Alan Blumlein
Encyclopedia
Alan Dower Blumlein was a British
electronics
engineer
, notable for his many inventions in telecommunication
s, sound recording, stereo
, television
and radar
. He received 128 patent
s and was considered as one of the most significant engineers and inventors of his time.
He died on 7 June 1942, aged 38, during the secret trial of an H2S airborne radar system
, then under development during World War II
when the Halifax bomber
he was flying in crashed at Welsh Bicknor
, Herefordshire
killing all on board.
, London
to Semmy Blumlein, a German-born naturalised British subject of Jewish descent,"[ Semmy Blumlein's] father Joseph B. Blumlein was Jewish", Burns, R. W. The Life and Times of A D Blumlein, p. 2. IET, 2000. ISBN 0-85296-773-X and Jessie Dower, a Scottish missionary's daughter. He was christened as a Presbyterian, though he later married in a Church of England
parish. His future career seems to have been determined by the age of seven, when he presented his father with an invoice for repairing the doorbell, signed "Alan Blumlein, Electrical Engineer" (with "paid" scrawled in pencil). His sister claimed that he could not read proficiently until he was 12. He replied "no, but I knew a lot of quadratic equations!"
After matriculating
at Highgate School
in 1921, he studied at City and Guilds College
(part of Imperial College
). He won a Governor's scholarship and joined the second year of the course. He graduated with a First-Class Honours
B.Sc
two years later.
In mid-1930, Blumlein met Doreen Lane, five years his junior. After two-and-a-half years of courtship the two were married. Lane was warned by acquaintances before the wedding that, "There was a joke amongst some of his friends, they used to call it 'Blumlein-itis' or 'First Class Mind'. It seems that he didn't want to know anyone who didn't have a first class mind." Best man J.B. Kaye thought that Lane and Blumlein were well matched.
. The company subsequently became International Standard Electric Corporation and then, later on, Standard Telephones and Cables
(STC).
During his time there, he measured the amplitude
/frequency response
of human ears, and used the results to design the first weighting
networks.
In 1924 he published (with Professor Edward Mallett) the first of his only two IEE
papers, on high-frequency resistance measurement. This won him the IEE's Premium award for innovation. The following year he wrote (with Norman Kipping) a series of seven articles for Wireless World
.
In 1925 and 1926, Blumlein and John Percy Johns designed an improved form of loading coil
which reduced loss and crosstalk in long-distance telephone lines. These were used until the end of the analogue telephony era. The same duo also invented an improved form of AC measurement bridge
which became known as the Blumlein Bridge. These two inventions were the basis for Blumlein's first two patents.
His inventions while working at STC resulted in another five patents, which were not awarded until after he left the company in 1929.
, where he reported directly to general manager Isaac Shoenberg
.
His first project was to find a method of disc cutting that circumvented a Bell patent in the Western Electric moving-iron cutting head then used, and on which substantial royalties had to be paid. He invented the moving-coil disc cutting head, which not only got around the patent but offered greatly improved sound quality. He led a small team which developed the concept into a practical cutter. The other principal team members were Herbert Holman and Henry "Ham" Clark. Their work resulted in several patents.
Early in 1931, the Columbia Graphophone Company and the Gramophone Company
merged and became EMI
. New joint research laboratories were set up at Hayes
and Blumlein was officially transferred there on 1 November the same year.
During the early 1930s Blumlein and Herbert Holman developed a series of moving-coil microphones, which were used in EMI recording studios and by the BBC
at Alexandra Palace
.
, and if the tap was at the supply end, it could be connected as a pure pentode
. Blumlein discovered that if the tap was placed at a distance 15-20% down from the supply end of the output transformer, the tube or valve would combine the positive features of both the triode and the pentode design.
In early 1931, Blumlein and his wife were at a local cinema. The sound reproduction systems of the early "talkies" invariably only had a single set of speakers - which could lead to the somewhat disconcerting effect of the actor being on one side of the screen whilst his voice appeared to come from the other. Blumlein declared to his wife that he had found a way to make the sound follow the actor across the screen.
The genesis of these ideas is uncertain, but he explained them to Isaac Shoenberg in the late summer of 1931. His earliest notes on the subject are dated 25 September 1931, and his patent had the title "Improvements in and relating to Sound-transmission, Sound-recording and Sound-reproducing Systems". The application was dated 14 December 1931, and was accepted on 14 June 1933 as UK
patent number 394,325.
