pzgr40
Well-Known Member
Cutaway model of a Depth Charge Pistol (DCP) Mk.XX. In contrast to the DCP Mk.VII described in this posting: http://www.bocn.co.uk/vbforum/threa...h-charge-pistol?highlight=depth+charge+pistol , the DCP Mk.XX is used only in aircraft released depth charges.
In top, the valve is placed. The valve mechanism is placed in a bronze valve body. The valve consists of a spindle with a rubber plug to the base that prevents water from entering the pipe below it, and a brass plate fitted through the top of the spindle over which the fork of the bomb tail propeller will fit. To the base of valve body a pipe is placed, connecting the valve with the firing pin mechanism body.
The firing pin mechanism is a closed body with six water inlet holes on the circumference, housing two steel discs which telescope over one another. These two discs fixate the spring loaded firing pin by pushing four steel balls inward in a recess in the firing pin. Between these two discs, a rubber bellow is placed which expands if water under pressure enters the bellow.
The valve mechanism is a safety mechanism that will prevent the DCP from unintended arming and activation. A DCP without this mechanism could be armed and activated if a ship sails through a heavy storm where the deck is engulfed in water, a ship sinks, or an airplane makes an emergency landing and sinks, with deadly consequences for crews trying to escape in lifeboats.
As stated before, this specific type DCP (Mk.XX) is intended for use in Aircraft released depth charges only. For ship mounted depth charges -launched with the K-gun- a different type of valve is used with a -smooth shaft- spring loaded valve that will close if a locking plate is pulled away. The locking plate is connected to the K-gun with a cord, and upon firing the locking plate remains and the valve closes. With the aircraft released type (Mk.XX) the propeller of the bomb tail will enshure the valve is closed with 22 revolutions. As it would be quite unlogical to close a valve with 22 revolutions aboard a ship –with multipe depth charges- allowing the submarine to escape, it can be safely assumed the DCP Mk.XX is for aircraft use only.
It will occur that there is no depth setting possibility to this DCP MK.XX, which can be explained as follows; the relatively short time lapse between spotting a submarine on the surface from an airplane, diving towards it for an attack, and releasing the depth charges does not allow the U-boat to dive very deep. Therefore the depth setting of this DCP is about 20 mtrs (180 feet), just above, either just below an U-boat starting it’s dive.
There is no possibillity to adjust this setting, exept for tensioning the firing pin spring, which is a factory setting, not to be adjusted.
Functioning of the DCP Mk.XX;
If the valve is open (Picture 14), water will enter the valve body, pass through the holes in the valve body (blue), as well as the centre hole in the pipe (green) and the two small green holes in top of the bellow housing. The pressure inside the rubber bellow and outside the bellow are equal, preventing the bellow from expanding. The fuze is prevented from any activation.
If the valve is closed (Picture 13), no water will enter through the green holes, water will enter only through the blue marked holes. This will allow a pressure build up inside the bellow, pushing the two telescoped discs above and below the bellow apart until the four locking balls -which lock the firing pin- can move outward, releasing the firing pin. This will activate the detonator, exploding the depth charge.
It must be noted that in contrast to the –ship mounted- Mk.7 and Mk.7 heavy type depth charges which use water pressure to move the booster charge over the detonator, the aircraft released type depth charge has the booster charge placed over the detonator standard, so it does not have to move.
The dimensions of the DCP Mk.XX are simillar to the DCP Mk.VII
Length of the complete fuze with detonator : 397mm
Diameter of the fuze : 88mm
Regards, DJH
In top, the valve is placed. The valve mechanism is placed in a bronze valve body. The valve consists of a spindle with a rubber plug to the base that prevents water from entering the pipe below it, and a brass plate fitted through the top of the spindle over which the fork of the bomb tail propeller will fit. To the base of valve body a pipe is placed, connecting the valve with the firing pin mechanism body.
The firing pin mechanism is a closed body with six water inlet holes on the circumference, housing two steel discs which telescope over one another. These two discs fixate the spring loaded firing pin by pushing four steel balls inward in a recess in the firing pin. Between these two discs, a rubber bellow is placed which expands if water under pressure enters the bellow.
The valve mechanism is a safety mechanism that will prevent the DCP from unintended arming and activation. A DCP without this mechanism could be armed and activated if a ship sails through a heavy storm where the deck is engulfed in water, a ship sinks, or an airplane makes an emergency landing and sinks, with deadly consequences for crews trying to escape in lifeboats.
As stated before, this specific type DCP (Mk.XX) is intended for use in Aircraft released depth charges only. For ship mounted depth charges -launched with the K-gun- a different type of valve is used with a -smooth shaft- spring loaded valve that will close if a locking plate is pulled away. The locking plate is connected to the K-gun with a cord, and upon firing the locking plate remains and the valve closes. With the aircraft released type (Mk.XX) the propeller of the bomb tail will enshure the valve is closed with 22 revolutions. As it would be quite unlogical to close a valve with 22 revolutions aboard a ship –with multipe depth charges- allowing the submarine to escape, it can be safely assumed the DCP Mk.XX is for aircraft use only.
It will occur that there is no depth setting possibility to this DCP MK.XX, which can be explained as follows; the relatively short time lapse between spotting a submarine on the surface from an airplane, diving towards it for an attack, and releasing the depth charges does not allow the U-boat to dive very deep. Therefore the depth setting of this DCP is about 20 mtrs (180 feet), just above, either just below an U-boat starting it’s dive.
There is no possibillity to adjust this setting, exept for tensioning the firing pin spring, which is a factory setting, not to be adjusted.
Functioning of the DCP Mk.XX;
If the valve is open (Picture 14), water will enter the valve body, pass through the holes in the valve body (blue), as well as the centre hole in the pipe (green) and the two small green holes in top of the bellow housing. The pressure inside the rubber bellow and outside the bellow are equal, preventing the bellow from expanding. The fuze is prevented from any activation.
If the valve is closed (Picture 13), no water will enter through the green holes, water will enter only through the blue marked holes. This will allow a pressure build up inside the bellow, pushing the two telescoped discs above and below the bellow apart until the four locking balls -which lock the firing pin- can move outward, releasing the firing pin. This will activate the detonator, exploding the depth charge.
It must be noted that in contrast to the –ship mounted- Mk.7 and Mk.7 heavy type depth charges which use water pressure to move the booster charge over the detonator, the aircraft released type depth charge has the booster charge placed over the detonator standard, so it does not have to move.
The dimensions of the DCP Mk.XX are simillar to the DCP Mk.VII
Length of the complete fuze with detonator : 397mm
Diameter of the fuze : 88mm
Regards, DJH
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