WW1 GERMAN FUZES GALLERY

The Gr Z c/80 percussion fuze was a stepstone in the German percussion fuzes story, whose previous arming mechanisms were up to then made of heavy transversal safety pins ejected by the centrifugal force when the shell was leaving the gun, just as in the percussion fuze M 1873. However, it kept the usual German graze action percussion system (percussion pin graze pellet and static starter).

This Gr Z c/80 fuze was organized on a principle somehow comparable to the French 'Budin Mle 1875 fuze'. Like in the French fuze, the safety of the Gr Z c/80 fuze at rest was insured by the position of the top of the percussion pin hidden inside of an internal mobile graze pellet, that was armed at the discharge. It must be noted that no safety spring was preventing the percussion pin from hitting the primer once armed, during the flight.

In a later model, named Gr Z c/82 fuze, an additional safety device was integrated, the top head descending into the fuze head by momentum action at the shot of discharge, therefore only bringing the primer in a position that could be hit by the graze pellet percussion pin.

This fuze was designed for high explosive ('Gr' = Granate - explosive shell) and incendiary heavy calibre shells of the :

• 15cm sFH, 15cm sFH02, 15cm sFH13, 15cm sFH13 L/17 heavy field howitzers
• 15cm sFH Kst heavy coast howitzers
• 15cm RK and 15cm lRK Ringkanonen
• 21cm TH mortars under turret

When used with high explosive shells, these fuzes were associated with a separate 'Z dlg 88' exploder (unknown explosive charge).

A variant named Gr Z c/82 (Kp) was equipped with a safety spring and a different inertia block. Externally, it was only distinguishable by the presence of a steel cap covering the fuze head.

These fuzes percussion systems were also used for the first German time and percussion fuzes Dopp Z c/85 whose percussion and concussion removable mechanism named DoppZdSchr c/85 ('DoppelzünderSchraube') was inserted into the time system (revolving discs) just before the shell firing.

Entirely made of brass, purely percussion-type and without delay, this fuze replicated almost indentically the arming and percussion systems of the same generation 'Dopp Z 92' time and percussion fuze, and that will be used in all the German time and percussion fuzes until 1905.

Just as this latter, the Gr Z 92 percussion fuze was secured with a two rods safety pin, to be removed before the shot. This liberated the movements of the graze arming system, whose massive mobile graze pellet (bearing a primer) slided back under the discharge momentum action and hit a fixed percussion pin protected at rest by a tulip spring cap having the shape of a crown and flattened under the pellet pressure, setting fire to a big gunpowder pellet.

This pellet combustion made possible the movements of the main percussion system graze pellet located in the fuze tail.

At impact, the primer-bearer cylinder was propelled against a percussion pin fixed onto a transverse bridge. The resulting flame was directed backwards through the fuze tail base hole, and bursted the gaine exploder.

This fuze was designed for the high explosive ('Gr' = Granate - Obus explosif) or gaz heavy shells of the

• 15cm sFH, 15cm sFH02, 15cm sFH13 et 15cm sFH13/L17 heavy field howitzers
• 21cm Br Mrs. (bronze), 21cm Mrs. (M1902), 21cm Mrs. (M1910) and 21cm lg.Mrs. (1916) mortars

It was associated with a 20g picric acid 'Z.dlg.92' exploder screwed to the fuze base.

Brass fuze derivated from an older Gr Z 96, with a steel mantle and attached exploder steel exploder.

The Gr Z 96/04 fuze was a percussion graze fuze with optionnal delay, built around two parallel graze action percussion systems located in the tail. These two apparatus were practically identical, designed on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge, but for the presence of a compressed gunpowder acting as a delay in the flame communication channel from the delayed percussion system to the detonator. The behaviour was selectable by the rotation of a setting stud commanding a vertical inner rod that deviated the flame to the adequate system. Depending on the selection it was positioned on 'oV' position (Ohne Verzögerung - without delay - let both systems activated) or on 'mV' position (mit Verzögerung - with delay - deactivating the undelayed percussion system).

The arming system was secured at rest by a two rods safety pin. It was based on a the 'Dopp Z 92' fuze design : an axial and massive mobile graze pellet bearing a starter, a percussion pin protected by a tulip spring cap, and compressed gunpowder pellet blocking the percussion system. In this specifice model, the graze action arming system commanded the combustion of two compressed gunpowder pellets, one for each percussion system, that liberated the movements of two stems blocking the two mobile pellets.

Another interesting characteristic of this fuze was its additional safety system for the exploder, inherited from the older type fuze Gr Z 96. At rest, its primer was placed within an isolated detonation room in wich it could explode without communicating the energy to the surronding relay-charge. At firing time, the combustion of a compressed black powder grain was freeing its movements inside a brass tube so that the landing shock inertia could push it just in front of a windows communicating with the explosive load.

That fuze was used with the high explosive shells ('Gr' = Granate - Explosive shell) of the :

• 15cm sFH, 15cm sFH02, 15cm sFH13 and 15cm sFH13/L17 heavy field howitzers
• Lg 15cm K long guns
• 15cm RK and lg 15cm RK Ringkanones
• 21cm Br Mrs. (bronze), 21cm Mrs. (M1902) and 21cm Mrs. (M1910) heavy mortars
• 21cm TH mortars in turret

The use of the GrZ 96/04 with heavy high explosive shells required the addition of an impressive 100g picric acid exploder attached to the fuze tail.

Brass or zinc alloy fuze, with steel cap and gaine. The GR Z 04 was an evolution of the Gr Z 96/04 fuze, including as this latter :

• a selectable optional delay (approximately 1 second) based on two identical parallel graze percussion systems designed on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge, one directly connected to the detonator, and the other one through a compressed gunpowder pellet delay,
• a graze arming system based on an axial and massive mobile graze pellet bearing a starter, a percussion pin protected by a tulip spring cap, and two big compressed gunpowder pellets blocking the percussion systems, inspired from the 'Dopp Z 92' fuze, and secured by a two rods safety pin,
• an evolution of the exploder safety masking at rest the primer into an isolated detonation room, but with a static primer and a mobile detonator charge.

The main difference with its predecessor was the delay selection method, not anymore mechanically by acting on a selection stud and rod, but pyrotechnically by rotation of a disc looking like the time-setting discs of the revolving discs time systems, only bearing the markings 'O/V' (Ohne Verzögerung - without delay - let both systems activated) and 'm.V.' (mit Verzögerung - with delay - deactivating the undelayed percussion system). Depending on the disc gunpowder ring position, the graze arming system flame was communicated either to the gunpowder pellet only liberating the movements of the stem blocking the delayed percussion system ('m.V.), or to both the gunpowder pellets liberating the movements of both delayed and non-delayed percussion systems ('o.V.').

The Gr Z 04 fuze was intensively used. It was mounted on the high explosive shells, false head high explosive shells, smoke and gaz shells of the :

• 10cm K, 10cm K97, 10cm K04 and 10cm K14 guns
• 10cm KISL, 10cm TK and 10cm TK Verst guns
• 13cm K09 guns
• 15cm KISL guns
• Lg 15cm K and 15cm K16 guns
• 15cm RK and lg 15cm RK 'Ringkanone' guns
• 15cm sFH, 15cm sFH02, 15cm sFH13 and 15cm sFH13/L17 heavy field howitzers
• 6-zöll.Russ Lg.K.M/04 6-in M1904 captured Russian howitzers
• 8-zöll.Russ.leichtek.C/77 8-in M1877 captured Russian howitzers
• 15 cm Mle 1886 and 1890 captured Belgian guns
• 21cm Br Mrs. (bronze), 21cm Mrs (M1902), 21cm Mrs (M1910) and 21cm Lg Mrs (1916) mortars
• 21 cm Mle 1889 captured Belgian howitzers

It was equipped from factory with a screwed 90 gr. picric acid exloder, including 10 gr. in the mobile detonator charge of the detonator safety system.

There are two known variants :

• the Gr Z 04 for gaz shells included a steel ring crimped on a reduced section tail, and covered with a magnesian cement (magnesium oxychloride) to provide isolation from the agressive gaz. It was marked with a cross on its cap.
• the Gr Z 04/14 produced in 1914, hybrid model manufactured from the Gr Z 04 mechanism, but equipped with the 'Gr Z 14' fuze exploder) (without safety system).

Despite its shape close to the Gr Z 04 fuze one, and therefore often confused with it, the Gr Z 14 fuze is a device with a totally different inner organization.

