Zeppelin and his airships

Count Ferdinand von Zeppelin was born at Constance on Lake Constance (Bodensee), Germany, July 8th, 1838. His boyhood was not unlike that of others in Central Europe; and, as a matter of course, young Zeppelin was enrolled at a military school at Ludwigsburg, from which he in due time graduated into a lieutenancy in the Wurttemberg Army, but he was not particularly enthralled with the quiet life of a garrison in peace time. His creative faculties demanded something more of life than the routine of inspections, drills and dress parades. When he died on March 8, 1917, in Berlin, the whole world mourned the loss of one whose genius and vision had developed the rigid airship into a practical vehicle of the sky, proved of inestimable value in peace and war. Zeppelin had lived to see more than a hundred rigid airships built from his designs and under his personal supervision. And so completely was his personality interwoven with the creation of these aerial giants that throughout the world all dirigible lighter-than-air craft are looked upon as the noted Zeppelins, and are referred to as such. It is an unconscious but none the less fitting tribute to the man who, starting when he was past the half century mark, has made possible the greatest of all vehicles for us to use in our new dominion—the air.

An Officer in the American Union Army

Here in America the Civil War was attracting the adventurous from all parts of the world and shortly after it started, Zeppelin came over to join the Union Army as a volunteer officer and thus to add to his military education, but Zeppelin was not only the officer.

He loved to roam in out of the way places and whenever opportunity afforded he organized hunting parties and went off on long sojourns in the then sparsely inhabited regions of the Mississippi Valley. Here he played the explorer and wrote letters back home dwelling on the pleasures of exploration and the possibilities in store for him who could invent something that would take one to the far and inaccessible parts of the earth.

Zeppelin's First Rigid Design

His impressions gained during the American Civil War, where he had the opportunity of making captive balloon ascensions, and also in the Franco-German War where he had the opportunity of watching the numerous balloons leaving Paris during the siege, no doubt, first originated in Zeppelin's mind the thought of developing a large rigid airship. In fact, as early as 1873 he designed a large rigid airship, sub-divided into single compartments and he emphasized the importance of such aircraft for long distance transportation in order to help in the civilization of mankind.

In 1887 Zeppelin submitted a memorandum to the King of Wurttemberg in which he explained in detail the requirements of a really successful airship and stated many reasons why such airships ought to be large and of rigid construction. However, nothing of importance was actually accomplished until he resigned as a General in 1891 in order to give his full time to his invention.

In 1894 at the age of 56 years, with the assistance of an Engineer, Kober, he had completed the design of a rigid airship, and the modern rigid airship of today is not essentially different from Zeppelin's first design. He submitted these designs to a special committee that had been appointed by the most famous of the German scientific authorities and was greatly disappointed over the decision of the committee which, although they could not find any essential faults

in the Count's design, could not recommend that an airship be built in accordance with Zeppelin's plans. Admitting that he was not the first to conceive the idea of rigid airships, Count Zeppelin, however, insisted that he had arrived at new principles and that these principles were sound. There had been several attempts to build rigids, but there always had been too much weight of the necessarily voluminous framework, which so anchored the craft with its own weight that it could not lift itself. The discovery of aluminum made this problem less difficult, however, and many models were designed with the framework of this light material.

Two years after Count Zeppelin had completed his first designs and while he was still endeavoring to arouse enough interest to warrant the construction of a rigid ship, an aluminum framework rigid ship was built by another group near Berlin. This ship was of approximately 150 feet in length, but of an essentially different design from Zeppelin's. The outer cover was made of metal. On its first trial flight it was compelled to land, due to engine trouble and the fact that the framework of the ship was not strong enough to stand the stresses of the landing, caused it to go to pieces and this failure was quickly seized upon by the then existing adversaries of the rigid airship as an argument against the construction of rigid airships with a metal framework. This was unfortunate to the cause of rigid airships, because while Zeppelin had not been identified with that attempt, all experimenters were included in the popular condemnation.

Zeppelin's improvements were beginning to be recognized and admitted, but the money necessary for the development was not forthcoming.

Financing the First Zeppelin Company

Zeppelin, in spite of many difficulties, succeeded in enlisting the necessary private capital and in 1898 organized a stock company

(Aktiengesellschaft zur Foerderung-der Motorlufts-schift'ahrt) to promote motor airship flights. It had a paid in capital of one million marks ($238,000).

With his characteristic sound judgment and thoroughness of purpose, Count Zeppelin chose the Lake Constance (Bodensee) country for his initial efforts. He had known the lake and local weather conditions from boyhood and was convinced that the smooth ample surface of this beautiful lake offered the best facilities for the handling, starting and landing of these extremely large craft, though it was not long before enough had been learned to alight with them on land.

