Rules for adjustment and firing
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The
first Bulgarian instructions for the artillery fire were the Rules for artillery adjustment and fire,
the so-called “Red booklet”, introduced in 1889 by the Artillery Inspector lt.col.
Petar Tantilov, adapting the Russian Rules
for firing for field batteries (Правила
стрельбы
для полевой
батареи), proposed two years before by the Russian general major
Vladimir Nikolaevich Shklarevich. This first Bulgarian handbook followed
strictly the doctrines of the The
“Red booklet” was completed with the Hand-tables
for the firing data (Наръчни
таблици за
даните на
стрелба), elaborated on the basis
of the data furnished by the factory. These firing tables included the angle of
elevation and the lateral deviation for every range from All
the rules and the directives were addressed to the battery, which was
regarded as the basic unit of artillery. Being composed by 4 two-guns
sections, it could be employed both as a whole, and subdivided into
sub-units, acting by half-batteries, sections and, exceptionally, also single
guns. No direction was anticipated for the employ of the greater units, like
the artillery division or the regiment. The first instructions for the employ
of a group of batteries were published only two years later, in 1891. The
Rules included the following chapters
: a)
Features of the projectiles. b)
General rules for firing. c)
Preparatory fire. d)
Adjustment and fire at close range. e)
Adjustment when it is difficult to distinguish the
rounds over the target from the short rounds. f)
Firing at moving targets. g)
Scale fire. h)
Firing at targets unseen by the aimer. i)
Shelling targets sheltered in dugouts and
earthworks. j)
Accountancy. k)
Tasks of the protective and observation lines. The projectiles. The first
chapter described in detail the main features and the effects of the various
kinds of projectiles, employed at that time by the Bulgarian artillery. Great
importance was deserved to the impact of an inaccurate determination of the
height of sight on the accuracy of the fire. The
common shell
(граната), acting both by the burst
of the charge and by the striking energy of its splinters, could be employed
against all the targets that should appear in a field battle, both animate
and inanimate. It was equipped with percussion
fuze, working on impact. Its effect depended on the character of the ground
and on the distance of the target. Unlike the principal European regulations,
that recommended to employ it only at a distance not greater than The shrapnel
(шрапнел) was equipped with a fuze that enabled to set with
precision the rate of burning. It burst into the air, before having hit the
ground, and spread the bullets on the target. The effect of the bullets on
animate targets depended upon their striking energy and their sectional
density, those of smaller diameter having the greater penetration. The main
problem was to know the point of burst that was determined by the interval of
burst (the horizontal distance between the point of burst and the target),
and the height of burst (the vertical distance of the point of burst above the
horizon). The closer the point of burst was to the target, the greater was
the velocity and, consequently, the effect of the bullets. The normal
interval was set at The case shot
(картеч) was a
cylindrical zinc case filled with round balls and was employed only against
animate targets at close ranges (400 – The
sharoha
(шароха) was a cylindrical cast iron
shell, whose head was a ball that continued to roll after the burst of the
proper shell, hitting the troops placed behind the front line. It was
regarded as ineffective already during the Russo-Turkish (1877-78) and in Generalities. Besides the
general rules for firing, the description of the individual duties in the
service of the piece and the direction about the correct manner to bring the
gun into position, the “Red booklet” dealt at length with the care of
ammunition and artillery materiel. It was a matter of the highest importance
their correct storage and maintenance, since their working order greatly
affected the accuracy of fire. In
order that all the parts worked easily and without unnecessary wear, the
materiel should be kept properly lubricated, assuring the constant
maintenance of a thin film of the proper lubricant between all working and
bearing surfaces and the surfaces on which they work or bear. Special
attention should be paid to the breech-block, whose mechanism should always
work perfectly to avoid severe accidents.
Preliminary
fire
(подготвителна
стрелба) was used to provide the
recruits with a little knowledge of the firing theory, showing them how the
fall of the projectiles depended upon the height of the sight and other
adverse conditions, like the battering charge, a wrong measurement,
inadequate maintenance of the materiel and so on. Fire for adjustment (пристрелка). The purpose of the adjustment in elevation (определение
на мерника)
was to find the distance (height of sight) up to the target as quickly and
accurately as possible, according with the real situation and the features of
the projectile employed. The most probable distance was at the middle of the
bracket obtained firing a shot in front and another behind the target
(нулева
вилка = straddle). Accurate though the
adjustment might be, a margin of error would be always, owing to the dispersion
of the shots and other accidental factors. The probable error was reduced
according with the law of probability,
by lowering down the bracket and by the repetition of the same observation. The ranging fire could be
effected in three different ways : – directly with shell : it was
employed against targets standing immobile into the open, usually starting
with a bracket not lower than 8 and not higher than 16 graduations.
