119-770: Stonehenge Aerodrome or Stonehenge Airfield was a short-lived military airfield of the Royal Flying Corps on Salisbury Plain in Wiltshire, England, in use from 1917 to 1921. It was built around 300 metres (980 ft) south-west of Stonehenge on the site of existing cottages, and spanned both sides of the New Direct Road turnpike (later designated as the A303 ). The base was opened in November 1917, construction having started earlier in that year, as part of
238-578: A dilution refrigerator . Faraday force magnetometry can also be complicated by the presence of torque (see previous technique). This can be circumvented by varying the gradient field independently of the applied DC field so the torque and the Faraday force contribution can be separated, and/or by designing a Faraday force magnetometer that prevents the sample from being rotated. Optical magnetometry makes use of various optical techniques to measure magnetization. One such technique, Kerr magnetometry makes use of
357-569: A flight sergeant from the base was charged with stealing six gallons of petrol and selling it to the local bus company. The Under-secretary of State to the Air Ministry George Tryon was asked in Parliament in early 1920 if the aerodrome was to be pulled down to remove the visual impact on Stonehenge, to which he replied "The retention of the aerodrome at Stonehenge has been the subject of very careful consideration, as
476-503: A guardhouse . Marham was 80 acres (32 ha). Both these Stations are now lost beneath the present RAF Marham . Similarly, Stations at Easton-on-the-Hill and Stamford merged into modern day RAF Wittering although they are in different counties. The Royal Flying Corps Canada was established by the RFC in 1917 to train aircrew in Canada. Air Stations were established in southern Ontario at
595-448: A " buffer gas " through which the emitted photons pass, and a photon detector, arranged in that order. The buffer gas is usually helium or nitrogen and they are used to reduce collisions between the caesium vapour atoms. The basic principle that allows the device to operate is the fact that a caesium atom can exist in any of nine energy levels , which can be informally thought of as the placement of electron atomic orbitals around
714-498: A "finishing school" for bomber pilots and navigators, and provided both day and night training. At the height of its activity in mid-1918, 60 day crews and 60 night crews were trained each month. The biography of David Clendon Hale, an American airman attached to the RAF, states that he completed a 32-day course as an observer at the night flying school at Stonehenge in May 1918. There was also
833-460: A 0.01 nT to 0.02 nT standard deviation while sampling once per second. The optically pumped caesium vapour magnetometer is a highly sensitive (300 fT/Hz ) and accurate device used in a wide range of applications. It is one of a number of alkali vapours (including rubidium and potassium ) that are used in this way. The device broadly consists of a photon emitter, such as a laser, an absorption chamber containing caesium vapour mixed with
952-706: A German Etrich Taube , which had approached their aerodrome while they were refuelling their Avro 504. Another RFC machine landed nearby and the RFC observer chased the German pilot into nearby woods. After the Great Retreat from Mons, the Corps fell back to the Marne where in September, the RFC again proved its value by identifying von Kluck's First Army's left wheel against the exposed French flank. This information
1071-783: A Naval Wing. By 1914, the Naval Wing had become the Royal Naval Air Service, having gained its independence from the Royal Flying Corps. By November 1914 the Flying Corps had significantly expanded and it was felt necessary to create organizational units which would control collections of squadrons; the term "wing" was reused for these new organizational units. The Military Wing was abolished and its units based in Great Britain were regrouped as
1190-475: A Special Duty Flight was formed as part of the Headquarters Wing to handle these and other unusual assignments. Magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment . Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, one that measures
1309-614: A central flying school and an aircraft factory. The recommendations of the committee were accepted and on 13 April 1912 King George V signed a royal warrant establishing the Royal Flying Corps. The Air Battalion of the Royal Engineers became the Military Wing of the Royal Flying Corps a month later on 13 May. The Flying Corps' initial allowed strength was 133 officers, and by the end of that year it had 12 manned balloons and 36 aeroplanes . The RFC originally came under
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#17327760042491428-516: A configuration which cancels the dead-zones, which are a recurrent problem of atomic magnetometers. This configuration was demonstrated to show an accuracy of 50 pT in orbit operation. The ESA chose this technology for the Swarm mission , which was launched in 2013. An experimental vector mode, which could compete with fluxgate magnetometers was tested in this mission with overall success. The caesium and potassium magnetometers are typically used where
1547-424: A conventional metal detector's range is rarely more than 2 metres (6 ft 7 in). In recent years, magnetometers have been miniaturized to the extent that they can be incorporated in integrated circuits at very low cost and are finding increasing use as miniaturized compasses ( MEMS magnetic field sensor ). Magnetic fields are vector quantities characterized by both strength and direction. The strength of
1666-470: A fixed position and measurements are taken while the magnetometer is stationary. Portable or mobile magnetometers are meant to be used while in motion and may be manually carried or transported in a moving vehicle. Laboratory magnetometers are used to measure the magnetic field of materials placed within them and are typically stationary. Survey magnetometers are used to measure magnetic fields in geomagnetic surveys; they may be fixed base stations, as in
1785-567: A fundraising effort was launched in August 1927 to raise enough money to demolish the aerodrome buildings and buy the land within the "Stonehenge skyline". The subscription target for this was £35,000 and the first £8,000 – with the King as the lead subscriber – was enough to start the demolition in October 1927. The fund continued for a number of years to secure the remaining land around the henge for
1904-486: A given number of data points. Caesium and potassium magnetometers are insensitive to rotation of the sensor while the measurement is being made. The lower noise of caesium and potassium magnetometers allow those measurements to more accurately show the variations in the field with position. Vector magnetometers measure one or more components of the magnetic field electronically. Using three orthogonal magnetometers, both azimuth and dip (inclination) can be measured. By taking
