THE WAR TANKS.

Taranaki Daily News, 17 January 1920, Page 12

THE WAR TANKS.

A SKETCH OF THEIR HISTORY. BRITISH ENGINEERING TRIUMPH. GERMANY'S VAIN REPLIES. Since the signing of the armistice there has been n sloadv and. progressive revelation of some <>i the scientific achievements to which, very directly, the. ultimate success of the Allies must; be largely attributed. There is much justification for the expression of the war as au ''engineers' war." Of the products of engineering which effected demoralising destruction of the enemy's lines, British war tanks achieved conspicuous success. Early in their career, says the Daily Telegraph, they demonstrated their success against the "impregnable" H'indenburg line. In breaking down all obstructions, clearing away wire entanglements, they worked with an efficiency as disastrous to the enemy as advantageous to our own forces.. This efficiency was moral as well as mechanical and military. Carrying guns and men light into the heart of the enemy's lines, they etleeted progress By surprise moves, which involved untold saving of both shells and lives. When they moved forward at almost a moment's notice, the enemy had no opportunity to resort to counter-measures.. Their appearance was at once an excuse for surrender, of which many of the enemy's forces gladly availed themselves. Even ancient war produced portable engines of destruction, and armored cars provided a natural development, and the use of those cars led to the appointment of a landship committee at the Admiralty to investigate the q'uestion of building landships. A brief survey of the early results which led to the later types of tanks, with an account of the engineering problems involved, was undertaken by Sir Eustace Tennyson d'Eyncourt in a paper before the British Association at Bournemouth. While it can hardly be claimed that the essential idea of the tank was altogether new, the impetus given to the development of the form in the modern tank was due to the circumstances attending the military situation at the end of 1914. Then it became apparent that the enemy's line of defence was becoming increasingly fortified, and that the enemy had so securely dug themselves in that a war of position had set it, and the problem was to effect h break through with a minimum sacrifice of life, and with the best prospects of making still more effective any advance already achieved by the break through. Proposals made with reference to a practicable type of war engine were immediately approved by the authorities, but the conditions imposed upon the designers were such as introduced engineering problems of an-, entirely new and by no means simple order. The machine had to be capable of fusing gaps at least sft. wide; fuel and water had to be carried at least twenty mi'es. and parapets sft thick and sft high, having an exterior slope of 1 in 1 had to' be negotiated. A reasonable limit of weight was imposed, because of bridges which had to be crossed—not greater than that produced by 14 tons on an axle with a pair of wheels. A crew of about ten men with two or more ma-chine-guns, and a light q.f. gun, were further requirements. Restrictions wore, however, imposed by a number of external limitations. ,Thus the dimensions were limited by the capacity of our railway trucks and by the loading gajiges of both English and French railways. The machine had to ofTer adequate protection to the crew and carry a heavy weight of armor armament, and fuel. Considerable stresses in operation demanded adequate strength, while engines and other parts had to be reliable, and, after standardisation, produced in bulk. Easy control and steerihg were essential, aii'd, in addition to being bullet proof, the machine had to be habitable and well ventilated. Such varying conditions were not altogether compatible, and a machine to combine the maximum number of these and other requirements, and at the same time to be low and inconspicuous, constituted a new and novel problem, fortunately completely solved by the skill, experience, and enthusiasm of British engineers.

ENGINE DEVELOPMENT. Tim most suitable type of engine was not necessarily a foregone conclusion. It. was possible that a special steam engine might have been produced, but this would have necessitated a larger, heavier and more conspicuous tank than with an engine of the internal combustion type, and in the same way that this latter type of prime mover contributed so largely to the Successful development of the airship, aeroplane, and submarine, so also did it contribute to the pronounced success of the landship. Moreover, there was the necessity for Using existing units and material already in production. As a consequence the 105-h.p. Daimler engine, with transmission as made for the Foster-Daimler tractor, was installed in the earlier type of tanks, Marks 1., 11., 111,, and IV. tanks being fitted with G-cylinder Daimler 105h.p. engines, running normally at 1000 • r.p.ni. A development of the' type was secured by the use of aluminium pistons, which increased the power, but for an increase in the speed of the tanks greater engine-power was necessary. Mr Ricardo's engine had, in the meantime, been developed and tried, and attained bulk production during 1917, after which a number of these engines of 150-h.p. ■were put in hand for the tanks of 1918. This engine was used in the Mark V. and VI. types, and ri»n at 1200 r.p.m. Increase in engine-power to 225-h.p. and up to 300-) i.p., with 12 cylinders and a speed of 1400 r.p.m. Was attained in the Mark VIII. tank, which, with a length of 34ft. 2Jin., was 7ft. 9'/ 2 in. longer than previous' machines, and had, therefore, increased trench-crossing capacity. In this tank there was the definite aim at combinimf ail the latest improvements and at the same time facilitating production l>y arranging for the manufacture of some of the parts in America and others in England, these being assembled in a specially-constructed factory in France.