If the first round was short, the range was increased; if over, it was
decreased; and rounds were fired successively increased or decreased in range
until the target was bracketed. Then the size of the bracket was successively
reduced by halving the last bracket obtained to 2 graduations for a range up
to The final limit of the bracket was repeated with another shot, to find
the most probable height of the sight : a)
if the straddle was obtained, the other limit of the
bracket was not repeated and the fire continued without changing the height
of sight : low bracket at 50-52 graduations, repeating the short limit (50)
and obtaining − +, the most
probable height of the sight was at 52, or repeating the large limit (52) and
obtaining − +, the most probable height the of sight was at 52; b)
if it was like the first observation, the other
limit of the low bracket was repeated and if this time the straddle was
obtained, the fire continued without changing the height of sight : low
bracket at 50-52 graduations, repeating the short limit (50) and obtaining −
−, the large limit (52) was repeated and obtaining + −, the most
probable height of the sight was at 52 (beginning with the large limit the
process was the same); c)
if the straddle was not obtained even at the other
limit, the fire was directed at the middle of the low bracket : low bracket
at 50-52 graduations, repeating the short limit (50) and obtaining − −,
and the large limit (52) and obtaining + +, the most probable height of the
sight was at 51. The most probable height of the sight should be verified firing a group
of four shots. When some of the rounds were short and some over the targets
owing to the dispersion of the shells, and not by an error in aiming the gun
or by accident, the adjustment was regarded as finished and the guns shifted
to fire for effect. The “Red booklet” listed five different cases that might occur
during the ranging fire, showing what the battery commander had to do in each
of them. – with shell and shifting to shrapnel :
at first the adjustment was made with shell, exactly as above, but after
having fired the group of 4 shots, one or two sections shifted to shrapnel
fire. The height of the sight for them was 1 or 2 graduations lower than the
height that with shells had obtained less short rounds or the same number of
rounds short and over the target. In the meantime the sections charged with
shells fired for effect and filled in the pauses, until the burning time of
the fuze had been set. Then the whole battery shifted to shrapnel fire,
adopting the height of the sight that had obtained the greater number of
short rounds : if the number of the rounds short and over was the same, the
height was narrowed by 1 graduation. In either case the fuze was set for a
normal burst. To control the interval of burst, one section fired a verifying
salvo, changing the elevation by 2 graduations. If no round fell over the
target, the elevation was changed again by 2 graduations. When one or more
rounds fell over, the guns kept the long limit of the bracket or narrowed the
elevation of the verifying salvo by 1 graduation. – directly with shrapnel : it was
regarded as exceptional, since it required low bursts, that might result in a
lot of graze bursts, that were not only absolutely ineffective, but also of
little value for the observation. It was made by section (two guns) exactly
as with shell, excepting that in this case two
observations were made for every height of the sight. The bracket could be
reduced up to 2 graduations also by means of a single observation, if
the other was lost, but the repetition of the limits and the groups should
always result from the correct number of the observations, even if it caused
a great waste of ammunition. After having fired the group of verifying shots,
the whole battery shifted to shrapnel fire simultaneously. If the number of
the rounds of the group over the target was less or equal to the number of
the short ones, the height of the sight was kept unchanged or narrowed by 1
graduation. The interval of burst was verified as above, with fuze set at low
burst to facilitate the observation. Shifting to fire for effect, the burning
of the fuze was shortened by 0.1-0.2 seconds, but the trajectory should never
be raised. The
adjustment in direction (определение
на отклонението) was required to overcome the
effect of wind and drift. In this case the sections commanders made the
changes in deflection according with the firing tables and taking into
account the slope of the axis of the guns and the direction and power of the
wind. With cross wind the correction was made by the battery commander. The
deviation was regarded as correct when the deflections of the shots on the
right and on the left were almost the same. The
adjustment in height of burst (определение
на височината на пръскане) was made observing a group of shrapnel shots having
the same fuze setting. The height was regarded normal when : – at
close range not less than half of the burst were low, and no burst were on
graze; – at
medium range at least one burst of every salvo was low, and not more than one
burst every two salvos was on graze; – at
long range there was no low burst in a salvo, and only one burst at most
every battery salvo was on graze. |