2023-421: A higher performance magnetometer than the proton magnetometer is needed. In archaeology and geophysics, where the sensor sweeps through an area and many accurate magnetic field measurements are often needed, caesium and potassium magnetometers have advantages over the proton magnetometer. The caesium and potassium magnetometer's faster measurement rate allows the sensor to be moved through the area more quickly for
2142-582: A magnetic field is measured in units of tesla in the SI units , and in gauss in the cgs system of units. 10,000 gauss are equal to one tesla. Measurements of the Earth's magnetic field are often quoted in units of nanotesla (nT), also called a gamma. The Earth's magnetic field can vary from 20,000 to 80,000 nT depending on location, fluctuations in the Earth's magnetic field are on the order of 100 nT, and magnetic field variations due to magnetic anomalies can be in
2261-459: A paper on measurement of the Earth's magnetic field. It described a new instrument that consisted of a permanent bar magnet suspended horizontally from a gold fibre. The difference in the oscillations when the bar was magnetised and when it was demagnetised allowed Gauss to calculate an absolute value for the strength of the Earth's magnetic field. The gauss , the CGS unit of magnetic flux density
2380-572: A presence of the Royal Naval Air Service with Handley Page heavy bombers. The No. 108 Squadron RAF unit was formed at Stonehenge (or possibly the nearby Lake Down Aerodrome) in November 1917, and was equipped with Airco DH.9 bombers. The site was closely linked to Larkhill military camp, and from 1917 the two sites were connected through spurs of the Larkhill Military Light Railway . In 1919,
2499-543: A report to the War Council on the future of air power . Because of its potential for the 'devastation of enemy lands and the destruction of industrial and populous centres on a vast scale', he recommended a new air service be formed that would be on a level with the Army and Royal Navy. The formation of the new service would also make the under-used men and machines of the Royal Naval Air Service (RNAS) available for action on
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#17327760042492618-450: A sample's magnetization. In this method a Faraday modulating thin film is applied to the sample to be measured and a series of images are taken with a camera that senses the polarization of the reflected light. To reduce noise, multiple pictures are then averaged together. One advantage to this method is that it allows mapping of the magnetic characteristics over the surface of a sample. This can be especially useful when studying such things as
2737-448: A senior sergeant and thirty-six other ranks (as fitters, riggers, metalsmiths, armourers, etc.). The average squadron also had on complement an equipment officer, armaments officer (each with five other ranks) and a transport officer, in charge of twenty-two other ranks. The squadron transport establishment typically included one car, five light tenders, seven heavy tenders, two repair lorries, eight motorcycles and eight trailers. Wings in
2856-480: A sine wave in a rotating coil . The amplitude of the signal is proportional to the strength of the field, provided it is uniform, and to the sine of the angle between the rotation axis of the coil and the field lines. This type of magnetometer is obsolete. The most common magnetic sensing devices are solid-state Hall effect sensors. These sensors produce a voltage proportional to the applied magnetic field and also sense polarity. They are used in applications where
2975-464: A single, narrow electron spin resonance (ESR) line in contrast to other alkali vapour magnetometers that use irregular, composite and wide spectral lines and helium with the inherently wide spectral line. Magnetometers based on helium-4 excited to its metastable triplet state thanks to a plasma discharge have been developed in the 1960s and 70s by Texas Instruments , then by its spinoff Polatomic, and from late 1980s by CEA-Leti . The latter pioneered
3094-570: A solenoid, a low power radio-frequency field is used to align (polarise) the electron spin of the free radicals, which then couples to the protons via the Overhauser effect. This has two main advantages: driving the RF field takes a fraction of the energy (allowing lighter-weight batteries for portable units), and faster sampling as the electron-proton coupling can happen even as measurements are being taken. An Overhauser magnetometer produces readings with
3213-451: A system that is more sensitive than either one alone. Heat due to the sample vibration can limit the base temperature of a VSM, typically to 2 kelvin. VSM is also impractical for measuring a fragile sample that is sensitive to rapid acceleration. Pulsed-field extraction magnetometry is another method making use of pickup coils to measure magnetization. Unlike VSMs where the sample is physically vibrated, in pulsed-field extraction magnetometry,
3332-656: Is adequate for most mineral exploration work. For higher gradient tolerance, such as mapping banded iron formations and detecting large ferrous objects, Overhauser magnetometers can handle 10,000 nT/m, and caesium magnetometers can handle 30,000 nT/m. They are relatively inexpensive (< US$ 8,000) and were once widely used in mineral exploration. Three manufacturers dominate the market: GEM Systems, Geometrics and Scintrex. Popular models include G-856/857, Smartmag, GSM-18, and GSM-19T. For mineral exploration, they have been superseded by Overhauser, caesium, and potassium instruments, all of which are fast-cycling, and do not require
3451-427: Is that it requires some means of not only producing a magnetic field, but also producing a magnetic field gradient. While this can be accomplished by using a set of special pole faces, a much better result can be achieved by using set of gradient coils. A major advantage to Faraday force magnetometry is that it is small and reasonably tolerant to noise, and thus can be implemented in a wide range of environments, including
3570-446: Is to mount the sample on a cantilever and measure the displacement via capacitance measurement between the cantilever and nearby fixed object, or by measuring the piezoelectricity of the cantilever, or by optical interferometry off the surface of the cantilever. Faraday force magnetometry uses the fact that a spatial magnetic field gradient produces force that acts on a magnetized object, F = (M⋅∇)B. In Faraday force magnetometry
3689-450: Is typically scaled and displayed directly as field strength or output as digital data. For hand/backpack carried units, PPM sample rates are typically limited to less than one sample per second. Measurements are typically taken with the sensor held at fixed locations at approximately 10 metre increments. Portable instruments are also limited by sensor volume (weight) and power consumption. PPMs work in field gradients up to 3,000 nT/m, which