Whereas work led by Harvey Fletcher
at Bell Labs at about the same time considered sound systems using multiple channels, Blumlein always aimed at a system with just two channels.
The patent covered many ideas in stereo, some of which are used today and some not. Some 70 claims include:
Binaural experiments began in early 1933, and the first stereo discs were cut later the same year.
Much of the development work on this system for cinematic use did not reach completion until 1935. In a few short test films (most notably, "Trains At Hayes Station" and, "The Walking & Talking Film"), Blumlein's original intent of having the sound follow the actor was fully realised.
His ideas included:
Blumlein was also largely responsible for the development of the waveform structure used in the 405-line
Marconi-EMI system - developed for the UK's BBC Television Service at Alexandra Palace
, the world's first scheduled "high definition" (240 lines or better) television service - which was later adopted as the CCIR System A.
His invention of the line type pulse modulator, (ref vol 5 of MIT Radiation Laboratory series) was a major contribution to high powered pulse radars, not just the H2S's system, and continues to be used today.
Blumlein was killed in the crash of a Handley Page Halifax
bomber while making a test flight on 7 June 1942. During the flight, the Halifax developed an engine fire which rapidly grew out of control. The bomber was seen to lose altitude, then rolled inverted and struck the ground.
After the RAF investigative board completed its report on the Halifax crash on 1 July 1942, it was distributed to a restricted list of approved recipients, but not publicly divulged. In the interests of wartime secrecy, the announcement of Blumlein's death was not made for another three years. The investigative board, headed by Chief Inspector Vernon Brown, found that the Halifax bomber crash was caused by engine fire, attributed to the unscrewing of a tappet
nut on the starboard outer engine, which had been improperly tightened by an RAF engine fitter while inspecting the engine some three hours prior to the crash. The loosened nut caused excessive valve clearance and a fracture of the valve stem
which resulted pumping ignited fuel outboard of the rocker cover and along the outside of the engine, causing a fire in the engine nacelle
. Constantly fuelled by the broken intake
, the fire burned rapidly along the wing and fuselage, eventually causing a large section of the wing to separate from the fuselage at approximately 350 feet of altitude. With the loss of all control over level flight, the rest of the plane inverted and struck the ground at approximately 150mph. The board found that the crew and passengers had not jumped immediately from the aircraft owing to several factors, including a loss of altitude while attempting to find an an emergency field, the rapidly-spreading fire, which blocked or impeded egress from the plane, and the fact that a sufficient number of parachutes were either not on board or were not being worn. Almost immediately following the crash, Prime Minister Churchill issued a directive requiring any test flights with civilians or scientific personnel to carry a sufficient number of parachutes for all individuals involved.
After the RAF investigative board completed its report on the Halifax crash, it was ordered to be kept secret by Prime Minister Churchill, and the cause of the crash was not revealed publicly, even to the relatives of the deceased. As a result, numerous unfounded rumours of German sabotage as the cause of the crash would circulate for many years afterwards.
British people
The British are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants...
electronics
Electronics
Electronics is the branch of science, engineering and technology that deals with electrical circuits involving active electrical components such as vacuum tubes, transistors, diodes and integrated circuits, and associated passive interconnection technologies...
engineer
Engineer
An engineer is a professional practitioner of engineering, concerned with applying scientific knowledge, mathematics and ingenuity to develop solutions for technical problems. Engineers design materials, structures, machines and systems while considering the limitations imposed by practicality,...
, notable for his many inventions in telecommunication
Telecommunication
Telecommunication is the transmission of information over significant distances to communicate. In earlier times, telecommunications involved the use of visual signals, such as beacons, smoke signals, semaphore telegraphs, signal flags, and optical heliographs, or audio messages via coded...
s, sound recording, stereo
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
, television
Television
Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...
and radar
Radar
Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio...
. He received 128 patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
s and was considered as one of the most significant engineers and inventors of his time.
He died on 7 June 1942, aged 38, during the secret trial of an H2S airborne radar system
H2S radar
H2S was the first airborne, ground scanning radar system. It was developed in Britain in World War II for the Royal Air Force and was used in various RAF bomber aircraft from 1943 to the 1990s. It was designed to identify targets on the ground for night and all-weather bombing...
