Direction for firing in field and
mountain QF artillery
The
rearmament of the Bulgarian artillery with modern quick-firing guns, occurred
in 1904, required the introduction of new firing rules to replace those
published only two years before, in Between
1905 and 1908 the new guns were intensively tested and finally the revised
standard version of the Наставление
за
стрелбата
въ полската и
планинската
скорострелна
артилерия was
published in 1908, followed in 1909 by a detailed exposition written by col.
Kalin Naydenov (Новото
наставление
на стрлбата
в полската и
планинската
артилерия на
практика, Sofia 1909),
that covered only the first four section of the Direction. Basically
the direction dealt with the quick-firing guns, but gave also some
instructions about the employment of the old not quick-firing guns on the new
conditions. It included five sections : I.
Ballistic data concerning guns and projectiles. II.
Measure of the dispersion and calculation of the
corrections for shrapnel fire. III.
Preparation of fire : determination of the range,
direction of fire from covered positions, measure of the angle of site,
observation of the bursts. IV. Determination
of the primary data: fire for adjustment and fire for effect. V.
Kinds of fires : demonstrative, training and
fighting fire. Instructions for writing firing reports. The
direction included also the firing tables of all kinds of field and mountain
guns adopted by the Bulgarian artillery. Generalities
rules.
The artillery took part in the combat only with its fire. Quick-firing
artillery shoot to break down any resistance with a rapid and powerful fire
of short duration from opportune and well chosen positions at the most
important targets in a particular moment. With the
enormous increase in fire effect due to the introduction of magazine rifles
and quick-firing artillery, troops, and especially infantry, did not expose
themselves except for a very short time to the artillery fire, utilizing to
the utmost all available cover. To succeed, the fire for effect should begin
as far as the objectives appeared, and consequently the process of adjustment
should be shortened as much as possible. The Direction did not prescribed precise ranging against a definite
target, but to cover a considerable extent with shrapnel bullets, to block
every attempt to every object to move about or remain there uncovered,
without being put out of action. Projectiles. The Direction
examined all kinds of projectiles employed both by quick-firing and not
quick-firing guns, describing in detail their main features and their
effects. It considered also the
projectiles fired by 120mm not quick-firing howitzers assigned to the heavy
field artillery, and by the 105mm quick-firing light field howitzer, that at
that time the Bulgarian Army intended to built in France. At that time the
120mm not quick-firing howitzer was equipped only with shrapnel and common
shells, but later it received also Schneider built torpedo shells. Time shrapnel was
regarded as the main projectile of field and mountain artillery against all
animate targets that were not under cover. It contained about 300 lead bullets (200 for
mountain guns), that, spreading out from the point of burst in the air,
formed a sheaf and covered a space of considerable width and depth.
Consequently shrapnel fire did not demand a complete adjustment, being
sufficient to approximate to the target. In addition shrapnel contained a
smoke-producing composition called colophan to make the burst more visible
and facilitate the adjustment. This characteristic could be used also for
tactical purposes. The rapid fire of a quick-firing battery with smoke-producing
shrapnel made a dense cloud of smoke in front of the enemy line, preventing
him from taking an effective aim or protecting the attacking troops. Shrapnel
was equipped with a double action fuze, which permitted not only to change at
will the point of burst (time fire), but also to burst on graze (percussion
fire). When the shrapnel burst, the body fell 10- At a range of 2500 m
and with an interval of burst of 50 m, the average density of hit was : – 75mm
QF and 87mm not QF field guns 1.5; – 105mm
QF field howitzer 1; – mountain
guns 0.5. Percussion shrapnel usually burst after having hitting the ground
or after having ricocheting. In this way it changed a little its direction
and greatly reduced its final velocity and therefore the living force of the
bullets. Against animate targets it was less effective than time shrapnel,
but it could destroy small inanimate targets like bridges, thin walls,
fences, light shelter. It could be used against shielded artillery, when high
explosive shells were lacking. |
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Percussion high
explosive shell was used either against shielded batteries at a range of |
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Even at close range and with hard ground it
required a very careful adjustment, since its effect was very local. It could
be successfully employed to harass the occupant of the hostile trenches,
waiting the moment when the troops were forced to man their parapets. Having
a very sensitive fuze the H.E. shell burst as soon as hit the ground, without
ricocheting, making two cones of dispersion : the lower one hit the target,
while the upper one scattered upward and was almost inoffensive. The angle of
the cone of dispersion was between 110°-140°. The explosion gave a very great
number of splinters (even 500-700), which, reaching a very high speed (up to
600 m/s), could inflict disabling wounds, if the target was at 30-40 paces.
