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Proximity fuze MK53 fuze removed from shell

A proximity fuze (also called a VT fuze, for "variable time") is a fuze that is designed to detonate an explosive device automatically when the distance to target becomes smaller than a predetermined value or when the target passes through a given plane. In an Explosive, Pyrotechnic device or military Munition, a fuse (or fuze) is the part of the device that initiates function An explosive material is a material that either is chemically or otherwise Energetically unstable or produces a sudden expansion of the material usually accompanied There are different sensing principles:

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Radio frequency sensing

Radio frequency sensing is the main sensing principle for shells and this is mostly in mind when one speaks of "proximity fuzes".

The WWII patent works as follows: The shell contains a micro-transmitter which uses the shell body as an antenna and emits a continuous wave of roughly 180 - 220 MHz. For biologic transmitters see Transmitter substance. A transmitter is an electronic device which usually with the aid of an antenna An antenna is a Transducer designed to transmit or Receive electromagnetic waves In other words antennas convert electromagnetic waves into As the shell approaches a reflecting object, an interference pattern is created. This pattern changes with shrinking distance: every half wavelength in distance (a half wavelength at this frequency is about 0. 7 meters), the transmitter is in or out of resonance. This causes a small oscillation of the radiated power and consequently the oscillator supply current of about 200 - 800 Hz, the Doppler frequency. The Doppler effect (or Doppler shift) named after Christian Doppler, is the change in Frequency and Wavelength of a Wave for This signal is sent through a band pass filter, amplified, and triggers the detonation when it exceeds a given amplitude. A band-pass filter is a device that passes frequencies within a certain range and rejects ( Attenuates frequencies outside that range

Before the fuze's invention, detonation had to be induced by direct contact, a timer set at launch, or an altimeter. All of these have disadvantages. The probability of a direct hit with a relatively small moving target is low; to set a time- or height-triggered fuze one must measure the height of the target (or even predict the height of the target at the time one will be able to get a shell or missile in its neighbourhood). A missile (see also pronunciation differences) is a self-propelled explosive Projectile used as a weapon towards a target With a proximity fuze, all one has to worry about is getting a shell or missile on a trajectory that, at some time, will pass close by the target. A shell is a payload-carrying Projectile, which as opposed to shot, contains an explosive or other filling though modern usage includes large solid projectiles This is still not a trivial task, but it is much easier to execute than previous methods.

Use of timing to produce air bursts against ground targets requires observers to provide information for adjusting the timing. This is not practical in all situations and is slow in any event. Proximity fuzes remove these problems.

The proximity fuze was developed mainly by the U.S. (with British collaboration) during World War II. The United States of America —commonly referred to as the The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located World War II, or the Second World War, (often abbreviated WWII) was a global military conflict which involved a majority of the world's nations, including Vannevar Bush, head of the U. Vannevar Bush ( March 11, 1890 &ndash June 30, 1974; pronounced "VAN-ee-var" ˈvæˌniː S. Office of Scientific Research and Development (OSRD) during this war, credited it with three significant effects. The Office of Scientific Research and Development (OSRD was an agency of the United States federal government created to coordinate scientific research for military purposes It was important in defense from Japanese Kamikaze attacks in the Pacific. For a topic outline on this subject see List of basic Japan topics. ( is a word of Japanese origin which in English usually refers to the Suicide attacks by military aviators from the Empire of Japan against The Pacific Ocean is the largest of the Earth 's Oceanic divisions It was an important part of the radar-controlled anti-aircraft batteries that finally neutralized the German V-1 bomb attacks on England. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. The Fieseler Fi 103, better known as V-1 (German Vergeltungswaffe 1 was an early Cruise missile used during World War Two England is a Country which is part of the United Kingdom. Its inhabitants account for more than 83% of the total UK population whilst its mainland Third, it was released for use in land warfare for use in the Battle of the Bulge, where it decimated German divisions caught in the open. The Ardennes Offensive (16 December 1944 – 25 January 1945 was a major German offensive launched towards the end of World War II through the forested Ardennes Mountains The Germans felt safe from timed fire because the weather prevented accurate observation. Bush cites an estimated seven times increase in the effect of artillery with this innovation.

Optical sensing

Optical sensing was also developed first in WWII, mainly for anti-aircraft missiles. It used then a toroidal lens, that concentrated all light out of a plane perpendicular to the missile's main axis onto a photo cell. When the cell current changed a certain amount in a certain time interval, the detonation was triggered.

Some modern air-to-air missiles make use of lasers. An air-to-air missile ( AAM) is a guided Missile fired from an Aircraft for the purpose of destroying another aircraft A laser is a device that emits Light ( Electromagnetic radiation) through a process called Stimulated emission. They project narrow beams of laser light perpendicular to the flight of the missile. As the missile cruises towards the target the laser energy simply beams out into space. However, as the missile passes its target some of the laser energy strikes the target and is reflected back towards the missile where detectors sense the reflected laser energy and trigger the missile warhead.

Acoustic sensing

Acoustic sensing used a microphone in a missile. The characteristic frequency of an aircraft engine is filtered and triggered the detonation. This principle was applied in German anti-aircraft missiles, which were mostly still in development when the war ended.

Naval mines can also use acoustic sensing, with modern versions able to be programmed to "listen" for the signature of a specific ship. A naval mine is a self-contained Explosive device placed in water to destroy Ships or Submarines Unlike Depth charges mines are deposited

Magnetic sensing

Magnetic sensing can only be applied to detect huge masses of iron such as ships. It is used in mines and torpedoes. Fuzes of this type can be defeated by degaussing, using non-metal hulls for ships (especially minesweepers) or by magnetic induction loops fitted to aircraft or towed buoys. A minesweeper is a Naval Warship designed to counter the threat posed by Naval mines The dedicated purpose-built minesweeper first appeared during Faraday's law of induction describes an important basic law of electromagnetism which is involved in the working of Transformers Inductors and many forms of

Pressure sensing

Some naval mines are able to detect the pressure wave of a ship passing overhead. A naval mine is a self-contained Explosive device placed in water to destroy Ships or Submarines Unlike Depth charges mines are deposited

References

See also

External links

The M734 Multioption Fuze for Mortar shells uses frequency modulated continuous wave (FMCW directional doppler ranging (DDR techniques and is

Dictionary

proximity fuze

-noun

  1. A fuze that is designed to detonate an explosive automatically when close enough to the target to destroy it
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