This fuze is in fact the percussion model designed for the heavy artillery high explosive shells, derivated from the new generation of 1914 German fuzes with a technology initially developped for the 'KZ 11' fuze, but also integratezd into the 'KZ 14' fuze for the field guns, and into the 'HZ 14' fuze for the field howitzers.

The Gr Z 14 was made in brass with a steel cap and gaine, and had a 45 mm thread. Like the other fuzes from the same generation, it was based on a two components graze arming system (mobile graze pellet with starter, and gunpowder pellet stopping a safety stem that blocks the main percussion system), and a main graze percussion system (mobile graze pellet bearing the starter and static percussion pin, with safety spring and blocked by a safety stem). If the inner organization was totally different, it was functionnally only a simplification of the Gr Z 04 fuze, being a heavy caliber shell percussion fuze with no optional delay nor exploder safety system. It was equipped with single rod safety pin for the graze arming system.

This fuze was used with numerous projectiles during the war. It was mounted on the high explosive shells, incendiary shells and gaz shells (green, yellow and blue cross) of the :

• 9cm K 73/88 guns
• 95 mm Mle 1888 captured French guns
• 10cm K97, 10cm K04 and 10cm K14 guns
• s 12cm K heavy guns
• 120 mm Mle 1878 captured French guns
• Russ.48 linen Feld Haubitzer M/04 und M/09 captured 48 lines M1904 and 1909 Russian howitzers
• 13cm K09 guns
• Lg 15cm K et 15cm K L/30 guns
• 15cm RK and lg 15cm RK Ringkanone guns
• 15cm sFH, 15cm sFH02, 15cm sFH13 and 15cm sFH13/L17 heavy field howitzers
• 6-zöll.Russ S.f.H.M/09 6-in M1909 captured Russian howitzers
• 15 cm Mle 1886 and 1890 captured Belgian guns

The Gr Z 14 was equipped with a 63 gr. picric acid exploder.

Some variants :

• Some fuzes were marked 'G Gr Z 14' or 'Kz Gr Z 14' seemingly for designating the size of the associated exploder ('G' - Grosser for the big one, and 'K' - Kurzer for the smaller one)
• A modified version (Gr Z 14 'n/A') added a centrifugal safety system to the main percussion system.
• the Gr Z 14 n/A for gaz shells included a steel ring crimped on a reduced section tail, and covered with a magnesian cement (magnesium oxychloride) to provide isolation from the agressive gaz. It was marked with a cross on its cap.

The sophisticated 'KZ 11' fuze for the German universal shell, appeared in 1911, introduced both a new two components arming system (mobile primer pellet and percussion system safety by stem and gunpowder pellet), and a new percussion graze action system (axial mobile graze pellet and static percussin pin, safety spring and safety stem blocking) that will be used by numerous German fuzes.

The graze action percussion fuzeKZ 14 used these two new systems without the KZ11 time system, and without any additional safety device. Simple and economic, it became the standard percussion fuze of the high explosive shell or gaz shell of the 7.7cm FK 96 n/A fielgun in 1914. Numerous specimens can still be observed nowadays in the former battlefields, but in various corroded conditions, depending on the material they are made of.

Indeed, even if the earlier productions were entirely made in brass, the allies blocus on Germany effect on noble metals availability induced the progressive use of less noble materials such as zinc, aluminium or steel. Numerous combinations of thes materials were used for the fuze body or cap. It seems the use of these alternative materials were sometimes shown on the fuze marking (KZ 14 Z, KZ 14 Zi, KZ 14 Zp, KZ 14 Zw or KZ 14 nA Zl).

Equipped from the factory with a crimped 20 to 22 gr picric acid exploder, it was mounted on the high explosive shells and gaz shells (green cross) of the

• 7.7cm FK 96 n/A and 7.7cm FK 16 fieldguns
• Infanterie Geschutz Russ 3-zöll Gebirgsk M/09 captured 3-in M1909 mountain Russian infantry guns

4 versions were developped on the base of the original KZ 14 that was subject to prematures in the bore :

• KZ 14 Fb integrating an additional centrifugal bolts safety for the percussion system
• KZ 14 Vorst with a single rod safety pin for the arming system
• KZ 14 mV with delay
• KZ 14 n/A with minor internal changes (gunpowder in a small container, and no spring on the safety stem)

These versions are hardly distinguishable on specimens found on the battlefilds, when there are no visible markings

Inherited from the 1914 German fuzes generation based on the technology developped for the 'KZ 11' de l'obus universel comme la fusée percutante 'KZ 14' fuze of the light field gun, the HZ 14 fuze was the medel initially dedicated to the light field howitzers, but used afterwards with numerous other guns and howitzers. Just like its generation fuzes, it included the graze action arming system with two components (mobile primer pellet and percussion system safety by stem and gunpowder pellet), and the pecussion system (axial mobile graze pellet and static percussin pin, safety spring and safety stem blocking) that was the German state of the art in 1914.

Its weight is still impressive when one can obeserve and manipulate a surviving brass specimen nowadays, and it is easy to imagine how deadly this piece could be alone, projected ahead after its shell burst !

Entirely made in brass at the beginning of the war, it was later built in different materials (steel, brass, zinc alloy) in order to save the copper alloys made precious by the allies blocus.

The HZ 14 fuze was mounted on the high explosive or gaz shells of the :

• 9cm K 73/88 guns
• 10cm K, 10cm K 97, 10cm K 04, and 10cm K 14 guns
• 10cm KISL, 10cm TK, 10cm TK (verst), and Kz 10cm TK guns
• 10cm lFH 98/09, 10cm lFH 16 and 10cm lFH Kp light field howitzers
• s 12cm K heavy guns

The HZ 14 fuze was associated from manufacture with a crimped exploder of 55 gr. picric acid.

Three versions followed the original model (HZ 14, introduced in 1914) that was too often subject to prematures in the howitzer bore :

• HZ 14 Fliehb. (Fb.) integrating an additional centrifugal safety to the percussion system,
• HZ 14 Vorst with one rod safty pin for the arming system,
• HZ 14 Vorst Fliehb. with both the additional centrifugal safety to the percussion system and one rod safty pin for the arming system.

The German Navy introduced in 1916 new percussion fuzes for the high explosive shells of its 15 cm guns that were also used on the Army on improvised cariages or even in railway artillery. The particularity that came with this Gr Z 16 fuze was mainly consisting in the introduction of a 5 centrifugal bolts security, typixcal of some already existing Navy fuzes (such the bottom fuzes Spgr.m.K. of the 21 cm or 38 cm shells) and that will be found later in the 'Quick action fuzes Gr Z 17' and the 'fuzes for armor piercing 7.7 cm anti-tank fuzes'.

In this model, the static percussion pin was screwed on the top of the fuze body that might be either entirely in steel with a top screw, or in steel with a top brass cover including a screw. The mobile graze pellet with the primer cap was maintained out of range of the percussion pin thanks to a 5 rotating bolts on eccentic pivot in closed position at rest. This position was locked by an sliding arming ring that was tightening the bolts (or more precisely preventing the movements of one of them). A small safety spring was also inserted between the bolts 'door' and the percussion pin.

At the shot start inside the barrel, the arming ring was pushed back under the effects of inertia, and was locked in that position by a staples blades system. This movement backwards was allowing the rotation of the bolts around their eccentric pivot under the effect of the centrifugal force progressively increasing with the accelaration of the shell inside the rifled gun bore, but these ones were still prevented from making this movement since they were pushed back on their support by the acceleration. This fuze designe was therefore particularily safe from shell bore explosions.

At the bore exit at the muzzle, the acceleration suddenly stopped and only the centrifugal force remained. Its action was making the bolts rotate, opening the 'door' to the primer-bearing graze pellet. In flight, the small safety spring placed between the pellet and the percussion pin was the only protection against unwanted explosion. But it was very easily compressed by the shock at the arrival of the shell on its target, triggering the primer ignition and the transfer of its flame to the shell through an axial channel.

The Gr Z 16 fuze also rarely existed in a version with an additional safety pin. It was in use wuth the high explosive shells of the :

• 15cm K.L/30 guns
• 15cm S.K.L/40 guns
• 12.5cm Mrs L/6.3 coast mortar

A new family of percussion fuzes was introduced in 1916 by the German Army, starting with the KZ 16 m.V. delayed percussion fuze dedicated to the 7.7cm FK 96 n/A fieldgun. This first model was quickly abandoned and replaced by the LKZ 16 having an identical inside mechanism, but with an elongated head for improved aerodynamic and penetration performances.