Their action in deep, however, was small and at a distance of more than 50
paces from the bursting point they were almost useless. Torpedo shell was the most powerful projectile of the field
artillery. It was employed by the field howitzers to destroy every kind of
inanimate targets. It was equipped with a delay-action fuze, when it should
penetrate the roof of splinters proof before exploding, but it was equipped
with a simple percussion fuze when it should explode on impact. It was able
to messed up earthworks, destroy armoured shelters and sound buildings and
sweeping away every kind of obstacle that might meet with
on the battlefield. The most powerful
effect was produced when it fell at an angle greater than 30° on a stiff
ground. In this case it made a crater Field howitzer shrapnel had almost the same action of gun shrapnel,
the main differences were : – the interval of burst should be lower, since
its trajectory was steeper; – the density of hits was greater and the beaten
area wider, since it contained more bullets; – the power of penetration of the bullets was
greater, since they were heavier. Firing at uncovered animate targets, the
howitzers employed the full charge to obtain a sloping trajectory, on the
contrary, firing at troops under cover, they employed the low charge to
obtain a steep trajectory. Common shell was used only by not quick-firing guns against
animate and inanimate targets. Against shielded guns it was preferred to the
shrapnel. Against animate targets at mid range, it was effective when it
burst no more than 20 m in front of the target and no more than 3-4 m behind
it. At close range and against high targets, the extent of the area of burst
could be little greater, increasing up to 30 m. Against wide animate targets
it was employed only out of the sphere of action of the shrapnel. At
mid ranges it could pierce an earthwork Case shot used only by not quick-firing guns to beat off close
attacks at a range of 400 m at most. The cone
of dispersion of the balls had an angle of opening of 6° with an axis of
dispersion of 1/10 of the length and a range of only 400 – Shrapnel
fire. Shrapnel
adopted by |
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The effect of shrapnel fire was somehow
affected by the range, the interval of burst, the height of burst, the size
of the targets, the ground and the shelters. Increasing the range, the shrapnel fire became less effective, since the
velocity of the bullets decreased and, with it, their striking power; the
trajectory became steeper and the bullets could not ricochet on the terrain;
the combustion of the fuze became less regular; the extent of the effective
area decreased. The greater effect was obtained up to |
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Shrapnel
bursting too far in front of the target and those bursting in the air above
the target produced little of no effect. Therefore the interval of burst of the shrapnel, i.e. the horizontal distance
between the point of burst and the target, should be carefully set, since
shrapnel were really effective only if they burst close to the target : the
greater was the interval of burst, the greater was the dispersion of bullets,
the less the density, and consequently the smaller the number of hits. The
normal interval of burst was put at The
height of burst, i.e. the vertical distance of the point of burst
above the horizon, should be carefully adjusted, taking into account
that the combustion of the fuze was not always uniform. A probable deviation
of The
effect of shrapnel fire increased with the size of the targets : the
greatest was their surface, the more vulnerable they were. The density of
hits required to hit a target could be easily obtained, knowing the area of
surface exposed, which, according with the estimate of that time, were as
follows : 1)
horse and rider, side view – horse and rider, front view – 2)
skirmisher, standing – skirmisher, kneeling – skirmisher, lying down – skirmisher, covered – Since shrapnel burst in air, the effect of
time fire depended less upon the character
of the terrain than any other kind of projectile. Nevertheless it had
some influence. Indeed, if the terrain in front of the target was level and
hard, the bullets would ricochet easily and loose little of their velocity,
being able to produce still effective hits. But if it was broken or soft, the
majority of the bullets would imbed themselves in the ground. The same
happened when the slope of ground was rising at the target. In addition the
width of the cone of dispersion was greatest when the slope of the ground was
equal to the angle of fall of the unexploded shrapnel. As the slope of the
ground increased, the width of the zone of dispersion decreased. When the
slope of the ground was greater that the angle of fall of the lowest bullet,
no effect was produced at all. Shrapnel fire was ineffective against troops under cover, i.e. located immediately
in rear of parapets or any kind of obstacle, since behind them there was a
blank space, where the bullets could not penetrate or were powerless and
ineffective. The depth of the blank space could be calculated multiplying the
height of the cover by 8, 6, 4, 3 for ranges of 1, 2, 3, 4 km respectively.
The closer the range, the most sloping the trajectory, the broadest the blank
space : with a cover Shrapnel
fuze correction. Shrapnel
usually employed the double-action delay fuze. With quick-firing field guns
the fuze was adjusted mechanically with a special fuze-setter,
while with not quick-firing guns it was set manually. For quick-firing field guns the fuze was calibrated with a height of
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Preparation of fire.
The primary firing data, that should be determined, were : 1) range, 2)
deflection, 3) angle of sight – for indirect laying, 4) corrector – for time
fire, 5) width, depth and kind
of the target. The
range to the target could be
measured on a map, or obtained by telemeter, battery telescope or field
glasses, or estimated by eye or by sound. While previously the distance was
estimated mainly by eye, this Direction
focused its attention to the use of the rangefinder. When it was published the Bulgarian Army employed
mainly the Souchier prismatic telemeter, adopted also by the Russian Army,
but the Goerz rangefinder The range according with the
effectiveness of the fire were : – for
field guns: up to 1500 m close, from 1500 m to 3500 m mid, more than 3500 m
great; – for
mountain guns: up to 1500 m close, from 1500 m to 3000 m mid, more than 3000
m great. The
correction in deflection was
necessary to overcome the effects of wind and drift. With moderate winds the deflection should be
changed, adding or subtracting 1 millième, depending upon the direction of
the wind, 2 millièmes with strong winds. With field guns every When the guns were placed in masked or covered
positions, before firing, the battery commander had to determine the angle of sight. It could be measured
by the battery telescope, by means of the sight
and quadrant, by means of the
graduated ruler, calculated on the map or obtained through theoretical
formulas. The corrector
was used to fix the height of burst of time-fuzed shrapnel, as shown above. Since nearly all kinds of objects might be the
target of the artillery fire –
infantry, cavalry and artillery in many different formations, field
fortifications, bridges, buildings, woods, balloon etc. – to be really
effective the fire should be distributed and adapted to the main features of
each of them. Finally
the Direction explained how to
prepare perspective sketch, that could be used to : – to
easily orient the high commander, when they arrived at the position or at the
observation post ; – to
direct and control the fire of an artillery division of a group of batteries,
when its head was distant; – to
offer to the battery commander information about the firing data related to
different points of the battlefield; – to
permit to the observers to show to the firing guns about the position of
their targets. |