Parseval Non-rigid Airships

P.L.1
P.L.2	P I
P.L.3	P II
P.L.4	built in Austria , 1914 a.D.
P.L.5	...
P.L.6	PL 6
P.L.7	delivered to Russia
P.L.8	P II (Ersatz)
P.L.9	sold to Turkey
P.L.10	nothing more known
P.L.11	P III
P.L.12	Charlotte
P.L.13	delivered to Japan
P.L.14	delivered to Russia
P.L.15	delivered to Italy
P.L.16	P IV
P.L.17	delivered to Italy
P.L.18	delivered to the UK
P.L.19	PL 19
P.L.20	not built
P.L.21	not built
P.L.22	not built
P.L.23	not built
P.L.24	not built
P.L.25	PL 25
P.L.26	PL 26
P.L.27	PL 27
R.K. 27	D-RK 27 "Trumpf - Schokolade"
PN1 28	D-PN 28 "Trumpf"
PN 29	D-PN 29 "Sidenhuset"
PN 30	D-PN 30 "Odol"

The Parseval Co. (Luftfahrzeng Gesellschaft) of Bitterfeld, Prussia, was well known before the war for its nonrigid ships fitted with girdle suspension and with two compensating ballonets. Of Germany's non-rigid airships only the Parseval types deserve special mention. Although only a limited number were built owing to the acute rubber shortage Germany experienced, the later Parseval ships were remarkable tor the large useful load they carried. They greatly exceeded in this respect their rigid contemporaries of the same size, but their speed was inferior. The most serious objection that came up against their use in warfare was the difficulty of keeping the envelope taut and so maintaining the shape of the hull when the ship was under way at high speed. This experience bears out the pre-war assumption that there is a limiting size beyond which it is not practical to build airships that depend on internal pressure for keeping their form, because the high internal pressure required demands a very heavy fabric;-which detracts from the useful load-and also because such ships are particularly liable to mishaps owing to failing pressure.

The development of the non-rigid German airship can best be traced through the Parseval types. Their development covered the period of years from 1906, when the experimental PV Type was placed in service, to 1917 when the PL-27 was constructed. The Parseval series were all built to the patents of Major von Parseval by the Luft-Fahrzeng-Gesellschaft (L.F.G.) at Berlin. That they were successful is attested by the fact that the company secured orders from Austria, England, Italy, Japan and Russia. The PL 22, 23 and 24 were laid down but never completed, probably because the rigid type was better adapted to purposes of war and the utility of the small non-rigid airship was eliminated with the advent of the large rigid types.

Starting with the PL-14, all Parseval airships had envelopes with the Parseval patent trajectory band system of car suspensions which was a very efficient system of non-rigid construction. The PL-25 had a small girder extending fore and aft from.the center of the ship about 60 ft., and with the PL-27 really comprised a semi-rigid airship, although the Germans classify it as non-rigid. Under the envelope of this ship there is a fore and aft keel with a. walkway which extends nearly the complete length of the ship. Beneath this, but forward, is the navigator’s car and immediately behind it is the first power car. About half way along the keel are two side power eggs similar to those used in the latter types of Zeppelin airships, and at almost the extreme aft end of the keel is located another power car. The keel walkway carried the gasoline tanks and the water ballast bags as in semi-rigid or rigid airships.

The last two Parseval airships built during the war differed from the well-known pre-war types in that a long metal girder was slung under the envelope in order better to distribute the disposable loads, such as gasoline, ballast, etc. Two wing cars were stayed to this girder amidships, while two more engine cars and a control car, forward, were suspended from it in the centerline. These large Parseval ships have thus, like the Schiitte-Lanz vessels, five separate cars, which system has the advantage of removing all noise and vibration from the control car, where the radio cabin was located.

Toward the end of the war the Parseval Company started experimenting with various aluminum alloys with a view to determining whether medium size airships could not be built more economically on the rigid principle than on the pressure system. These experiments dealt in particular with duralumin tubing, which, it is said, the company intends to use in the framework of an experimental airship.

The PL-27 differs fundamentally from pre-war Parsevals by its higher fineness ratio, the use of a cruciform empennage and the fitting of the cars in a manner reminiscent of the 1914 Schutte-Lanz— from which the L-30 Zeppelin class was incidentally developed in 1916. Like the S.L.II, the PL-27 has a Separate control car forward, while the power plant is split up in four power cars, arranged in the "quadrilateral" fashion which became famous on the super-Zeppelins. The three coaxial cars seemed to be rigidly connected with the keel which runs along the belly of the ship, hence it must be assumed that the keel itself is rigid in its entire length and was not a hinged affair of the kind used on the Gross-Basenach and the Italian "Military" airships. As the wing cars also appear to be rigidly attached to the underside of the hull, it may be supposed that the keel flares out on either side sufficiently to afford rigid points of suspension to the wing car struts.

The keel girder is obviously trussed to the envelope by means of an internal rigging system, but the nature of this is, for lack of data, a matter for speculation. It is possible that the keel is supported by circumferential fabric strips which surround the gas holder proper, such as was the case in the Siemens-Schuckert airships of 1911, the patents for which were acquired by the Prussian army. The excellent streamline of the PL-27 is noteworthy, for it is rather unusual for a semirigid of such large size to hold its shape so well.