Now the giant Zeppelins can land at will with perfect safety on either land or water. Today Lake Constance is recognized as the best place in the world for the training of airship personnel.

The eyes of the entire aeronautical world were focused on the floating airship shed (Plate 1), which Count Zeppelin built and anchored in a bay close to his workshops at Manzell, near Fried richshafen . During the months that he was making the parts in the shop and assembling his ship in the shed, there was much speculation as to its appearance. It was generally thought by others who had experimented with aircraft that Zeppelin had some very laudable ideas, but as a rule persons were skeptical concerning his ability to produce a practical machine. Interest increased and when he announced that he would fly on July 2nd, 1900, all those interested in aeronautics, who could make the trip, came to Friedrichshafen and for several days before the flight delivered professional opinions predicting failure.

The First Zeppelin Flight

They solemnly averred that the airship would bend with the weight of the gondolas under its ends. They said if it bent, the engines and steering apparatus would not function. Further, they feared the ship would keel over in mid-air because, and they backed this assumption with figures and formulas based on their professional engineering knowledge and technique, as they pointed out, the center of gravity was too high. Then again the motors would surely explode the ship because the gondolas which held them were too close to the body. All expected Zeppelin to fail, and they were on hand as witnesses when first the big cigar shaped bag was floated out of its shed (Plate 1).

It was a huge thing in those days, 419.8 feet long (128 meters), with a diameter of 38.3 feet (11.7 meters). It was made up of an immense aluminum framework including 24 longitudinal girders running from nose to tail and drawn together at the ends. Joining the girders were 16 rings, (reinforced with diagonal wires), formed of transverse girders, which held the body together. On the bottom side of the body was fixed a bridge-like construction which strengthened the framework sideways and attached to it were two motor gondolas.

Over this vast framework Zeppelin had stretched an envelope of smooth cotton cloth, to lessen the friction through the air and to protect the gas bags from the direct rays of the sun. There were 16 single gas cells made of rubberized balloon cloth placed inside the framework. All were equipped with safety valves and several were provided with maneuvering valves. All together they contained 388,410 cubic feet (11,COO cubic meters) of hydrogen gas, which Zeppelin was confident would lift 24,450 pounds (12,000 kilograms). Immediately after the ship had been floated from the hangar Zeppelin permitted it to rise off the pontoons on which it had rested and the first successful rigid airship flight was an accomplished fact. He nosed his craft up through the air, the two 16 horsepower motors sending it along slowly at 13.5 miles per hour (6 meters per second).

Notwithstanding this low speed the craft responded to the controls and Zepplin a few minutes later demonstrated that he could alight safely as well as take off.

The First Company Dissolved Through Lack of Funds

Zeppelin made three flights with his first airship, on the third making 17.8 miles per hour (8 meters per second) but the funds had become exhausted and overtures to the Government and industrial concerns failing, he dissolved the stock company and began anew his struggle for capital. Somehow or other people were not interested in aerial navigation. They were less willing to invest their resources in experimental machines. For five years Zeppelin labored tirelessly to make persons believe in his project. He personally traveled the length and breadth of the land endeavoring to show that this was an enterprise so stupendous in its possibilities and importance to the world that it should be substantially endorsed.

Assisted by the King of Wurttemberg

It was not until 1905 that King William of Wurttemberg having supplied the funds and an aluminum manufacturer having lent him sufficient material for another frame that Zeppelin, now 67 years old, was able to start work on his second rigid airship. He completed it that fall after working incessantly day and night, making important changes over the first design, strengthening and at the same time lightening the framework and adding considerably to the efficiency of the steering apparatus. Motors also had been developing during that period and he was able to find two 85 horsepower motors for his power plants.

And then, as the ship was being taken out of the hangar the first time, the forward steering gear was broken, and the craft was literally driven by the wind the entire length of Lake Constance, not stopping

till it was brought up against the Swiss shore, whence with much difficulty it was returned to the workshops and repaired. The next time he flew, Zeppelin took the ship to a height of 1640 feet (500 meters) over the lake before motor trouble developed and he was forced to land at Allgau. Though he had no assistance aside from his crew and had made no preparations the inventor was successful in landing; and he moored her there in an open field for the night while repairing the motors. Before they could be started again a winter storm swept against the craft and it was so badly damaged that Count Zeppelin with a heavy heart was forced to give orders to dismantle it.

Handicapped by Motor Trouble

There was world-wide comment over the accident which was not due to structural defect or design. Zeppelin explained that he could have survived the storm had he been able to keep his motors running. But everybody thought his dream was shattered, one more glorious failure. But Zeppelin did not agree with public sentiment. The following April he commenced his third ship, throwing into the venture his last resources along with all the enthusiasm and confidence of youth. It was this that enabled him to announce its completion in October 1906. It was exactly like the one destroyed at Allgau except for the stabilizers at the stern which had been added to permit of smooth flying (Plate 2).