, then under development during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
when the Halifax bomber
Handley Page Halifax
The Handley Page Halifax was one of the British front-line, four-engined heavy bombers of the Royal Air Force during the Second World War. A contemporary of the famous Avro Lancaster, the Halifax remained in service until the end of the war, performing a variety of duties in addition to bombing...
he was flying in crashed at Welsh Bicknor
Welsh Bicknor
Welsh Bicknor is an area of Herefordshire, England. Despite its name, it is not currently in Wales, but was historically a detached parish of the county of Monmouthshire....
, Herefordshire
Herefordshire
Herefordshire is a historic and ceremonial county in the West Midlands region of England. For Eurostat purposes it is a NUTS 3 region and is one of three counties that comprise the "Herefordshire, Worcestershire and Gloucestershire" NUTS 2 region. It also forms a unitary district known as the...
killing all on board.
Early life
Alan Dower Blumlein was born on 29 June 1903 in HampsteadHampstead
Hampstead is an area of London, England, north-west of Charing Cross. Part of the London Borough of Camden in Inner London, it is known for its intellectual, liberal, artistic, musical and literary associations and for Hampstead Heath, a large, hilly expanse of parkland...
, London
London
London is the capital city of :England and the :United Kingdom, the largest metropolitan area in the United Kingdom, and the largest urban zone in the European Union by most measures. Located on the River Thames, London has been a major settlement for two millennia, its history going back to its...
to Semmy Blumlein, a German-born naturalised British subject of Jewish descent,"
Church of England
The Church of England is the officially established Christian church in England and the Mother Church of the worldwide Anglican Communion. The church considers itself within the tradition of Western Christianity and dates its formal establishment principally to the mission to England by St...
parish. His future career seems to have been determined by the age of seven, when he presented his father with an invoice for repairing the doorbell, signed "Alan Blumlein, Electrical Engineer" (with "paid" scrawled in pencil). His sister claimed that he could not read proficiently until he was 12. He replied "no, but I knew a lot of quadratic equations!"
After matriculating
Matriculation
Matriculation, in the broadest sense, means to be registered or added to a list, from the Latin matricula – little list. In Scottish heraldry, for instance, a matriculation is a registration of armorial bearings...
at Highgate School
Highgate School
-Notable members of staff and governing body:* John Ireton, brother of Henry Ireton, Cromwellian General* 1st Earl of Mansfield, Lord Chief Justice, owner of Kenwood, noted for judgment finding contracts for slavery unenforceable in English law* T. S...
in 1921, he studied at City and Guilds College
City and Guilds of London Institute
The City and Guilds of London Institute is a leading United Kingdom vocational education organisation. City & Guilds offers more than 500 qualifications over the whole range of industry sectors through 8500 colleges and training providers in 81 countries worldwide...
(part of Imperial College
Imperial College London
Imperial College London is a public research university located in London, United Kingdom, specialising in science, engineering, business and medicine...
). He won a Governor's scholarship and joined the second year of the course. He graduated with a First-Class Honours
British undergraduate degree classification
The British undergraduate degree classification system is a grading scheme for undergraduate degrees in the United Kingdom...
B.Sc
Bachelor of Science
A Bachelor of Science is an undergraduate academic degree awarded for completed courses that generally last three to five years .-Australia:In Australia, the BSc is a 3 year degree, offered from 1st year on...
two years later.
In mid-1930, Blumlein met Doreen Lane, five years his junior. After two-and-a-half years of courtship the two were married. Lane was warned by acquaintances before the wedding that, "There was a joke amongst some of his friends, they used to call it 'Blumlein-itis' or 'First Class Mind'. It seems that he didn't want to know anyone who didn't have a first class mind." Best man J.B. Kaye thought that Lane and Blumlein were well matched.
Telecommunications
In 1924 Blumlein started his first job at International Western Electric, a division of the Bell LabsBell Labs
Bell Laboratories is the research and development subsidiary of the French-owned Alcatel-Lucent and previously of the American Telephone & Telegraph Company , half-owned through its Western Electric manufacturing subsidiary.Bell Laboratories operates its...
. The company subsequently became International Standard Electric Corporation and then, later on, Standard Telephones and Cables
Standard Telephones and Cables
Standard Telephones and Cables Ltd was a British telephone, telegraph, radio, telecommunications and related equipment R&D manufacturer. During its history STC invented and developed several groundbreaking new technologies including PCM and optical fibres.The company began life in London as...
(STC).
During his time there, he measured the amplitude
Amplitude
Amplitude is the magnitude of change in the oscillating variable with each oscillation within an oscillating system. For example, sound waves in air are oscillations in atmospheric pressure and their amplitudes are proportional to the change in pressure during one oscillation...