Thus the machine was designed to take alternatively the Liberty 12eylinder aero engine. In the Mark VIII. tank the engine was housed in an entirely separate compartment from the general interior of the tank. This arrangement had advantages in that more space w,as provided for and- occupied by the officers and guns' crews, and a further improvement lay in the fact of decreased liability to disablement, as in previous types tanks had been hit by shell and the whole tank set on fire oil account of the engine being in the middle and not at the end of the machine. The carrying capacity of the Mark IX. tank was, in addition to the crew of four, fifty men, but this type did not jarrv six-pounder guns, as was usual

with the "male" machine of ihe earlier types. It liad an available carrying space of 13ft. (fin. long in the centre of the machine by sft. Sin. wide.

LIGHT TRACK PRESSURE. It was quite in the early history of tank production that the large-wheeled tractor type was, after experiment, abandoned in favor of the caterpillar type. The former type required a large wheel in order successfully to negotiate rough ground, and this at once involved a machine too Jiigii awl too conspicuous to be. deemed a sateens. While, however, the development of the caterpillar i vpe presented many difficulties in view of the weight and dimensions necessary for carrying the armor and guns, early experiments indicated this as the most promising type. The earliest tanks were of the order of twenty-eight tons in weight, while with Mark VIII., a total weight of thirty-seven tons was attained. The distribution of this weight over a large base to prevent the tanks from sticking in the mud which was a feature, of so much of the battleground was a problem to which early attention 1 was given, and a decrease in ground pressure became essential. The pressure per square inch of ground is fixed by the weight of the tank and the area of the track in contact with the ground. The bottom outline of the tank is thus arranged so that the arc of track contact increases rapidly as the machine sinks into the mud. The track, flat under the centre of the machine, is carried up ill front and slightly up towards the rear end in a curve'designed to keep an equal length of ground contact both fore and aft of the centre of gravity when sunk on soft ground. The increase of length of ground contact, however, limits the ability of the machine to steer. In Marks 1., IV., and V. machines the ground pressure varied from 281b per square inch without sinkage t'd 111b when sunk about loin deep, that is to the belly or floor of the machine. The condition of the ground in Flan4ers necessitated a decrease in the track pressure and an increase in the width of the tracks from 2<Hin to 26Jin, and in some of the later machines a minimum track pressure of 51b was attained, which is less than that under the average human foot.

ANTI-TANK DEVICES. The surprise to the enemy—and even to mauy of our own officers and pien—occasioned by the appearance of tanks in numbers during the later part of 1916 is now well known, and their efforts subsequently made to produce tanks were not characterised by originality of design or success"in operation. The Germans were undoubtedly heavily handicapped by the difficulty in obtaining essential parts, and their first tanks were of a very cumbersome type, combining many defects which had already been surmounted in our own tanks. Of one type carrying armor one inch in thickness only a few were produced, and these were poor in achievement. It is said that their best tank units were composed of machines which had been captured from the British. Resort had therefore to be made to anti-tank devices. Of these deeper and wider trendies constituted the first effort. The second effort made use of special artillery, which were told off to deal with the approach of tanks. These specially allocated guns probably constituted the. best anti-tank device used by the enemy. Their machine-guns were provided with special armor-piercing bullets, which pierced the thinner armor of our earlier machines. Later, our tanks carried heavier armor, which was impervious to these bullets. A certain amount of execution was effected by a special rifle of J-ineh bore fired from the shoulder and provided' with armorpiercing bullets; but the "kick" of these rifles was not a pleasant experience. Other devices included mines, which were fired as the tanks passed over, and the best obstruction to the passage of tanks was considered to be a stretch of marshy ground in front of the lines. The paper concluded with a reference to the fact that British engineers had been able to introduce a new engine of war far in advance of anything which had been devised by the enemy, and that in this advance British engineers kept ahead to the end of the war, and maintained a supremacy in initiative and production. If but the same spirit of research, co-operation, and output can be maintained during the critical daVs of reconstruction and industrial competition, there need be no fear for the ultimate success of British engineering.