Part 5

*Weakness of Type.* The L-I (_Luftschiff_, or airship), the first of the German airships designed for purely military purposes, was a Zeppelin 525 feet long by 50 feet in diameter, of 777,000 cubic feet capacity, and 22 tons displacement. Its three sets of motors developed 500 horsepower and it had a speed of 52 miles per hour. It was launched at Friedrichshafen in 1912, and after a number of successful cross-country trips, it was tried in connection with naval maneuvers off Heligoland. Before the trial had proceeded very far, a sudden squall broke the backbone of the huge gas bag and hurled it into the sea, drowning fifteen out of the crew of twenty-two. It is a striking commentary on the frailness of these aerial monsters that every one of the big airships built up to that time had met disaster in an equally sudden manner but from a totally different cause in each instance. The L-II was slightly shorter but had 5 feet longer beam and displaced 27 tons. She was designed particularly for naval use, had four sets of motors developing 900 horsepower, and was fitted with a navigating bridge like that of a ship. It was confidently thought that all possible shortcomings had been remedied and success finally achieved in the L-II, but before there was any opportunity to demonstrate its efficiency, the airship exploded in mid-air, killing its entire crew.

_Effectiveness Grossly Overrated._ Despite this unbroken chain of disasters, the German official press bureau spread broadcast the prowess of the Zeppelin, its magnificent ability, and its remarkable achievements as an engine of war—in theory, since this was a year or two prior to the outbreak of hostilities. Had it not been for the forced descent of the Zeppelin IV at Luneville, where it was taken possession of by the French, these tales might have been accepted at their face value. But the log of the commander of this airship showed that its maximum speed was but 45 miles per hour, the load 10,560 pounds, and the ascensional effort 45,100 pounds. The fuel consumption averaged 297 pounds per hour while the fuel capacity was only sufficient for a flight of seven hours. During its flight, it had reached an altitude of only 6,250 feet, to accomplish which over 3 tons of ballast had to be dropped. It was also shown that the critical flying height of these huge airships is between 3,500 and 4,000 feet, Zeppelin himself declaring that his machines were useless above 5,000 feet. This probably accounts for the fact that the early raids on English towns were carried out at a height but slightly in excess of 2,000 feet. Later types, however, are said to have reached high altitudes.

Shortly before the outbreak of the war the L-5 was completed. This had a capacity of about 1,000,000 cubic feet, motors aggregating 1,000 horsepower or over, and a reputed speed of 65 miles per hour. Just what was the fate of this particular ship did not become known, since information of a military character has not been permitted to leak out of Germany from that time on. But capture or destruction has accounted for many of the intermediate numbers of the series; big German airships have been brought down in England, in the North Sea, in France, and at Saloniki, their loss culminating in the disaster to four out of the fleet of five that attempted a raid over London but were caught by adverse winds which exhausted their fuel supply so that they were blown out of control, toward the south of France. French anti-aircraft batteries or aeroplanes accounted for three of these, while the fourth, the L-49, was captured intact.

*L-49.* An essential part of the equipment of every form of German military apparatus is a means of destroying it in case of capture. In the case of the big airships, the officers are provided with revolvers loaded with incendiary bullets, which are fired into the gas bag, so that until the L-49 was forced to descend in the south of France by the activities of a battle plane, plus a lack of fuel, no airship of a recent type had ever been captured intact. In this case, the commander fired his pistol at the balloon but missed and was prevented from firing again by a French peasant who "covered" him with a shotgun. The wireless operator succeeded in using a sledge hammer on some of the apparatus of the very completely equipped wireless cabin before he was captured but did not do sufficient damage to prevent reassembly of the parts with little trouble. With the exception of the earlier type of Zeppelin that was forced to descend at Luneville prior to the war, the L-49 was the first that was ever known to have landed undamaged in hostile territory, as practically all the others were destroyed in the air, most of them having been wrecked either by aeroplane or anti-aircraft fire. Fig. 22 shows the L-49 as it rested on a hillside at Bourbon-les-Baines, France, and Fig. 23 shows a close view of the nose of the monster.

_Standardized Parts._ Comparing the L-49 with many of its predecessors led to the conclusion that it was one of the latest types, but an inspection of its construction revealed the use of many parts produced in quantities from standard patterns as well as a lack of the finish that has always characterized airship construction. Appearance and comfort had both been sacrificed with a view to saving the last ounce of superfluous weight in order to carry more fuel and ammunition. Evidently the production of these large airships has been reduced to a manufacturing basis and they are constructed in series in much the same manner as motor cars, though on a reduced scale.

