Part 20
Because, as I have already explained, the lumbermen did not consider spruce a profitable wood to handle, few of the spruce forests had been penetrated by railroads. So Disque and his Legionaries set out to build railways themselves—13 lines with more than 300 miles of trackage. The forests tapped by these new lines and their branches have, it is estimated, an ultimate production of 33,000,000,000 feet of lumber, a quantity almost beyond the comprehension of the human brain. In order to visualize it, it must be translated into commonplace, every-day terms. Let us assume that it requires 20,000 feet of lumber to build an average 5 or 6 room house. Taking this as a basis, the railways built by Disque and his spruce squadrons have brought within the reach of commerce enough timber to build almost 2,000,000 of these comfortable American homes, with sufficient waste wood to keep them heated for a generation. When the war ended, 174,000,000 feet of aircraft lumber had been cut and shipped—enough to build dwellings for the inhabitants of a good-sized city.
The government planned to have all the airplane stock from the Northwest cut at the one great cut-up plant at Vancouver, near Portland. This huge mill, the largest in the world, was built by the army in forty-five days and has handled more than a million and a half feet of lumber in twenty-four hours. But with the extension of the airplane programme, whereby the Spruce Division was called upon to furnish stock for all the Allies, more capacity was required and three other great plants of almost equal size were planned, one being ready for opening, one almost completed, and one projected when the Armistice was signed. These four huge mills would, it is estimated, have furnished the United States and her allies with close to 100,000,000 feet of airplane lumber a month.
The silent, peaceful forests of the Northwest seemed separated from the war by a million miles, a score of generations. But when the word was flashed from Washington to Disque to “Go ahead,” the primeval silence of the woods was suddenly shattered by a million bellowing echoes of battle. The war had come to America. Almost overnight the battle-front moved 6,000 miles westward—from the forests of the Argonne to the forests of Oregon. The trucks were brought in—endless caravans of grunting, straining monsters; the soldiers came, 30,000 in all; the loggers, graders, hard-rock men, sawyers, surveyors, engineers; the pile-drivers, the donkey-engines, the steam-shovels perched on wheels, the train-loads of food and tools and powder; the patient, sweating horses and the creaking wagons, thousands upon thousands of them. The wood roads were black with traffic; they fairly smoked with the fierce fight for speed. The highways were dust in the early fall, where the 5 or 15 ton loads ground the roads to powder. Then the wet weather came—fogs, mists, drizzles, showers, floods—the rainy season that grows the incomparable forests of the Northwest.
They splashed through it all, soldiers and Legionaries alike; they waded, they swam, they shivered and swore, and beat their hands over the brush fires—but the stream of supplies never stopped nor checked. The railway gangs, following close on the heels of the axemen, laid their twin lines of steel through the dripping forest faster than Kitchener laid down his desert railway to Khartoum, the locomotives crawling one mile, two miles, deeper into the wilderness each night. Night and day the forest trails were busy. Shuttling back and forth, loaded both ways with materials and men, teams and trucks and trains struggled for speed. Headlights, lanterns, shouted warnings, guided the night traffic along the sombre, shut-in ways. Clankings, clatterings, gasoline coughings, the honk of horns and the hoot of locomotives filled the air. The silent forest became a bedlam of sound, of action.
The spruce! The fir! The wings of victory! Berlin heard it, saw it first. The splitting blasts that showered the forest lakes with stones, the shouting, heaving din of the construction-camps, the crash of the trees as they fell before the axe and saw of the woodsmen, the whine of the cables through the sheaves as the huge logs were snaked into position for loading, the rumble and roar of the heavy-laden log-trains, the shriek of the giant saws in the mills—all these sounds fell upon the listening ears at German Great Headquarters with a growing menace, as ominous as the tattoo of the machine-guns, as the thunderous blast of the great Allied cannon, as the victorious cheers of the charging Yanks. They meant that the spruce was coming! The planes were coming! A few months more and the boasted Hindenburg Line would be a joke. The Germans knew that they could not build trenches in the clouds. That was the real reason why they were attacked by yellow fever in the fall of 1918.