Successful Trials with the Third Zeppelin

Experiments with this craft were immediately successful. Zeppelin guided it over the lake between three and four hours in a single flight, making wide circles and maneuvering under absolute control, remarkable in view of its size. The ship also showed superior speed, making 28.8 miles per hour (13 meters per second).

This ship brought Zeppelin and his assistants their first public recognition. The German Government offered the inventor a new floating shed (Plate 3), larger than the old one, which would enable him to improve his craft and enlarge them. To him this was the most essential. He more than any other apparently realized that he must increase their size to develop practical weight lifting capacity.

The Government Becomes Interested

Meanwhile he continued his demonstration flights with his third ship, culminating on October 1st, 1907, in a brilliant 8 hour flight of more than 218.5 miles (350 kilometers). Thereupon the Government officials declared their willingness to take over Count Zeppelin's ships if they fulfilled certain requirements, among them a twenty-four hour flight. Early the next summer Zeppelin took out another new ship, LZ-4 (Plate 3), somewhat larger than its predecessors, holding 529,650 cubic feet (15,000 cubic metres) of hydrogen. This increased size gave it a carrying capacity of 37,478 pounds (17,000 kilograms) which, with increased motor power—each engine estimated at approximately 100 horsepower—made it a practical weight carrying and speedy craft. Count Zeppelin with an eye to the passenger and military possibilities had also built into the forward part of the hull, on top, an observation platform. It marked the beginning of refinement in design and conveniences which has been continued unceasingly . Here was an airship which Zeppelin felt worthy of demonstrating to the public at large.

Zeppelins for Commerce and War

His great flight on July 1st, 1908, was as successful as it surely was daring for he took the new rigid up over the Swiss Alps to Lucerne and back again.

The world was astounded, particularly his contemporaries, a majority of whom unhesitatingly flooded the grand old man with

enthusiastic messages of congratulation. Just as he had worked so devotedly to bringing forth something in which the German people could have faith, so was his faith justified. The public was wildly enthusiastic. Everybody was proud of the accomplishment on German soil and joyfully acclaimed Zeppelin whose lone ideas were now the ideas of a nation. His triumph was not only official but national. His vision was the vision of the people and it was an accomplished fact.

Rarely had there been such national interest shown in any sort of venture as that represented by the vast throngs that gathered from all parts of the empire to witness the start of the official duration flight on August 4th that year. Zeppelin planned to sail the ship down the Rhine Valley toward Mainz and return. He got away on schedule and disappeared in the soft haze, all Germany receiving reports of his progress as the ship appeared for a few moments over a village and then out of sight once more.

But disaster awaited the gallant ship. On the return flight motor trouble caused a forced landing at Echterdingen near Stuttgart. A storm blew up and the airship was torn from its moorings. As it was being whirled into the air, the entire structure was suddenly enveloped in a solid flame and Zeppelin a few moments later was gazing at the twisted skeleton of his latest efforts.

The Zeppelin Endowment

It was thought then that Zeppelin had built his last airship. He had employed all his own personal resources in that venture, and though the rigid had performed remarkably, even his closest friends could see nothing but failure in further attempts to establish the new science. But they were wrong. Zeppelin had been more successful than he realized. His persistent efforts had continuously improved the rigid type. Each flight was better and more efficient than the

ones preceding it. All this had been noted by the people. When it was learned that Count Zeppelin had no funds with which to continue , a popular subscription campaign was started in various sections , with the result that within a few weeks 6,000,000 marks (approximately $1,500,000) had been contributed and turned over to Zeppelin for him to use as he saw fit in carrying on his experiments. Here indeed was recognition. For the money had come from persons of high and low degree, from huts and palaces. The Zeppelin fund was truly representative of the people. It made the shops and hangar on Lake Constance a popular institution. For the first time in his life the inventor found his airship enterprise on a firm financial basis. With this foundation he was able to increase his shop and laboratory facilities and make important changes in his organization.

Instead of being forced to produce something for demonstration flights alone, he was able to concentrate on practical development. His personnel was ably qualified for the new work. Many of his assistants had been with him since the beginning. His progress had been theirs in the new science of lighter-than-air engineering. Many of these men are still with the Zeppelin organization which retains the original name created by the popular support of the German people.