The LKZ16 fuze is quite commonly observed on the former battlefields. It appearance is very simple, since the usually visible part of the fuze is just a steel or zinc alloy cone. In fact, this part is only a steel top that covers the aluminium and brass percussion mechanism. The shape has good aerodynamics properties and was particularly designed for elongated shape shells with improved range.

The fuze mechanism was a pure and simple graze action percussion system with a mobile graze pellet carrying the primer, and a static percussion pin protected by a safety spring.

The fuze was secured by a double safety system activated by the centrifugal force :

• a percussion system safety - two centrifugal safety bolts, blocked by springs but allowed to move under the action of the shell spin were stopping the percussion system mobile pellet movements at rest
• an exploder safety - a lock (drawer) that could slide horizontally under the effects of the same force was preventing the flame created by the percussion system detonator to reach the exploder at rest, while it placed a small picric acid charge in line when it was armed,.

, The delayed models had a little gunpowder delay between the percussion system primer and the detonator ('LKZ 16 m.V.'). This device was not present in the non-delayed models ('LKZ 16 o.V.' ou plus simplement 'LKZ 16').

Associated with a 23 gr. picric acid exploder, it was in use with the explosive projectiles of the

• 7.7cm FK 96 n/A and 7.7cm FK 16 field guns
• 3 inches infantry guns (mountain russian guns model 1909) (Infanterie Geschutz Russ 3-zöll Gebirgsk M/09)

Although pretty similar at the first sight with the LKZ 16 because of the conical shape and dimensions, this fuze is indeed quite different. The EKZ 16 is indeed an simple effect super_quick model ('Empfindlicher Kanone Zunder'), whose explosion was occuring before the shell could dig into the ground, at the very first contact with the target. This kind of behavior was wanted when surface effects had to be maximised (anti-infantry or against barbwires), or for gaz shells.

In order to behave that way, a hollow steel or solid aluminium alloy percussion rod was located in the steel or zinc alloy fuze head axis. The rod projected around 1 inch from the fuze top, and had a percussion pin on its end inside the fuze body. When the shell landed on the target, the rod extension touched it instants before the shell body and was pushed back. This movement compressed the safety spring, and made the percussion pin meet the static pellet carrying the primer violently.

Like the LKZ 16, the fuze mechanism was secured by a double safety system activated by the centrifugal force :

• a direct action system safety - two centrifugal safety bolts, blocked by springs but allowed to move under the action of the shell spin were stopping the direct action system mobile rod movements at rest, and a creep spring retaining the rod being pushed back by the wind in flight,
• an exploder safety - a lock (drawer) that could slide horizontally under the effects of the same force was preventing the flame created by the percussion system detonator to reach the exploder at rest. It was itself secured by a two bolts centrifugal system.

, The fuze was delivered to the batteries with the percussion rod separated, and a lead cap covering the top hole, for an assembly just before use. A rope attached to the lead cover was carrying a tag saying « Draht mit Platte abreissen, Stecklift einstossen, so weit ungefärbt Sonst Blingänger» ("Insert the percussion rod along the whole painted part, or else the shell will misfire").

Equipped with a 23 gr. picric acid exploder, the EKZ 16 fuze was in use with the explosive shells and gaz shells (blue cross) of the

• 7.7cm FK 96 n/A and 7.7cm FK 16 field guns

The EKZ 16 c fuze was a streamlined version of the instantaneous percussion fuze EKZ 16, and having the same percussion rod in solid aluminium or hollow steel, and a similar interrnal mechanism. It was therefore also a single effect instantaneous (or super quick) fuze.

The EKZ 16 c fuze also had the adequate safety and arming systems :

• a direct action system safety similar to the EKZ 16 one - two centrifugal safety bolts, blocked by springs but allowed to move under the action of the shell spin were stopping the direct action system mobile rod movements at rest, and a creep spring retaining the rod being pushed back by the wind in flight,
• an exploder safety similar to the LKZ 16 one - a lock (drawer) that could slide horizontally under the effects of the same force was preventing the flame created by the percussion system detonator to reach the exploder at rest, while it placed a small picric acid charge in line when it was armed,.

The cone was made in zinc alloy, while the inner mechanism was made in steel and zinc alloy. Associated with a 23 gr. picric acid exploder, it was in use with the explosive shells of the

• 7.7cm FK 16 field guns

The KZ 16 f10cm K was a superquick percussion fuze, equipped with a long percussion rod protected at rest by a steel cap screwed on a thread.

Its internal organization was pretty similar to the one of the EKZ 16 c, and it was therefore a twin effect fuze as well (direct action and percussion)

Just like in this latter, the KZ 16 f10cm K fuze was equipped with three different centrifugal safety systems : a two centrifugal bolts safety device for the direct action rod, another one for the graze pellet of the percussion system, and a centrifugal lock safety secured by two centrifugal bolts for the exploder.

That fuze was in use with the high explosive shells of the

• 10cm K 97, 10cm K 04, 10cm K 14 et 0cm K 17 guns
• 10cm K.I.S.L. guns under protected mount
• 10cm T.K. and 10cm T.K. verst. guns under turret
• Kz 10cm T.K. short guns under turret

The fuze KZ 16 f10cm K, made of steel, alumium or zinc alloy, seemed to be used as a substitution of the HZ14 vorst, for the above mentionned guns.

Exploder charge : 70 grammes of picric acid.

The HZ 16 percussion fuze, with optionnal delay, is typical of the middle-war years, by its materials choice : the head and the detonator are in steel, the body and the mechanism are in zinc-alloy.

The classical percussion mechannism located under the steel cap (static percussion pin protected by a creep spring, mobile graze pellet carrying the starter and secured at rest by two centrifugal bolts) was similar to the one of the LKZ 16 fuze.

It was communicating to the fuze tail of the fuze by two parallel channels. One of them was equipped with a black powder grain delay. An external selection stud allowed the shutting of the non-delayed channel when one wanted to use the delayed function ('m.V.' position).

The HZ 16 fuze was equipped by an additional exploder safety system comparable to the one of the LKZ 16 fuze between the two flame communication channels and the exploder. It was composed by a drawer, sliding in a notch under the action of the centrifugal force : blocked at rest by two centrifugal bolts equipped with springs, it sealed the communicating channel between the detonator and the fuze head. Under the action of the shell spin, during its flight, it slided and put an exploding channel in the pyrotechnic axis.

That fuze equipped the gas shells and explosive shells of the

• 10cm lFH 98/09, 10cm lFH 16 and 10cm lFH Kp light field howitzers

The HZ 16 fuze was associated with a 58 gr picric acid exploder

A simple look on the wartime schemes of the two fuzes demonstrates that the EHZ 16 fuze is a HZ 16 fuze to which a super-quick direct action rod system has been added. It then becomes a triple effect percussion fuze since it keeps the two percussion modes with delay and without delay of its predecessor, in addition to the additional super-quick behavior.

In order to obtain this transformation, the steel cap have been drilled in its axis, so that an aluminium rod could be introduced. The rod base was inserted into a mobile cylinder whose base was carrying the percussion pin, now mobile. The HZ 16 fuze safety systems were kept (centrifugal bolts safety system for the mobile graze pellet of the percussion system, and exploder centrifugal safety by a mobile lock), but a small modification of the percussion system design allowed its centrifugal safety system to act as well for retaining the super-quick system rod backwards movements at rest.

The fuze was delivered to the batteries with the percussion rod separated, and a lead cap covering the top hole. A rope attached to the lead cover was carrying a tag saying « Draht mit Platte abreissen, Stecklift einstossen, so weit ungefärbt Sonst Blingänger» ("Insert the percussion rod along the whole painted part, or else the shell will misfire").

The rod was only inserted in the hole before the fire, and only when a super-quick behavior was needed. In the absence of that rod, the EHZ 16 was behaving exactly as a HZ 16 percussion fuze with or without delay depending on the external deay selection stud.

The EHZ 16 fuze equipped the gas shells and explosive shells of the

• 10cm lFH 98/09, 10cm lFH 16 and 10cm lFH Kp light field howitzers

The EHZ 16 fuze was associated with a 58 gr picric acid exploder

At fisrt sight, the EKZ 17 fuze looks identical to the EKZ 16 fuze, but the inner mechanisms of the two models are completely different. The new fuze is still a super quick model thanks to the presence of a direct action rod system, but the design has been simplified to the extreme limit, most probably to save costs and production time in this late period of the war, when resources became more and more rare.