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3808-650: Is very important to understand the magnetic properties of materials in physics, chemistry, geophysics and geology, as well as sometimes biology. SQUIDs are a type of magnetometer used both as survey and as laboratory magnetometers. SQUID magnetometry is an extremely sensitive absolute magnetometry technique. However SQUIDs are noise sensitive, making them impractical as laboratory magnetometers in high DC magnetic fields, and in pulsed magnets. Commercial SQUID magnetometers are available for sample temperatures between 300 mK and 400 K, and magnetic fields up to 7 tesla. Inductive pickup coils (also referred as inductive sensor) measure
3927-852: The 6th Wing had been created and in November 1915 a 7th Wing and 8th Wing had also been stood up. Additional wings continued to be created throughout World War I in line with the incessant demands for air units. The last RFC wing to be created was the 54th Wing in March 1918, just prior to the creation of the RAF. Following the creation of brigades, wings took on specialised functions. Corps wings undertook artillery observation and ground liaison duties, with one squadron detached to each army corps. Army wings were responsible for air superiority, bombing and strategic reconnaissance. United Kingdom based forces were organised into home defence and training wings. By March 1918, wings controlled as many as nine squadrons. Following Sir David Henderson's return from France to
4046-530: The Administrative Wing . The RFC squadrons in France were grouped under the newly established 1st Wing and the 2nd Wing . The 1st Wing was assigned to the support of the 1st Army whilst the 2nd Wing supported the 2nd Army . As the Flying Corps grew, so did the number of wings. The 3rd Wing was established on 1 March 1915 and on 15 April the 5th Wing came into existence. By August that year
4165-469: The INTERMAGNET network, or mobile magnetometers used to scan a geographic region. The performance and capabilities of magnetometers are described through their technical specifications. Major specifications include The compass , consisting of a magnetized needle whose orientation changes in response to the ambient magnetic field, is a simple type of magnetometer, one that measures the direction of
4284-457: The Meissner effect on superconductors. Microfabricated optically pumped magnetometers (μOPMs) can be used to detect the origin of brain seizures more precisely and generate less heat than currently available superconducting quantum interference devices, better known as SQUIDs. The device works by using polarized light to control the spin of rubidium atoms which can be used to measure and monitor
4403-611: The Royal Naval Air Service on 1 July 1914, although a combined central flying school was retained. The RFC's motto was Per ardua ad astra ("Through adversity to the stars"). This remains the motto of the Royal Air Force (RAF) and other Commonwealth air forces. The RFC's first fatal crash was on 5 July 1912 near Stonehenge on Salisbury Plain ; Captain Eustace B. Loraine and his observer, Staff Sergeant R.H.V. Wilson, flying from Larkhill Aerodrome , were killed. An order
4522-601: The Western Front and end the inter-service rivalries that at times had adversely affected aircraft procurement. On 1 April 1918, the RFC and the RNAS were amalgamated to form a new service, the Royal Air Force (RAF), under the control of the new Air Ministry . After starting in 1914 with some 2,073 personnel, by the start of 1919 the RAF had 4,000 combat aircraft and 114,000 personnel in some 150 squadrons. With
4641-413: The atomic nucleus . When a caesium atom within the chamber encounters a photon from the laser, it is excited to a higher energy state, emits a photon and falls to an indeterminate lower energy state. The caesium atom is "sensitive" to the photons from the laser in three of its nine energy states, and therefore, assuming a closed system, all the atoms eventually fall into a state in which all the photons from
4760-419: The magneto-optic Kerr effect , or MOKE. In this technique, incident light is directed at the sample's surface. Light interacts with a magnetized surface nonlinearly so the reflected light has an elliptical polarization, which is then measured by a detector. Another method of optical magnetometry is Faraday rotation magnetometry . Faraday rotation magnetometry utilizes nonlinear magneto-optical rotation to measure
4879-467: The 19th century included the Hall effect , which is still widely used. Magnetometers are widely used for measuring the Earth's magnetic field, in geophysical surveys , to detect magnetic anomalies of various types, and to determine the dipole moment of magnetic materials. In an aircraft's attitude and heading reference system , they are commonly used as a heading reference. Magnetometers are also used by
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4998-681: The 20th century. Laboratory magnetometers measure the magnetization , also known as the magnetic moment of a sample material. Unlike survey magnetometers, laboratory magnetometers require the sample to be placed inside the magnetometer, and often the temperature, magnetic field, and other parameters of the sample can be controlled. A sample's magnetization, is primarily dependent on the ordering of unpaired electrons within its atoms, with smaller contributions from nuclear magnetic moments , Larmor diamagnetism , among others. Ordering of magnetic moments are primarily classified as diamagnetic , paramagnetic , ferromagnetic , or antiferromagnetic (although
5117-526: The Air Council are in full sympathy with the desire that existing disfigurements in the neighbourhood of Stonehenge should be removed at the earliest moment possible. The station is, however, of great importance to the Royal Air Force owning to its proximity to Larkhill and other artillery camps, and until an alternative arrangement can be found the aerodrome will have to remain". Flying operations were stopped in 1920, leading to formal closure in 1921, when
5236-454: The Battle of Aubers Ridge. Operations from balloons thereafter continued throughout the war. Highly hazardous in operation, a balloon could only be expected to last a fortnight before damage or destruction. Results were also highly dependent on the expertise of the observer and was subject to the weather conditions. To keep the balloon out of the range of artillery fire, it was necessary to locate
5355-508: The British Army's highly detailed 1:10,000 scale maps introduced in mid-1915. Such were advances in aerial photography that the entire Somme Offensive of July–November 1916 was based on the RFC's air-shot photographs. One of the initial and most important uses of RFC aircraft was observing artillery fire behind the enemy front line at targets that could not be seen by ground observers. The fall of shot of artillery fire were easy enough for