The Beginning of the Zeppelin Organization

With the 6,000,000 marks presented to him Count Zeppelin founded the "Zeppelinstiftung zur Foerderung der Luftfahrt" (Zeppelin Endowment for the Propogation of Air Navigation). This organization is the exclusive shareholder of Luftschiffbau Zeppelin (the constructing company), and through this controls the many subsidiary companies, each one producing essential parts of the Zeppelin so that the entire organization is practically independent of outside sources. The various organizations have been added to and

developed at intervals since the Zeppelin Endowment was created in 1908. They are not only concerned with producing airships and all their parts but with developing airplanes, seaplanes and power plants, with the special machinery so important to the success of the new aircraft which Zeppelin continuously produced and which proved superior to other products, due in no small part to the splendid organization developed by means of the popular fund, the profits from which under the terms by which Count Zeppelin accepted it, must continuously be thrown back into the treasury "to be used exclusively for the propogation and development of air navigation." When Count Zeppelin died in 1917 his assistants were placed under obligations to carry on the work and administer the Zeppelin Endowment according to the original terms which do not limit its activities to national boundaries, but encourage the development of aerial navigation throughout the world.

Early Development and Flights

Commencing in 1908 Zeppelin devoted his energies to perfecting aircraft. There were many epoch making achievements, not only the record flights and increasing efficiency and performance tests but continuous discoveries and inventions no less important and significant because they were for the time being accomplished within the walls of laboratory and factory. They constitute one of the most remarkable chapters in this age of mechanics and engineering, and are worthy of further explanation later on.

One of the first flights, under the new organization, was that of the new Zeppelin Z-1, April 1st, 1909, from Lake Constance to Munich. Before it could land at Munich a heavy southwest wind pushed it back from the field over which it hovered. The Commander decided to "weather the storm" in the air; and for the first time in the history of aerial navigation the airship remained aloft,

her nose against the wind, her motors turning over just enough to keep her in the same spot. Eleven hours later the Z-1 was still up but shortly afterward signalled that she was being forced to land because her fuel supply was becoming exhausted. Soldiers detailed for the purpose assisted in mooring her fast in a field near Loiching, where guarded by hundreds she lay all night in the storm, unharmed, though repeatedly assailed by squalls which often swept against her with 40 miles per hour (18 meters per second) velocity. The next day she went up and hopped over to Munich and received a wildly enthusiastic greeting from the thousands who had followed her adventure with personal pride and interest. The Z-1 spent four hours flying over Munich and then turned on her heels and back to her harbor at Friedrichshafen. If there was anything necessary to silence the few critics who still entertained doubts as to the ultimate practicability of rigid airships, that flight of the Z-1 accomplished the purpose.

Count Zeppelin meanwhile was rebuilding his "Echterdingen" airship and on May 29th, 1909, he took it out of Manzell toward the north of Germany. He kept on until he reached Bitterfeld before turning back toward Lake Constance. After 38 hours in the air during which he had traversed 683.5 miles (1100 kilometers) he landed at Goppingen for gasoline. In landing the ship struck a tree but the damage was quickly repaired and the rigid was able to return under its own power to the air harbor on Lake Constance.

After a thorough overhauling Count Zeppelin flew the same airship to Berlin, at the express invitation of the Kaiser, who gave a dinner in his honor at the Royal Palace following an enthusiastic popular reception from the entire populace in the capitol. On his return to Lake Constance he met severe storms and a broken pro

peller compelled a landing. It was found that a piece of the blade had penetrated one of the gas bags; and three days were required to repair the damage. Finally, after 27 hours in the air, the ship once more rested in its home shed. It is said that this flight forever established Zeppelin in the confidence of the people and the Government . His ships acquired the reputation of the builder in being able to surmount tremendous difficulties. The Zeppelin headquarters at Friedrichshafen became the German Mecca. But the Germans were not alone in their pilgrimage for thousands of persons interested in aeronautics journeyed to Lake Constance on the shores of which great plants had grown up on the land which Zeppelin had purchased for his wonder city of the air.

In the fall of 1908 the members of the Reichstag and the Bundersrath came to Friedrichshafen, a hundred or more trusting themselves to the Zeppelin ship, the sole feature of the national celebration. Thousands of watercraft dotted the clear waters of the lake as the Zeppelin went up again and again tiWL -Stei,£apacity with the leaders of German political, financial, and industrial life (Plate 4). Zeppelin was hailed as a national hero, and more, for it was generally recognized that his great vehicles possessing such speed and durability were world travelers and as such would do much toward bringing all parts of the world together and thereby eliminating national borders—as far as trade, travel, and commerce were concerned , at least.

