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United States. Army. Ordnance Dept.

Handbook of artillery : including mobile, anti-aircraft and trench matériel online

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that the projectile follows the movement of the rear sight, going
higher as the sight is raised, and to the right or left as the sight is
moved to the right or left.

The second method for direct laying is to use a telescope with cross
hairs which takes the place of the open sights although its principle
of operation is the same.

The angle of elevation of a gun must be measured in the vertical
plane through the axis of the piece. It frequently happens that a
mobile piece must be fired under conditions in which the axis about
which it turns in elevation (trunnion axis) is not level, thereby throw-
ing the sight plane out of the vertical. If this is the case, the sight
arm must be revolved about an axis parallel to the axis of the gun
until the sight arm is vertical. Most wheeled mounts have such a
provision made on their sights.
Independent Line of Sight.

In order to relieve the gun pointer from the responsibility of set-
ting the elevation on the sight standard and elevating the piece, some
guns are provided with what is known as the independent line of
sight. It will be noted that the actual quadrant elevation of the
piece consists of two parts:

(a) The elevation necessary to reach the target if it were on the

same level as the gun.

(39)




40

(6) The correction to this elevation required by the difference of
level of the gun and target (angle of site).

With the independent line of sight the two parts of the quadrant
elevation are applied to the gun independently. An intermediate
rocker and two elevating systems, A and B, are provided as shown
in Figure N.

The sight is fixed to the rocker, and for direct fire the gun pointer
manipulates the lower elevation system A, which moves the rocker
as well as the gun in elevation. In this way the angle of site is auto-
matically corrected, when the line of sight is brought upon the
target.

The other elevating mechanism, B, is between the rocker and the
gun and is manipulated by another cannoneer who elevates the gun

until the proper range appears
on a range scale.

The change in range does not
affect the setting of the lower ele-
vating mechanism, and the gun
pointer is thus free to devote his

FIG. N. , . .

whole time to keeping his line of

sight upon the target and is not compelled to take his eye from the
telescope. The above method has the objection, however, that it is
difficult to make the necessary correction in the range drum for differ-
ence in level of trunnion axis.

Various modifications of this general method of securing the inde-
pendent line of sight are in use and will be discussed with the guns
to which they pertain.

The gun is said to be laid indirectly when it is laid by means other
than aiming directly through the sights at the targets.

The fire from modern field pieces is so accurate and destructive
that it is always necessary to establish field batteries in position out
of the view of the enemy for the sake of protection. Indirect sight-
ing becomes then of necessity, the usual method of sighting such guns.

The panoramic sight affords the means of aiming the gun in indi-
rect laying by directing the line of sight on any object in view from
the gun; at the same time it affords the advantage of a telescopic
sight in direct or indirect aiming.

This panoramic sight is a telescope so fitted with a rotating head,
reflectors and prisms, that a magnified image of an object anywhere in
view may be brought to the eye without change in the position of
the observer's eye.

The panoramic sight is often mounted in connection with the
range-sighting mechanism, but in some cases in order to divide
the duties of laying for direction and elevation, the panoramic sight
is mounted on a shank on the left side of the cradle and used in
laying for direction, while the range quadrant for laying in elevation



41



is placed on the right side of the cradle and used by another
cannoneer.

In connection with the range quadrant a range level is provided,
which is a special form of clinometer. It is used in setting off the
angle of site, thereby correcting for difference in level of the gun or
target. The range quadrant is graduated in degrees or in fractions
of the range (mils). In the case of howitzers, the different zones of
fire are sometimes shown.

While the use of the range quadrant separates the duties of the
cannoneers in aiming, it does not comply with the conditions for the

independent line of sight. The sight

and range quadrant being attached to
the cradle, both move in elevation with
the gun. The independent line of sight
permits of the gun being moved and set-
in elevation without any change in po-
sition of the sight used for direction
aiming.

Leveling plates or similar surfaces are
provided on all guns and howitzers on
which a gunner's quadrant (see p. 42)
can be used in obtaining or checking
the elevation.

It is not the intention to go into de-
tail in this handbook regarding the fire-
control equipment employed for direct-
ing the fire of anti-aircraft materiel, but
as the development is so new, and they
are so closely involved with artillery
during operations, it is quite necessary to devote some space to the
fire-control equipment.