/frequency response
Frequency response
Frequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input...
of human ears, and used the results to design the first weighting
Noise weighting
A noise weighting is a specific amplitude-vs.-frequency characteristic that is designed to allow subjectively valid measurement of noise. It emphasises the parts of the spectrum that are most important....
networks.
In 1924 he published (with Professor Edward Mallett) the first of his only two IEE
Institution of Electrical Engineers
The Institution of Electrical Engineers was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E...
papers, on high-frequency resistance measurement. This won him the IEE's Premium award for innovation. The following year he wrote (with Norman Kipping) a series of seven articles for Wireless World
Wireless World
Wireless World was the pre-eminent British magazine for radio and electronics enthusiasts. It was one of the very few "informal" journals which were tolerated as a professional expense.- History :...
.
In 1925 and 1926, Blumlein and John Percy Johns designed an improved form of loading coil
Loading coil
In electronics, a loading coil or load coil is a coil that does not provide coupling to any other circuit, but is inserted in a circuit to increase its inductance. The need was discovered by Oliver Heaviside in studying the disappointing slow speed of the Transatlantic telegraph cable...
which reduced loss and crosstalk in long-distance telephone lines. These were used until the end of the analogue telephony era. The same duo also invented an improved form of AC measurement bridge
Wheatstone bridge
A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. Its operation is similar to the original potentiometer. It was invented by Samuel Hunter Christie in 1833 and...
which became known as the Blumlein Bridge. These two inventions were the basis for Blumlein's first two patents.
His inventions while working at STC resulted in another five patents, which were not awarded until after he left the company in 1929.
Sound recording
In 1929 Blumlein handed in his notice at STC and joined the Columbia Graphophone CompanyColumbia Graphophone Company
The Columbia Graphophone Company was one of the earliest gramophone companies in the United Kingdom. Under EMI, as Columbia Records, it became a very successful label in the 1950s and 1960s...
, where he reported directly to general manager Isaac Shoenberg
Isaac Shoenberg
Sir Isaac Shoenberg was an electronic engineer born in Russia who was best known for his role in history of television....
.
His first project was to find a method of disc cutting that circumvented a Bell patent in the Western Electric moving-iron cutting head then used, and on which substantial royalties had to be paid. He invented the moving-coil disc cutting head, which not only got around the patent but offered greatly improved sound quality. He led a small team which developed the concept into a practical cutter. The other principal team members were Herbert Holman and Henry "Ham" Clark. Their work resulted in several patents.
Early in 1931, the Columbia Graphophone Company and the Gramophone Company
Gramophone Company
The Gramophone Company, based in the United Kingdom, was one of the early recording companies, and was the parent organization for the famous "His Master's Voice" label...
merged and became EMI
EMI
The EMI Group, also known as EMI Music or simply EMI, is a multinational music company headquartered in London, United Kingdom. It is the fourth-largest business group and family of record labels in the recording industry and one of the "big four" record companies. EMI Group also has a major...
. New joint research laboratories were set up at Hayes
Hayes, Hillingdon
Hayes is a town in the London Borough of Hillingdon, West London. It is a suburban development situated west of Charing Cross. Hayes was developed in the late 19th and 20th centuries as an industrial locality to which residential districts were later added in order to house factory workers...
and Blumlein was officially transferred there on 1 November the same year.
During the early 1930s Blumlein and Herbert Holman developed a series of moving-coil microphones, which were used in EMI recording studios and by the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
at Alexandra Palace
Alexandra Palace
Alexandra Palace is a building in North London, England. It stands in Alexandra Park, in an area between Hornsey, Muswell Hill and Wood Green...
.
Ultra-Linear Amplifier
In June 1937, Blumlein patented one of his most important audio inventions, the Ultra-Linear amplifier (Patent 496,883, dated 5 June 1937). A deceptively simple design, the circuit provided a tap on the primary winding of the output transformer to provide feedback to the second grid, which improved the amplifier's linearity. With the tap placed at the anode end of the primary winding, the tube (valve) could be connected as a triodeTriode
A triode is an electronic amplification device having three active electrodes. The term most commonly applies to a vacuum tube with three elements: the filament or cathode, the grid, and the plate or anode. The triode vacuum tube was the first electronic amplification device...
, and if the tap was at the supply end, it could be connected as a pure pentode
Pentode
A pentode is an electronic device having five active electrodes. The term most commonly applies to a three-grid vacuum tube , which was invented by the Dutchman Bernhard D.H. Tellegen in 1926...