The Neic Construction Plant

It was during the same year that Zeppelin abandoned the floating shed at Manzell, where all his ships had been built. New work shops were located on shore near Friedrichshafen (Plate 4). Half of the original contribution went into the new construction plant which was incorporated as Luftschitfban-Zeppelin, G.m.b.H. (the Zeppelin Air

ship Building Co., Ltd.). Here the construction of the new Zeppelins was begun with augmented forces of engineers and workmen. Naturally the first airship was ordered by the Deutsche Luftschiffahrt A. G. ("DELAG")—the German Airship Transportation Company—which had a paid in capital of 3,000,000 marks ($714,000 .00) subscribed by a number of public spirited men solely to start a Zeppelin passenger and mail service. It was planned to employ larger ships than those with which Zeppelin had convinced the public, to secure greater lifting and carrying capacity. These ships developed rapidly.

Military Value Proved by Commercial Operation

They attracted attention among the military authorities who had decided that the Zeppelins offered advantages over the existing types of observation aircraft, that they were in no way difficult to handle in the air or on the ground and, in fact, were better adapted' to military purposes than others previously built. A deciding factor in favor of the Zeppelins was the ease with which they could be put into their sheds after each flight. The Government, accordingly, ordered three airships built and equipped for military service. Their performance was kept secret but they were accepted and obviously performed equally as well as their contemporary commercial craft. There was the Zeppelin "Sachsen" which flew to Vienna from Baden-Baden in less than eight hours. This commercial flight led the German army to buy three more military ships of the "Sachsen" type.

Activities Early in the War

The Navy followed suit and in October, 1912, bought the L-1 (Plate (J), for experimental and training purposes in connection with the fleet. The L-1 carried 706,200 cubic feet (20,000 cubic meters) of Hydrogen and proved its worth on its trial flight from Friedrich

shafen, thence north over Germany to Helgoland in the North Sea, thence to the Baltic, side trips here and there, and finally to the airship harbor at Johannisthal where it was to be stationed. The flight lasted 34 hours.

This persuaded the Naval officials that Zeppelins were essential in marine warfare both for offense and defense. Another order was placed, this time for a Zeppelin of much larger dimensions. It was christened the L-2 and delivered in September, 1913 (Plate 6). This ship represented an utterly new departure in design, later universally adopted. A corridor was built forming a keel on the inside and bottom of the ship (Plate 7). It had a gas capacity of 953,370 cubic feet (27,000 cubic meters) and was equipped with four motors of 180 horsepower each.

Being the first of the kind it was inevitable that the corridor arrangement should develop a flaw. It lacked proper ventilation. Hydrogen leaked out from the ship and was drawn into the motor gondolas. On one of its first flights this caused an explosion on the L-2 which sent it to the ground a wreck.

Operations with the Fleet

Early in the spring of 1914 another Zeppelin, the L-3 (Plate 8) was delivered. It held 787,400 cubic feet (22,300 cubic meters) of hydrogen and carried besides its own weight approximately 19,840 pounds (9,000 kilograms). The average speed was 43.5 (70 kilometers ) per hour with motors aggregating 630 horsepower. It carried at least 6,614 pounds (3,000 kilograms) to a height of 9,186 feet (2,800 meters). The L-3 was the only naval airship Germany possessed at the beginning of the war.

Following the ideas of the inventor both the German army and navy used the Zeppelins for strategical reconnoissance in the early days of the conflict. The Zeppelins flew the western and eastern

boundaries of the empire seeking information concerning the movements of the Allied armies. This proved dangerous, however, for the airships then could not rise to high altitudes; and consequently were exposed to enemy fire from the batteries below and airplanes above.

The L-3 operated with the fleet in the North Sea and her activities served to show the value of supplying as quickly as possible Zeppelins able to fly high and with greater speed than ever. It was also found advisable to cease flying over land by day. The Zeppelins became the night cruisers of the air, and were assigned the task of destroying railway junctions, bridges and ammunition dumps along the enemy line of advance.

The Navy soon acquired the Zeppelins L-4, L-5, L-6 and L-7, which joined the L-3 in the North Sea operations where they became indispensable as the eyes of the fleet and a continual menace to the enemy attempting to establish himself on the German Coast. All these airships were duplicates of the L-3 except in minor details. Their hulls long and cylindrical, of uniform cross sections, that is excepting the ends each part was the same size as the others. This was the first attempt at standard construction and it permitted quantity production more economical and quicker for they were not compelled to design and fabricate each section as it was needed. The plant at Friedrichshafen had been expanded and was working to capacity. Every effort was made to save time. The result was remarkable for they were able to produce one Zeppelin every six weeks. Late in 1914 the Zeppelin Z-11 was delivered to the army and the L-8 to the navy.

The Growth of the Zeppelins

Larger sheds (Plates 8 and 9) were completed at Friedrichshafen enabling Zeppelin to build bigger ships which could give the performances he felt was essential.