Many of the terms and instruments used in connection with anti-
aircraft artillery are similar to those employed with field artillery
materiel, but the methods of application in most cases differ.

In the direct fire of anti-aircraft artillery the following angles
resulting in the laying of the gun to the predicted future position
of the target are involved.

1. Present azimuth and elevation. These are obtained by direct
sighting upon the target.

2. Principal lateral and vertical deflections.

3. Secondary lateral and vertical deflections.

4. Superelevation.

In the determination of the principal lateral and vertical deflec-
tions, two methods of fire control have been established:

1. Linear speed.

2. Angular speed.




PANORAMIC SIGHT, MODEL OF
1917.



42



Each method assumes rectilinear travel of the target, i. e., that
the pilot of the aircraft will fly a straight course at unchanging
speed and constant altitude during the time required for the deter-
mination of the fuse range, setting of the fuse, loading and firing
the gun, and for the projectile to reach its point of burst. Each
method is based upon sound mathematical reasoning and involves
automatic apparatus of rather complex, but easily operated, mechan-
ical and electrical design, in order to resolve the data required in
the laying of the gun.

In the first method the quantities required in the resolution of
the formulae are :




GUNNER'S QUADRANT, MODEL OF 1918.

(a) Presentation (angle of approach), i. e., the horizontal pro-
jection of the angle made between the vertical plane of sight and
the axis of the fuselage of the airplane.

(6) Engine speed of the target.

(c) Altitude of the target.

(d) Time of flight of the projectile to the future position of the
target.

The resolution of the formulas deriving the lateral and vertical
deflection corrections is accomplished upon a device known as
" Anti-aircraft artillery deflection computer." The readings ulti-
mately obtained from this instrument are given in mils. They are
transmitted telephonically or by direct announcement to the gun
layers who immediately lay the gun to its future position, while the



43

telescope pointers remain sighted unon the present position of the
target.

The great advantage of this method lies in the fact that the pre-
sentation and engine sDeed can be estimated with reasonable accuracy,.
The altitude of the airplane is determined from altimetry stations,
and the time of flight is known when fuse range has been determined
from a telemeter.

In the angular speed method the lateral and vertical angular
velocity of the target is measured. These are multiplied by the total
element of time mentioned in the aforesaid and gives the respective
displacements. The fact that the angular velocity of an airplane in
ordinary flight is never uniform makes this method more difficult of
apprehension but as applied in our instrument design gives results
appreciably better than the linear s^eed method and is consequently
used more generally. The instruments resolve the lateral and ver-
tical deflection corrections in mils and also the fuse range. These
are telephoned to the gun layers who function the sighting system
mechanisms.

The element fuse range is required for two main purposes in anti-
aircraft gunnery: (a) For the setting of the fuse, and (6) as a function
in automatically giving superelevation to the gun i. e., the angle
between the line of sight to the predicted future position of the
target and the axis of the bore of the gun when ready to fire.

Secondary deflections are required in making allowances for wind-
age, ballistics, drift, etc. These are set by giving secondary move-
ment to mechanisms of the sighting system.

When firing, "indirect" or at night, which essentially is indirect
fire, three elements pertaining to the predicted future position of the
target are transmitted from this apparatus at the fire-control station
in order to accomplish the laying of the gun and setting of the fuse:

1. Azimuth.

2. Quadrant elevation.

3. Fuse range.

Secondary deflections involve, in addition to those common to
direct firing, corrections for parallax when firing "indirect."

At night the alliance of listening apparatus and searchlights assist
in accomplishing the resolution of the gun-laying elements at the
fire-control station.

Altimetry, which is a basic factor in the computation of the prin-
cipal and secondary deflection corrections, is obtained in one of two
ways :

(a) Monostatic.

The monostatic or one-station instrument is an optical device that
determines the altitude by automatic triangulation through the coin-
cidence of light rays along a self-contained base.



44

(6) Bistatic.

This is a system in which two stations are set up and oriented
along a base line of known length, frequently as great as 4,000
yards. The height or vertical distance of the target above the base
line is then determined geometrically by projecting its altitude
horizontally into the vertical plane passing through this base line.