_General Design._ In its general construction the L-49 was along the same lines that have characterized the Zeppelin since its inception, the outer envelope being stretched over a rigid frame of aluminum girders, inclosing a large number of independent balloons inflated with the usual hydrogen gas, no trace being discovered of the non-inflammable gas, the discovery of which had been hailed by the German press. The commander’s cabin was suspended well forward with the wireless room directly behind it, while a V-shaped gangway, recessed in the envelope proper so as to present no additional head resistance, ran back from the latter the whole length of the ship. This and the gun platform on top, mounting two machine guns and reached by a ladder suspended in a well amidships, have been familiar features of all the recent Zeppelins. The main envelope contained nineteen independent gas bags, each of which was made integral with an air balloonet to take care of the expansion and contraction of the hydrogen with varying altitudes and temperatures. Distributed along the lower part of the frame inside the envelope were a series of 50-gallon water-ballast tanks.

_Power Plant._ No less than nine large motors were employed to drive the huge gas bag, the maximum horsepower probably aggregating 1,600 to 2,000. The motors were distributed in five different locations, the largest being suspended just abaft the wireless room. The remainder were placed in self-contained units in the form of gondolas suspended from the sides of the frame, as shown in Fig. 24, the outline being that of a blunt-nosed fish. Each of these gondolas carried two motors placed side by side and coupled up so that either one or both could be employed to drive the single propeller. For cruising speeds one motor in each gondola supplied sufficient power or in some gondolas both motors could remain idle. No accommodation was provided for attendants in the gondolas, any of which could easily be reached by light ladders from the inclosed gangway.

To insure greater safety, the fuel supply was divided among sixteen tanks, all of which were interconnected with each other and the engines so that gasoline from any tank or tanks could be diverted to any particular engine. The supply of lubricating oil for each engine was carried in a tank in the gondola itself.

_Control._ Vertical and horizontal stabilizing surfaces of conventional form were built on the sharply tapering rear end of the frame, the elevator and rudder being similar to those used in aeroplane construction, except that the rudder was in two sections, the larger of which was placed on top of the envelope. The control of these surfaces, the operation of all the engines, the control of the water ballast, the air supply to the balloonets, and the fuel supply to the motors were all concentrated at a panel board in the commander’s cabin, the forward end of which bore a close resemblance to the bridge of a man-of-war. By means of thirty-eight push buttons, half red and half white, air could be released from or pumped into the balloonets, while in a similar manner the contents of any one of the water-ballast tanks could be emptied. Elaborate controls were provided for the power plant, it being possible to vary the speed or stop any one or more of the motors from the bridge. The rudder and elevators were operated by means of small hand wheels, similar to a marine steering wheel. One of the most prominent features of the operating cabin was a huge chart frame, capable of carrying a large scale map covering a considerable area, as well as an ample supply of maps. Few instruments were found in the captured ship and it is thought highly probable that everything not fastened in place had been dumped overboard at the last to increase its lifting power.

Apart from the use of standardized fittings and parts and the employment of a great deal more power in a slightly different manner than had characterized the earlier types of Zeppelins, the L-49 revealed nothing of unusual importance in airship design and certainly none of the world-beating features that German propaganda had been heralding for some time previous.

*Destruction of Zeppelins.* Mention has already been made of the fact that practically the only use made by Germany of her huge airships has been the bombardment of open cities, and that always at night. From the first of September, 1914, up to the end of 1917, between thirty and forty had met disaster, but only two were captured intact. The first of these was discovered by a Russian cavalry patrol while at anchor and its crew of thirty men were made prisoners. This was at an early period in the war, while the second one to be captured was the L-49, already referred to, which formed one of a squadron of five evidently sent out on a bombing expedition against London. Owing to adverse winds, they never reached their destination and four of them were known to have been put out of action, all except the L-49 being destroyed in the air. Not a few of these big airships have fallen victims to their own weakness and succumbed to the elements, in one instance a high wind tearing the airship loose from its moorings while the crew was not aboard. This was at Kiel, and after traveling a number of miles unguided, the big bag fell into the North Sea. In quite a number of other cases head winds have prevented the return of the raiders to their base and they have either been destroyed by their crews or wrecked at sea in attempting to return. In still other instances the unwieldy monsters have been wrecked by high winds when attempting to land, as was so frequently the case prior to the war.