The first of these, the LZ-38, left the shed in April, 1915, and joined the army. It had 1,130,000 cubic feet (32,000 cubic meters) of hydrogen capacity and was fuller, that is, its ratio of length to diameter was 9 to 1 where in the former ships it was 11 to 1. The wider girth afforded more freedom in design and the stern was drawn out much finer, resulting in more speed; on later ships reaching 58.1 miles per hour (26 meters per second). The LZ-38 could carry a useful load of 30,865 pounds (14,000 kilograms) besides her own weight, more than 37% of her total lift. The Zeppelins of this type (Plate 10-LZ-77) proved from the day they were first flown equal to all the demands made upon them.

North Sea Patrol Flights

They cruised over the North Sea scouting and guarding the coastline, remaining in the air for thirty hours at a time. They flew out from the western outlet of the Kiel Canal, northward along the shores of Denmark to the Norwegian coast and thus were able virtually to command the sea hundreds of miles around with powerful glasses.

One day when the true details of the Skagerrak Naval Battle are given to the world, it will realize the vital part which the Zeppelins played. They consistently hampered the enemy's mine laying operations and rendered timely and valuable support to the counteractions of the fleet. In discovering mines they were particularly effective; and this work alone, about which the world was uninformed , justified fully the time and labor put into their construction. Ten Zeppelins of the L-38 type were delivered to the navy in 1915, numbered from L-10 to L-19 inclusively. Approximately as many were turned over to the army during the year, each one being slightly improved. Zeppelin and his staff of experts were always able to profit by the practical experience which the ships were undergoing almost daily.

Zeppelins Become Lighter and Stronger

The hulls were strengthened and made more rigid, yet lighter, machine guns were mounted at proper points of vantage and bomb dropping apparatus so perfected that heavy loads of explosives could be carried in absolute safety, yet instantly released and with remarkable accuracy. An observation car was added to each new ship.

The Zeppelin Observation Car

This car was one of the most unique inventions developed during the war. It could be lowered with an observer aboard, fully one kilometer (3,280 feet) below the Zeppelin. Here the observer could get his bearings while his ship lay far above hidden in the clouds. The ship could fly or drift above the clouds to a point directly over the spot to be bombed, then by lowering the car with the observer through and just below the clouds, he was able to direct both the operations of the ship and the bombing. A telephone connection ran up through the supporting cable. He was able to signal for bomb releases and navigate so efficiently that any objective could be attacked without danger of the enemy seeing the Zeppelin lurking behind the clouds.

Another Zeppelin, the L-20 was delivered to the navy early in 1916. It had hydrogen capacity of 1,271,160 cubic feet (36,000 cubic meters) though the diameter was the same as the others. The L-20 carried a useful load of 37,478 pounds (17,000 kilograms), and an increase of 1,312 feet (400 meters) over their ceiling and made the same speed with the same horsepower.

During the year Zeppelin delivered seven more ships of this type, but possessing greater efficiency. The navy received five of them and the army two.

Anti-Aircraft Defenses Compel Zeppelins to Fly Higher

The Allies meanwhile had developed anti-aircraft defenses and their airplanes possessed greater climbing ability. To meet these new conditions the airships were continuously compelled to fly higher. They also required speed greater than the average of 54 miles per hour (25 meters per second) because while navigating over the North Sea they frequently encountered winds of from 33.5 to 40 miles per hour (15 to 18 meters per second).

To meet these conditions the L-30 was built (Plate 9). It had a gas capacity of 1,942,000 cubic feet (55,000 cubic meters) and was nearly twice as large as the original 1,129,920 cubic feet (32,000 cubic meters) four motored ships. The L-30 was ready in May, 1916. It was almost perfectly streamlined. The long cylindrical hull, so convenient from a production standpoint, had been abandoned. The L-30's stern tapered gracefully to a fine point. It was driven by six 240 horsepower Maybach motors, arranged practically as before. One was located in the forward gondola with a direct drive propeller, another three motors in the rear gondola, one with a direct drive and two others each in a separate gondola located opposite each other on the sides of the hull amidships, so as not to interfere with the efficiency of the propeller in the rear gondola.

The L-30 carried 63,933 pounds (29,000 kilograms), about 45% of its total lift. Other Zeppelins of her class had a useful lift of 50% due to better design and superior materials. This represented a marked advance, as the preceding types lifted only 37% of their weight. The ceiling had been increased, too, by more than 3,280 feet (1,000 meters). They could now ascend from 11.800 to 14,750 feet (3,600 to 4,500 meters), depending on the load and weather conditions. They made a speed of 63 miles per hour (28 meters per second).

