The Mastery of the Air Part 3
At length, in 1908, there came a turning-point in his fortunes. The German Government, which had watched the Count's progress with great interest, offered to buy his invention outright if he succeeded in remaining aloft in one of his dirigibles for twenty-four hours. The Count did not quite succeed in his task, but he aroused the great interest of the whole German nation, and a Zeppelin fund was established, under the patronage of the Kaiser, in every town and city in the Fatherland. In about a month the fund amounted to over L300,000.
With this sum the veteran inventor was able to extend his works, and produce air-ship after air-ship with remarkable rapidity.
When, war broke out it is probable that Germany possessed at least thirteen air-ships which had fulfilled very difficult tests. One had flown 1800 miles in a single journey. Thus the East Coast of England, representing a return journey of less than 600 miles was well within their range of action.
CHAPTER X. A Zeppelin Air-ship and its Construction
After the Zeppelin fund had brought in a sum of money which probably exceeded all expectations, a company was formed for the construction of dirigibles in the Zeppelin works on Lake Constance, and in 1909 an enormous air-ship was produced.
In shape a Zeppelin dirigible resembled a gigantic cigar, pointed at both ends. If placed with one end on the ground in Trafalgar Square, London, its other end would be nearly three times the height of the Nelson Column, which, as you may know, is 166 feet.
From the diagram here given, which shows a sectional view of a typical Zeppelin air-ship, we may obtain a clear idea of the main features of the craft. From time to time, during the last dozen years or so, the inventor has added certain details, but the main features as shown in the ill.u.s.tration are common to all air-craft of this type.
Zeppelin L1 was 525 feet in length, with a diameter of 50 feet. Some idea of the size may be obtained through the knowledge that she was longer than a modern Dreadnought. The framework was made of specially light metal, aluminium alloy, and wood. This framework, which was stayed with steel wire, maintained the shape and rigidity of her gas-bags; hence vessels of this type are known as RIGID air-ships. Externally the hull was covered with a waterproof fabric.
Though, from outside, a rigid air-ship looks to be all in one piece, within it is divided into numerous compartments. In Zeppelin L1 there were eighteen separate compartments, each of which contained a balloon filled with hydrogen gas. The object of providing the vessel with these small balloons, or ballonets, all separate from one another, was to prevent the gas collecting all at one end of the ship as the vessel travelled through the air. Outside the ballonets there was a ring-shaped, double bottom, containing non-inflammable gas, and the whole was enclosed in rubber-coated fabric.
The crew and motors were carried in cars slung fore and aft. The ship was propelled by three engines, each of 170 horse-power. One engine was placed in the forward car, and the two others in the after car. To steer her to right or left, she had six vertical planes somewhat resembling box-kites, while eight horizontal planes enabled her to ascend or descend.
In Zeppelin L2, which was a later type of craft, there were four motors capable of developing 820 horse-power. These drove four propellers, which gave the craft a speed of about 45 miles an hour.
The cars were connected by a gangway built within the framework. On the top of the gas-chambers was a platform of aluminium alloy, carrying a 1-pounder gun, and used also as an observation station. It is thought that L1 was also provided with four machine-guns in her cars.
Later types of Zeppelins were fitted with a "wireless" installation of sufficient range to transmit and receive messages up to 350 miles. L1 could rise to the height of a mile in favourable weather, and carry about 7 tons over and above her own weight.
Even when on ground the unwieldy craft cause many anxious moments to the officers and mechanics who handle them. Two of the line have broken loose from their anchorage in a storm and have been totally destroyed.
Great difficulty is also experienced in getting them in and out of their sheds. Here, indeed, is a contrast with the ease and rapidity with which an aeroplane is removed from its hangar.
It was maintained by the inventor that, as the vessel is rigid, and therefore no pressure is required in the gas-chamber to maintain its shape, it will not be readily vulnerable to projectiles. But the Count did not foresee that the very "frightfulness" of his engine of war would engender counter-destructives. In a later chapter an account will be given of the manner in which Zeppelin attacks upon these islands were gradually beaten off by the combined efforts of anti-aircraft guns and aeroplanes. To the latter, and the intrepid pilots and fighters, is due the chief credit for the final overthrow of the Zeppelin as a weapon of offence. Both the British and French airmen in various brilliant sallies succeeded in gradually breaking up and destroying this Armada of the Air; and the Zeppelin was forced back to the one line of work in which it has proved a success, viz., scouting for the German fleet in the few timid sallies it has made from home ports.