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The engines and the planes themselves being in production, the next problem to be solved by the War Department was to provide our new aerial navy with armament in the form of machine-guns. Fighting in the air, it should be remembered, is entirely a development of the Great War, the adaptation of machine-guns for airplane use having practically all taken place since 1914. Though the records show that a machine-gun was successfully fired from an airplane in this country in 1912, and though the French had a few heavy planes fitted with mitrailleuses at the outbreak of the war, it was not until 1915 that machine-guns were carried by planes on active service. Prior to that time aviators depended on service and automatic rifles, pistols, shotguns shooting large shot held together by wires—miniature editions of the chain-shot used by early sea-fighters—and also carried darts and grenades to drop on the enemy. As a matter of fact, in one of the first aerial combats of the war, which took place on the Eastern Front between a Russian aviator and an Austrian, weapons were not used at all. The Russian determined to wreck his adversary and, in pursuance of this plan, so manœuvred his plane that the tips of his wings were just beneath the wings of the Austrian. He then suddenly elevated that end of his plane, hoping to upset the Austrian, but the result was that both machines collided and fell to the ground. Major Eric T. Bradley, formerly in the British Army but now an officer of the American Air Service, tells of having flown over the lines in 1915 armed with a twelve-gauge double-barrel shotgun loaded with buckshot tied together with wire, which swished through the air like the lash of a whip and occasionally hit something—usually by chance.
The development of methods for controlling machine-guns so that they can be fired through the area traversed by the propeller has had a vast effect on aerial combat, and an understanding of the problems involved is necessary in order to appreciate the difficulties which had to be overcome. The various devices which have been developed for controlling the fire of a machine-gun so as to cause the bullets to miss the blades of the propeller are commonly known as synchronizing or interrupter gears. These terms are, however, somewhat inaccurate, as it is only occasionally that the speed of the propeller is equal to the rate of fire of the gun, which is the condition of synchronization; moreover, the gun is not interrupted, but is caused to fire at the proper moment so that the bullet will miss the propeller-blade. “Gun control” would be a more descriptive name for the device.
Tractor airplanes—those which have the engine and propeller in front—were early found to be better suited to combat work than planes of the “pusher” type, which have the propeller behind, because they possess greater manœuvring powers and are better able to defend themselves. With these planes was developed the fixed aircraft machine-gun. This gun is fixed rigidly to the plane, pointing straight ahead, parallel to the line of flight. The first fixed guns were mounted on the upper plane so as to shoot over the arc described by the propeller, but these were not satisfactory owing to the difficulty in reloading the gun. To overcome this very obvious disadvantage the gun was lowered, which brought its line of fire inside the arc described by the propeller blades. Thus arose the difficulty caused by shooting into the propeller, to solve which countless experiments were made and numerous expedients tried. At first the blades were armored at the points where the bullets would strike, with steel of a shape calculated to cause the bullets to glance off, but this system was never satisfactory. Then the experiment was tried of wrapping the propeller with linen to keep it from splintering, as it was found that several bullets could be fired through a propeller thus treated without causing it to break. Throughout the summer of 1915 all of the Nieuport fighting-planes used by the French were fitted with fixed guns shooting through the propeller—if a bullet hit the propeller it either went through it or it wrecked it.
There is considerable disagreement as to who invented the device for controlling the fire of a machine-gun so as not to strike the blade of the propeller, but it is admitted that the Germans were the first to make any extensive use of it, introducing it on the Fokker monoplanes, which caused so much damage on the Western Front in 1915. Shortly thereafter the Allies adopted similar devices. When the United States entered the war neither the Ordnance Department nor the Aviation Section of the Signal Corps had had any experience worthy of the name with aircraft guns. And if they were ill-informed on the subject of guns, they were appallingly ignorant on the subject of gun controls. A few months of study and experiments served to materially increase the War Department’s knowledge along these lines, however, and by the time the planes were ready to receive the guns we had adopted a device known as the Constantinisco control. I should explain, perhaps, that there are two distinct types of gun control, both of which were in use when hostilities ceased. One is hydraulic, the other mechanical. The operation of both types is somewhat similar. In each case a cam mounted on the shaft of the engine actuates a plunger which in turn operates the rest of the mechanism. In the mechanical gun control the impulse of the cam is transmitted to the gun through a series of rods, causing the gun to fire at the exact moment when there is no propeller-blade in front of the muzzle. In the hydraulic type the impulse of the cam is transmitted to the gun through a system of copper tubes containing oil under high pressure. The hydraulic control, known as the Constantinisco, was adopted for use on American planes, particularly the De Havilland 4, which carries two fixed Marlins, each firing at the rate of 650 shots a minute. By employing the maximum rate of fire, 1,300 shots could be fired in a minute through the blades of the propeller, which would make 1,600 revolutions in the same space of time—without the blades being struck by a single bullet.