. Blumlein discovered that if the tap was placed at a distance 15-20% down from the supply end of the output transformer, the tube or valve would combine the positive features of both the triode and the pentode design.
Stereophonic sound
In 1931, Blumlein developed what he called "binaural sound", now known as stereophonic sound (stereo).In early 1931, Blumlein and his wife were at a local cinema. The sound reproduction systems of the early "talkies" invariably only had a single set of speakers - which could lead to the somewhat disconcerting effect of the actor being on one side of the screen whilst his voice appeared to come from the other. Blumlein declared to his wife that he had found a way to make the sound follow the actor across the screen.
The genesis of these ideas is uncertain, but he explained them to Isaac Shoenberg in the late summer of 1931. His earliest notes on the subject are dated 25 September 1931, and his patent had the title "Improvements in and relating to Sound-transmission, Sound-recording and Sound-reproducing Systems". The application was dated 14 December 1931, and was accepted on 14 June 1933 as UK
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
patent number 394,325.
Whereas work led by Harvey Fletcher
Harvey Fletcher
Harvey Fletcher was an American physicist. Known as the "father of stereophonic sound" he is credited with the invention of the audiometer and hearing aid...
at Bell Labs at about the same time considered sound systems using multiple channels, Blumlein always aimed at a system with just two channels.
The patent covered many ideas in stereo, some of which are used today and some not. Some 70 claims include:
- A "shuffling" circuit, which aimed to preserve the directional effect when sound from a spaced pair of microphones was reproduced via a pair of loudspeakers instead of stereo headphones;
- The use of a coincident pair of velocity microphones with their axes at right angles to each other, which is still known as a "Blumlein PairBlumlein PairBlumlein Pair is the name for a stereo recording technique invented by Alan Blumlein for the creation of recordings that, upon replaying through headphones or loudspeakers, recreate the spatial characteristics of the recorded signal....
"; - Recording two channels in the single groove of a record using the two groove walls at right angles to each other and 45 degrees to the vertical;
- A stereo disc-cutting head;
- Using hybrid transformers to matrix between left and right signals and sum and difference signals;
Binaural experiments began in early 1933, and the first stereo discs were cut later the same year.
Much of the development work on this system for cinematic use did not reach completion until 1935. In a few short test films (most notably, "Trains At Hayes Station" and, "The Walking & Talking Film"), Blumlein's original intent of having the sound follow the actor was fully realised.
Television
Television was developed by many individuals and companies throughout the 1920s and 1930s. Blumlein's contributions, as a member of the EMI team, started in earnest in 1933 when his boss, Isaac Shoenberg, assigned him full-time to TV research.His ideas included:
- Resonant flyback scanning (the use of a tuned circuit in the creation of a sawtooth deflection waveform). (British Patent No. 400976, application filed April 1932.)
- Use of constant-impedance network in power supplies to obtain voltage regulation independent of load frequency, extending down to DC (421546, filed 16 June 1933).
- Black-level clamping (422914, filed 11 July 1933 by Blumlein, Browne and Hardwick). This is an improved form of DC restoration, compared to the simple DC restorer (consisting of a capacitor, diode and resistor) which had been patented by Peter Willans three months earlier.
- The slot antennaSlot antennaA slot antenna consists of a metal surface, usually a flat plate, with a hole or slot cut out. When the plate is driven as an antenna by a driving frequency, the slot radiates electromagnetic waves in similar way to a dipole antenna. The shape and size of the slot, as well as the driving frequency,...
. (515684, filed 7 March 1939.)
Blumlein was also largely responsible for the development of the waveform structure used in the 405-line
405-line
The 405-line monochrome analogue television broadcasting system was the first fully electronic television system to be used in regular broadcasting....
Marconi-EMI system - developed for the UK's BBC Television Service at Alexandra Palace
Alexandra Palace
Alexandra Palace is a building in North London, England. It stands in Alexandra Park, in an area between Hornsey, Muswell Hill and Wood Green...
, the world's first scheduled "high definition" (240 lines or better) television service - which was later adopted as the CCIR System A.
H2S radar
Blumlein was so central to the development of the H2S airborne radar system (to aid bomb targeting), that after his death in June 1942, many believed that the project would fail. However it survived and was a factor in shortening the Second World War. Blumlein's role in the project was a closely guarded secret at the time and consequently only a brief announcement of his death was made some two years later, in order to avoid providing solace to Hitler.His invention of the line type pulse modulator, (ref vol 5 of MIT Radiation Laboratory series) was a major contribution to high powered pulse radars, not just the H2S's system, and continues to be used today.
