingdom in the department of chemical engineering during the Second World War. The device was used by the British for the dispersal of fog from around the runways of RAF bomber stations, allowing the landing of aircraft returning from raids over Germany in poor visibility.

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[edit] The System

The device consisted of two pipelines situated along both sides of the runway and through which a fuel (usually the petrol from the airfield's own fuel dump) was pumped along and then out through burner jets positioned at intervals along the pipelines. The vapours were lit from a series of burners, producing walls of flame. The FIDO installation usually stored its fuel in four circular upright tanks built at the edge of the airfield with a low brick bund wall in case of leakage. The tanks were usually encased in ordinary brickwork as protection from bomb splinters or cannon fire.

When fog prevented returning Allied aircraft from locating and seeing their runways to land, they would be diverted to FIDO equipped airdromes. RAF night bombers which were damaged on their missions were also diverted to FIDO airfields due to the need to make certain they could land when they arrived. When FIDO was needed, the fuel pumps were started to pour flammable liquid into the pipe system and a jeep with a flaming brand lashed to its rear drove fast down both sides of the runway to ignite the fuel at the outlets in the pipes. The result was a row of burning flame along the side of the runway that could be seen for a great distance from the air. The heat from the flames dispersed the fog so that the allied airplanes could have suitable visibility to find the airfield and land. Once landed the crews would find shelter where they could, and their planes would be refuelled and if needed repaired before flying back to their normal bases the next day.

[edit] The Procedure for aircrew before the introduction of FIDO

Prior to the introduction of FIDO, fog had been responsible for losses of a number of aircraft returning from operations. Often large areas of the UK would be simultaneously fog-bound and it was recommended procedure in these situations for the pilot to point the aircraft towards the sea and then, while still over land, for the crew to bail-out by parachute, leaving the aircraft to subsequently crash in the sea. With raids often consisting of several-hundred aircraft this could amount to a large loss of bombers.

[edit] The use of FIDO

FIDO used huge quantities of fuel, as much as 100,000 gallons [125,000 US gallons, 450,000 litres] per hour. Over twice this amount was used by airfields with longer runways such as RAF Carnaby. Large fuel storage tanks filled with low grade petrol and possibly kero and other fuel were connected by pumps to provide this fuel to the runway pipes. Although extravagant in the use of fuel consumed, the device more than made up for the costs involved in the reduction in aircraft losses.

FIDO systems were used at many airbases in England during World War II. Among the RAF fields equipped with FIDO were RAF Carnaby, RAF Manston, and RAF emergency fields at Tilstock and Skipton, and have been used to bring commercial planes into fog-covered airports in the United States.

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