CHAPTER XI. The Semi-rigid Air-ship
Modern air-ships are of three general types: RIGID, SEMI-RIGID, and NON-RIGID. These differ from one another, as the names suggest, in the important feature, the RIGIDITY, NON-RIGIDITY, and PARTIAL RIGIDITY of the gas envelope.
Hitherto we have discussed the RIGID type of vessel with which the name of Count Zeppelin is so closely a.s.sociated. This vessel is, as we have seen, not dependent for its form on the gas-bag, but is maintained in permanent shape by means of an aluminium framework. A serious disadvantage to this type of craft is that it lacks the portability necessary for military purposes. It is true that the vessel can be taken to pieces, but not quickly. The NON-RIGID type, on the other hand, can be quickly deflated, and the parts of the car and engine can be readily transported to the nearest balloon station when occasion requires.
In the SEMI-RIGID type of air-ship the vessel is dependent for its form partly on its framework and partly on the form of the gas envelope. The under side of the balloon consists of a flat rigid framework, to which the planes are attached, and from which the car, the engine, and propeller are suspended.
As the rigid type of dirigible is chiefly advocated in Germany, so the semi-rigid craft is most popular in France. The famous Lebaudy air-ships are good types of semi-rigid vessels. These were designed for the firm of Lebaudy Freres by the well-known French engineer M. Henri Julliot.
In November, 1902, M. Julliot and M. Surcouf completed an air-ship for M. Lebaudy which attained a speed of nearly 25 miles an hour. The craft, which was named Lebaudy I, made many successful voyages, and in 1905 M.
Lebaudy offered a second vessel, Lebaudy II, to the French Minister of War, who accepted it for the French nation, and afterwards decided to order another dirigible, La Patrie, of the same type. Disaster, however, followed these air-ships. Lebaudy I was torn from its anchorage during a heavy gale in 1906, and was completely wrecked. La Patrie, after travelling in 1907 from Paris to Verdun, in seven hours, was, a few days later, caught in a gale, and the pilot was forced to descend. The wind, however, was so strong that 200 soldiers were unable to hold down the unwieldy craft, and it was torn from their hands. It sailed away in a north-westerly direction over the Channel into England, and ultimately disappeared into the North Sea, where it was subsequently discovered some days after the accident.
Notwithstanding these disasters the French military authorities ordered another craft of the same type, which was afterwards named the Republique. This vessel made a magnificent flight of six and a half hours in 1908, and it was considered to have quite exceptional features, which eclipsed the previous efforts of Messrs. Julliot and Lebaudy.
Unfortunately, however, this vessel was wrecked in a very terrible manner. While out cruising with a crew of four officers one of the propeller blades was suddenly fractured, and, flying off with immense force, it entered the balloon, which it ripped to pieces. The majestic craft crumpled up and crashed to the ground, killing its crew in its fall.
In the ill.u.s.tration facing p. 17, of a Lebaudy air-ship, we have a good type of the semi-rigid craft. In shape it somewhat resembles an enormous porpoise, with a sharply-pointed nose. The whole vessel is not as symmetrical as a Zeppelin dirigible, but its inventors claim that the sharp prow facilitates the steady displacement of the air during flight. The stern is rounded so as to provide sufficient support for the rear planes.
Two propellers are employed, and are fixed outside the car, one on each side, and almost in the centre of the vessel. This is a some what unusual arrangement. Some inventors, such as Mr. Spencer, place the propellers at the prow, so that the air-ship is DRAWN along; others prefer the propeller at the stern, whereby the craft is PUSHED along; but M. Julliot chose the central position, because there the disturbance of the air is smallest.
The body of the balloon is not quite round, for the lower part is flattened and rests on a rigid frame from which the car is suspended.
The balloon is divided into three compartments, so that the heavier air does not move to one part of the balloon when it is tilted.
In the picture there is shown the petrol storage-tank, which is suspended immediately under the rear horizontal plane, where it is out of danger of ignition from the hot engine placed in the car.
CHAPTER XII. A Non-rigid Balloon
Hitherto we have described the rigid and semi-rigid types of air-ships.