5474-641: The French coast to the Bay of the Somme and followed the river to Amiens . When the BEF moved forward to Maubeuge the RFC accompanied them. On 19 August the Corps undertook its first action of the war, with two of its aircraft performing aerial reconnaissance . The mission was not a great success; to save weight each aircraft carried a pilot only instead of the usual pilot and observer. Because of this, and poor weather, both of
5593-488: The HQ, and three Landing Grounds, one per each flight . Stations tended to be named after the local railway station, to simplify the administration of rail travel warrants. Typically a training airfield consisted of a 2,000 feet (610 m) grass square. There were three pairs plus one single hangar, constructed of wood or brick, 180 feet (55 m) x 100 feet (30 m) in size. There were up to 12 canvas Bessonneau hangars as
5712-414: The RFC supported the British Army by artillery co-operation and photographic reconnaissance . This work gradually led RFC pilots into aerial battles with German pilots and later in the war included the strafing of enemy infantry and emplacements , the bombing of German military airfields and later the strategic bombing of German industrial and transport facilities. At the start of World War I
5831-434: The RFC that same year. By November 1914 the Royal Flying Corps, even taking the loss of the Naval Wing into account, had expanded sufficiently to warrant the creation of wings consisting of two or more squadrons. These wings were commanded by lieutenant-colonels. In October 1915 the Corps had undergone further expansion which justified the creation of brigades , each commanded by a brigadier-general . Further expansion led to
5950-435: The RFC, commanded by Brigadier-General Sir David Henderson , consisted of five squadrons – one observation balloon squadron (RFC No 1 Squadron) and four aeroplane squadrons. These were first used for aerial spotting on 13 September 1914 but only became efficient when they perfected the use of wireless communication at Aubers Ridge on 9 May 1915. Aerial photography was attempted during 1914, but again only became effective
6069-494: The Royal Flying Corps consisted of a number of squadrons . When the Royal Flying Corps was established it was intended to be a joint service. Owing to the rivalry between the British Army and Royal Navy, new terminology was thought necessary in order to avoid marking the Corps out as having a particularly Army or Navy ethos. Accordingly, the Corps was originally split into two wings: a Military Wing (i.e. an army wing) and
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#17327760042496188-525: The Stonehenge landscape. 51°10′37″N 1°49′59″W / 51.177°N 1.833°W / 51.177; -1.833 Royal Flying Corps The Royal Flying Corps ( RFC ) was the air arm of the British Army before and during the First World War until it merged with the Royal Naval Air Service on 1 April 1918 to form the Royal Air Force . During the early part of the war,
6307-535: The War Office in August 1915, he submitted a scheme to the Army Council which was intended to expand the command structure of the Flying Corps. The Corps' wings would be grouped in pairs to form brigades and the commander of each brigade would hold the temporary rank of brigadier-general . The scheme met with Lord Kitchener 's approval and although some staff officers opposed it, the scheme was adopted. In
6426-622: The adoption of a continually offensive stance operationally in efforts to pin the enemy back led to many brave fighting exploits and high casualties – over 700 in 1916, the rate worsening thereafter, until the RFC's nadir in April 1917 which was dubbed ' Bloody April '. This aggressive, if costly, doctrine did however provide the Army General Staff with vital and up-to-date intelligence on German positions and numbers through continual photographic and observational reconnaissance throughout
6545-705: The air raids on London and the south-east of England led to the creation of the London Air Defence Area in August 1917 under the command of Ashmore who was promoted to major-general. Two of the first three RFC squadrons were formed from the Air Battalion of the Royal Engineers: No. 1 Company (a balloon company) becoming No. 1 Squadron, RFC , and No. 2 Company (a 'heavier-than-air' company) becoming No. 3 Squadron, RFC . A second heavier-than-air squadron, No. 2 Squadron, RFC ,
6664-510: The aircraft could not receive. Originally only a special Wireless Flight attached to No. 4 Squadron RFC had the wireless equipment. Eventually this flight was expanded into No. 9 Squadron under Major Hugh Dowding . However, in early 1915 the Sterling lightweight wireless became available and was widely used. In 1915 each corps in the BEF was assigned a RFC squadron solely for artillery observation and reconnaissance duties. The transmitter filled
6783-419: The aircraft, constructed from wood, wire and fabric, were liable to weather damage. Other airfield buildings were typically wooden or Nissen huts . Landing Grounds were often L-shaped, usually arrived at by removing a hedge boundary between two fields, and thereby allowing landing runs in two directions of 400–500 metres (1,300–1,600 ft). Typically they would be manned by only two or three airmen, whose job
6902-469: The airman reported the position of the ranging round using the clock code, the battery adjusted their firing data and fired again, and the process was repeated until the pilot observed an on-target or close round. The battery commander then decided how much to fire at the target. The results were mixed. Observing artillery fire, even from above, requires training and skill. Within artillery units, ground observers received mentoring to develop their skill, which
7021-455: The balloons some distance away from the front line or area of military operations. However, the stable platform offered by a kite-balloon made it more suitable for the cameras of the day than an aircraft. For the first half of the war, as with the land armies deployed, the French air force vastly outnumbered the RFC, and accordingly did more of the fighting. Despite the primitive aircraft, aggressive leadership by RFC commander Hugh Trenchard and
7140-473: The battery they were colocated with. This led to concerns as to who had responsibility for them and in November 1916 squadron commanders had to be reminded "that it is their duty to keep in close touch with the operators attached to their command, and to make all necessary arrangements for supplying them with blankets, clothing, pay, etc" (Letter from Headquarters, 2nd Brigade RFC dated 18 November 1916 – Public Records Office AIR/1/864) The wireless operators' work
