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Pencil detonator AI simulator
(@Pencil detonator_simulator)
Hub AI
Pencil detonator AI simulator
(@Pencil detonator_simulator)
Pencil detonator
A pencil detonator or time pencil is a time fuze designed to be connected to a detonator or short length of safety fuse. They are about the same size and shape as a pencil, hence the name. They were introduced during World War II and developed at Aston House, Hertfordshire, UK.
One type, the British Number Ten 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 contained a glass vial of cupric chloride (the liquid was widely and erroneously reported to be sulfuric acid[original research?]), while beneath the vial was a spring-loaded striker under tension and held in place by a thin metal wire. The timer was started by crushing the copper section of the tube to break the vial of cupric chloride, which then began to slowly erode the wire holding back the striker. When the wire eventually parted, the striker was propelled down the hollow centre of the detonator, hitting the percussion cap at the other end of the detonator.
Number ten delay switches had delays ranging from 10 minutes to 24 hours and were accurate to within plus or minus two or three minutes in an hour's delay, and plus or minus an hour in a 12-hour delay, though environmental conditions could affect this. The switches were typically issued in packs of five, 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.
Crush the end of the thin copper tube containing the cupric chloride 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. 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 and the brass safety strip (holding back the striker) should be removed and discarded. However, if the inspection hole is obstructed (before the safety strip is removed) the striker has been released so the pencil detonator should be discarded and another one selected. The final step is to insert the end of the pencil which has the actual detonator fitted into the explosives and leave the area.[This quote needs a citation]
Another, subsequent type was developed by Millis Jefferis of MD1 known as the "Lead Delay switch" or officially "Switch, No. 9, L Delay". Instead of relying on the chemical action of a corrosive liquid on metal (which was subject to temperature variation), it used a piece of metal under stress – the metal in question being a lead alloy that was extremely affected by mechanical creep. A piece of this lead was notched to a set diameter, the diameter setting the time delay. When the starting pin was removed, this wire was placed under tension by the spring-loaded striker, and began to gradually stretch. After a certain time, it would snap at the notch and allow the striker to hit the percussion cap.
The delay could be set from a matter of minutes to hours. Manufacture was entirely by MD1. Generally speaking L-delays were slightly less reliable[citation needed] and had shorter delays, but were more reliable underwater (if a No. 10 fuze developed a leak, water would dilute the corrosive liquid and increase the delay or stop the fuze from working).
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. It was also possible to connect a pencil detonator to so-called "instantaneous fuse" (not to be confused with detonating cord) which had an unusually fast burn rate of over 7 metres per second.
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 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. Pencil detonators could be used with any explosive provided a suitable booster was attached. However, plastic explosives (which did not require a booster) were particularly useful during the sabotage missions in which they were often employed. There were also a number of special charges issued with a time pencil already incorporated e.g. some types of limpet mines.
Pencil detonator
A pencil detonator or time pencil is a time fuze designed to be connected to a detonator or short length of safety fuse. They are about the same size and shape as a pencil, hence the name. They were introduced during World War II and developed at Aston House, Hertfordshire, UK.
One type, the British Number Ten 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 contained a glass vial of cupric chloride (the liquid was widely and erroneously reported to be sulfuric acid[original research?]), while beneath the vial was a spring-loaded striker under tension and held in place by a thin metal wire. The timer was started by crushing the copper section of the tube to break the vial of cupric chloride, which then began to slowly erode the wire holding back the striker. When the wire eventually parted, the striker was propelled down the hollow centre of the detonator, hitting the percussion cap at the other end of the detonator.
Number ten delay switches had delays ranging from 10 minutes to 24 hours and were accurate to within plus or minus two or three minutes in an hour's delay, and plus or minus an hour in a 12-hour delay, though environmental conditions could affect this. The switches were typically issued in packs of five, 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.
Crush the end of the thin copper tube containing the cupric chloride 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. 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 and the brass safety strip (holding back the striker) should be removed and discarded. However, if the inspection hole is obstructed (before the safety strip is removed) the striker has been released so the pencil detonator should be discarded and another one selected. The final step is to insert the end of the pencil which has the actual detonator fitted into the explosives and leave the area.[This quote needs a citation]
Another, subsequent type was developed by Millis Jefferis of MD1 known as the "Lead Delay switch" or officially "Switch, No. 9, L Delay". Instead of relying on the chemical action of a corrosive liquid on metal (which was subject to temperature variation), it used a piece of metal under stress – the metal in question being a lead alloy that was extremely affected by mechanical creep. A piece of this lead was notched to a set diameter, the diameter setting the time delay. When the starting pin was removed, this wire was placed under tension by the spring-loaded striker, and began to gradually stretch. After a certain time, it would snap at the notch and allow the striker to hit the percussion cap.
The delay could be set from a matter of minutes to hours. Manufacture was entirely by MD1. Generally speaking L-delays were slightly less reliable[citation needed] and had shorter delays, but were more reliable underwater (if a No. 10 fuze developed a leak, water would dilute the corrosive liquid and increase the delay or stop the fuze from working).
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. It was also possible to connect a pencil detonator to so-called "instantaneous fuse" (not to be confused with detonating cord) which had an unusually fast burn rate of over 7 metres per second.
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 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. Pencil detonators could be used with any explosive provided a suitable booster was attached. However, plastic explosives (which did not require a booster) were particularly useful during the sabotage missions in which they were often employed. There were also a number of special charges issued with a time pencil already incorporated e.g. some types of limpet mines.
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