We have seen that the former maintains its shape without a.s.sistance from the gas which inflates its envelope and supplies the lifting power, while the latter, as its name implies, is dependent for its form partly on the flat rigid framework to which the car is attached, and partly on the gas balloon.
We have now to turn our attention to that type of craft known as a NON-RIGID BALLOON. This vessel relies for its form ENTIRELY upon the pressure of the gas, which keeps the envelope distended with sufficient tautness to enable it to be driven through the air at a considerable speed.
It will at once be seen that the safety of a vessel of this type depends on the maintenance of the gas pressure, and that it is liable to be quickly put out of action if the envelope becomes torn. Such an occurrence is quite possible in war. A well-directed sh.e.l.l which pierced the balloon would undoubtedly be disastrous to air-ship and crew. For this reason the non-rigid balloon does not appear to have much future value as a fighting ship. But, as great speed can be obtained from it, it seems especially suited for short overland voyages, either for sporting or commercial purposes. One of its greatest advantages is that it can be easily deflated, and can be packed away into a very small compa.s.s.
A good type of the non-rigid air-ship is that built by Major Von Pa.r.s.eval, which is named after its inventor. The Pa.r.s.eval has been described as "a marvel of modern aeronautical construction", and also as "one of the most perfect expressions of modern aeronautics, not only on account of its design, but owing to its striking efficiency."
The balloon has the elongated form, rounded or pointed at one end, or both ends, which is common to most air-ships. The envelope is composed of a rubber-texture fabric, and externally it is painted yellow, so that the chemical properties of the sun's rays may not injure the rubber.
There are two smaller interior balloons, or COMPENSATORS, into which can be pumped air by means of a mechanically-driven fan or ventilator, to make up for contraction of the gas when descending or meeting a cooler atmosphere. The compensators occupy about one-quarter of the whole volume.
To secure the necessary inclination of the balloon while in flight, air can be transferred from one of the compensators, say at the fore end of the ship, into the ballonet in the aft part. Suppose it is desired to incline the bow of the craft upward, then the ventilating fan would DEFLATE the fore ballonet and INFLATE the aft one, so that the latter, becoming heavier, would lower the stern and raise the bow of the vessel.
Along each side of the envelope are seen strips to which the car suspension-cords are attached. To prevent these cords being jerked asunder, by the rolling or pitching of the vessel, horizontal fins, each 172 square feet in area, are provided at each side of the rear end of the balloon. In the past several serious accidents have been caused by the violent pitching of the balloon when caught in a gale, and so severe have been the stresses on the suspension cords that great damage has been done to the envelope, and the aeronauts have been fortunate if they have been able to make a safe descent.
The propeller and engine are carried by the car, which is slung well below the balloon, and by an ingenious contrivance the car always remains in a horizontal position, however much the balloon may be inclined. It is no uncommon occurrence for the balloon to make a considerable angle with the car beneath.
The propeller is quite a work of art. It has a diameter of about 14 feet, and consists of a frame of hollow steel tubes covered with fabric.
It is so arranged that when out of action its blades fall lengthwise upon the frame supporting it, but when it is set to work the blades at once open out. The engine weighs 770 pounds, and has six cylinders, which develop 100 horse-power at 1200 revolutions a minute.
The vessel may be steered either to the right or the left by means of a large vertical helm, some 80 square feet in area, which is hinged at the rear end to a fixed vertical plane of 200 square feet area.
An upward or downward inclination is, as we have seen, effected by the ballonets, but in cases of emergency these compensators cannot be deflated or inflated sufficiently rapidly, and a large movable weight is employed for altering the balance of the vessel.
In this country the authorities have hitherto favoured the non-rigid air-ship for military and naval use. The Astra-Torres belongs to this type of vessel, which can be rapidly deflated and transported, and so, too, the air-ship built by Mr. Willows.
CHAPTER XIII. The Zeppelin and Gotha Raids
In the House of Commons recently Mr. Bonar Law announced that since the commencement of the war 14,250 lives had been lost as the result of enemy action by submarines and air-craft. A large percentage of these figures represents women, children, and defenceless citizens.
One had become almost hardened to the German method of making war on the civil population--that system of striving to act upon civilian "nerves"
by calculated brutality which is summed up in the word "frightfulness".
But the publication of these figures awoke some of the old horror of German warfare. The sum total of lives lost brought home to the people at home the fact that bombardment from air and sea, while it had failed to shake their MORAL, had taken a large toll of human life.