7259-643: The building of headquarters/administration offices, mess buildings, fuel and weapon stores, wireless huts and other support structures as well as the aircraft hangarage and repair facilities. Narborough and Marham both started off as Night Landing Grounds a few miles apart. One was an RNAS Station, the other RFC. Narborough grew to be the largest aerodrome in Britain at 908 acres (367 ha) with 30 acres (12 ha) of buildings including seven large hangars, seven motorised transport (MT) garages, five workshops, two coal yards, two Sergeants' Messes, three dope sheds and
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#17327760042497378-588: The cockpit normally used by the observer and a trailing wire antenna was used which had to be reeled in prior to landing. The RFC's wireless experiments under Major Herbert Musgrave, included research into how wireless telegraphy could be used by military aircraft. However, the most important officers in wireless development were Lieutenants Donald Lewis and Baron James in the RFC HQ wireless unit formed in France in September 1914. They developed both equipment and procedures in operational sorties. An important development
7497-890: The components of the magnetic field in all three dimensions. They are also rated as "absolute" if the strength of the field can be calibrated from their own known internal constants or "relative" if they need to be calibrated by reference to a known field. A magnetograph is a magnetometer that continuously records data over time. This data is typically represented in magnetograms. Magnetometers can also be classified as "AC" if they measure fields that vary relatively rapidly in time (>100 Hz), and "DC" if they measure fields that vary only slowly (quasi-static) or are static. AC magnetometers find use in electromagnetic systems (such as magnetotellurics ), and DC magnetometers are used for detecting mineralisation and corresponding geological structures. Proton precession magnetometer s, also known as proton magnetometers , PPMs or simply mags, measure
7616-441: The conduct of operations. Fired at constantly by friend and foe, and not hesitating to fly in every kind of weather, they have remained undaunted throughout. Further, by actually fighting in the air, they have succeeded in destroying five of the enemy's machines." Early in the war RFC aircraft were not systematically marked with any national insignia . At a squadron level, Union Flag markings in various styles were often painted on
7735-544: The conspicuous white circle of the "day" marking. Later in September, 1914, during the First Battle of the Aisne , the RFC made use of wireless telegraphy to assist with artillery targeting and took aerial photographs for the first time. From 16,000 feet a photographic plate could cover some 2 by 3 miles (3.2 km × 4.8 km) of front line in sharp detail. In 1915 Lieutenant-Colonel JTC Moore-Brabrazon designed
7854-539: The creation of divisions , with the Training Division being established in August 1917 and RFC Middle East being raised to divisional status in December 1917. Additionally, although the Royal Flying Corps in France was never titled as a division, by March 1916 it comprised several brigades and its commander (Trenchard) had received a promotion to major-general, giving it in effect divisional status. Finally,
7973-673: The crucial observation of the 1st German Army's approach towards the flank of the British Expeditionary Force. This allowed the BEF Commander-in-Chief Field Marshal Sir John French to realign his front and save his army around Mons. Next day, the RFC found itself fighting in the Battle of Mons and two days after that, gained its first air victory. On 25 August, Lt C. W. Wilson and Lt C. E. C. Rabagliati forced down
8092-452: The dipole moment of a sample by mechanically vibrating the sample inside of an inductive pickup coil or inside of a SQUID coil. Induced current or changing flux in the coil is measured. The vibration is typically created by a motor or a piezoelectric actuator. Typically the VSM technique is about an order of magnitude less sensitive than SQUID magnetometry. VSMs can be combined with SQUIDs to create
8211-510: The direction of an ambient magnetic field, in this case, the Earth's magnetic field . Other magnetometers measure the magnetic dipole moment of a magnetic material such as a ferromagnet , for example by recording the effect of this magnetic dipole on the induced current in a coil. The first magnetometer capable of measuring the absolute magnetic intensity at a point in space was invented by Carl Friedrich Gauss in 1833 and notable developments in
8330-406: The electrons once again can absorb a photon of light. This causes a signal on a photo detector that measures the light passing through the cell. The associated electronics use this fact to create a signal exactly at the frequency that corresponds to the external field. Another type of caesium magnetometer modulates the light applied to the cell. This is referred to as a Bell-Bloom magnetometer, after
8449-447: The external applied field. Often a special arrangement of cancellation coils is used. For example, half of the pickup coil is wound in one direction, and the other half in the other direction, and the sample is placed in only one half. The external uniform magnetic field is detected by both halves of the coil, and since they are counter-wound, the external magnetic field produces no net signal. Vibrating-sample magnetometers (VSMs) detect
8568-547: The field vector and the horizontal surface). Absolute magnetometers measure the absolute magnitude or vector magnetic field, using an internal calibration or known physical constants of the magnetic sensor. Relative magnetometers measure magnitude or vector magnetic field relative to a fixed but uncalibrated baseline. Also called variometers , relative magnetometers are used to measure variations in magnetic field. Magnetometers may also be classified by their situation or intended use. Stationary magnetometers are installed to
8687-482: The field, most brigades were assigned to the army. Initially a brigade consisted of an army wing and corps wing; beginning in November 1916 a balloon wing was added to control the observation balloon companies. Logistics support was provided by an army aircraft park, aircraft ammunition column and reserve lorry park. All operating locations were officially called "Royal Flying Corps Station name ". A typical Squadron may have been based at four Stations – an Aerodrome for
8806-547: The field. The oscillation frequency of a magnetized needle is proportional to the square-root of the strength of the ambient magnetic field; so, for example, the oscillation frequency of the needle of a horizontally situated compass is proportional to the square-root of the horizontal intensity of the ambient field. In 1833, Carl Friedrich Gauss , head of the Geomagnetic Observatory in Göttingen, published
