To the second stage belongs naval airship L 2, which was destroyed by fire a month after completion in 1913. In 1916 a fourth stage made its appearance, of which the first ship was L 30, completed in May, and to which the ill-fated L 33 belonged. This type is known as the super-Zeppelin, and has been developed through various stage until L 70, the latest product before the armistice. In this stage the following are its main features:
Stage 4.
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 class. The G class 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 assists 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 bombshell of war exploded in our midst.