The mechanism is reduced to its stricty minimum : a magnesium allot rod is inserted into a hole drilled axially inside a massive cone. It carries the percussion pin on its base, placed in front of a static primer directly mounted with a detonator inside the exploder. Thge percussion pin and the primer are kept separated at rest by a safety creep spring.

The only arming system is a simple lateral centrifugal lock pushed at rest into a hole at the base of the rod by a spring, and retracting in flight under the action of the shell spin. The exploder had no specific safety device.

It was therefore a simple effect fuze (strictly super quick without any additional percussion behavior).

The massive ogive was entirely made in zinc alloy, or by assembly of a pig iron upper part and a zinc alloy base either by a thread ('EKZ 17 Zi E Gew') or by a dovetail joint made at pouring time ('EKZ 17 Zi E Guss').

The fusée EKZ 17 fuze equipped the high explosive and gaz shells (green cross, yellow cross and bluie cross) of the :

• 7.7cm FK 96 n/A and 7.7cm FK 16 fieldguns

It was delivered to the batteries with an attached 23 gr picric acid exploder, and with the rod aside and the fuze hole closed by a removable lead seal.

The EHZ 17 fuze is the howitzer dedicated version of the super quick EKZ 17 fuze. The internal devices were identical. Only the external dimensions were different, with a rounder head shape and the 57.5mm thread diameter adapted to the light field howitzer shells.

The EHZ 17 fuze equipped the gas shells and explosive shells of the

• 10cm lFH 98/09, 10cm lFH 16 and 10cm lFH Kp light field howitzers

It was delivered with the rod separated and the cone hole closed by a lead seal, and with an attached 23 gr picric acid exploder.

A variant is known with a mobile primer pellet 'EHZ 17 Bew' ('Beweglicher schlagbolzen' - mobile primer), therefore giving an additional percussion behavior (double effect fuze)

The Gr Z 17 fuze, as a instantaneous apparatus triggered by a percussion hollow rod, secured at rest by a inertia centifugal bolts system was a brand new design that will become preponderant after WW1.

This safety system that had been introduced earlier by the Navy, particularily in some heavy caliber bottom fuzes and in the 'Gr Z 16 fuze',was made of a ring of 5 imbricated centrifugal bolts that were rotating on an axis under the action of the shell spin. This movement was only made possible after the shell launch since these locks were retained by a ring until the departure shock momentum made it move backwards.

Once the safety system has been desactivated, the percussion pin attached to the head mobile brass rod was separated from the base starter-bearer just by a simple safety spring.

The top head plug was either made of brass or steel, while the body was in steel.

A variant Hb Gr Z 17 is akso known, with a cylindrical top plug.

Used with an exploder, it equipped the gaz shells and explosive shelles of the :

• 15cm sFH, 15cm sFH02, 15cm sFH13 et 15cm sFH13/L17 heavy field howitzers
• 18cm VH L/22 heavy howitzers
• 21cm Mrs (M1902), 21cm Mrs (M1910) and 21cm Lg Mrs (1916) mortars

Faced to the irruption of British tanks on the Somme battlefield as soon as summer 1916, the Germans had to quickly invent the corresponding anti-tank weapons. Re-inforced explosive charge grenades, landmines and dedicated high power rifles were distributed to the infantrymen until the end of the war, but early fights experience showed that conventional high explosive shells of the commen 7.7cm fieldguns could 'do the job' pretty well if hitting the target at sensitive places under good ballistics conditions (speed, angle).

The German Army required the developement of a specific armor-piercing 77mm shell on the basis of the conventional high explosive 7,7cm K Gr 15, named 7,7cm K Gr 15 mP ('mP' ='mit Panzerkopf'). This high explosive shell, theoritically efficient up to a 5000 m range but practically used within distances lower than 1500 m, was also containing a smoke generating composition in its bottom. It was topped by a massive extra-hard quenched steel cone able to pierce 20mm armor plates, and contained a specific delayed percussion fuze that triggered the explosion once inside the vehicle.

The Aufschlagzünder mV fur K.Gr. 15 m.P. fuze had an aluminium body. Its intern mechanism was a percussion-type one, with a centrifugal safety device similar to the one of the 'Gr Z 16 fuze', and a small delay both mechanical (the starter flame had to follow a sinuous path) and pyrotechnic (with a compressed black powder disc). The fuze and cone thread diameter was 51.5mm.

Equipped with a 25g TNT exploder, this fuze was used with the armor-piercing explosive shells of the

• 7.7cm FK 96 n/A fieldguns
• 7.7cm FK 16 fieldguns

This projectile was most probably the one used in Flequières on November 20th 1917 by the German Leutnant Müller, sole survivor of its 7,7cm FK96 n/A battery, who destroyed 16 British tanks before being killed, in one of the many famous heroïc acts of WW1.

In 1863, the Hauptmann Richter, of Spandau arsenal near Berlin, starts the design of a revolutionary pyrotechnic time mechanism, based on the variation of the length of a compressed gunpowder circular track by the rotation of a revolving disc. The 'Richtersche Zeitzunder' (Richter time fuze) is adopted by the German Army in 1869, and will participate to the Germano-French war in 1870 at the side of its two daughters, the time fuzes '8 cm FeldSchrapnellzünder c/70' and '9 cm FeldSchrapnellzünder c/70'. This will contribute to the artillery technological advance that was one of the major components of the German victory.

From the c/70 marks, the technique of separating the time system, definitely mounted on the shell at the factory, and the graze action arming system (concutor) included inside a removable threaded plug ('BolzenSchraube 70') and assembled just before the use was adopted for safety reasons.

This modification of the Richter system gave birth to several time fuzes including the SchrapnelZunder c/71 with discs, and the FeldSchrapnellZunder c/73 with a single disc, afterwards associated to a new 'BolzenSchraube 73', and all having the same reckognizable truncated cone profile.

The time fuze SchrapnellZunder 83 appeared in 1883, equipped with a new concussion system in removable plug 'BolzenSchraube 83'. Still inspired by the Richter system, its profile was however radically different with a mobile upper revolving disc having a diameter equal to the lower fixed disc, and an upper blocking bolt.

Once assembled, the top plug concussion system, with a static lower percussion pin and a mobile pellet bearing the starter, allowed the shell initial acceleration to ignite the gunpowder circular track located under the mobile revolving disc and communicating to the fuze tail by a hole in the lower static disc. The position of this hole compared to the gunpowder track was tuned by rotating the revolving upper disc and gave the exact time needed to communicate the flame to the shell main explosive via a gunpowder room located inside the fuze hollow tail.

The upper disc was graduated in hectometres from 0 to 35 with 200 m steps. Another range of graduations was engraved in the static lower disc and gave the equivalent value in seconds of flight, from 0 to 14. This secondary graduation was found useless (and most probably source of mistakes), therefore a simplified model was introduced in 1884 keeping only the upper graduations in hectometres in the upper rotating disc. This version was named the time fuze SchrapnellZunder 84.

Appeared in Germany in 1869, the Richter system revolutionned the fuzes technique with the introduction of revolving discs pyrotechnic time mechanisms. It evolved for about 20 years, giving birth to several types of time fuzes with growing complexity, before the apparition of the next generation in 1891. A very important evolution step of this evolution was reached in 1885 : until then, the Richter system evolutions only created time fuzes, but that year a new removable plug, completely redesigned, allowed to a new fuzes evolution to behave as 'double effect' fuzes, that is Time and Percussion.

This new removable plug, called 'DoppZdrSchr c/85' ('DoppelZundersSchraube c/85') was protected under a steel cap giving it a characteristic egg profile. It included both the concussion system and a percussion system copied from the 'Gr Z c/80' percussion fuzes. It was assembled before the shooting on 1- or 2- revolving discs time system bodies, similar to the new profile of the time fuzes 'Schr Zdr 83 and 84'.

A second version of removable double effect plugs version named 'DoppZdrSchr c/86' ('DoppelZundersSchraube c/86') introduced the new graze action mobile pellet and percussion pin mounted on a transversal bridge that was later to equip several fuzes beginning with the time and percussion 'Dopp Z 91'.