8925-452: The first practical aerial camera. These semi-automatic cameras became a high priority for the Corps and photo-reconnaissance aircraft were soon operational in numbers with the RFC. The camera was usually fixed to the side of the fuselage, or operated through a hole in the floor. The increasing need for surveys of the western front and its approaches, made extensive aerial photography essential. Aerial photographs were exclusively used in compiling
9044-561: The following locations: The RFC was also responsible for the manning and operation of observation balloons on the Western front . When the British Expeditionary Force (BEF) arrived in France in August 1914, it had no observation balloons and it was not until April 1915 that the first balloon company was on strength, albeit on loan from the French Aérostiers. The first British unit arrived 8 May 1915, and commenced operations during
9163-413: The force on the sample can be measured by a scale (hanging the sample from a sensitive balance), or by detecting the displacement against a spring. Commonly a capacitive load cell or cantilever is used because of its sensitivity, size, and lack of mechanical parts. Faraday force magnetometry is approximately one order of magnitude less sensitive than a SQUID. The biggest drawback to Faraday force magnetometry
9282-465: The ground or a signalling lamp to give visual confirmation that the signals had been received. The wireless communication was one way as no receiver was mounted in the aircraft and the ground station could not transmit. Details from: "Henry Tabor's 1916 War Diary" . By May 1916, 306 aircraft and 542 ground stations were equipped with wireless. An unusual mission for the RFC was the delivery of spies behind enemy lines. The first mission took place on
9401-406: The ground. The Royal Engineers' Air Battalion had pioneered experiments with wireless telegraphy in airships and aircraft before the RFC was created. Unfortunately the early transmitters weighed 75 pounds and filled a seat in the cockpit. This meant that the pilot had to fly the aircraft, navigate, observe the fall of the shells and transmit the results by morse code by himself. Also, the wireless in
9520-470: The growing recognition of the potential for aircraft as a cost-effective method of reconnaissance and artillery observation, the Committee of Imperial Defence established a sub-committee to examine the question of military aviation in November 1911. On 28 February 1912 the sub-committee reported its findings which recommended that a flying corps be formed and that it consist of a naval wing, a military wing,
9639-452: The laser pass through unhindered and are measured by the photon detector. The caesium vapour has become transparent. This process happens continuously to maintain as many of the electrons as possible in that state. At this point, the sample (or population) is said to have been optically pumped and ready for measurement to take place. When an external field is applied it disrupts this state and causes atoms to move to different states which makes
9758-773: The last units transferred to the School of Army Co-operation at Old Sarum Airfield . Disused huts and equipment were disposed of by auction. After closure of the site, it was reverted to the previous owners, who then sold the site for use as a pig farm. It therefore appears on 1920s maps as the "Pedigree Stock Farm". In 1921, the Wiltshire Times reported that the derelict site was different to other decommissioned military installations locally, having at least six "huge solidly-built hangars" which they estimated to be 240 feet (73 m) by 190 feet (58 m) in size and built in stone and brick. The former aerodrome, now pig farm,
9877-401: The magnetic dipole moment of a material by detecting the current induced in a coil due to the changing magnetic moment of the sample. The sample's magnetization can be changed by applying a small ac magnetic field (or a rapidly changing dc field), as occurs in capacitor-driven pulsed magnets. These measurements require differentiating between the magnetic field produced by the sample and that from
9996-437: The magnetic field. Survey magnetometers can be divided into two basic types: A vector is a mathematical entity with both magnitude and direction. The Earth's magnetic field at a given point is a vector. A magnetic compass is designed to give a horizontal bearing direction, whereas a vector magnetometer measures both the magnitude and direction of the total magnetic field. Three orthogonal sensors are required to measure
10115-641: The military as a triggering mechanism in magnetic mines to detect submarines. Consequently, some countries, such as the United States, Canada and Australia, classify the more sensitive magnetometers as military technology, and control their distribution. Magnetometers can be used as metal detectors : they can detect only magnetic ( ferrous ) metals, but can detect such metals at a much greater distance than conventional metal detectors, which rely on conductivity. Magnetometers are capable of detecting large objects, such as cars, at over 10 metres (33 ft), while
10234-438: The morning of 13 September 1915 and was not a success. The plane crashed, the pilot and spy were badly injured and they were both captured (two years later the pilot, Captain T.W. Mulcahy-Morgan escaped and returned to England). Later missions were more successful. In addition to delivering the spies the RFC was also responsible for keeping them supplied with the carrier pigeons that were used to send reports back to base. In 1916,
10353-423: The nation. Demolition of buildings took place from 1927, and in 1928 a labourer was killed falling through a roof of one the buildings being demolished. The last of the three largest hangars was demolished in August 1930, and the remaining buildings were cleared from the site in the early 1930s. The buried iron and concrete from the demolition and levelling of the site can still be seen in magnetometer surveys of
10472-647: The next year. By 1918, photographic images could be taken from 15,000 feet and were interpreted by over 3,000 personnel. Parachutes were not available to pilots of heavier-than-air craft in the RFC – nor were they used by the RAF during the First World War – although the Calthrop Guardian Angel parachute (1916 model) was officially adopted just as the war ended. By this time parachutes had been used by balloonists for three years. On 17 August 1917, South African General Jan Smuts presented
10591-410: The operator to pause between readings. The Overhauser effect magnetometer or Overhauser magnetometer uses the same fundamental effect as the proton precession magnetometer to take measurements. By adding free radicals to the measurement fluid, the nuclear Overhauser effect can be exploited to significantly improve upon the proton precession magnetometer. Rather than aligning the protons using
