Short parallel portion of hull, long rounded bow and long tapering stern. In all respects a good streamline shape.

Internal keel walking way.

Balanced monoplane rudders and elevators.

Five cars. Two forward (combined as in Stage 3), one aft, and two amidships abreast.

Six engines and six propellers. The after one of the forecar and the sidecars each contain one engine driving direct a pusher propeller. The after car contains three engines, two of which drive two wing propellers; the third, placed aft, drives direct a pusher propeller.

In this stage the type of girders was greatly altered.

A company known as the Schutte-Lanz Company was also responsible for the production of rigid airships. They introduced a design, which was a distinct departure from Zeppelin or anyone else. The hull framework was composed of wood, the girders being built up of wooden sections.

The shape of these ships was much more of a true streamline than had been the Zeppelin practice, and it was on this model that the shape of the super-Zeppelin was based. These ships proved of use and took part in raids on this country, but the Company was taken over by the Government and the personnel was amalgamated with that engaged on Zeppelin construction during the war.

ITALY

In 1908, Italy, stimulated by the progress made by other continental nations, commenced experimental work. Three types were considered for a commencement, the P type or Piccolo was the first effort, then followed the M type, which signifies "medium sized," and also the semirigid Forlanini.

In the Forlanini type the envelope is divided into several compartments with an internal rigid keel and to-day these ships are of considerable size, the most modern being over 600,000 cubic feet capacity. During the war, Italian airships were developed on entirely dissimilar lines to those in other countries. Both we and our Allies, and to a great extent the Germans, employed airships exclusively for naval operations; on the other hand, the Italian ships were utilized for bombing raids in conjunction with military evolutions.

For this reason height was of primary importance and speed was quite a secondary consideration, owing to the low velocity of prevailing winds in that country. Flights were never of long duration compared with those carried out by our airships. Height was always of the utmost importance, as the Italian ships were used for bombing enemy towns and must evade hostile gunfire. For this reason weight was saved in every possible manner, to increase the height of the "ceiling."

In addition to the types already mentioned, three other varieties have been constructed since the war--the Usuelli D.E. type and G cla.s.s. The G cla.s.s was a rigid design which has not been proceeded with, and, with this single exception, all are of a semirigid type in which an essentially non-rigid envelope is reinforced by a metal keel. In the Forlanini and Usuelli types the keel is completely rigid and a.s.sists in maintaining the shape of the envelopes, and in the Forlanini is enclosed within the envelope. In the other types the keel is in reality a chain of rigid links similar to that of a bicycle. The form of the envelope is maintained by the internal pressure and not by the keel, but the resistance of the latter to compression enables a lower pressure to be maintained than would be possible in a purely non-rigid ship.

The M type ship is of considerable size, the P smaller, while the D.E.

is a small ship comparable to our own S.S. design. The review of these three countries brings the early history of airships to a conclusion.

Little of importance was done elsewhere before the war, though Baldwin"s airship is perhaps worthy of mention. It was built in America in 1908 by Charles Baldwin for the American Government. The capacity of the envelope was 20,000 cubic feet, she carried a crew of two, and her speed was 16 miles per hour. She carried out her trial flight in August, 1908, and was accepted by the American military authorities. During the war both the naval and military authorities became greatly interested in airships, and purchased several from the French and English. In addition to this a ship in design closely resembling the S.S. was built in America, but suffered from the same lack of experience which we did in the early days of airship construction.

We must now see what had been happening in this country in those fateful years before the bombsh.e.l.l of war exploded in our midst.

CHAPTER III

BRITISH AIRSHIPS BUILT BY PRIVATE FIRMS

It has been shown in the previous chapter that the development of the airship had been practically neglected in England prior to the twentieth century. Ballooning had been carried out both as a form of sport and also by the showman as a Sat.u.r.day afternoon"s sensational entertainment, with a parachute descent as the piece de resistance.

The experiments in adapting the balloon into the dirigible had, however, been left to the pioneers on the Continent.

PARTRIDGE"S AIRSHIP

It appears that in the nineteenth century only one airship was constructed in this country, which proved to be capable of ascending into the air and being propelled by its own machinery. This airship made its appearance in the year 1848, and was built to the designs of a man named Partridge. Very little information is available concerning this ship. The envelope was cylindrical in shape, tapering at each end, and was composed of a light rigid framework covered with fabric.

The envelope itself was covered with a light wire net, from which the car was suspended. The envelope contained a single ballonet for regulating the pressure of the gas. Planes, which in design more nearly resembled sails, were used for steering purposes. In the car, at the after end, were fitted three propellers which were driven by compressed air.

Several trips of short duration were carried out in this airship, but steering was never successfully accomplished owing to difficulties encountered with the planes, and, except in weather of the calmest description, she may be said to have been practically uncontrollable.