Faster Zeppelins for Scouting

These Zeppelins proved exceedingly valuable for scouting. They were flown in all kinds of wind and weather. So great was their capacity for fuel that there was no task too great for them to undertake . But then, airplanes were constantly being improved, and they could rise quickly to high altitudes. The planes carried machine guns firing phosphorous incendiary bullets fatal to the hydrogen filled hull of the Zeppelins if overtaken. Airplanes, naturally, could outdistance airships, and there was no escaping them. The Zeppelins were compelled to fly still higher than the L-30 type. There shortly appeared other Zeppelins carrying loads of more than 39 tons or 60% of the total lift of the ship; and they could fly at an altitude of 19,684 feet (6,000 meters) with 13,228 or 15,432 pounds (6,000 or 7,000 kilograms ), without depending on the thrust from the motors.

In the fall of 1917 "altitude" motors were developed, larger and having supercompression. They did not develop full power at sea level but instead functioned normally at 10,000 feet altitude above sea level. They, moreover, gave ample power higher than that. They speeded up the Zeppelins to 70.5 miles per hour (31.5 meters per second).

The Zeppelin company built thirty-six ships of this type (Plate 10-L43), from 1916 to 1918; and they were used by the army and navy. The British R-34, which crossed the Atlantic in 1919, was an exact duplicate of the Zeppelin L-30 type.

Zeppelin Vision of World Transport

Count Zeppelin was working on his post-war plans for commercial aerial transport when he died in March, 1917. His latest ships had demonstrated their worth as cargo carriers, not only in war but in peace. Before hostilities commenced he had seen thousands of passengers carried in his Zeppelins. An account of these operations will be found in Chapter III.

His Will Carried Out After His Death

They had justified the inventor's faith and inspiration. He had never abandoned his ideas of world transportation and was completing a survey of requirements and conditions to be met when, during a flight, he contracted inflammation of the lungs. Though mortally ill and old in years—he was seventy-eight—Count Zeppelin held conferences in his sick chamber, passing on to his assistants the big idea of airship transportation. They have since continued the work where Count Zeppelin left it. Following the funeral at Stuttgart airships dropped garlands and wreaths of flowers on his grave, in honor of the man who had done so much and had perfected an organization capable of performing the tasks remaining.

'The Record Flight of L-59

There is ample proof of what a modern Zeppelin can accomplish when commercially operated and not forced to operate at the highest possible altitude and maintain maximum speed. In November, 1917, the Zeppelin L-59 (Plate 11) was sent to German East Africa with medicines and ammunition for the beleaguered colonial troops. The Zeppelin was especially prepared for the flight, all superfluous equipment, such as bomb dropping apparatus and armament being removed, all available space reserved for the cargo. The L-59 was longer by 98.5 feet (30 meters) than the others. . This made room for two additional gas bags. Inside her 744)^ foot hull (227 meters) were 2,381,000 cubic feet (68,000 cubic meters) of hydrogen. She could carry 50 tons easily. With only five motors she averaged 62.0 miles per hour (28 meters per second).

Flown from Germany to Jambol in Southern Bulgaria, the L-59 was there loaded with 9 tons of machine gun ammunition and 4 tons of medical supplies and with 21 tons of gasoline for the motors.

1+225 Miles in Less than Four Days

The great Zeppelin sailed out of Jambol (Plate 12) at 9 o'clock in the morning, crossing northwestern Asia Minor, then the Aegian Sea, south of Smyrna and on between the Islands of Crete and Rhodes and across the Mediterranean, reaching the African Coast by daybreak the next day.

The great Sahara Desert was then crossed, the L-59 passing over the oasis of Farafrah and then Dakhla. Military headquarters at Berlin, meanwhile, were trying to reach the Zeppelin by wireless. The German Intelligence Office had intercepted a British wireless message to the effect that the Colonial troops had surrendered to the British. The L-59 had passed through a severe storm the night before and had taken in her radio antenna; and it was not until she was over Djebel Ain, west of Khartum that she listened in and picked up the message. In a day and a half the L-59 had traversed 1865 miles (3.000 kilometers). Without stopping the Zeppelin was turned about; and after retracing its path across the Sahara, thence over the Mediterranean to Adalia on the coast of Asia Minor, and flying high over Asia Minor and the Black Sea, arrived back in Jambol in less than four days from the time it set out from that port. There remained sufficient fuel aboard for two or three days additional flying. The ship, under the same conditions, could have flown from Hamburg to Khartum and return. As it was she traveled 4,225 miles (0,800 kilometers) on a non-stop flight which, though it occurred in 1917, today remains the world's record for all kinds of aircraft, airship or airplane.

