Proximity fuze: Difference between revisions

{{Use dmy dates|date=October 2020}}

[[Image:MK53 fuze.jpg|upright=1.35|thumb|Proximity fuze MK53 removed from shell, circa 1950s]]

 

 

==Background==

 

Proximity fuzes are also useful for producing [[air burst]]s against ground targets. A contact fuze would explode when it hit the ground; it would not be very effective at scattering shrapnel. A timer fuze can be set to explode a few meters above the ground but the timing is vital and usually requires [[Artillery observer|observers]] to provide information for adjusting the timing. Observers may not be practical in many situations, the ground may be uneven, and the practice is slow in any event. Proximity fuzes fitted to such weapons as [[artillery shell|artillery]] and [[mortar shell]]s solve this problem by having a range of set burst heights [e.g. {{cvt|2|,|4|or|10|m|ft|0}}] above ground that are selected by gun crews. The shell bursts at the appropriate height above ground.

The fuze was later found to be able to detonate artillery shells in [[air burst]]s, greatly increasing their anti-personnel effects.{{sfn|Baldwin|1980|pp=xxxi, 279}}

 

 

In the post-World War II era, a number of new proximity fuze systems were developed, using radio, optical, and other detection methods. A common form used in modern air-to-air weapons uses a [[laser]] as an optical source and time-of-flight for ranging.<ref>[https://www.youtube.com/watch?v=LyDlq77GVPM Critical Challenge: A History of the Proximity Fuze presented] by Stephen Phillips</ref>

In the US, NDRC focused on radio fuzes for use with anti-aircraft artillery, where acceleration was up to 20,000&nbsp;{{mvar|g}}, compared to about 100&nbsp;{{mvar|g}} for rockets and much less for dropped bombs.{{sfn|Baxter|1968|p=224}} In addition to extreme acceleration, artillery shells were spun by the rifling of the gun barrels to close to 30,000 rpm, creating immense centrifugal force. Working with [[Western Electric Company]] and [[Raytheon Company]], miniature hearing-aid tubes were modified to withstand this extreme stress. The T-3 fuze had a 52% success against a water target when tested in January, 1942. The [[United States Navy]] accepted that failure rate. A simulated battle conditions test was started on 12 August 1942. Gun batteries aboard cruiser {{USS|Cleveland|CL-55}} tested proximity-fuzed ammunition against radio-controlled drone aircraft targets over [[Chesapeake Bay]]. The tests were to be conducted over two days, but the testing stopped when drones were destroyed early on the first day. The three drones were destroyed with just four projectiles.<ref name="Brennan, 1968" /><ref>{{cite book |last=Howeth |first=Linwood S. |title=History of Communications-Electronics in the United States Navy |date=1963 |publisher=United States Government Printing Office |lccn=64-62870 |page=498 |url=https://babel.hathitrust.org/cgi/pt?id=uiug.30112064674325;view=1up;seq=530}}</ref>

 

 

====VT (Variable Time)====

In order to be used with gun projectiles, which experience extremely high acceleration and centrifugal forces, the fuze design also needed to utilize many shock-hardening techniques. These included planar electrodes, and packing the components in wax and oil to equalize the stresses.{{citation needed|date=May 2021}} To prevent premature detonation, the inbuilt battery that armed the shell had a several millisecond delay before its electrolytes were activated, giving the projectile time to clear the area of the gun.<ref>Smith, Peter C. Kamikaze: To Die for the Emperor. Pen and Sword, 2014, p.42</ref>

 

 

===Development===

The Pentagon refused to allow the Allied field artillery use of the fuzes in 1944, although the United States Navy fired proximity-fuzed anti-aircraft shells in the July 1943 [[Battle of Gela (1943)|Battle of Gela]] during the invasion of Sicily.<ref>{{cite book |last1=Potter |first1=E.B. |last2=Nimitz |first2=Chester W. |author-link2 =Chester W. Nimitz |title =Sea Power |url=https://archive.org/details/seapowernavalhis0000pott |url-access=registration |publisher =Prentice-Hall |date =1960 |location =Englewood Cliffs, New Jersey |pages =[https://archive.org/details/seapowernavalhis0000pott/page/589 589]–591 |isbn=978-0137968701 |via=Internet Archive}}</ref> After General [[Dwight D. Eisenhower]] demanded he be allowed to use the fuzes, 200,000 shells with VT fuzes (code named "POZIT"<ref>{{cite book|author=Albert D. Helfrick|title=Electronics in the Evolution of Flight |url=https://books.google.com/books?id=EumPJQBViz4C&pg=PA78|year=2004|publisher=Texas A&M UP|page=78|isbn=978-1585444137}}</ref>) were used in the Battle of the Bulge in December 1944. They made the Allied heavy artillery far more devastating, as all the shells now exploded just before hitting the ground.<ref>{{cite book|author=Rick Atkinson|title=The Guns at Last Light: The War in Western Europe, 1944-1945|url=https://books.google.com/books?id=FUQ9lEHO0QoC&pg=PA460|year=2013|pages=460–462, 763–764|publisher=Henry Holt and Company |isbn=978-1429943673}}</ref> German divisions were caught out in open as they had felt safe from timed fire because it was thought that the bad weather would prevent accurate observation. U.S. General [[George S. Patton]] credited the introduction of proximity fuzes with saving Liège and stated that their use required a revision of the tactics of land warfare.{{sfn|Bush|1970|p=112}}

 

 

==Sensor types==

 

=== Acoustic ===

 

 

During [[WW2]], the [[National Defense Research Committee]] (NDRC) investigated the use of acoustic proximity fuzes for [[Anti-aircraft warfare|anti-aircraft]] weapons but concluded that there were more promising technological approaches. The NDRC research highlighted the [[speed of sound]] as a major limitation in the design and use of acoustic fuzes, particularly in relation to missiles and high-speed aircraft.<ref name="NDRC-1946"/>

 

=== Magnetic ===

{{main|Magnetic proximity fuze|Magnetic pistol}}

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 [[Minesweeper (ship)|minesweepers]]) or by [[electromagnetic induction|magnetic induction]] loops fitted to aircraft or towed [[buoy]]s.

 

== Gallery ==

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