Proximity fuze

proximity fuseproximityproximity fusesproximity fuzesVT fuzeproximity detonatedproximity fusedRadio proximity fuzeVariable Time (VT)variable time fuze
A proximity fuze is a fuze that detonates an explosive device automatically when the distance to the target becomes smaller than a predetermined value.wikipedia
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Fuze

exploderfuzingfuse
A proximity fuze is a fuze that detonates an explosive device automatically when the distance to the target becomes smaller than a predetermined value.
In the United States and some military forces, fuze is used to denote a sophisticated ignition device incorporating mechanical and/or electronic components (for example a proximity fuze for an artillery shell, magnetic/acoustic fuze on a sea mine, spring-loaded grenade fuze, pencil detonator or anti-handling device) as opposed to a simple burning fuse.

Tizard Mission

British mission, led by TizardSir Henry TizardTizard delegation
The British shared a wide range of possible ideas for designing a fuze, including a photoelectric fuze and a radio fuze, with United States during the Tizard Mission in late 1940.
The shared technology included radar (in particular the greatly improved cavity magnetron which the American historian James Phinney Baxter III later called "the most valuable cargo ever brought to our shores"), the design for the proximity VT fuse, details of Frank Whittle's jet engine and the Frisch–Peierls memorandum describing the feasibility of an atomic bomb.

Samuel Curran

Sir Samuel CurranSamuel Crowe CurranCurran
British military researchers at the Telecommunications Research Establishment (TRE) Samuel C. Curran, William A. S. Butement, Edward S. Shire, and Amherst F. H. Thomson conceived of the idea of a proximity fuze in the early stages of World War II.
He is the inventor of the scintillation counter, the proportional counter, and the proximity fuze.

Air burst

airburstair-burstaerial burst
Proximity fuzes are also useful for producing air bursts against ground targets.
During World War II a "proximity fuze" was developed, which was controlled by a doppler radar device within the shell that caused it to explode when near the target.

National Institute of Standards and Technology

NISTNational Bureau of StandardsBureau of Standards
Also eventually pulled in were researchers from the National Bureau of Standards (this research unit of NBS later became part of the Army Research Laboratory). In December 1940, Tuve invited Harry Diamond and Wilbur S. Hinman, Jr, of the United States National Bureau of Standards (NBS) to investigate Berkner's improved fuze and develop a proximity fuze for non-rotated, or fin-stabilized, projectiles to use against the German Luftwaffe.
During World War II, military research and development was carried out, including development of radio propagation forecast methods, the proximity fuze and the standardized airframe used originally for Project Pigeon, and shortly afterwards the autonomously radar-guided Bat anti-ship guided bomb and the Kingfisher family of torpedo-carrying missiles.

Applied Physics Laboratory

Johns Hopkins University Applied Physics LaboratoryJohns Hopkins Applied Physics LaboratoryApplied Physics Lab
Work on the radio shell fuze was completed by Tuve's group, known as Section T, at The Johns Hopkins University Applied Physics Lab (APL).
The Laboratory succeeded in developing the variable-time proximity fuze that played a significant role in the Allied victory.

W. A. S. Butement

Alan ButementWilliam A. S. ButementWilliam Alan Stewart Butement
British military researchers at the Telecommunications Research Establishment (TRE) Samuel C. Curran, William A. S. Butement, Edward S. Shire, and Amherst F. H. Thomson conceived of the idea of a proximity fuze in the early stages of World War II.
In less than a year, however, (in September 1940), Butement's concept was moved dramatically toward mass production when it was exported under the technology transfer arrangements of the Tizard Mission, and subsequently a variation of his circuit became adopted in the United States as the proximity fuse or VT (variable-time) fuse, the most-manufactured electronic device of the war.

John Cockcroft

Sir John CockcroftJohn Douglas CockcroftCockcroft
As early as September 1939, John Cockcroft began a development effort at Pye Ltd. to develop tubes capable of withstanding these much greater forces.
Later in the war, the fruits of the Tizard Mission came back to Britain in the form of the SCR-584 radar set and the proximity fuze, which were used to defeat the V-1 flying bomb.

Merle Tuve

Merle A. TuveMerle Anthony TuveM. A. Tuve
The National Defense Research Committee assigned the task to the physicist Merle A. Tuve at the Department of Terrestrial Magnetism.
He led in the development of the proximity fuze at the Johns Hopkins University Applied Physics Laboratory and also made contributions to experimental seismology, radio astronomy, and optical astronomy.

Harry Diamond Laboratories

Harry Diamond LaboratoryDiamond Ordnance Fuze LaboratoriesU.S. Army Diamond Ordnance Fuze Laboratory
Later, the Ordnance Development Division of the National Bureau of Standards (which became the Harry Diamond Laboratories – and later merged into the Army Research Laboratory – in honor of its former chief in subsequent years) developed the first automated production techniques for manufacturing radio proximity fuzes at a low cost.
The Harry Diamond Laboratories (HDL) was a research facility of the Ordnance Development Division of the National Bureau of Standards and later the US Army, most notable for its work on proximity fuzes in World War II.