10710-400: The picotesla (pT) range. Gaussmeters and teslameters are magnetometers that measure in units of gauss or tesla, respectively. In some contexts, magnetometer is the term used for an instrument that measures fields of less than 1 millitesla (mT) and gaussmeter is used for those measuring greater than 1 mT. There are two basic types of magnetometer measurement. Vector magnetometers measure
10829-471: The pilot to see, providing he was looking in the right place at the right time; apart from this the problem was communicating corrections to the battery. Development of procedures had been the responsibility of No 3 Squadron and the Royal Artillery in 1912–13. These methods usually depended on the pilot being tasked to observe the fire against a specific target and report the fall of shot relative to
10948-476: The pilots lost their way and only one was able to complete his task. On 22 August 1914, the first British aircraft was lost to German fire. The crew – pilot Second Lieutenant Vincent Waterfall and observer Lt. Charles George Gordon Bayly, of 5 Squadron – flying an Avro 504 over Belgium, were killed by infantry fire. Also on 22 August 1914, Captain L E O Charlton (observer) and his pilot, Lieutenant Vivian Hugh Nicholas Wadham, made
11067-515: The previously mentioned methods do. Magnetic torque magnetometry instead measures the torque τ acting on a sample's magnetic moment μ as a result of a uniform magnetic field B, τ = μ × B. A torque is thus a measure of the sample's magnetic or shape anisotropy. In some cases the sample's magnetization can be extracted from the measured torque. In other cases, the magnetic torque measurement is used to detect magnetic phase transitions or quantum oscillations . The most common way to measure magnetic torque
11186-412: The protons to align themselves with that field. The current is then interrupted, and as protons realign themselves with the ambient magnetic field, they precess at a frequency that is directly proportional to the magnetic field. This produces a weak rotating magnetic field that is picked up by a (sometimes separate) inductor, amplified electronically, and fed to a digital frequency counter whose output
11305-500: The resonance frequency of protons (hydrogen nuclei) in the magnetic field to be measured, due to nuclear magnetic resonance (NMR). Because the precession frequency depends only on atomic constants and the strength of the ambient magnetic field, the accuracy of this type of magnetometer can reach 1 ppm . A direct current flowing in a solenoid creates a strong magnetic field around a hydrogen -rich fluid ( kerosene and decane are popular, and even water can be used), causing some of
11424-522: The responsibility of Brigadier-General Henderson , the Director of Military Training, and had separate branches for the Army and the Navy. Major Sykes commanded the Military Wing and Commander C R Samson commanded the Naval Wing. The Royal Navy , however, with priorities different from those of the Army and wishing to retain greater control over its aircraft, formally separated its branch and renamed it
11543-502: The roundel was applied to the fuselage sides as well as the wings. To minimise the likelihood of "friendly" attack, the rudders of RFC aircraft were painted to match the French, with the blue, white and red stripes – going from the forward (rudder hingeline) to aft (trailing edge) – of the French tricolour . Later in the war, a "night roundel" was adopted for night flying aircraft (especially Handley Page O/400 heavy bombers), which omitted
11662-534: The sample is secured and the external magnetic field is changed rapidly, for example in a capacitor-driven magnet. One of multiple techniques must then be used to cancel out the external field from the field produced by the sample. These include counterwound coils that cancel the external uniform field and background measurements with the sample removed from the coil. Magnetic torque magnetometry can be even more sensitive than SQUID magnetometry. However, magnetic torque magnetometry doesn't measure magnetism directly as all
11781-528: The scaling up of military flying capability for World War I . The aerodrome was not complete when the war ended, but construction continued past the end of the war. The airfield closed in 1921, and was fully demolished by the early 1930s as part of a concerted effort to restore the natural landscape around Stonehenge. The airfield was used for the training of bomber pilots at the No 1 School of Aerial Navigation and Bomb Dropping. The establishment has been described as
11900-436: The squadron 'flights' (annotated A, B, C etc.) the basic tactical and operational unit, each commanded by a captain. A 'recording officer' (of captain/lieutenant rank) would act as intelligence officer and adjutant, commanding two or three NCOs and ten other ranks in the administration section of the squadron. Each flight contained on average between six and ten pilots (and a corresponding number of observers, if applicable) with
12019-551: The square root of the sum of the squares of the components the total magnetic field strength (also called total magnetic intensity, TMI) can be calculated by the Pythagorean theorem . Vector magnetometers are subject to temperature drift and the dimensional instability of the ferrite cores. They also require leveling to obtain component information, unlike total field (scalar) instruments. For these reasons they are no longer used for mineral exploration. The magnetic field induces
12138-435: The target, the battery adjusted their aim, fired and the process was repeated until the target was effectively engaged. One early communication method was for the flier to write a note and drop it to the ground where it could be recovered but various visual signalling methods were also used. This meant the pilots had to observe the battery to see when it fired and see if it had laid out a visual signal using white marker panels on
12257-452: The two scientists who first investigated the effect. If the light is turned on and off at the frequency corresponding to the Earth's field, there is a change in the signal seen at the photo detector. Again, the associated electronics use this to create a signal exactly at the frequency that corresponds to the external field. Both methods lead to high performance magnetometers. Potassium is the only optically pumped magnetometer that operates on
12376-445: The vapour less transparent. The photo detector can measure this change and therefore measure the magnitude of the magnetic field. In the most common type of caesium magnetometer, a very small AC magnetic field is applied to the cell. Since the difference in the energy levels of the electrons is determined by the external magnetic field, there is a frequency at which this small AC field makes the electrons change states. In this new state,
