Introduced during World War II, a pencil detonator or time pencil is a chemically activated time fuze designed to be connected to a detonator or short length of safety fuse. 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 In an Explosive, Pyrotechnic device or military Munition, a fuse (or fuze) is the part of the device that initiates function For the Ratt album see Detonator (album A detonator is a device used to trigger an Explosive device. In an Explosive, Pyrotechnic device or military Munition, a fuse (or fuze) is the part of the device that initiates function Pencil detonators are so-called because they have approximately the same shape and dimensions as a pencil.
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Types
No. 10 delay switch
One type, the British No. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located 10 delay switch (official name, "Switch, No. 10, Delay" and often referred to as a "timing pencil"), was made of a brass (or in later versions aluminium) tube, with a copper section at one end which contains a glass phial of cupric chloride (the liquid was widely and erroneously reported to be sulfuric acid), while beneath the phial was a spring-loaded striker under tension and kept in place by a thin metal wire. Brass is any Alloy of Copper and Zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties WikipediaNaming Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Copper(II chloride is the Chemical compound with the formula CuCl2 Sulfuric (or sulphuric acid, H 2 S[[oxygen O]]4 is a strong Mineral acid. The timer is started by crushing the copper section of the tube to break the phial of cupric chloride which then slowly eats through the wire holding back the striker. The striker then flies down the hollow centre of the detonator and hits the percussion cap at the other end of the detonator. The percussion cap, introduced around 1830, was the crucial invention that enabled muzzle-loading firearms to fire reliably in any weather
No. 10 delay switches had delays ranging from 10 minutes to 24 hours and were accurate to within plus or minus 2 or 3 minutes in an hour's delay and plus or minus an hour in a 12-hour delay, though environmental conditions could affect this. ± The The switches were typically issued in packs of 5, all the switches in a pack having the same delay. In use, two switches with the same delay (from different packs if possible) would be placed in the explosive charge in case one switch failed.
Using a No. 10 delay switch:
Crush the end of the thin copper tube containing acid with pliers, or under the heel of your boot. Copper (ˈkɒpɚ is a Chemical element with the symbol Cu (cuprum and Atomic number 29 Pliers are Hand tools designed primarily for gripping objects by using Leverage. There is no need to crush the end of the tube completely flat. All that is required is to crush and dent the tube sufficiently to break the glass vial, thereby releasing the liquid contained within. Then remove and discard the brass safety strip holding back the striker. Check the inspection hole next to the brass safety strip. If the inspection hole is unobstructed (i. e. it is possible to see right through to the other side) then the countdown has started. However, if the inspection hole is obstructed, the striker has previously been released, in which case the pencil detonator should be discarded and another one selected. The final step is to insert the other end of the pencil detonator (which has the actual detonator fitted) into the explosives and leave the area. For the Ratt album see Detonator (album A detonator is a device used to trigger an Explosive device.
No. 9 delay switch (L-delay)
Another type, known as the "Switch, No. 9, L Delay", contained a thin, notched wire of a special lead alloy that was extremely affected by mechanical creep. Characteristics Lead has a dull luster and is a dense, Ductile, very soft highly An alloy is a Solid solution or Homogeneous mixture of two or more elements, at least one of which is a Metal, which itself has Creep is the tendency of a solid material to slowly move or deform permanently under the influence of stresses It occurs as a result of long term exposure to levels of When the starting pin was removed, this wire was placed under tension by the spring loaded striker, and began to gradually stretch. After a delay it would snap at the notch and allow the striker to hit the percussion cap. Generally speaking L-delays were slightly less reliable and had shorter delays, but were more reliable underwater (if a No. 10 fuze developed a leak, it would dilute the corrosive liquid and increase the delay, or stop working altogether).