A machine-gun intended for aerial use must be absolutely reliable in operation. If a gun jams on the ground there is usually time to overhaul it or to replace it. Not so in the air. There a jam or a malfunction is almost certain to prove disastrous, if not fatal, to the gunner, who is left completely at the mercy of his adversary. An aircraft gun must also function properly in any position in which it is likely to be placed by the manœuvres of the plane. Likewise, an intensely high rate of fire is essential. For groundwork 500 shots per minute is reckoned as sufficient for the machine-gun, for a higher rate of fire would only result in several bullets hitting the same man. But a considerably higher rate of fire—up to 1,000 shots a minute, in fact—is demanded of aircraft guns, this being necessitated by the great speed at which airplanes move. The gunner, remember, can train on his target for only a few seconds, sometimes for only a fraction of a second, at a time, and it is essential, therefore, that he should have at his command the greatest possible volume of fire. Do you appreciate that, were an airplane flying parallel to, say, a high board fence, at a speed of 100 miles an hour, and shooting at right angles at that fence with a gun firing 880 shots a minute, _the bullet-marks on the fence would be ten feet apart_?
Single-seater machines carry only fixed guns, which are mounted with the barrel parallel to the axis of the airplane. These guns, which are synchronized so as to shoot through the propeller, are put into action by a trigger on the “joy-stick” of the plane and are aimed by pointing the entire airplane at the enemy. Flexible guns are used only on two-place machines, being operated by the observer or gunner. They are carried on the Universal mount, which permits of the gun being pointed in any direction. All of the flexible aircraft guns used by the Allies were based on the principle of the Lewis gun, the invention of a retired American army officer, Colonel Isaac Lewis. The chief difference between the ground and aircraft models is that in the latter the cooling radiator is eliminated, as aircraft guns are never fired continuously for any length of time.
When the United States entered the war the Vickers was the only type of fixed gun in use on either English or French planes and was used on all the planes which General Pershing bought in France. When the Equipment Division of the Signal Corps faced the machine-gun situation in September, 1917, it was alarmed to find that the entire production of Vickers in the United States had already been contracted for to supply the imperative requirements of the infantry. There was another gun on the market at this time, however—the Marlin—and toward its development for aircraft use the officers of the Signal Corps bent all their energies. Though the Marlin was adopted in the face of violent opposition, it resulted in providing sufficient fixed guns to arm the American planes, the wisdom of the action being proved by the fact that up to the time of the Armistice no other fixed guns were ready for delivery. The Marlin has been adapted to all American-built planes which carry fixed or synchronized guns, over 37,000 having been produced up to December, 1918. This gun shoots .30-calibre ammunition at the rate of 600 to 650 shots a minute and is fed from a belt of the disintegrating metal-link type. In December, 1917, the first order was placed for Lewis aircraft guns, over 39,000 of them being delivered to the American Air Service within the following twelvemonth. A notable improvement in the aircraft model of the Lewis gun was an increase in the depth of the magazine pan, so that each magazine holds 97 cartridges instead of 47 as previously. The Browning aircraft machine-gun was just coming into production when the war ended. This weapon embodies the best features of every known machine-gun and would probably have replaced all other types in use. It is a belt-fed gun of the recoil type—both the Marlin and Lewis are gas-operated—is as near fool-proof as a machine-gun can be made, and has the amazing rate of fire of 950 shots a minute. Of it the inventor is said to have remarked: “If it had four more parts it could play a tune; if it had seven more parts it could talk.”
The ammunition for fixed aircraft guns, such as the Marlin and Browning, is carried in belts containing a maximum of 500 rounds. In the earlier days of the war these belts were of woven web, but it was found that taking care of them, when empty, in the limited space of the fuselage, was always a source of annoyance and not infrequently a source of danger to the aviator. To remedy this a belt was designed and furnished to the American Expeditionary Forces which consisted of small metallic links held together by the cartridges themselves. As the gun fires, the links drop apart, chutes being provided so that they fall clear of the airplane. Another minor though interesting feature of aircraft armament is the small electric heater which is now provided for the purpose of keeping the gun warm and thus preventing the oil from congealing in high altitudes.
Efforts to make the bursts of fire from aircraft guns of maximum effectiveness have led to the development of three distinct types of ammunition—tracer, armor-piercing, and incendiary. The tracer type of ammunition was developed to assist the gunner in correcting his aim, and is equally useful by night or day, as the course of the bullet can be traced by a trail of white smoke in the daytime and by a bright spark at night. Armor-piercing ammunition has a projectile consisting of a hard steel core with a soft nickel casing. The object of this ammunition, as its name implies, is to pierce any of the metallic parts of an enemy plane, particularly the gasoline-tanks or the engine, the soft nickel casing acting as a lubricant and preventing the steel core from glancing off. Incendiary ammunition is loaded with yellow phosphorus. When the cartridge is fired the rifling in the barrel of the machine-gun opens a small hole in the case of the projectile, thus permitting the phosphorus to come in contact with the air, whereupon it immediately ignites and sets fire to any inflammable part of a plane which it may hit. It is customary to load the belts or pans of aircraft machine-guns with these three types of special ammunition in a certain sequence, depending upon the notions of the pilot himself. A sequence commonly used was, first, the tracer cartridge, which assisted the gunner in correcting his aim; next, two or three armor-piercing cartridges, in the hope that they would pierce the enemy’s gasoline-tank or damage his engine; and then one or two incendiary cartridges, which if the gasoline-tank was pierced would ignite the leaking gasoline and set fire to the machine. This sequence was continued throughout the loading of the belt or pan.