HUGH BELL"S AIRSHIP

In the same year, 1848, Bell"s airship was constructed. The envelope of this ship was also cylindrical in shape, tapering at each end to a point, the length of which was 56 feet and the diameter 21 feet 4 inches. A keel composed of metal tubes was attached to the underside of the envelope from which the car was suspended. On either side of the car screw propellers were fitted to be worked by hand. A rudder was attached behind the car. It was arranged that trials should be carried out in the Vauxhall Gardens in London, but these proved fruitless.

BARTON"S AIRSHIP

In the closing years of the nineteenth century appeared the forerunners of airships as they are to-day, and interest was aroused in this country by the performances of the ships designed by Santos-Dumont and Count Zeppelin. From now onwards we find various British firms turning their attention to the conquest of the air.

In 1903 Dr. Barton commenced the construction of a large non-rigid airship. The envelope was 176 feet long with a height of 43 feet and a capacity of 235,000 cubic feet; it was cylindrical in shape, tapering to a point at each end. Beneath the whole length of the cylindrical portion was suspended a bamboo framework which served as a car for the crew, and a housing for the motors supplying the motive power of the ship. This framework was suspended from the envelope by means of steel cables. Installed in the car were two 50 horse-power Buchet engines which were mounted at the forward and after ends of the framework. The propellers in themselves were of singular design, as they consisted of three pairs of blades mounted one behind the other. The were situated on each side of the car, two forward and two aft. The drive also include large friction clutches, and each engine was under separate control.

To enable the ship to be trimmed horizontally, water tanks were fitted at either end of the framework, the water being transferred from one to the other as was found necessary.

A series of planes was mounted at intervals along the framework to control the elevation of the ship.

This ship was completed in 1905 and was tried at the Alexandra Palace in the July of that year. She, unfortunately, did not come up to expectations, owing to the difficulty in controlling her, and during the trial flight she drifted away and was destroyed in landing.

WILLOWS No. 1

From the year 1905 until the outbreak of war Messrs. Willows & Co. were engaged on the construction of airships of a small type, and considerable success attended their efforts. Each succeeding ship was an improvement on its predecessor, and flights were made which, in their day, created a considerable amount of interest.

In 1905 their first ship was completed. This was a very small non-rigid of only 12,500 cubic feet capacity. The envelope was made of j.a.panese silk, cylindrical in shape, with rather blunt conical ends. A long nacelle or framework, triangular in section and built up of light steel tubes, was suspended beneath the envelope by means of diagonally crossed suspensions.

A 7 horse-power Peugeot engine was fitted at the after end of the nacelle which drove a 10-feet diameter propeller. In front were a pair of swivelling tractor screws for steering the ship in the vertical and horizontal plane. No elevators or rudders were fixed to the ship.

WILLOWS No. 2

The second ship was practically a semi-rigid. The envelope was over twice the capacity of the earlier ship, being of 29,000 cubic feet capacity. This envelope was attached to a keel of bamboo and steel, from which was suspended by steel cables a small car. At the after end of the keel was mounted a small rudder for the horizontal steering.

For steering in the vertical plane two propellers were mounted on each side of the car, swivelling to give an upward or downward thrust. A 30 horse-power J.A.P. engine was fitted in this case. Several successful flights were carried out by this ship, of which the most noteworthy was from Cardiff to London.

WILLOWS No. 3

No. 2, having been rebuilt and both enlarged and improved, became known as No. 3. The capacity of the envelope, which was composed of rubber and cotton, was increased to 32,000 cubic feet, and contained two ballonets. The gross lift amounted to about half a ton. As before, a 30 horse-power J.A.P. engine was installed, driving the swivelling propellers. These propellers were two-bladed with a diameter of 61 feet. The maximum speed was supposed to be 25 miles per hour, but it is questionable if this was ever attained.

This ship flew from London to Paris, and was the first British-built airship to fly across the Channel.

WILLOWS No. 4

The fourth ship constructed by this firm was completed in 1912, and was slightly smaller than the two preceding ships. The capacity of the envelope in this instance was reduced to 24,000 cubic feet, but was a much better shape, having a diameter of 20 feet, which was gradually tapered towards the stern. A different material was also used, varnished silk being tried as an experiment. The envelope was attached to a keel on which was mounted the engine, a 35 horse-power Anzani, driving two swivelling four-bladed propellers. From the keel was suspended a torpedo-shaped boat car in which a crew of two was accommodated. Originally a vertical fin and rudder were mounted at the stern end of the keel, but these were later replaced by fins on the stern of the envelope.

This ship was purchased by the naval authorities, and after purchase was more or less reconstructed, but carried out little flying. At the outbreak of war she was lying deflated in the shed at Farnborough. As will be seen later, this was the envelope which was rigged to the original experimental S.S. airship in the early days of 1915, and is for this reason, if for no other, particularly interesting.

WILLOWS No. 5

This ship was of similar design, but of greater capacity. The envelope, which was composed of rubber-proofed fabric, gave a volume of 50,000 cubic feet, and contained two ballonets. A 60 horsepower engine drove two swivelling propellers at an estimated speed of 38 miles per hour. She was constructed at Hendon, from where she made several short trips.

MARSHALL FOX"S AIRSHIP