_Aeroplane and Anti-Aircraft Fire Effective._ Before the war broke out the ability of either the aeroplane or the anti-aircraft gun to overcome the Zeppelin was purely theoretical, but actual experience has demonstrated that much of the theory was well founded. At least three Zeppelins have been destroyed by British aviators in mid-air, all or most of the crews being killed, while probably an equal number have been accounted for by French aviators in open battle. The war had not been under way a month before French anti-aircraft gunners showed their skill by bringing down-a "Zep," while only a week later a Russian battery accomplished the same feat, in this instance killing the entire crew. In 1916, British and French gunners succeeded in either "winging" or setting on fire three or four, while two dropped into the North Sea and one was blown up by its crew, having run out of fuel while raiding Scotch towns.

_Bombing Raids against Zeppelin Sheds._ Not the least of the disadvantages from which such huge and unwieldy craft suffer is the fact that the correspondingly large structures required to house them make exceedingly easy marks for the raiding aviator. Bombing, however, is such an uncertain art that even such large buildings as these cannot be struck from any altitude with a fair degree of accuracy. Consequently, in the number of raids that have been carried out against Zeppelin sheds, success has been due very largely to the temerity of the aviators, who have descended within a few hundred feet of their mark despite the fire directed at them from all quarters. At least three and probably more of the big airships have been destroyed in this manner by British aviators, who have made flights of several hundred miles to reach their destination, while the destruction of as many more has been ascribed by the Germans to the "accidental" explosion of a bomb in the shed. In view of the great precautions taken against accident from the explosion of the bombs carried by the airship itself, it is not considered at all likely that there was anything accidental about the wrecking of these craft.

One of the earliest attempts against Zeppelin headquarters at Friedrichshafen on Lake Constance, which resulted in the destruction of the L-31, is typical of the plan followed in attacks of this kind. Two British aviators flew from their base in France, about 250 miles distant, at a high altitude. They became separated before reaching their destination owing to a mist. This, however, prevented their discovery until they had dropped within a few hundred feet of the surface of the lake, which it was necessary to do to obtain a view of the airship sheds. The first pilot dropped his cargo of bombs from a height of only 100 feet or so over the shed and was rewarded by seeing it catch fire. He had hardly straightened out on his return course before he heard the attack of his companion. The latter was not so fortunate in escaping unscathed, as a bullet pierced his fuel tank and compelled him to descend. In the majority of instances, however, the raiders have succeeded not only in carrying out their task but in escaping undamaged as well.

CAPTIVE BALLOONS

*Military Value.* As an aid to military operations, the use of the captive balloon dates back many years. It was extensively employed in the Civil war and more recently in the Boer war, but with the advent of both the dirigible and the aeroplane, it was generally considered outside of Germany that its reason for existence had passed away. The German military plans included a large number of balloons for artillery observation purposes and they were used right from the start. It was only when the fighting settled down to trench warfare, however, that they came into prominence and the aid that they rendered the German batteries put their opponents at a serious disadvantage. Like the bayonet, which was also generally considered to have been relegated to military operations of the past, the captive balloon is now playing a very important role, particularly on the western front. In favorable weather, anywhere from ten to forty of these aerial observation posts will be visible from a single point on the line.

*Spherical Type Defective.* The captive balloon of the present day, however, bears no resemblance to its predecessors. From a sphere, it has been developed into a form that more nearly resembles the dirigible and at the same time, it embodies some of the features of the aeroplane. The old spherical balloon was always at the mercy of the wind, which not only governed the altitude to which the balloon would rise but also made things extremely uncomfortable as well as dangerous for the observers. With 1,000 feet of cable out, such a balloon rises to an equivalent height on a perfectly, calm day. But even a light wind cuts this height down by 100 or 200 feet, while if a strong wind is blowing, the balloon is held down to within a few hundred feet of the ground regardless of the length of cable paid out. Every strong gust beats it over at a perilous angle and the resulting shocks to the basket are so severe that its occupants can have little thought for anything but their own safety. Strong cross gusts set both the bag and basket to spinning and jumping in a manner that would make the results of the severest storm at sea seem mild by comparison, since the movements of the basket are executed with such rapidity that they seem to be in almost every plane simultaneously. As a result, the old type of captive balloon was available for service only in the calmest weather.