When altitude has been determined, telementry, which involves
the functions, angle of site, to the future position of the target and
altitude, is readily accomplished with the aid of automatic devices.

When firing against airplanes at night, searchlights are used to
illuminate the objective. When it is able to find it and keep it in
its field, firing can be conducted in the same manner as in day-
time. Many sound detecting instruments have been made ; one of
the recent types is the ''Paraboloid." A surface in the shape of a
paraboloid, movable in azimuth and site, focuses the sound waves
when its axis is placed in their direction ; they swing from one side of
the focus to the other when the axis of the instrument is turned.
The sound is received by trumpets placed on either side of the focus
and joined in pairs to the ears of two observers who adjust the
instrument, the one for azimuth, the other for site.

Briefly, the foregoing describes the fundamentals of anti-aircraft
artillery fire-control methods. Being the most precise form of
gunnery, anti-aircraft artillery involves material capable of the
highest degree of facility and accuracy in the automatic measurement
of deflections and the maneuvering of its gun-laying mechanisms in
order that effective fire may be conducted against a target whose
movements are subject to such large displacements.



ACCOMPANYING VEHICLES.



In addition to the piece itself, a number of vehicles are necessary
in batteries, sectors, and regimental organizations of field artillerj 7
for maneuvering and serving the piece. The type of vehicles vary
with the different guns and the various organizations. Some of the
more common vehicles such as limbers, caissons, etc., are described
in a general way in this chapter, while their special features are
described in detail with the materiel with which they are issued.
Other special vehicles such as reels, store and battery wagons, etc.,
are also described with the materiel to which they pertain.

The caisson is essentially a conveyance for the transportation of
ammunition in the field. It generally consists of a chest for ammu-
nition mounted on two wheels and axle. In front it is fitted with a
short pole having a lunette for attachment to other vehicles and in
the rear with a pintle, to which additional vehicles may be attached.
Various tools are usually carried on the caisson, and seats are pro-
vided for the accommodation of the personnel.

The limber is a two-wheeled vehicle designed primarily to increase
the mobility and faciliate the maneuvering and deployment of field
artillery. There are several types of limbers in use, the principal
ones being the carriage and caisson limbers.

The carriage limber is attached to the trail of the piece when
traveling. For light field pieces, a chest for ammunition is pro-
vided on the carriage limber. In the case of heavy pieces, the chest
is dispensed with and the trail of the piece rests on the top section
of the limber. A pole is provided at the front for horse or motor
traction, and the rear is equipped with a pintle for attachment of
the carriage.

The caisson limber is used for hauling the caisson and is provided
with a chest for carrying ammunition.

The forge and store limbers are designed to carry supplies and
equipment, the forge limber carrying the tools and supplies for the
farrie'rs shop. The battery wagon and the store wagon are two-
wheeled vehicles equipped with chests for tools, supplies, and spare
parts.

With batteries of heavier field artillery, some of the vehicles are
dispensed with, especially the caissons, battery wagons, forge, and
store limbers, the ammunition being carried in motor trucks, in which
most of the spare parts and supplies are also carried.

(45)



46




47

Light field artillery is usually drawn by horses although some of
these batteries are now motorized, i. e., hauled by either caterpillar
tractors or motor trucks.

In addition to this, provisions are made for a limited number of
trailers for use in carrying light guns at high speed behind motor
vehicles. These trailers are rubber tired and for high-speed condi-
tions; the complete gun, with carriage, may be placed on this trailer
instead of being transported on its own wheels.

The recent struggle in Europe brought about problems which
heretofore have never existed in warfare; and to meet these changes
have been made in every arm of the service, but the greatest and




75-MILLIMETER GUN CARRIAGE MOUNTED ON A 3-INCH FIELD GUN TRAILER.

most radical change being the motorization of artillery. Mechanical
transport is at this time in such a state of development that there
is no reed of dwelling upon its numerous advantages over animal
draft.

The origin aj x heavy artillery was limited to guns emplaced in
permanent fortifications and guns of large caliber which were only
moved with great difficulty. Light horse-drawn guns and howitzers
comprised the mobile artillery for use in the field. This type of
artillery was ideal for quick action at short ranges.