The fuze removable plug had mushroom shape. This upper mobile mass head included two starters placed in front of two percussion pins mounted on the static body and protected by a tulip shaped spring. The departure shock made the 'mushroom' head move back and flatten the spring, causing the starter to be triggered. The resulting flame was used both for lighting the compressed gunpowder track contained into the rotating discs time system, and to burn a big compressed gunpowder pellet located into the upper part of the plug tail and blocking the movements of the percussion graze action mobile pellet bearing the main starter. When the percussion behavior was acting, the landing shock propelled the freed percussion pellet on the percussion pin mounted on a static transversal bridge, and the flame was transmitted to the shell by a hole on the base of the plug tail.

The single rotating disc time system was a slight evolution of the one of the 'Schr Zdr 83 and 84', with hectometres graduations on the upper mobile disc (from 3 to 31.5), and equivalent graduations in combustion time on the lower static disc (from 1 to 13 seconds). These latters had been removed on the SchrapnellZunder 84 version, and were also sometimes masked under a black vernish on the new time and percussion fuzes. Whe the time behavior was acting, the portion of compressed gunpowder track burnt until the end of the selected duration, then the flame was tranmitted to the shell via 6 channels machined inside the time fuze body.

This evolution gave birth to two types of fuzes : the 2-discs 'Dopp Z c/85' time and percussion fuzes, and the single disc 'Dopp Z c/86' time and percussion fuze. This last one is by far the best known and was still sometimes used in 1914 on the shrapnell projectiles of the old

• 9cm K 73/88 field guns

These two fuzes therefore have an important role in the military pyrotechnics history, since they are the very first double effect (time and percussion) rotating discs fuzes of the German army, a prolific family that will include several variants between 1891 and 1916.

A very last evolution of the Richter system occured in 1888, with the mounting of a M 1888 exploder on the 1886 type time and percussion fuze body, mounted in the factory on the shell and still only receiving the removable concussion / percussion plug just before fire. The last pieces of this 'Dopp Z c/88' time and percussion fuze, ultimate evolution of the Richter systems with removable plugs, were used until 1916 mostly in a percussion behavior with the high explosive shells of the old

• s 12cm K heavy guns

Following and inheriting some of the technical devices of the Dopp Z c/88 fuze (including its percussion system), the Dopp Z 91 starts a new generation of German time and percussion fuzes by integrating the graze action arming system into the time fuze body, previously removable in a top plug to be mounted just before use.

Single disc time and percussion fuze made in brass and graduated from 3 to 45 hundreds of metres, this Dopp Z 91 fuze is also the first German fuze that introduces the graze action arming system based on a massive gunpowder pellet and a percussion pin protected by a tulip spring, first appeared under a primitive form with the 'Dopp Z 86' fuze, and that will be seen again in the 'Dopp Z 92', 'Gr Z 92', 'Dopp Z 92 nF', 'Gr Z 96 et Gr Z 96/04', and 'Gr Z 04' fuzes.

The graze action arming system operated both for the arming of the percussion system and the ignition of the time system. It was secured with a two rods safety pin, to be removed before the shot. This liberated the movements the graze arming system, whose massive mobile graze pellet (bearing the primer) slided back under the discharge momentum action and hit a fixed percussion pin protected at rest by a spring cap having the shape of a tulip (sometimes compared to a crown) flattened under the pellet pressure, setting fire to a big gunpowder pellet.

This pellet combustion made possible the movements of the percussion system graze pellet located in the fuze tail.

At impact, the primer-bearer cylinder was propelled against a percussion pin fixed to a transverse bridge. The resulting flame was directed backwards through the fuze tail base hole, and bursted the exploder (with high explosive shells) or communicated with the rear gunpowder chamber of the shrapnel shells via the axial tube.

The gunpowder pellet combustion flame also set fire to the gunpowder circular track of the time system, setup to the needed time by rotation of the graduated head to the desired range. After this time, the flame was communicated to the exploder gaine (for high explosive shells) or to the rear gunpowder chamber (for shrapnel shells) by 6 holes located on a circle around the fuze tail base.

This fuze was designed for the high explosive ('Gr' = Granate - Obus explosif) or shrapnel shells of the

• 9cm K 73/88 guns

When used with high explosive shells, it was associated with a separate 'Z.dlg.91' exploder (unknown picric acid charge).

The two discs time and percussion fuze Dopp Z 92 was an evolution of the Dopp Z 91 fuze. Like this latter, it was using the same classical graze action arming system secured by a two rods safety pin and based on a massive gunpowder pellet and a percussion pin protected by a tulip spring appeared in its primitive shape in the old Dopp Z 86 fuze, and the tail graze percussion system based on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge.

Just considering these components needed for the percussion fuze behaviour (selected by setting the graduated ring onto the roman cross), the Dopp Z 92 fuze was therefore almost identical to the same generation percussion fuze 'Gr Z 92'.

The major evolution compared to the Dopp Z 91 was given by the existence of two time rings instead of one, the lower one only being graduated (from 1 to 28 seconds for the first version).

Entirely made of brass, it was developped in several versions :

• Dopp Z 92 : initial version, graduated from 1 to 28 seconds
• Dopp Z 92 o Vorst : same one without safety pin
• Dopp Z 92 F H : graduated from 5 to 56 hundreds of metres, dedicated to athe M98 shrapnel shell of the 10cm light field howitzer
• Dopp Z 92 f10cm K : graduated from 1 to 26 seconds, dedicated to different 10cm guns
• Dopp Z 92 K15 : graduated from 1 to 26 seconds, dedicated to different 15cm guns, but fully identical to the Dopp Z 92 f10cmK
• Dopp Z 92 lg Brlg : graduated from 1 to 41 seconds for longer ranges
• Dopp Z 92 lg Brlg o Az : graduated from 1 to 41 seconds for longer ranges, without percussion system for anti-aircraft use.

This fuze and its versions were extensively used with numerous projectiles during WW1. It was mounted on shrapnel and high explosive shells of the :

• 9cm K 73/88 guns
• 9cm BAK anti-baloons guns
• 10cm K, 10cm K97, 10cm K04 and 10cm K14 guns
• 10cm KISL guns on shielded carriage, 10cm TK guns under turret, kz 10 cm TK short guns under turret, and 10cm TK Verst guns under reinforced turret
• 13cm K09 guns
• s 12cm K heavy guns
• Lg 15cm K guns
• 15cm RK and lg 15cm RK Ringkanone guns
• 15cm sFH, 15cm sFH02, 15cm sFH13 and 15cm sFH13/L17 heavy field howitzers
• 15 cm TH howitzer under turret
• 15cm KISL guns on protected carriage and 15 cm Verst KIRL guns on wheeled carriage
• 15 cm KIKstI 07 guns on coastal carriage
• 21cm RK Ringkanone guns

The reason why this new version of the classical Dopp Z 92 fuze is far from being evident, since the inner devices - graze arming system and percussion system - of this two discs time and percussion fuze Dopp Z92 nF ('n.F.' = neue Form - nuw shape) look identical, as seen on the wartime schemes. It was also equipped with a two rods safety pin blocking the graze safety system.

The only noticeable differences were in the external shape, more round, and sometimes the material used that could be brass, but also aluminium.

The Dopp Z 92 nF was graduated from 2 to 41 seconds on its lower ring, like the elongated combustion time Dopp Z 92 lg Brlg fuze version, justifying the slightly modified Dopp Z92 lg Brlg nF name that was sometimes used as well. A version without safety pin was developped with the Dopp Z92 nF o.Vorst. fuze

This fuze was mounted on the shrapnel shells, incendiary shells and high explosive shells of the :

• 9cm K 73/88 guns
• 10cm K, 10cm K97, 10cm K04 and 10cm K14 guns
• Lg 15cm K guns
• 15cm sFH, 15cm sFH02, 15cm sFH13 and 15cm sFH13/L17 heavy field howitzers

The two discs time and percussion fuze Dopp Z 96 was a device specifically designed for the 7.7cm FK96 n/A fieldgun, standard light gun of the IInd Reich field artillery in 1914.

In its initial version graduated from 0 to 50 hundreds of metres, this fuze was an other variation of the classical two discs time and percussion system of the Dopp Z 92 fuze, with the same classical graze action arming system secured by a two rods safety pin and based on a massive mobile pellet and a static percussion pin protected by a tulip spring, and the tail graze percussion system based on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge. The time system, ignited by the graze action arming system, was a two discs one. The upper disc, with the graduation engraved, was static and attached to the fuze body.

Despite these similarities, the will to develop a lightened fuze specifically adapted to the shells of the light fieldgun was obvious, illustrated both by the inner components dimensions that were reduced, and by the choice of the materials, only steel and aluminium instead of the heavier brass, long before the war economical restrictions imposed this choice on other German fuzes.

