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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. Pencil detonators are so-called because they have approximately the same shape and dimensions as a pencil. Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki TÅjÅ Casualties Military dead: 17,000,000 Civilian dead: 33,000...
In an explosive device, a fuse (or fuze) is the part of the device that causes it to function. ...
A detonator is a device used to trigger bombs, shaped charges and other forms of explosive material and explosive devices. ...
In an explosive device, a fuse (or fuze) is the part of the device that causes it to function. ...
Types
No. 10 delay switch One type, the British "Switch, No. 10, Delay", is made entirely of aluminium (or brass in early versions), apart from a copper section at one end which contains a glass vial of a green corrosive liquid. (The liquid was widely reported as sulphuric acid, but was actually cupric chloride, which corrodes iron through a redox reaction.) Underneath the vial is a spring-loaded striker under tension, held back by a thin steel wire. After the liquid is released by crushing the copper tube it slowly eats through the wire holding back the spring-loaded striker. The centre of the pencil detonator is hollow to allow the freed striker to fly down it and hit the percussion cap on the detonator at the other end. General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Atomic mass 26. ...
Brass is any alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses, each of which has unique properties[1]. Note that in comparison bronze is principally an alloy of copper and tin. ...
General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Atomic mass 63. ...
Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ...
Copper(II) chloride is the higher chloride of copper, with the formula CuCl2. ...
Illustration of a redox reaction Redox (shorthand for oxidation/reduction reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ...
The percussion cap or primer was the crucial invention that enabled firearms to fire in any weather. ...
Using a pencil detonator is a straightforward process:-
Crush the end of the thin copper tube containing acid with pliers, or under the heel of your boot. 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 safety pin holding back the striker. Finally, insert the other end of the pencil detonator into the explosives. Leave the area. General Name, Symbol, Number copper, Cu, 29 Chemical series transition metals Group, Period, Block 11, 4, d Appearance metallic pinkish red Atomic mass 63. ...
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. 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). For PB or pb as an abbreviation, see PB. General Name, Symbol, Number lead, Pb, 82 Chemical series poor metals Group, Period, Block 14, 6, p Appearance bluish gray Atomic mass 207. ...
An alloy is a combination, either in solution or compound, of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties. ...
In materials science, creep is the term used to describe the tendency of a material to move or to deform permanently to relieve stresses. ...
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 device, a fuse (or fuze) is the part of the device that causes it to 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. (It is widely reported that the wire thickness varied also, but in fact all used exactly the same 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. 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. There were also a number of special charges issued with a time pencil already built in, such as some types of limpet mines. In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. ...
Helical or coil springs designed for tension A spring is a flexible elastic object used to store mechanical energy. ...
Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ...
Fig. ...
An explosive booster acts as a bridge between a low energy explosive and a low sensitivity (but typically high energy) explosive. ...
A C-4 plastic explosive. ...
Polish wz. ...
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. 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. 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 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. Gear with escapment mechanism For other uses, see Clockwork (disambiguation). ...
The plus-minus sign (±) is a mathematical symbol commonly used to indicate the precision of an approximation, or as a convenient shorthand for a quantity with two possible values. ...
In the fields of science, engineering, industry and statistics, accuracy is the degree of conformity of a measured or calculated quantity to its actual (true) value. ...
A common mercury thermometer A thermometer is a device which measures temperature or temperature gradient, using a variety of different principles. ...
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. 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 immune to detection or jamming via electronic countermeasures because they use a chemical time fuze. For this reason they may still have applicability in special situations. Mushroom cloud from the nuclear explosion over Nagasaki rising 18 km into the air. ...
The Special Air Service Regiment (SAS) is the principal special forces unit of the British Army, and arguably the most well trained special forces unit in current existence. ...
The Special Operations Executive (SOE), sometimes referred to as the Baker Street Irregulars after Sherlock Holmess fictional group of spies, was a World War II organization initiated by Winston Churchill and Hugh Dalton in July 1940 as a mechanism for conducting warfare by means other than direct military engagement. ...
The French Resistance is the name used for resistance movements during World War II which fought the German occupation of France and the collaborationist Vichy regime, and was a vital and some say decisive factor in the defeat of Hitler and the Nazi revolution. ...
This does not cite its references or sources. ...
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 two pounds. The bomb detonated as planned, but Hitler survived with minor injuries. Claus von Stauffenberg The July 20 Plot was an attempt to assassinate Adolf Hitler, the dictator of Germany, on July 20, 1944. ...
Adolf Hitler Adolf Hitler (April 20, 1889 – April 30, 1945, standard German pronunciation in the IPA) was the Führer (leader) of the National Socialist German Workers Party (Nazi Party) and of Nazi Germany from 1933 to 1945. ...
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