National Defense Research Committee

NDRCNational Defence Research CommitteeNational Defense Research council
The National Defense Research Committee assigned the task to the physicist Merle A. Tuve at the Department of Terrestrial Magnetism.

Pye Ltd.

PyePye TMCPye Radio
As early as September 1939, John Cockcroft began a development effort at Pye Ltd. to develop tubes capable of withstanding these much greater forces.
Pye was also responsible for the early development work on the proximity fuze for anti-aircraft shells.

Julius and Ethel Rosenberg

Julius RosenbergEthel RosenbergEthel and Julius Rosenberg
While working for a defense contractor in the mid-1940s, Soviet spy Julius Rosenberg stole a working model of an American proximity fuze and delivered it to the Soviet intelligence.
Rosenberg provided thousands of classified reports from Emerson Radio, including a complete proximity fuse.

Shell (projectile)

shellshellsartillery shell
With a proximity fuze, the shell or missile need only pass close by the target at some time during its trajectory.
Depending on the type of fuse used the HE shell can be set to burst on the ground (percussion), in the air above the ground, which is called air burst (time or proximity), or after penetrating a short distance into the ground (percussion with delay, either to transmit more ground shock to covered positions, or to reduce the spread of fragments).

Oslo Report

reportwas received
A German neon lamp tube and a design of a prototype proximity fuze based on capacitive effects was received by British Intelligence in mid November 1939.
This was done, and he sent the Report along with a vacuum tube from a prototype proximity fuze.

Contact fuze

contact fuseimpact fuzecontact
They provide a more sophisticated trigger mechanism than the common contact fuze or timed fuze.

Powel Crosley Jr.

Powel Crosley, Jr.Powel CrosleyCrosley
The main suppliers were Crosley, RCA, Eastman Kodak, McQuay-Norris and Sylvania.
During World War II, Crosley's facilities produced more proximity fuzes than any other U.S. manufacturer, and made several production design innovations.

Printed circuit board

circuit boardPCBprinted circuit boards
It was among the first mass-production applications of printed circuits.
Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II.

Kirtland Air Force Base

Kirtland AFBKirtland FieldAlbuquerque Army Air Base
The anti-aircraft artillery range at Kirtland Air Force Base in New Mexico was used as one of the test facilities for the proximity fuze, where almost 50,000 test firings were conducted from 1942 to 1945.
It was built to the south to serve as the base for testing the top-secret proximity fuze, a device that played an important role in defeat of the German Vergeltungswaffe (V-1) rocket.

Sylvania Electric Products

SylvaniaGTE SylvaniaSylvania Corporation
The main suppliers were Crosley, RCA, Eastman Kodak, McQuay-Norris and Sylvania.
During World War II, Sylvania was chosen from among several competing companies to manufacture the miniature vacuum tubes used in proximity fuse shells due to its quality standards and mass production capabilities.

Harry Diamond (engineer)

Harry DiamondHarry Diamond (P)
In December 1940, Tuve invited Harry Diamond and Wilbur S. Hinman, Jr, of the United States National Bureau of Standards (NBS) to investigate Berkner's improved fuze and develop a proximity fuze for non-rotated, or fin-stabilized, projectiles to use against the German Luftwaffe.
Much of the basic proximity fuze technology was developed under his direction.

Fire-control system

fire controlfire control systemfire-control director
A particularly successful application was the 90 mm shell with VT fuze with the SCR-584 automatic tracking radar and the M-9 electronic fire control computer.
In combination with the VT proximity fuze, this system accomplished the astonishing feat of shooting down V-1 cruise missiles with less than 100 shells per plane (thousands were typical in earlier AA systems).

Office of Scientific Research and Development

OSRDOffice of Scientific R&DOSRD contracts
The research was widely varied, and included projects devoted to new and more accurate bombs, reliable detonators, work on the proximity fuze, guided missiles, radar and early-warning systems, lighter and more accurate hand weapons, more effective medical treatments, more versatile vehicles, and, most secret of all, the S-1 Section, which later became the Manhattan Project and developed the first atomic weapons.

Doppler effect

Doppler shiftDopplerDoppler shifts
Given their previous work on radio and radiosondes at NBS, Diamond and Hinman developed the first all solid-state radio doppler proximity fuze, which employed the Doppler effect of reflected radio waves using a diode detector arrangement that they devised.
Moreover, the proximity fuze, developed during World War II, relies upon Doppler radar to detonate explosives at the correct time, height, distance, etc.

SCR-584 radar

SCR-584K-78 trailerM-9/SCR-584 Anti-Aircraft System
A particularly successful application was the 90 mm shell with VT fuze with the SCR-584 automatic tracking radar and the M-9 electronic fire control computer.
Automatic gunlaying (using, among others, the SCR-584 radar) and the proximity fuze played an important part in Operation Diver, (the British operation to counter the V1 flying bombs).