As the artillery became a more important factor, large caliber long-
range guns were required. The movements of this heavy artillery in
18322820 4



48

the field could only be accomplished in one way by motorizing
it. The result is the development of the extremely mobile heavy
artillery.

In applying motor transportation to artillery, types of motor
vehicles of widely varying capacity and duty are required. In most
cases commercial cars and trucks are used, but in a few instances
special types have been developed. Motor equipment is still under-
going changes, all tending to produce apparatus of unfailing depend-
ability and maximum mobility and flexibility.

Motor apparatus of the following types have been selected as the
most suitable for accomplishing this motorization: First, passenger
cars, both light and heavy; second, motor cycles with and without
side cars; third, trucks; fourth, four-wheeled trailers: and fifth,
tractors of the caterpillar type.

Passenger cars are furnished when on the march and when occupy-
ing a position on the lines. Batteries are supplied with light touring
cars, staff cars, and motorcycles with side cars. Battalion and regi-
mental headquarters are also supplied with light touring cars and
Westfield military bicycles. A motorcycle is ideal for liaison and
work of similar nature requiring rapid transportation for one or
two individuals. The motorcycle is particularly useful when trav-
eling in convoy and for keeping the various units of an organization
in close touch with each other.

Motor trucks are necessary for carrying supplies and ammunition
from the depots and distributing them to the various units. A great
many trucks are required to insure unfailing supplies when artillery
is in action. Because of 'the uncertain conditions of the roads back
of the lines sturdy trucks that can pull through under the most
unfavorable conditions are employed.

In bringing the guns into position it is often necessary to cross
ground plowed by exploded shells, to go through mud and deep sand.
and to ford streams which can not be negotiated by a wheeled type
of motor vehicle, thus the type of apparatus adapted for this purpose
is the caterpillar tractor.

The problem of the care and maintenance of motor equipment in
the field is met by issuing the repair and artillery supply^ trucks to
each battery supply and headquarters company of motorized artillery.

The artillery supply truck is really a motorized store wagon carry-
ing spare parts, tools, etc., for the particular kind of unit to which
it is assigned.

The artillery repair truck consists of a small machine shop mounted
on wheels. Its equipment is complete, including a lathe, drill press,
air hammer, forge, etc. Electric power is supplied by a small gen-
erator driven by an individual gasoline motor mounted on the truck.



49

The equipment is designed to make all repairs in the field, both to
artillery materiel and motor vehicles.

The motor equipment makes transportation a comparatively easy
matter, permitting it to be moved with rapidity, either on the offensive
or defensive. The value of this equipment becomes more apparent




as the nature of warfare changes from that of position to that of
movement.

Detailed descriptions of the above motor vehicles are given in
separate handbooks pertaining to motor equipment materiel.



37-MILLIMETER GUN MATERIEL, MODEL OF 1916.



Experience has shown that the infantry can not carry out its
mission, by its own weapons, except at prohibitive less of personnel.
Our automatic rifle is practically useless for ranges greater than
500 meters, and then only against personnel. The individual
rifle does not offer the necessary volume of fire, while the rifle
grenade, and even more so, the hand grenade, is a clcse combat
weapon. Hence the taking of a machine-gun nest by a unit (con-
sisting of an automatic rifle squad, hand bombers, and rifle grenadiers)
attacking the flanks, will not prove very successful, particularly
if machine-gun nests are echeloned to considerable depth, and
executing cress fire.

Such conditions calls for some form of artillery, effective at from
400 to 1,500 meters, against both personnel and materiel, raid




37-MILLIMETER GUN CARRIAGE AND AMMUNITION CART, LIMBERED.

capable of immediate action. The field artillery is not available
because of difficulty of communication and length of time neces-
sary to get into action. The heavy artillery is not sufficiently
mobile. Its dispersion is too great for small, definite targets, there-
by calling for vast amount of ammunition, extremely difficult to
transport.

The necessity of providing an accompanying gun for certain units
of infantry has led to the adoption of a 37-millimeter gun (devel-
oped by the French Army) .

