The Zeppelin R Class was a type of rigid airship developed by Zeppelin Luftschiffbau in 1916 for use by the Imperial German Navy and the German Army for bombing and naval patrol work. Introduced in July 1916 at a time when British air defences were becoming increasingly capable, several were lost in the first months of operation, leading the Germans to reconsider their technical requirements and eventually to develop airships capable of bombing from a greater height. Most surviving examples were modified to meet these requirements, by reducing weight at the expense of performance. A total of 17 were built.
Background
Work on the R class started in March 1915, when the German Navy asked both Zeppelin and Schütte-Lanz to prepare studies for a new class of airship which would be limited in size by the existing sheds. The proposals were rejected by the Navy's aviation department, and a decision was made to design a new class of six-engined airships regardless of size. Double sheds at Tondern and Seddin were to be lengthened and six new double hangars would be constructed, four of them at a new base at Ahlhorn. A new large assembly shed was built at Friedrichshafen, and a second Zeppelin factory at Staaken near Berlin was established.
Design and development
Influenced by aerodynamicist Paul Jaray, the hull shape was more streamlined than the preceding P class, although traditionalists in the company insisted that a portion of the hull should be parallel sided to prevent instability. The structure consisted of 20 wire braced 13-sided transverse frames, all but the rear three and front two frames made up of kingpost-braced girders. These were spaced 10 m (32 ft 9 in) apart, with an intermediate frame in the middle of each bay, and were attached to a triangular section ventral keel, the apex of which was braced to the ends of the outer ends of the lower transverse frame girders on each side. The transverse frames were connected by 13 principal longitudinal girders, of which the one at the top of the hull was a more substantial W-section girder. There were secondary longitudinal girders between the principal girders. A central axial bracing cable running the length of the hull was fitted to reduce the load on the transverse bracing of the mainframes in the case of the deflation of a single gasbag. This feature was the subject of a Schütte Lanz patent, and had not previously been used by Zeppelin.
As in the preceding P and Q classes, the forward control car contained a single engine driving a pusher propeller and an aft engine car contained three engines, one driving a pusher propeller at the rear of the car and the other two driving propellers mounted on brackets on either side of the hull via driveshafts: these were reversible. Unlike the previous design, which had the three engines mounted in line, the two engines driving the hull-mounted propellers were side by side. The additional two engines were carried in small engine cars either side of the hull, accessed by a catwalk from the keel gangway.
The bomb load was carried in a compartment in the centre of the keel. The keel also accommodated the rubberised canvas ballast bags and the main fuel tanks, which could be jettisoned in an emergency. Fuel was pumped from these tanks to individual gravity tanks above each engine car. As a legacy of the loss of the crew of LZ 54 (L 19), two lightweight lifeboats, made of canvas stretched over a wooden frame, were carried. A total of 10 machine guns were carried as defensive armament: three in the forward platform on top of the hull, one in an aft gun position behind the rudders, two in both the forward and aft gondolas and one in each of the wing cars either side of the hull.
Following the loss of four of the first R class Zeppelins to be built during raids on England, a decision was made to develop airships capable of operating at greater altitude, and most of the remaining R class were modified in order to reduce weight: one engine was removed from the aft gondola, the defensive armament was removed and the bomb load reduced by half. This increased the ceiling to over 4900 mn (16,080 ft) Later an improved streamlined rear gondola was fitted.