Later a new version Dopp Z 96 nA ('nA' = neue Art - new design') was graduated from 0 to 53.5 hundreds of metres, then in subsequent versions from 0 to 71.5, 0 to 65 and 0 to 70 hundreds of metres. Externally very similar to the earlier version but for the graduations, in included indeed a brand new graze action arming system, this time composed of a lighter mobile graze pellet separated from the static percussion pin by a spring instead of the usual 'tulip'. This version did not include any safety pin.

That fuze in all its versions was used in big quantities? It was mounted at the beginning of the war on the shrapnel shells and high explosive shells of the :

• 7.7cm FK96 n/A and 7.7cm FK16 fieldguns.

Used as is for the shrapnel shells, it was completed by an additional 'Z.dlg.92' screwed exploder containing 20g picric acid for the high explosive shells.

The Dopp Z 96 fuzes can be observed frequently nowadays in museums or on former battlefields, but in this latter case the surviving bodies are often badly corrded, because of the not so noble nature of its components.

Little is known about the Dopp Z 98 fuze that was developped exclusively for use with the howitzer shell '10cm FeldHaubitze schrapnell 1898', and was very likely an evolution of the Dopp Z 92 fuze.

Graduated from 2 to 56 hectometers, and equipped with a tail detonator like the other 'Dopp' zunders, it has been abandoned before the war at the same time than the shell it has been designed for. However, some fuzes of this type can still be observed nowadays on battlefield (including on the former eastern front), so it is probable that some old stocks of these ammunitions were used anyway during WW1.

That fuze was used with the shrapnell shells of the :

• 10cm lFH 98/09 feld haubitze (105mm field howitzer)

Just like many other nations before the WW1, the German Army developped for its field artillery different 'universal shells' that could behave as high explosive or shrapnel shells. Complex and never as good as the pure high explosive or shrapnel shells, this ammunition had another disadvantage to require the use of sophisticated fuzes able to activate the different functions of the shell. The HZ 05 fuze was therefore designed for the universal shells of the light field howitzers 10cm lFH 98/04. Later, the KZ 11 fuze will follow for the universal shells of the 7.7cm FK96 n/A light field guns.

Technically, the original HZ 05 fuze was a quadruple effect fuze :

1. time effect for shrapnel shell behavior
2. percussion effect without delay for high explosive shell behavior
3. percussion effect with delay for high explosive shell behavior
4. time effect for high explosive shell behavior

This particularly complex system was made of brass, with aluminium time discs, brass delay setting and flame distribution disc, and steel or brass cap.

It was using technologies introduced by earlier fuzes :

• The axial graze action arming system was inspired from the 'Dopp Z 92' fuze, based on a massive mobile pellet and a static percussion pin protected by a tulip spring, secured by a two rods safety pin.
  
  
• The time system was a two discs one similar to the one of the 'Dopp Z 92' fuze, with static upper disc and mobile lower disc graduated from 3 to 53 hundreds of metres (later extended to 63, then 70 hundreds of metres for the 'HZ 05 l B') version. At the end of the combustion time preset by rotation of the graduated lower disc, the flame could be directed by the use of a valve commanded by the distribution mobile disc either to the exploder for a time high explosive behavior (disc position on the graduation marked 'nur G. Bz.'), or to a gunpowder ring located around the fuze tail and pierced with 6 holes for a shrapnel time behavior (disc position on the graduation without legend). The mobile disc setting was fixed by the means of an internal needle actioned by the departure momentum.
  
  
• Finally, the HZ 05 fuze included a percussion system with optional delay inherited from the Gr Z 96/04 fuze, based on two identical parallel graze percussion systems designed on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge, one directly connected to the exploder, and the other one through a compressed gunpowder pellet delay. The selection of the delayed or non delayed percussion system was realized by rotating the distribution mobile disc (position on 'm.V.' mark for delayed system).

This fuze exploder, loaded with 85 gr. picric acid, was aquipped of a safety device that will be later used on many other German fuzes, based on an interruption of the flame communication channel to the primer by the means of a lateral mobile drawer actioned by the centrifugal force created in flight by the shell spin around its axis.

Another interesting specificity was given by the fact the exploder could be burst also by the time system by a channel linked to the lower time disc through a small delay, so that it would explode just after the fuze is ejected from the shell behaving in shrapnel mode.

The relative lack of efficiency of the universal shells induced their progressive removal from the Army (obsolete in July 1916) as well as their specific fuze, but the design of the HZ05 was later simplified in order to give birth to two derivated versions intensively used during WW1 :

• The HZ 05 Gr. fuze (for 'Granate' - high explosive shell) was a triple effect fuze (percussion without delay, percussion with delay, time) dedicated to high explosive shells or gaz shells. It was a simplified HZ 05 fuze with the same graze action arming system, percussion system and time system, but lacking the 6-holes gunpowder ring around the fuze tail. The mobile distribution disc was only used to select the optional delay, so it was now only marked with a line without legend and another one marked 'm.V.'.
  Graduated from 3 to 53 hundreds of metres, it also existed in a version graduated from 3 to 63 hundreds of metres then from 3 to 70 hundreds of metres, in which case it was often named HZ 05 Gr.l B.
  
  
• The HZ 05 Schr. fuze (for 'Schrapnel') was a double effect fuze (time and percussion without delay) dedicated to shrapnel shells. It was also a simplified HZ 05, with the same graze action arming system and time system as the original fuze, but whose double percussion systeme and secured detonator has been replaced by a single undelayed percussion system based on a cylindrical graze pellet bearing a starter and a static percussion pin transverse bridge located in the fuze tail. The flame was therefore communicated to the shrapnel shell rear charge through the central tube either by the percussion system primer in the fuze tail, or through the 8 windows of the gunpowder ring around the fuze tail linked to the time system. There was no more mobile distribution disc, its volume being integrated into the steel or zinc alloy fuze cap.
  
  

Depending on the version, the HZ 05 fuze was mounted on universal shells, shrapnel shells, high explosive shells or gaz shells of the :

• 10cm lFH 98/09, 10cm lFH 16 and 10cm lFH Krupp ('Kp') light field howitzers

The vesrion used with high explosive shells were associated with a 55 gr picric acid exploder.

Just as the HZ 05 fuze that had been introduced for similar ammunitions of the light field howitzers, the use of the German 'universal shells' of the light field gun 7.7cm FK96 n/A needed the design of special fuzes able to command the different behaviors of this polyvalent shell (with lead balls and rear charge for shrapnel behavior, reinforced wall thickness and TNT filling between the balls for a high explosive behavior).

For this purpose appears in 1911 the 'KZ 11' fuze, designed in light materials just like the Dopp Z 96 fuze of the shrapnel shells from the same fieldgun, but much more sophisticated. It was a triple effect fuze :

1. time effect for shrapnel shell behavior
2. percussion effect without delay for high explosive shell behavior
3. time effect for high explosive shell behavior

It was entirely made in aluminium and steel.

The KZ 11 introduces a brand new system integrating the graze action arming system and the percussion system safety functions, that will be used from then in numerous other fuzes like the LKZ 11, KZ 14, HZ 14 and Gr Z 14 : It includes two parallel vertical cylindric rooms located under the fuze cap. One of them contains the graze action arming system, with a light mobile pellet bearing the primer separated at rest from a static percussion pin by a simple spring, without safety pin. At the shot departure, the mobile pellet compressed the spring under the momentum action, and the resulting flame is communicated to both the gunpowder ring of the first time ring of the time system, and to the second cylinder.

The safety device of the percussion system is located in this second cylinder : a big compressed gunpowder pellet forbids the movement of a vertical stem blocking the percussion system located inside the fuze tail. When the flame communicated by the time pellet system burns this gunpowder pellet, the stem is liberated and pushed up by a previously compressed spring. The gasses emitted by this consumption are ejected outside the fuze by a gaz escape.

The time system was a two discs one : the upper, static, was graduated from 2 to 50 hundreds of metres, and the lower, mobile, with the setup rule and on each side a correction system graduation from '-8' ('L') to '+8' ('K'). The flame emitted by the lower disc at the end of the combustion time could be directed by a valve either to the exploder for high explosive behavior or the shell (position 'G' - 'Granate'), or to a circular gunpowder track around the tail and pierced with 6 windows communicating with the shell rear charge for a shrapnel behavior of the shell (position 'S' - 'Shrapnel'). It must be noted that a 'KZ 11 lB' version with a combustion time elongated to 70 hundreds of metres existed too.