*Modern Kite Balloon.* It should not be supposed that the improved type of observation balloon now in use in such large numbers provides any unusual amount of ease or comfort, since it is also prey to the wind and does a great deal of swinging about as well as jerking when the wind is more than 15 or 20 miles an hour. But it has been improved to a point where the wind not only serves to elevate, instead of depressing it, but also to steady it. The new type. Fig. 25, is technically known as a kite balloon, because, in addition to the appendages attached to the bag itself for steadying purposes, it is equipped with a tail to assist in keeping it heading into the wind. This consists of a number of bucket-shaped pieces of heavy canvas attached to the tail cable by bridles so as to catch the wind and hold it, thus placing a heavy strain on the cable and preventing the balloon from swinging violently. As is the case with practically everything used at the front, the technical name of the new type of balloon is prominent by its absence. It is a _Drache_ (kite) to the Germans and a "blimp" to Tommy Atkins. Both its shape and attitude when aloft bear a close resemblance to a huge sausage, so that the term "sausage" is used by all the belligerents in common to a large extent. A side view of an American type is shown in Fig. 26.

It will be noted from Figs. 25 and 26 that the suspension of the basket and the appendages attached to the balloon at the rear hold it in a position which is roughly the equivalent on a large scale of the curve of an aeroplane wing. It has both camber and an angle of incidence, so that the wind serves to elevate it instead of beating it down. This lifting effect is further increased by tubes of large diameter, open at the forward end only and curving around the end of the gas bag at the rear. (It is also equipped with an air balloonet, the same as a dirigible.) The wind enters the lower end of this tubular member, which is in a line with the longitudinal axis of the balloon, but it must pass around the curve at the end of the gas bag before it can fully inflate it, so that it performs the double function of increasing the lift and steadying the balloon, though the latter is its chief purpose. The basket is suspended quite a distance below the gas bag and has accommodation for two observers. Like scores of other inventions that the Germans were the first to utilize on a large scale in the present war, the kite balloon was not a German creation but was originally developed in France.

*Methods of Inflation.* The average capacity of the kite balloons used for observation purposes is 28,000 cubic feet. They are inflated with hydrogen either from a portable generating plant forming part of the equipment of the balloon company or from a supply carried under high pressure in heavy steel "bottles" similar to those used for transporting oxygen or carbonic acid gas intended for industrial use. Since the balloon companies are stationed about 4 miles back of the firing line, the use of the portable plant is practical, but it has been found more economical and more convenient to generate the gas on a large scale at special establishments in France and England and send it to the front in containers. With a portable plant, several hours are necessary to inflate the gas bag, whereas with a large supply of the gas at hand under high pressure, the operation may be carried out in less than an hour.

The balloon naturally works under the same difficulties as all lighter-than-air craft, that is, there is a constant leakage of the hydrogen through the fabric in addition to that lost by the expansion of the gas on warm days when the summer sun beats down directly on the gas bag. Where a field generating plant is employed, quick inflation of a new balloon or replacement of loss is accomplished by the used of several "nurses", Fig. 27. These are simply large gas bags which are kept replenished by the gas plant working constantly, in other words, they are storage tanks, and when it is necessary to inflate the balloon quickly, their contents are simply transferred to it.

*Balloon Company.* Though aeronautical in character, the kite balloon service is actually a branch of the artillery, to which it is directly attached. A balloon company accordingly consists of twelve to twenty artillery officers of varying ranks and about 120 to 130 men. Of the officers, six to eight are artillery lieutenants or captains and go aloft as observers, this number being necessary because the strain of watching constantly is very great and the observers must be relieved at frequent intervals, the balloon otherwise being kept up continuously, both day and night. There are also a number of sergeants, each of whom is in charge of a different branch of the work, such as the inflation, transport, telephone service, and winding machine. No less than fifteen 3-ton to 5-ton motor trucks are necessary for each balloon company besides two or more motorcycle messengers, the care of the machines usually being entrusted to the corporals of the company. The remainder of the company are practically laborers, whose chief duties are to attach the ballast bags to the ropes when it is intended to hold the balloon on the ground for any length of time and to utilize their own weight for the same purpose when the balloon is about to go aloft or is only on the ground temporarily. In addition, every company has its surgeon and assistants, quartermaster, cooks, company clerk, and other attaches necessary to complete its organization, since a balloon company serves as an independent unit.