The 3 7-millimeter. gun, also known as the 1 -pounder or infantry
accompanying gun, is the smallest weapon of the field-gun type in
use by the American Army. It is used by advancing infantry
outfits, chiefly for destroying concrete machine-gun emplacements,
outposts, and other points of resistance. Recent developments
and modifications of this weapon have found wide application for

(50)



51




52 .

its use and, due to its extreme portability, this gun is adaptable for
tanks, tractors, and aircraft.

As this gun is intended to follow infantry over any kind of ground,
its construction is designed to give great mobility. The personnel
is organized for rapid fire; the possible rapidity of fire is 35 shots
per minute.

Each gun unit is composed essentially of two elements :

(1) The gun on a tripod mount, capable of being set on wheels.

(2) A light wagon serving as a limber and carrying ammunition,
spare parts, and accessories.

The gun and limber when joined are normally hauled by one
horse or mule, but near the enemy they are separated and moved
by man.

In action the gun is operated by two men, one keeping it on the
aiming point and the other loading and firing. The gun must be
cocked by hand in order to load for the first round, but thereafter
the counterrecoil of the barrel cocks the piece, and it is only neces-
sary to open the breech mechanism, which ejects the case, insert a
new cartridge, close the breech, and fire.

When used as a tripod mount, it is separated into portable groups
for transportation and each unit is carried by two men. One group,
weighing 104 pounds, consists of the gun and cradle and the other of
the trails, weighing 84 pounds. With the combination tripod mount,
the gun is transported on a wheeled carriage which is limbered to a
two-wheeled ammunition cart, drawn by one mule or horse.

Weights, dimensions, and ballistics.

Weight of gun and recoil mechanism (with flash hider and sight) . . . .pounds. . 104

Weight of recoil group do 34

Weight of barrel group do 38

Weight df breech group do 18

Weight of flash hider do. ... 2. 5

Length of gun calibers . . 20

Range (H. E. Shell Mark II) meters. . 3, 650

Muzzle velocity .feet per second . . 1 . 204

Weight of projectile pounds. . 1. 234

Length of recoil inches. . 7-10

Maximum ande of elevation degrees . . 21

Maximum angle of depression do 14

Amount of traverse to right do 22

Amount of traverse to left do .... 16

Weight of axle, complete pounds . . 36. 25

Weight of wheels, each do 68

Weight of trails (including pintle and float) do 84

Diameter of wheels inches. . 37. 75

Width of track do 33

Weight of gun and carriage, complete pounds. . 360

Over-all length of vehicle inches. . 75

Over-all height of vehicle do 37.75

Over all .vidth of vehicle . . . .do. . 57



53

The gun is composed mainly of a steel alloy barrel. A front clip
of bronze and an aluminum jacket serve as supports and guides for
the whole barrel. The breech housing is screwed to the rear end of
the barrel and forms a receptacle for the breechblock.

The breechblock is of the Nordenfeld type and with the exception
of size is practically the same as that used on the French 75 milli-
meter field gun. J t screws into the breech housing and is opened
and closed by being rotated 156 degrees about its axis, which move-
ment is limited in each direction by a stop. The breechblock is
cylindrical in form, rotates in a threaded seat and is operated by a
handle which when moved to the left causes the eccentric hole in
the block to register with the bore and also operates the extractor
thus ejecting the empty cartridge case. Pulling the lever to the
right rotates the block so that the port in the block is drawn away
from the bore and a solid surface containing the firing pin backs up
to the base of the cartridge.

The action of the powder gases on the breechblock at the moment
of discharge produces the recoil of the united barrel and breechblock.




TRIPOD MOUNT IN FIRING POSITION.

The purpose of the recoil mechanism is to control and limit the recoil
and to return the barrel to the firing position, at the same time pre-
venting a sudden return which might disturb the aim of the gun.

The recoil cylinder consists of a cylinder containing a piston,
piston valve, counter recoil spring in three sections, and counterrecoil
buffer. The piston rod, which is hollow and open at the piston end,
is pierced with holes for the passage of oil both during recoil and


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Online LibraryUnited States. Army. Ordnance DeptHandbook of artillery : including mobile, anti-aircraft and trench matériel → online text (page 4 of 19)