Aircraft in war

With the new century came the modern military airship—to stay, at any rate, until the heavier-than-air principle of aërial navigation has so developed as to absorb those features of utility the airship has and the aëroplane has not.

During the fourteen years which have seen the construction of practical airships, three distinct types have been evolved—(i.) rigid, (ii.) non-rigid, (iii.) semi-rigid. In considering the airships of Great Britain, France, and Germany, I propose to class them together as to types rather than under nationalities.

Each type has its own peculiar advantages. The choice of type must depend upon the circumstances under which it is proposed to be employed.

I. Rigid Type.

(i.) Zeppelin (German).—There are not many examples of the rigid type. The most important is undoubtedly the Zeppelin. This form of airship before the present war had elicited the interest of the aëronautical world for the long-distance records it had established. Indeed, no little sympathy had been extended to Count Zeppelin for his perseverance in the face of the gravest difficulties. Now the Zeppelin has accumulated notoriety instead of fame as having been the means of carrying on a form of warfare repugnant to the British nation, and condemned by the Hague Convention. Imagine some seventeen huge bicycle wheels made of aluminium, with their aluminium spokes complete, and these gigantic wheels to be united by longitudinal pieces of aluminium, and in this way seventeen sections to be formed, each of which contains a separate balloon, and it is easy to grasp the construction of the Zeppelin airship. It consists of a number of drum-shaped gas-bags, all in a row, held together by a framework of aluminium. They form a number of safety compartments. The bursting of one does not materially matter—the great airship should still remain in the air. The dimensions of individual Zeppelins have varied to some extent. The largest that has been built (“Sachsen,” 1913) had a cubic capacity of 21,000 cubic metres (742,000 cubic feet), and a length of 150 metres (492 feet). The aluminium framework containing the balloons has an outer covering of cloth. On each side of the frame of the airship are placed two pairs of propellers. In the original airship of 1900 these were four-bladed, and made of aluminium. They were small, being only 44 inches in diameter, but they revolved at a very high speed. In the later airships the screws have been considerably modified in detail, size, and shape. For instance, in the Zeppelin which descended accidentally at Lunéville, in France, it was found that the back pair of the propellers on each side were four-bladed, the front pair two-bladed. The screws are driven by motors placed in the two aluminium cars beneath the airship. These cars are connected by a covered gangway, which also serves as a track for a movable balance weight, by means of which a considerable change of balance can be effected. The motive power in the first Zeppelin was only two Daimler motors of 16 horse power each. With this low power little success was attained, but gradually the motive power has been increased. We find that in the naval Zeppelin, L 3, 1914. The motive power is three Maybach motors, giving total h.p. 650, whereas in the types building the total h.p. is 800.

The stability of these aërial monsters is attained by the use of large projecting fins. Horizontal steering is effected by a large central rudder and pairs of double vertical planes riveted between the fixed horizontal stability planes. For vertical steering there are sixteen planes provided in sets of four on each side of the front and rear ends of the balloons. These can be independently inclined upwards or downwards. When the forward ones are inclined upwards and the after planes downwards, the reaction of the air on the planes as the airship is driven forwards causes the front part to rise and the rear part to sink, and the airship is propelled in an inclined direction to a higher level. The favourite housing place for the Zeppelin airships has in the past been on Lake Constance, near Friedrichshafen, so that they could be taken out under protection from the direction of the wind. It is also much safer for large airships to make their descent over the surface of water. It has been estimated that the most powerful Zeppelins have a speed of some fifty miles an hour.

When on April 3rd, 1913, Z 16, in the course of a journey from Friedrichshafen, was forced to descend on French soil at Lunéville, excellent opportunity was afforded the French of a close inspection of its details.

The following were the exact dimensions, etc.:—

On the top of the ship was a platform, on which a mitrailleuse could be mounted.

It was only a few weeks before the present war that the new Zeppelin, L Z 24, attained a new world’s record of altitude and duration of flight. The height attained was 3,125 metres. The voyage without a break lasted thirty-four hours fifty-nine minutes. On May 22nd, 1914, it left Friedrichshafen at 7.16 a.m. Bâle was reached at 10 a.m. At 6 p.m. it passed Frankfort, at 9 Metz, at 10.30 Bingen, at 2 a.m. Brême. At 4 a.m. it arrived above Heligoland, from whence it made for Potsdam, where it was hailed 9.20 a.m. At 5.15 p.m. it landed at Johannisthal.

That journey certainly showed the long-range powers of the latest Zeppelins. If, as will be seen, it is comparatively easy for a few well-directed aëroplanes to wreck them in mid-air, still they have ceased to be military or naval playthings.

(ii.) Schutte-Lanz (German).—The Schutte-Lanz rigid airship is an attempt to secure the advantages of the rigid type without the fragilities of the Zeppelin. The framework, which contains the separate gas compartments, is made of fir wood. The gas-bags are claimed to be very strong. These are filled, excepting two, which remain empty when there is only sea-level pressure; when, however, the gas expands, it flows into the latter. These become full when an altitude of some 2,000 metres is reached. A centrifugal pump is employed for distributing the gas.