Death
Handley Page Halifax
The Handley Page Halifax was one of the British front-line, four-engined heavy bombers of the Royal Air Force during the Second World War. A contemporary of the famous Avro Lancaster, the Halifax remained in service until the end of the war, performing a variety of duties in addition to bombing...
bomber while making a test flight on 7 June 1942. During the flight, the Halifax developed an engine fire which rapidly grew out of control. The bomber was seen to lose altitude, then rolled inverted and struck the ground.
After the RAF investigative board completed its report on the Halifax crash on 1 July 1942, it was distributed to a restricted list of approved recipients, but not publicly divulged. In the interests of wartime secrecy, the announcement of Blumlein's death was not made for another three years. The investigative board, headed by Chief Inspector Vernon Brown, found that the Halifax bomber crash was caused by engine fire, attributed to the unscrewing of a tappet
Tappet
A tappet is the noise made by a worn cam follower, however the term is widely used to represent the cam follower itself. In mechanical engineering it is a projection which imparts a linear motion to some other component within an assembly...
nut on the starboard outer engine, which had been improperly tightened by an RAF engine fitter while inspecting the engine some three hours prior to the crash. The loosened nut caused excessive valve clearance and a fracture of the valve stem
Poppet valve
A poppet valve is a valve consisting of a hole, usually round or oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The shaft guides the plug portion by sliding through a valve guide...
which resulted pumping ignited fuel outboard of the rocker cover and along the outside of the engine, causing a fire in the engine nacelle
Nacelle
The nacelle is a cover housing that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the...
. Constantly fuelled by the broken intake
Inlet manifold
In automotive engineering, an inlet manifold or intake manifold is the part of an engine that supplies the fuel/air mixture to the cylinders...
, the fire burned rapidly along the wing and fuselage, eventually causing a large section of the wing to separate from the fuselage at approximately 350 feet of altitude. With the loss of all control over level flight, the rest of the plane inverted and struck the ground at approximately 150mph. The board found that the crew and passengers had not jumped immediately from the aircraft owing to several factors, including a loss of altitude while attempting to find an an emergency field, the rapidly-spreading fire, which blocked or impeded egress from the plane, and the fact that a sufficient number of parachutes were either not on board or were not being worn. Almost immediately following the crash, Prime Minister Churchill issued a directive requiring any test flights with civilians or scientific personnel to carry a sufficient number of parachutes for all individuals involved.
After the RAF investigative board completed its report on the Halifax crash, it was ordered to be kept secret by Prime Minister Churchill, and the cause of the crash was not revealed publicly, even to the relatives of the deceased. As a result, numerous unfounded rumours of German sabotage as the cause of the crash would circulate for many years afterwards.
Personal life
Alan Blumlein had two sons, Simon Blumlein and David Blumlein, Headmaster Emeritus of a prep school in Ealing, London.Tributes
- Alan Blumlein Way is a road on the TektronixTektronixTektronix, Inc. is an American company best known for its test and measurement equipment such as oscilloscopes, logic analyzers, and video and mobile test protocol equipment. In November 2007, Tektronix became a subsidiary of Danaher Corporation....
campus in Beaverton, OregonBeaverton, OregonBeaverton is a city in Washington County, Oregon, United States, seven miles west of Portland in the Tualatin River Valley.As of the 2010 census, the population is 90,267. This makes it the second-largest city in the county and Oregon's sixth-largest city...
, in keeping with their policy of naming roads after those who made significant contributions to the knowledge and understanding in the field of electronics.
See also
- H2S radarH2S radarH2S was the first airborne, ground scanning radar system. It was developed in Britain in World War II for the Royal Air Force and was used in various RAF bomber aircraft from 1943 to the 1990s. It was designed to identify targets on the ground for night and all-weather bombing...
- Blumlein PairBlumlein PairBlumlein Pair is the name for a stereo recording technique invented by Alan Blumlein for the creation of recordings that, upon replaying through headphones or loudspeakers, recreate the spatial characteristics of the recorded signal....
, a stereo recording technique invented by Alan Blumlein. - Stereophonic soundStereophonic soundThe term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
- Blumlein transmission line, used to create high-voltage pulses with short rise and fall times.