The percussion system located in the fuze base included a mobile pellet bearing the primer (blocked at rest by the stem commanded by the arming system), and a percussion pin protected by a safety spring.

The high explosive behavior of the shell required the association of the KZ 11 with a 23 gr picric acid exploder.

It was mounted on the universal shells of the :

• 7.7cm FK 96 n/A fieldguns

This high sophistication had a cost : this fuze was one of the most complex of the period, with around 105 elementary pieces. The universal shell was declared obsolete in 1916, but new KZ 11 versions adapted to more conventionnal ammunitions, high explosive or gaz, ground use or anti-aircraft, were developped on its basis :

• KZ 11 Gr dedicated to the high explosive shells and gaz shells of the 7.7cm FK96 nA and 7.7cm FK 16 fieldguns, therefore without the flame divesrion selector nor fuze base winows. Graduated from 0 to 50 hundreds of metres and sometimes marked KZ 11 Gr kB. Its head was somehow more ogival
• KZ 11 Gr lB, identical to the latter, but with extended graduations from 0 to 72 hundreds of metres ('lange Brennlänge')
• KZ 11 Gr nur Bz without percussion system ('nur Brennzünder') for use in anti-aircraft missions with the 7.7cm FK 96 nA fieldguns
• KZ 11 Gr lB o Az without percussion system and graduated from 3 to 30 seconds for use with the 7.62cm Russian guns in anti-aircraft missions

Externally, the LKZ 11 Gr fuze looks like a simple aerodynamic improvement of the KZ 11 Gr fuze (version of the KZ 11 fuze dedicated to the high explosive shells whose time or percussion systems flame is directly communicated to the detonator), with an elongated cap allowing it to be mounted on streamlined shells. However, this fuze differs by some noticeable changes.

The graze action arming system and the time system was kept identical to the ones of the KZ 11 Gr. In the original model, the mobile upper disc was graduated from 4 to 72 hundreds of metres. Like the KZ 11, it was made of steel and aluminium, with sometimes some brass for the body, and zinc alloy for the ogival cap.

The percussion system safety devices with blocking stem and safety spring had been replaced by a centrifugal system with two bolts with springs blocking the graze pellet and pulled back by the shell spin.

Moreover, the exploder was equipped with an arming system with centrifugal lock, preventing the flame of the percussion primer or the one from the time system to communicate with the exploder explosive before an obturating lock rotates under the action of the centrifugal force.

Associated with a 23 gr picric acid detonator, the LK Z 11 Gr was mounted on the high explosives shells of the :

• 7.7cm FK 96 n/A and 7.7cm FK 16fieldguns

Another version is also known :

• LKZ 11 Gr kB, graduated from 0 to 50 hundreds of metres (Kurze Brennlänge - reduced burning time).

In 1915, a new triple effect fuze for the high explosive shells of the heavy artillery appeared, named Dopp Z 15. Its graze action arming system was the classic one based on based on a massive gunpowder pellet and a percussion pin protected by a tulip spring, gunpowder pellet blocking the percussion system by a stem and secured by a two rods safety pin. This system was inspired by the 'Dopp Z 92' fuze.

The two discs time system communicated the flame to the exploder primer. The mobile lower disc was graduated from 2 to 41 seconds. Its movements were blocked at shell departure by a needle activated by the shock momentum.

The percussion system was made of two apparatus, one with delay and the other one without. The delayed device was secured by a centifugal bolt whose movements were made possible by the combustion of a gunpowder pellet triggered by the safety graze system. The delayed device was lateral and blocked by a mechanical system (stem and gear) commanded by a setting stud on the fuze head. Set on the 'm.V.' position, the setting stud deactivated the system without delay and the fuze acted with a delay. Set on the 'o.V.' position, both devices were activated, so the fuze acted without delay.

The attached big 90 gr picric acid exploder was equipped with a safety system identical to the one of the Gr Z 04 fuze with an isolated detonating room (10 gr picric acid in the mobile charge).

The Dopp Z 15 fuze was mounted on the high explosive shells, aiming shells or smoke shells of the :

• 10cm K, 10cm K 04 and 10cm K 14 guns.
• 13cm K 09 guns
• lg. 15cm K guns
• 15cm sFH, 15cm sFH 02, 15cm sFH 13, and 15cm sFH 13/L17 heavy field howitzers

The Dopp Z 15 fuze had a brass body and a steel cap, and an upper ogive either in brass, steel or zinc alloy.

Some specimens were marked 'Dopp Z 15 umg.' ('umg. = umgeändert - transformed), with no known reason.

Although principally using high explosive shells rmed with percussion fuzes for its combat missions, the German Navy also had to equip with anti-personal ammunitions in order to destroy the enemies manning the ship decks or onshore defenses, or for anti-aircraft use. Therefore the Marine arsenals mnufactured time and percussion fuzes specifically designed for the long barrel marine tubes with long range end high initial acceleration.

This context is the reason of the apparition of the Dopp Z S/43 ('S/43' as '43 sekunden') time and percussion fuze. Modest in size and pretty sophisticated, it resisted well to the violent accelerations produced by the long Navy guns, and allowed remarkable long combustion times thanks to the use of a slow burning powder composition for the time tracks. It had a 50 mm diameter thread on its base, adapted to the standard of the marine shells.

This fuze concussion system located into the fuze ogival head was based on a top mobile pellet bearing a primer and projected backwards onto a static percussion pin under the effect of the shock of departure. The safety of the concussion system was insured by the means of a to spring retaining the movements of the mobile pellet from the top, a thin soft metal plate retaining its movements from the above, and in some models a simple rod traversing safety pin.

The concussion system ignition transmitted the flame to the combustion track start of the time system (through radial channel equipped with a small pyrotechnic delay to avoid prematures in the tube), and to a compressed gunpowder pellet located under the concutor percussion pin and blocking at rest the movements of the percussion system.

The time system was composed of two discs, the upper being static and the lower being mobile and graduated from 1 to 43 seconds by 0.2 seconds steps.

The percussion system was based on one of the classic german types with a static percussion pin located on a transverse bridge and a graze action pellet bearing the percussion primer and blocked at rest by a safety compressed gunpowder pellet. It did not have any safety spring in between the two pieces.

At the end of the selected combustion time and/or at impact, the flame of the time system and/or tye percussion system was communicted to the rear gunpowder room, setting fire to the shell. When used with high explosive shells, this fuze was associted with a 'Gr. Zdlg C/98 m. 0.05 Sek. Verz.' detonator M 1898.

The Navy time and percussion fuzes were also used with the shells of the Navy tubes adapted to the Army during the war as well as the ones of the flak, although keeping their Marine typical 50mm thread.

The Dopp Z S/43 fuze mainly equipped the high explosive shells of the :

• 10.5cm S.K. L/35 guns
• 12.5cm Mrs L/6.3coast mortars
• 15cm K L/30 heavy guns
• 15cm S.K. L/40 heavy guns
• 8.8cm flak and 10.5cm flak anti-aircraft guns

Some variants are known :

• the 'Dopp Z S/43' without safety pin
• the 'Dopp Z S/43 m. Vorst.' with a single rod safety pin
• the 'Dopp Z S/43 Sp.' ('Spitze') with an elongated fuze head
• the 'Dopp Z S/43 o. Az.' without percussion system and therefore purely time fuze, dedicated to the flak

Shape varians are observed for the intermediate disc between the shell ogival head and the static disc. In some models this piece is cylindrical, interrupting the fuze profile with some kind of a circulat groove. In other models its perimetric sides are machined so that they hace the same angle than the surrounding pieces, therefore not interrupting the smooth fuze ogival shape. Initial models were all made in brass. War economy also affected this fuze, with the later use of cheaper steel for the fuze head and the intermediate disk.

The ships of the German Navy were using 8.8cm L/30, L/35 and L/45 for the anti-torpedo defense, the attack of ship decks personnals, and later the anti-aircraft defense.

The time and persussion fuze Dopp Z S/26 ('S/26' for '26 sekunden') has been specifically created around 1916 to equip the shells of these weapons. Its inner organization was almost the same as the 'Dopp Z S/43' fuze, but for the use of a gunpowder with a classical combustion speed for the time track, and the presence of a safety spring in the percussion pyrotechnic mechanism, preventing during the flight an unwanted movement of the graze action pellet blocked before the shot by a safety compressed gunpowder pellet. Its mobile disc was engraved with 1 to 26 seconds graduations with 1/5th steps, and a cross for selecting the pure percussion behavior.