Another branch of sky warfare which was being rapidly developed was aerial bombing. Though bombs of a sort were used by Italian aviators against the Arabs during the Libyan campaign, and by American soldiers of fortune serving with the Villista forces in northern Mexico, these attempts were so amateurish and ineffective as to merit no serious consideration. It may be said that the first bombs dropped from an aircraft in the history of warfare were those loosed from the German Zeppelin which raided Antwerp in August, 1914. I speak with a certain personal knowledge of my subject, for the first bomb dropped on the night in question exploded less than a hundred yards from the window in which I was sitting, demolishing a house and killing three persons.
Many people seem to be under the impression that bomb-dropping is about as simple as dropping a brick out of an upper-story window onto the head of a man beneath. This is not so. As a matter of fact, it is extremely difficult to drop a bomb from an airplane so that it will hit a desired target, for, owing to the speed at which the plane travels, the bomb when released does not drop to the ground vertically, but falls in a parabolic curve, something like that described by a man who jumps from a street-car when it is in motion. For this reason the bomb must be released some moments before the airplane is directly over the target, the ability of an aviator to determine the exact moment to pull his release mechanism being acquired only through long experience. Bomb-sights have recently been perfected, however, which have largely eliminated this element of chance. These sights have numerical scales mathematically calculated, so that when adjusted for height, air-speed as shown by the air-speed indicator, and calculated speed of the wind with or against the airplane, two sighting points are moved into such a position that if the bomb is dropped when the desired target comes in line with them, it will reach its objective—provided, of course, the aviator has made his calculations and set his sights correctly. All this sounds rather complicated, I know, and it _is_ complicated, but if the pilot uses the sight correctly his chances of hitting his target are enormously increased. All bombing planes are fitted with quick-release mechanisms, which hold the bombs firmly in a vertical or horizontal position, according to the type and size carried. On the smaller bombing planes, such as the De Havilland 4, the release mechanisms are placed underneath the fuselage or the lower wings, but on the large types, such as the Handley-Page, the bombs are carried inside the fuselage. By a quick jerk of a lever the pilot releases his bomb precisely as a hangman, by jerking a lever, drops the trap on which the condemned man stands. And the consequences are usually much the same in both cases.
[Illustration: BOMBING PRACTICE.
An illustration of how the enemy’s lines of communication can be destroyed by bombs dropped from airplanes.
_Photograph by Signal Corps, U. S. A._]
[Illustration: EGGS OF DEATH.
Attaching dummy bombs to the rack of a bombing plane.
_Photograph by Signal Corps, U. S. A._]
[Illustration: PIGEONS HAVE BEEN REPEATEDLY USED WITH SUCCESS FROM BOTH AIRPLANES AND BALLOONS.]
[Illustration: THE EYE IN THE SKY; AN AIRPLANE CAMERA IN OPERATION.
During the offensive in the Argonne the American Photographic Sections made 100,000 aerophotographs of battle lines in four days.
_Photograph by U. S. Air Service._]
There were three distinct types of bombs—demolition, fragmentation, and incendiary—in use by the American Air Service when the war ended. American demolition bombs are made in 50, 100, 250, 500, and 1,000 pound weights, the 100 and 250 pound sizes being used chiefly. These bombs consist of a light steel casing filled with TNT or other high explosive and a detonator separated from the explosive by a safety-pin. When the bomb is released from the airplane the safety-pin is automatically pulled out, permitting the detonator to slide down into such a position that the bomb will explode the instant it strikes the ground. These demolition bombs are primarily designed for use against buildings, fortifications, and other heavy structures where a high-explosive charge is desired. Had the war continued long enough to have permitted of our aviators letting loose a few 1,000-pound bombs on some of the trans-Rhine strongholds, the Germans would have learned what the San Francisco earthquake was like. Fragmentation bombs are considerably smaller, the size most frequently used weighing twenty pounds. They have a thicker case than the demolition bombs and are constructed so as to explode a few inches above the ground. These bombs are for use against troops in trenches or in the open and depend upon the scattering of the fragments for their effect. Incendiary bombs weigh about fifty pounds and contain charges of oil emulsion, thermite, and metallic sodium, which burn for several minutes with the intense heat of a plumber’s blow-lamp. They are used against ammunition-depots, storehouses, and other structures of inflammable construction, the purpose of the metallic sodium being to discourage the efforts of any one who attempts to put out the fire, as it explodes violently when water is poured on it.