12495-416: The vector components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the vector magnetic field. Magnetometers used to study the Earth's magnetic field may express the vector components of the field in terms of declination (the angle between the horizontal component of the field vector and true, or geographic, north) and the inclination (the angle between
12614-591: The war. At the start of the war, numbers 2, 3, 4 and 5 Squadrons were equipped with aeroplanes. No. 1 Squadron had been equipped with balloons but all these were transferred to the Naval Wing in 1913; thereafter No. 1 Squadron reorganised itself as an 'aircraft park' for the British Expeditionary Force. The RFC's first casualties were before the Corps even arrived in France: Lt Robert R. Skene and Air Mechanic Ray Barlow were killed on 12 August 1914 when their (probably overloaded) plane crashed at Netheravon on
12733-552: The way to rendezvous with the rest of the RFC near Dover . Skene had been the first Englishman to perform a loop in an aeroplane. On 13 August 1914, 2, 3, and 4 squadrons, comprising 60 machines, departed from Dover for the British Expeditionary Force in France and 5 Squadron joined them a few days later. The aircraft took a route across the English Channel from Dover to Boulogne , then followed
12852-540: The wings (and sometimes the fuselage sides and/or rudder). However, there was a danger of the large red St George's Cross being mistaken for the German Eisernes Kreuz (iron cross) marking, and so of RFC aircraft being fired upon by friendly ground forces. By late 1915, therefore, the RFC had adopted a modified version of the French cockade (or roundel ) marking, with the colours reversed (the blue circle outermost). In contrast to usual French practice,
12971-412: The zoology of magnetic ordering also includes ferrimagnetic , helimagnetic , toroidal , spin glass , etc.). Measuring the magnetization as a function of temperature and magnetic field can give clues as to the type of magnetic ordering, as well as any phase transitions between different types of magnetic orders that occur at critical temperatures or magnetic fields. This type of magnetometry measurement
13090-457: Was also formed on the same day. No. 4 Squadron, RFC was formed from No. 2 Sqn in August 1912, and No. 5 Squadron, RFC from No. 3 Sqn in July 1913. By the end of March 1918, the Royal Flying Corps comprised some 150 squadrons. The composition of an RFC squadron varied depending on its designated role, although the commanding officer was usually a major (in a largely non-operational role), with
13209-479: Was issued after the crash stating "Flying will continue this evening as usual", thus beginning a tradition. In August 1912, RFC Lieutenant Wilfred Parke RN became the first aviator to be observed to recover from an accidental spin when the Avro G cabin biplane, with which he had just broken a world endurance record, entered a spin at 700 feet above ground level at Larkhill. Four months later, on 11 December 1912, Parke
13328-521: Was killed when the Handley Page monoplane in which he was flying from Hendon to Oxford crashed. Aircraft used during the war by the RFC included: On its inception in 1912 the Royal Flying Corps consisted of a Military and a Naval Wing, with the Military Wing consisting of three squadrons each commanded by a major. The Naval Wing, with fewer pilots and aircraft than the Military Wing, did not organise itself into squadrons until 1914; it separated from
13447-435: Was named in his honour, defined as one maxwell per square centimeter; it equals 1×10 tesla (the SI unit ). Francis Ronalds and Charles Brooke independently invented magnetographs in 1846 that continuously recorded the magnet's movements using photography , thus easing the load on observers. They were quickly utilised by Edward Sabine and others in a global magnetic survey and updated machines were in use well into
13566-604: Was not available to RFC aircrew. There were undoubtedly some very skilled artillery observers in the RFC, but there were many who were not and there was a tendency for ' optimism bias ' – reporting rounds as being on target when they were not. The procedures were also time-consuming. The ground stations were generally attached to heavy artillery units, such as Royal Garrison Artillery Siege Batteries, and were manned by RFC wireless operators, such as Henry Tabor. These wireless operators had to fend for themselves as their squadrons were situated some distance away and they were not posted to
13685-399: Was often carried out under heavy artillery fire in makeshift dug-outs. The artillery batteries were important targets and antennas were a lot less robust than the guns, hence prone to damage requiring immediate repair. As well as taking down and interpreting the numerous signals coming in from the aircraft, the operator had to communicate back to the aircraft by means of cloth strips laid out on
13804-471: Was one of the main targets for campaigners who wanted to restore the landscape around Stonehenge to a more natural setting, and the airfield and Amesbury and Military Camp Light Railway were high priorities for removal after the National Trust took possession of the Stonehenge land in 1923. In 1927 the aerodrome site was put up for sale by the pig farmer, with interest from developers. As a result,
13923-680: Was significant as the First Army's manoeuvre allowed French forces to make an effective counter-attack at the Battle of the Marne . Sir John French 's (the British Expeditionary Force commander) first official dispatch on 7 September included the following: "I wish particularly to bring to your Lordships' notice the admirable work done by the Royal Flying Corps under Sir David Henderson. Their skill, energy, and perseverance has been beyond all praise. They have furnished me with most complete and accurate information, which has been of incalculable value in
14042-517: Was the Zone Call procedure in 1915. By this time maps were 'squared' and a target location could be reported from the air using alphanumeric characters transmitted in Morse code. Batteries were allocated a Zone, typically a quarter of a mapsheet, and it was the duty of the RFC signallers on the ground beside the battery command post to pick out calls for fire in their battery's Zone. Once ranging started
14161-739: Was to guard the fuel stores and assist any aircraft which had occasion to land. Accommodation for airmen and pilots was often in tents, especially on the Western Front. Officers would be billeted to local country houses , or commandeered châteaux when posted abroad, if suitable accommodation had not been built on the Station. Landing Grounds were categorised according to their lighting and day or night capabilities: Stations that were heavily used or militarily important grew by compulsorily purchasing extra land, changing designations as necessary. Aerodromes would often grow into sprawling sites, due to
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