Percussion igniter
Another type of time pencil had a percussion cap but no detonator attached. Instead there was a crimping attachment at one end to allow pyrotechnic fuse to be crimped on. When a time pencil of this type fired, it would light the fuse which would burn towards a detonator crimped onto the other end. Because standard safety fuse burns at around half a metre per minute, it is not practicable to provide delays of more than a few minutes in this way. In an Explosive, Pyrotechnic device or military Munition, a fuse (or fuze) is the part of the device that initiates function
Characteristics
Pencil detonators are colour coded to indicate the nominal time delay, which can range from 10 minutes through to 24 hours. No. 10 delays were normally issued in a tin of 5, all of the same delay, while L-delays were issued in a larger tin which included a mixture of different delays to suit a variety of operations. The time delay of a No. 10 varies according to the concentration of the corrosive liquid in the vial. In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance It is widely reported that the wire thickness varied also, but in fact all used the same diameter of wire. The time delay of a No. 9 is determined solely by the thickness of the notch in the wire, the spring tension, and the temperature. A spring is a flexible elastic object used to store mechanical Energy. In Physics String Tension is the magnitude of the pulling force exerted by a string cable chain or similar object on another object Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Pencil detonators could be used with any explosive provided a suitable primer was fitted, however plastic explosives were particularly useful with the sabotage missions for which they were often employed. An explosive booster acts as a bridge between a low energy Explosive and a low sensitivity (but typically high energy explosive Plastic explosive (or the obsolete term plastique) is a specialised form of Explosive material. There were also a number of special charges issued with a time pencil already built in, such as some types of limpet mines. A naval mine is a self-contained Explosive device placed in water to destroy Ships or Submarines Unlike Depth charges mines are deposited
After being activated a pencil detonator is silent in operation. It does not fizz or make any other noise. However, unlike clockwork timers, pencil detonators only give approximate time delays. A clockwork is the inner workings of either a mechanical Clock or a device that operates in a similar fashion For example, a 2 hour pencil detonator might be accurate to plus or minus 5 minutes, whereas the version offering a 6 hour delay could have a precision of plus or minus 15 minutes. ± The Both No. 9 and No. 10 delays were also significantly affected by the ambient temperature, and were issued along with a chart of temperature corrections — but no thermometer. The thermometer is a device that measures Temperature or Temperature gradient using a variety of different principles it comes from the Greek roots The main virtue of pencil detonators is their small size, plus the fact that they are very quick and easy to use. These are important points during covert operations.
Usage
For very high value targets it is recommended that two pencil detonators from different batches are used together. That way if one detonator fails the other will surely blow the charge. Note that if both detonators were going to work, the explosion will occur at the minimum of the two times; thus this method will also slightly reduce the average delay.
Pencil detonators saw heavy use during the Second World War by the Special Air Service, Special Operations Executive and groups such as the French Resistance. 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 The Special Air Service ( SAS) is a Special forces regiment within the British Army which has served as a model and inspiration for the special The Special Operations Executive ( SOE) (sometimes referred to as "the Baker Street Irregulars " after Sherlock Holmes ' fictional group of helpers The French Resistance is the collective name used for the French Resistance movements which fought against the Nazi German A number of pencil detonators were used to detonate the massive amatol charge hidden inside HMS Campbeltown during the St Nazaire Raid of 1942. Amatol is a highly Explosive material made from a mixture of TNT and Ammonium nitrate. As USS Buchanan See also USS Buchanan (DD-131, L1=USS Buchanan USS Buchanan was a ''Wickes'' class destroyer ordered The St Nazaire Raid (also called Operation Chariot) was a successful British seaborne attack on the heavily defended docks of St The ship exploded over an hour later than anticipated.
Approximately 12 million pencil detonators were produced in Britain during the war. However, in recent years they have been superseded by electronic timers which are more accurate and provide much longer delay times. Interestingly, pencil detonators are by nature completely immune to detection or jamming via electronic countermeasures. Electronic Countermeasures ( ECM') are a subsection of Electronic warfare which includes any sort of electrical or electronic device designed to trick For this reason they may still have applicability in special situations. As at April 2008, what appears to be a modern version of the L-delay is currently produced by Armstec Ltd [1].
Usage In The 1944 Plot To Assassinate Hitler
The briefcase bomb used in the July 20 plot used a captured British pencil detonator inserted into a block of British plastic explosives weighing approximately two pounds. The bomb was set to 30 minutes and detonated as planned, but Hitler survived with minor injuries. Hi and welcome to Wikipedia! Please understand that this article is frequently vandalized and vandalism is reverted immediately Stauffenberg could not prepare the second block, though. Claus Philipp Maria Schenk Graf von Stauffenberg ( 15 November 1907 &ndash 21 July 1944) was a German army officer He got rid of it while driving through the forest to the airfield. The car driver, Leutnant Erich Kretz, reported about seeing Werner von Haeften throwing something in the wood in the back mirror. Werner Karl von Haeften ( 9 October 1908 - 21 July 1944) was an Oberleutnant in the Wehrmacht, who took part in the military-based [2]
See also
External links
- Schematic of a time pencil
- Photograph of a time pencil (107 kB, JPEG)]
- Additional photographs of time pencils (269 kB, GIF)
- Electronic fuze detection method (cannot detect pencil detonators)
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