This fuze, initially designed for the Navy and used as such, was also used for the anti-aircraft applications ('flak').

The Dopp Z S/26 mainly equipped the high explosive shells of the :

• Navy Quick firing guns of 8.8cm anti-torpedo, anti-aircraft et anti-crew
• Anti-aircraft guns of 8.8cm flak and 10.5cm flak

One variant is known :

• the 'Dopp Z S/26 o. Az.' fuze, without percussion system and therefore purely time fuze, dedicated to the flak

There was also a shape variant with a sharper ctop cap, and material variations, with steel or Zamac partially replacing the brass usually used for the whole fuze in the early productions.

Several variants of time and percussion fuzes with different combustion times were adopted by the German Navy. Together with the 'Dopp Z S/26' and 'Dopp Z S/43' fuzes, one can also find the Dopp Z 56 fuze. The internal organisation of this fuze was very similar to the one of the other Marine fuzes.

Very little information can be found for it, for sure a clue indicating its use was not frequent. As it is a Krupp made fuze internal Krupp designation would be "Dopp.Z. 56 hm" but these Krupp designations are rarely seen in any documents. Some wartime allied intelligence documents are naming it "Dopp Z ? (56)" without any official identification marking, and interprete the 0 to 56 graduation marks as seconds. This is a mistake that has been demonstrated by one of this website's contribuor Stefan Wagner. The scale of the time ring is graduated in hectometers (numbers) and half hectometers (line)

Hectometer scales can be easily distinguished from time scales. Time scales are constant/linear: The distance from one second to the next one the ring always equals, as the combustion speed of the gunpowder track is constant. Distance scales are logarithmic because the projectile slows down on it's travel. The first hectometers on the ring have a small distance the last hectometers have a much larger distance on the scale.

The Dopp Z 56 fuze mainly equipped the high explosive shells of the :

• 15cm S.K. L/40 heavy guns

I saw on a forum an information stating this fuze has been in use with the light minewerfers. This seems highly improbable as the design of the trench artillery fuzes is fundamentally different from the one of the classic artillery fuzes, given the radically different balistic conditions.

The Bd Z 06 'Boden Zunder' - 'bottom fuze' was a device that was screwed on the bottom of heavy explosive shells, whose nose cone was solid and massive in order to improve the penetrating properties of the projectile.

Entirely made of brass, this fuze had two percussion systems aligned vertically in the same central axial channel : From the fuze tail to the fuze base, this pyrotechnic column was composed of

• a static percussion pin for the delayed system, attached to the fuze tail bottom
• a mobile graze pellet carrying one primer at each of its extremities, the one in front of the static percussion pin being the delayed system primer, and the one at the other side being the non-delayed system one
• a gunpowder delay composition channel in the mobile graze pellet, linking the delayed percussion system primer to the detonator
• a small detonator in the mobile graze pellet, under the non-delayed system primer
• a mobile graze pellet carrying the non-delayed sytem percussion pin.

The arming system was common to both the mobile pellets (the one carrying the two primers and the percussion pin one), blocked at rest by the same compressed spring bolt hold by a gunpowder pellet. This pellet was ignited by a primer hit by a pin at departure time under the action of the deformation of a diaphragm located in the fuze base by the pressure of the gun gasses.

A fuze base gaz escape also existed linked to all the internal pyrotechnic devices, closed at rest by a compressed gunpowder pellet burnt by the gun departure hot gasses.

In the case of a non-delayed behavior, the non-delayed system mobile graze pellet carrying the pin was liberated by positionning the bottom selector on the 'o/V' mark (allowing the flame of the diaphragm arming system to burn a gunpowder pellet blocking a lock). At the arrival on the target, the top (delayed) percussion system was triggered by having the mobile graze pellet primer hitting the static percussion pin, while the rear (non-delayed) mobile graze pellet percussion pin went forward to hit the rear primer. This latter instantaneously ignited the detonator charge.

In the case of a delayed function, the non-delayed system mobile graze pellet carrying the pin was kept static by positionning the bottom selector on the 'm/V' (preventing the lock gunpowder to burn). At the arrival on the target, only the top (delayed) percussion system was triggered by having the mobile graze pellet primer hitting the static percussion pin. This set fire to the delay channel, 0.3 seconds before bursting the detonator.

This fuze also integrated a detonator safety system. The detonator located in the mobile graze pellet was positionned at rest in an isolated detonation room, not communicating with the fuze outside. On the contrary, when the mobile graze pellet was projected onwards, this positioned the detonator in front of windows communicating with the exploder (unknown charge) in wich the fuze tail was inserted.

The Bd Z 06 fuze was used with the high explosive shells of the :

• 13cm K 09 guns
• 15 cm K.I.Kst L 07 guns on coast defense mounting Mle 1907
• 21cm Br Mrs (bronze) and 21cm Mrs (M1902) mortars
• 28cm Kst.I.Kst.H.L coast howitzers

Although externally pretty similar to the Bd Z 06 fuze from 1906, the 1910 Bd Z 10 fuze was an complete re-design of the internals. In the new fuze, the complex twin percussion apparels systems has been replaced by a single non delayed percussion system linked to the detonator via three selectable channels for a non delay, small delay or long delay behavior)

The massive percussion system, parallel to the fuze axis, had a static percussion pin attached to the fuze bottom, and a massive mobile graze pellet carrying a primer, whose forward movements were made easier by 8 steel balls guiding the pellet base tail. This percussion system was secured at rest by a compressed spring lateral bolt hold by a gunpowder pellet. This arming system was the same as the one of the Bd Z 06, activated by the gun gasses pressure through 6 holes in the fuze base onto a diaphragm, whose deformation projected a pin to a small primer.

Like in the Bd Z 06 too, a fuze base gaz escape also existed linked to all the internal pyrotechnic devices, closed at rest by a compressed gunpowder pellet burnt by the gun departure hot gasses.

The flame created by the percussion system was transferred to the detonator via three channels, a long delay channel always open, a small delay and a no delay ones whose opening was selectable by rotation the fuze base delay selector :

• when set to 'o.V.', the selector opened the way leading to the no delay channel and closed the way leading to the small delay one. Therefore the non-delay channel let the flame reach the detonator before the long delay channel could do so, giving way to a non-delay explosion.
• when set to '1.V.', the selector closed the way leading to the no delay channel and opened the way leading to the small delay one. Therefore the small delay channel let the flame reach the detonator before the long delay channel could do so, giving way to a small delay explosion.
• when set to '2.V.', the selector closed both the ways leading to the no delay channel and the small delay one. Therefore the only available channel for the flame reaching the detonator was the long delay one, giving way to a long-delay explosion.

The detonator, transverse to the fuze axis, was secured by a safety mechanism based on a mobile piston shutting the communication between the detonator and a lateral opening in the fuze tail. This piston was blocked at rest by a small ball blocked by a gunpowder pellet whose combustion was triggered by the diaphragm arming system. A compressed spring pushed the piston forward as soon as the ball could set back, bringing a communication channel between the detonator and the lateral opening.

The Bd Z 10 fuze could be associated with two sizes of exploders : 100 gr or 25 gr picric acid.

When assembled with a big 100 gr picric acid exploder it was often marked lg Bd Z 10 ('lg' = 'lang', refferring to the long exploder). It was then used with the high explosive shells of :

• 13cm K 09 guns
• 15cm KISL protected mounting guns
• 15 cm K.I.Kst L 07 guns on coast defense mounting Mle 1907
• 21 cm RK ringkanone guns
• 21 cm Br Kst Mrs bronze coast howitzers
• 21cm Br Mrs. (bronze), 21cm Mrs (M1902), 21cm Mrs (M1910) and 21cm Lg Mrs (1916) mortars
• 28cm Kst.I.Kst.H.L coast howitzers

The Bd Z 10 fuze could also be associated with a smaller 25 gr picric acid exploder (without any other change), and was in this case marked 'kz BdZ10' ('lg' = 'kurz', refferring to the short exploder). It was then used with the high explosive shells of :

• 10 cm Kst K coast guns
• 10 cm Kst KIRL coast guns on wheeled mounting
• 21cm Mrs (M1902), 21cm Mrs (M1910) and 21cm Lg Mrs (1916) mortars
• 28cm Kst.I.Kst.H.L coast howitzers
• 30.5cm Kst.H coast howitzers
• 42cm M-Gerät and 42cm Gamma-Gerät heavy howitzers