The volume of this airship is 26,000 cubic metres (918,000 cubic feet). It will be seen, therefore, that this mammoth airship in size surpasses even the largest Zeppelins.

II. Semi-rigid.

(i.) Lebaudy (French).—This airship is a crossbreed between the rigid and non-rigid systems. By this method of construction a considerable amount of support can be imparted to the gas-bag, though it does not dispense with the services of the ballonet, as does the entirely rigid type. To the genius of M. Julliot, Messrs. Lebaudy Brothers’ engineer, we are indebted for the introduction of this excellent type. It no doubt forms an exceedingly serviceable military airship. In the Lebaudy original airship the underside of the balloon consisted of a flat, rigid, oval floor made of steel tubes; to these the stability planes were attached, and the car with its engine and propellers was suspended. This secured a more even distribution of weight over the balloon. The gas-bag was dissymmetrical in form. Though not exactly resembling that excellent pattern, “La France,” it partook of the important quality of having the master diameter near the front. The car was a steel frame, covered with canvas, and in the form of a boat. The screw propellers were placed on either side of the car.

In 1909, as the British Government at that time possessed only very small airships, the nation raised a sum of money by subscription to present the Government with one of efficient size. The military authorities compiled a list of somewhat severe tests which, in their opinion, they thought an airship should be able to perform before acceptance. At the request of the Advisory Committee, of which Lord Roberts was chairman, the writer went to France in an honorary capacity to select the type of airship to be adopted. There was at that time only one firm of airship makers in France who were willing to undertake the formidable task of making an airship that would come up to the requirements of the British Government—the brothers Lebaudy, whose engineer and airship designer was M. Julliot.

The semi-rigid airship which M. Julliot designed and executed was without doubt a chef d’œuvre of its kind. The rigid tests it had to undergo necessitated a modification of some of the details that were conspicuous in the airships the constructor had previously built.

In this airship the girder-built underframe was not directly attached to the balloon, but suspended a little way beneath it.

The gas envelope had a cubic capacity of 353,165.8 cubic feet; the length was 337¾ feet. There were two Panhard-Levasseur motors of 135 h.p. each.

On October 26th, 1910, this airship made an historic and record flight over the Channel from Moisson to Aldershot in five hours twenty-eight minutes, at a speed of some thirty-eight miles an hour, sometimes against a wind of twenty-five miles an hour. Unfortunately, owing to a miscalculation by those responsible, the shed which had to receive the new airship on its arrival was made too small to house it safely. While the airship was being brought into the shed its envelope was torn and placed hors de combat.

Since this airship was made the Lebaudy brothers have ventured to still further increase the size of their semi-rigid airships.

(ii.) Gross (German).—This airship may be described as being more or less a German reproduction of the Lebaudy type. It forms part of the German airfleet. A considerable number have been made of various sizes (for dimensions, etc., see table, German Airships, Chapter IV., page 38).

III. Non-rigid.

This type is dependent for its maintenance of form on the pressure of the gas inside the envelope. It is all-important that the envelope of a navigable balloon should not lose its shape—that it should be kept distended with sufficient tautness, so that it may be driven through the air with considerable velocity. On this account the non-rigid type depends entirely on the ballonet system, which consists of having one or more small balloons inside the outer envelope, into which air can be pumped by means of a mechanically driven fan or ventilator to compensate for the loss of gas from any cause. The ballonets occupy about a quarter of the whole volume of the envelope. Such a type is exceedingly well suited for the smaller-sized airships, destined rather for field use than long-range offensive service. Such airships are quickly inflated and deflated. They are also easily transported. Even the Lebaudy or Gross semi-rigid types, though not so clumsy or difficult of transport as the Zeppelins, require more wagon service than the absolutely non-rigid.

The British Government have evolved several non-rigid airships of moderate dimensions which have been exceedingly useful as ballons d’instruction. For obvious reasons it is not desirable that particulars concerning them should be published at the present crisis.

(i.) Parsifal (German).—Very numerous examples of non-rigid airships could be cited, but it will suffice now to mention two, the German Parsifal and the French Clement-Bayard. The Parsifal is the only type that the German nation has allowed to be supplied to foreign countries. For instance, our Navy possesses one. It has also been supplied to Austria, Italy, Russia, and Japan. On account of its portability it is perhaps the most generally useful type of airship that has been designed, if we exclude long-range service. It has been exceptionally free from accidents on account of its subtleness. The originator of the Parsifal seems to have thoroughly grasped the sound idea that to attain success in navigating a subtle medium like air the machine should be correspondingly subtle—as, indeed, are the animal exponents of flight.

In the Parsifal the exclusion of the element of rigidity has been carefully studied. All that is rigid about it is the car and motor, and this can be conveyed in one cart.