Larger Zeppelins More Powerful

During the summer of 1918 the Zeppelins were again given higher climbing ability to meet the ever-increasing efficiency of planes and anti-aircraft guns. Another gas bag was added to the new ships

(Plates 13 and 14), which brought them up to 2,189,220 cubic feet (62,000 cubic meters) capacity. In order not to diminish the speed two motors were added in respective gondolas, making seven engines in all, aggregating 1820 horsepower. They could carry 94,798 pounds (43,000 kilograms) or about 60% of their total lift. It was planned to add improvements enabling them to reach an altitude of 26,240 feet (8,000 meters) but the armistice halted all military activities and there was no occasion at that time for commercial craft to fly so high.

The Most Remarkable Scientific Development in the History of Aeronautics

Looking back over the development of the Zeppelins (Plate 15), one fails to find such remarkable and quick advance in any other medium of transportation. The history of engineering does not record in any other science progress comparable to that, of the relatively new science of lighter-than-air as represented by the Zeppelins during the four years of war.

Seventy Percent Speed Increase

Their speed had increased from 46.6 to 87.5 miles per hour (75 to 130 kilometers per hour) approximately 70%. Their horsepower averaged 2,000. To carry useful loads of 44 tons their hydrogen capacity had been raised from 706,200 to 2,189,220 cubic feet (20,000 to 62,000 cubic meters). Other commercial ships were built embodying the improvements developed during the war. A description of them will be found in Chapter III.

Refinement in Design

This progress was made possible only by continuous experiments. Ideas and suggestions were adopted regardless of expense or chance of failure. In this way the Zeppelins had the advantage of every conceivable refinement in design. Their hulls, motor gondolas, in

fact, all braces and wires were streamlined so as to offer the least air resistance.

The rubberized cloth gas cells, or bags, used in 1914 had been discarded for others of light yet strong cotton cloth (and often silk), lined with goldbeater's skin to make them hydrogen proof.

Many of the experiments were as costly as they were painstaking but the Zeppelin engineers had learned early in their work that airships can not be built satisfactorily without long and arduous experiments to support each innovation. By continually striving to increase efficiency they secured simplified control systems and ships that handled more easily, hulls that were far more rigid yet lighter than their predecessors. Even the framework was lightened as by degrees it was made stronger. Many structural parts were standardized , facilitating production and repairs.

One has an idea of the innumerable parts necessary in the skeleton of a Zeppelin when he learns that more than 250,000 small crossties are required in making the triangular shaped girders in the frame work of a 1,977,300 cubic foot (56,000 cubic meters) ship which crosstie is a masterpiece of construction, because of its ingenious shape and finish.

Eighty-Eight Zeppelins During the War

Few persons know that during the war alone LuftschiffbauZeppelin designed and built 88 airships at their four great construction plants, as follows:

That in itself was a remarkable achievement which could have been accomplished only by possessing the scientific knowledge borne of experience. But it is not all.

One Hundred and Fifteen Zeppelins Built and Operated

From the day Count Zeppelin built his first ship until the last in 1919, a total of 115 Zeppelins were built and operated. The first three were experimental. Nine Zeppelins were successfully operated commercially in the transportation of passengers. Forty were delivered to the German army and 63 to the navy.

Scientific Comparison

There exists in the field of engineering an impartial, positive and unswerving means of determining the relative merits of things; and that is by a technical analysis of their success. By it one may recognize the values of the principles and construction methods involved . It is commonly said that nothing succeeds like success; and this is virtually true of the Zeppelins. Their record for efficiency remains unsurpassed, as a matter of fact, unequalled. It has never been denied that they were superior to contemporary craft or that they failed to maintain an increasing advantage over them. This comparison is justified by the following figures which we will first attempt to explain.

It will be noted that there are three kinds of efficiency, (1) Speed (the aerodynamical figure), (2) Lift (the constructional figure) and (3) All-around efficiency (the combined quality figure).

The first relates to the efficiency of airship propulsion as effected by degrees of refinement in form, lessening of resistance, conservation of power, etc. It is simply the relation between the speed and engine power. Inasmuch as higher speed with the same power or the same speed with less power means economy of operation; therefore , the higher figure indicates superior quality.

Secondly, referring to the lift, this constructional figure indicates the relative useful or pay loads carried with the smallest amount of material used in the ship itself, because the ship, which must also be carried is "dead weight." As we must consider all ships equal as far as structural safety is concerned, the technical performance is determined by judging the relative performance in carrying useful loads (for ships of similar size), or equal loads with smaller ships, which means economy of operation. The higher figure indicates superior quality. It should be noted that this constructional figure is applicable only to comparison of airships of similar size, speed and service requirements. For general comparison, however, ships of approximately the same size may be considered.

Thirdly, all-around efficiency (the combined quality figure) is somewhat arbitrarily chosen by considering both the speed and carrying qualities together. It is not based on scientific deduction , but rather is a practical means of estimating general worth, as speed and carrying capacity are the main requirements of an airship.