Page:EB1922 - Volume 31.djvu/1244

2,050 f.s. It did remarkably well in the war, and the only altera- tion made was to bend the trail so as to give room for 5 more of elevation beyond the 12 for which the carriage was built. The simple collimateur sight was replaced by a panorama telescope for all-round laying from the covered position. The gun was originally fitted with an arrangement which necessitated raising the trail shoulder-high on coming into action to allow the brake-blocks to fall under the wheels and then lowering it (" abatage "), but a modification which rendered this unneces- sary had been brought out in 1914.

FIG. 9. French 75-mm. field gun.

A new French field gun was in 1921 under trial. This fires streamline shell with super-charge at long ranges, and ordinary shrapnel and H.E. shell at medium ranges. A reduced charge is also provided, partly to save unnecessary wear of the gun and partly because, during the war, the flat trajectory of the French gun caused trouble when the artillery had to fire over the heads of the infantry. The 1921 gun is fitted both for horse draught and for traction by cross-country agricultural machines.

A very interesting modern equipment is the Schneider field gun shown in fig. 10. This was designed in 1918 to comply with the re- quirements of the French Government, but was not brought out till alter the war. It is a i6-pdr. firing a streamline shell with M.V. of 2,000 f.s. and ranging 13,200 yd. at 40 elevation. It marks a new departure in axle-traversing equipments in that the carriage affords a traverse of no less than 15 degrees. The shape of the shield is such as to clear the wheels at extreme traverse. The buffer and

FIG. 10. Schneider field gun.

recuperator are of the well-known Schneider pattern, but compressed nitrogen is normally used instead of compressed air as being less liable to corrode the recuperator reservoir. The cradle extended to the rear is a pattern which has come into favour since field-gun carriages have been required tt> give high angles of elevation. Its weight partly balances the gun and allows it to be set farther forward so that it has more room to recoil without striking the ground. Moreover, the open trough cradle is constructionally simple and suited for mass production in time of war. The cradle alone is not heavy enough to balance the forward preponderance, and balance springs are used enclosed in cylinders, one on each side of the cradle; one of these is visible in the illustration. The wheels, 4 ft. 7 in. in diameter, have stout solid-rubber tires, and it is claimed that the gun can be drawn over paved roads behind a motor lorry at 8 m. an hour without injury. The weight in action is 30 cwt., against 22} cwt. for the French service field gun. This illustrates the modern tendency to increase the weights of field artillery in view of the introduction of motor traction.

Although this gun is a great improvement on any field gun used in the war, it would be unwise to accept it as the last word in field artillery. For instance, it is doubtful whether the traverse of 15 would nowadays be accepted as sufficient for firing from a gun-pit or for engaging tanks. For these purposes the split-trail equipment in- vented by the French Col. Deport (one of the designers of the original soixante-quinze) would appear to be the most suitable.

The Italian Deport split-trail field gun was issued in 1912 (see fig. n). The gun itself is not remarkable; it was designed to take the same ammunition and give the same ballistics as the Krupp field gun already in the Italian service. It is a 14'3-pdr., M.V. 1,670 f.s., with a semi-automatic breech action. The peculiarity lies in the carriage. The trail is divided longitudinally, and each half is at- tached by a vertical hinge to the axle bed so that on coming into action the two halves can be opened out laterally at an angle of 60" to each other. Instead of the ordinary spade, there is a stout spife at each of the two trail ends which can be driven down by a hammer, so that the trail ends are nailed to the ground. The cradle with the gun is pivoted on the axle bed and can be traversed 30 right or left. In ordinary field equipments, in which the upper carriage traverses on a pivot, the gun traverses only some 2j right or left; if it were traversed much out of line with the spade, the carriage would over- turn sideways on firing. Axle-traversing gives somewhat more trav- erse, but even this is inadequate for modern tactical needs. In the split-trail equipment the carriage 'is perfectly steady so long as the line of recoil is between the two halves of the trail.

FIG. II. Deport field gun.

This enlarged lateral field of fire is of great value in modern war- fare. In the first place, the gun may have to command a consider- able arc of fire from a cramped gun-pit, and, to do so, an ordinary field gun must be traversed on its wheels. Being usually out of sight of the enemy it is layed by a distant mark in flank or rear or by aiming-posts. For accurate shooting the gun must be traversed without shifting it laterally; any displacement of the gun would mean a considerable error in direction. Under these conditions the split-trail carriage is of great advantage, since it offers a fixed pivot about which the gun can be traversed without moving the trail or wheels. In the second place, a field gun must now be capable of hitting a moving tank, and this, especially at short range, implies rapid traversing through a wide arc. A split-trail gun can keep up rapid fire on a tank crossing its front, while the fire of an ordinary gun would be checked and delayed by the necessity of constantly lifting the spade and swinging round the trail.

A further peculiarity of the Deport gun is the high angle of eleva- tion obtainable with the split trail, since there is nothing in the way of the recoil. The Italian gun can be elevated to 50 to the horizontal. The inventor introduced this feature for the purpose of firing at aircraft, which in those days were expected to fly within 3,000 ft. of the ground. Even so, a low-velocity gun with curved trajectory such as the Italian field gun would not have been of much use. But the increased elevation has proved valuable as a means of obtaining the long range which is now required of a field gun.

The Deport field gun has double recoil gear. That is to say, the gun is not mounted directly on the cradle containing the main recoil gear, but on a pedestal sliding on the main cradle, which has a small buffer and recuperator of its own. This arrangement has the advantage of keeping the recoil gear cool, since the hot gun is at some distance from the main buffer and the heating due to the friction of the liquid in the buffer is divided between two buffer-cylinders. Otherwise this duplication of the recoil gear constitutes an undesir- able complication, especially with regard to considerations of mass production in war-time. The gun and carriage proved quite serv- iceable during the war; no alterations were made in them, and in spite of the somewhat low power of the gun the equipment was re- tained in the service afterwards.

The Schneider split-trail field gun of 1914 is a great improvement on the Italian gun, since it fires a streamline shell of 16 Ib. with M.V.