The size of the Parsifals has been advisedly limited. The majority of them are not more than a third of the cubic capacity of the Zeppelins. A distinctive feature is the distance of the car from the gas-bag. This in the first types constructed was nine metres, though in more modern forms the figure is less. Owing to the distance of the car from the main body the attaching cords are distributed with equal tension over the whole length of the envelope. In the Parsifal airships there are two ballonets, one at the front and one at the back of the gas-bag. They are not only used for keeping the envelope rigidly expanded, but also to facilitate rising and falling, air being admitted into the one and expelled from the other, as the case may be. Another distinctive feature is the four-bladed propellers. These have fabric surfaces, and are weighted with lead. When at rest the blades are limp, but in revolving, owing to centrifugal force, they become endowed with the necessary rigidity. The dimensions of the Parsifals vary considerably, the smallest made had a capacity of 3,200 cubic metres (1908), the largest more recent ones have a capacity of 11,000 cubic metres. A very useful size is the P L 8 (1913), station Cologne, of which the dimensions are:—

(ii.) Clement-Bayard.—It is a question whether it is advisable to extend the non-rigid system to the amount that has been latterly done in the case of such a construction as the Clement-Bayard. This type of French airship is familiar to many in this country, as it was the first airship to cross the Channel from France to England.

The cubic capacity of this airship was 6,300 cubic metres. A feature was the comparatively large size of the ballonet used. To realise how the Clement-Bayards have grown since this type of airship came to this country, see table, French Military Airships, page 34.

Astra-Torres Type.—The Astra-Torres airships may be said to form a rather special subdivision of the non-rigid class, for, though there is no rigid metal in its construction, an unbendableness of keel is assured by panels of cloth so placed horizontally as to be kept rigid by the pressure of the air in a ballonet. Thus the virtue of rigidity is attained without the extra weight generally appertaining thereto, and a greater speed with economy of weight and size. The British naval authorities possess one of these airships. For dimensions, etc., of the latest Astra-Torres airships, see table, French Military Airships, page 34.

It will have been seen from the above short descriptions of distinctive types of airships Germany is the only nation which makes a very marked feature of retaining the rigid form. It is true France has evolved one form of rigid, the Spiess, in which the framework is made of wood, but she undoubtedly has a preference for the semi-rigid and non-rigid types. The rigid type has not found much favour in Great Britain.

Reckoning from the year 1911, France appears to have nineteen military dirigibles, and she may have one or two older ones in repair. Some of these are building; and as in France there are many eminent aëronautical factories, there are always also a number of private airships built, or in building, of various sizes and various types. These firms have enormous private airship hangars, and every convenience for making, filling, and storing. The number of military hangars in France is seven, at the following towns: Epinal, Maubeuge, Belfort, Rheims, Toul, and Verdun, where there are two.

In the spring of 1913 the Italian military dirigible fleet consisted of two units of Series M—M1 and M2—dirigibles of 12,000 cubic metres, and three units building of Series M—M3, M4, and M5.

These dirigibles of the M series were found in practice to be the most successful; they attained a speed of 70 kilometres per hour, and a height of 2,000 metres; they are all semi-rigid. The Italian Government is ambitious of rivalling in its aëronautical fleet that of Germany, and decided in that year, 1913, on a new series—Series G. These were to be of 24,000 cubic metres, and to travel at a speed of 100 kilometres the hour.

Airships.

At the present moment Italy is building some very large airships, some even bigger than the Zeppelin, and she practises ascents diligently with those she has. One of the new airships building for the Italian navy is a Parsifal of 18,000 cubic metres.

Great attention is paid in Russia to aëronautics. The Russians have no national types of dirigibles or aëroplanes yet developed; but they manufacture in their own country.

They have thirteen dirigibles (one is rumoured to be destroyed), semi-rigid and non-rigid, amongst them a Lebaudy made in 1910, Parsifals of 1911 and 1913, an Astra of 1913. The Parsifal of 1913 has a speed of 43–68 m.p.h. (km.).

Formerly Austria-Hungary led the way in aëronautics amongst the nations of the Triple Alliance. Germany particularly looked to her for flying machines, and the first Etrichs were hers; but military aëronautics in Austria-Hungary are now at a low ebb.

The decline is ascribed to monopoly and centralisation. At the present moment Austria has one dirigible, in a feeble condition, and about ten aëroplanes of foreign make. Two German houses, the Albatross and D.F.W., have quite lately opened branches in Austria.

The dual monarchy began well; in 1909 she had a small Parsifal, in 1910 a Lebaudy, in 1911 the Körting. These three perished in accidents. Her own system, the Boemches, presented to her by a national subscription, failed in speed; but though she has no dirigibles to inhabit them she has three good hangars!

Belgium has three airships, all non-rigid—two Godards and one Astra. Although not of very late construction, all three have innovations and interesting features. The Astra is private property.