The Albatros W.4 was a floatplane fighter based on the Albatros D.I and designed to intercept British flying boats and sea planes that were attacking German air stations on the North Sea coast.
Work on the W.4 began in May-June 1916 after the German Navy ordered Albatros and six other companies to design single-seat floatplane or flying boat fighters. Albatros received an order for three W.4 prototypes on 16 May, and the first aircraft was ready for testing by August.
The W.4 was largely based on the Albatros D.I, but it was increased in size. The wingspan was increased by 3ft 4in, it was 3ft longer and 350lb heavier when fully loaded. The twin floats also meant that it was higher than the D.I.
The W.4 was a standard Albatros design. The fuselage had a wooden framework and was covered with plywood. The wings had wooden spars and ribs and were fabric covered. The W.4 was a single bay biplane with wings of equal chord and almost equal span. Ailerons were carried on the upper wing in most aircraft, but on all four wing tips in the last two production batches. The fuselage was slab sided, but with curved tops and bottoms. The tail was something of an interim design. It had the curved edges that were an Albatros trademark, but the horizontal surfaces didn't have the almost semi-circular profile of later Albatros aircraft. The ventral fin of the D.I was removed. The vertical surface was curved, but the rudder had a straight trailing edge. The prototypes and the first four production batches used ear type radiators mounted on the side of the fuselage, but these didn’t perform well at sea and from the fifth batch were replaced with a radiator carried in the upper wing.
Early tests revealed a number of problems with the W.4. The floats weren't satisfactory and the prototype was returned to Albatros to have longer ones installed. These would also disappoint, and a series of different designs of single-step floats were to be installed on the aircraft. The prototype was tail heavy in flight but this was fixed by altering the stagger of the wings.
On 5 September 1916 a batch of ten pre-production aircraft was ordered. Nine of these aircraft were delivered in February 1917 and underwent frontline evaluation. Once again the floats were judged to be unsatisfactory, with a very short life span. As first produced the lower wings also had a short life span, suffering from sea water damage, but this problem was also largely eliminated.
A total of 118 Albatros W.4s were built, and 91 were delivered to the German Navy between July and December 1917. The W.4 had a fairly limited front line career, and probably saw most combat on the Eastern Front. During its front line career it was used to fly standing patrols off German bases. It was faster and better armed than most enemy seaplanes that it encountered, but was less successful against the heavily armed flying-boats of the RNAS, which carried out raids on the German coast from their bases at Felixstowe and Yarmouth (aircraft such as the Felixstowe F.2A could carry between four and nine machine guns).
By the end of 1917 it had been replaced by two seat fighters such as the Hansa-Brandenburg W.12, which proved to be much more suitable for service over the sea. Of the 118 Albatros W.4s produced, 89 were still intact at the start of August 1918 and only 21 had been written off. By the same date four were still in use on the North Sea, five had been sent to Turkey, fifty six were in storage and the remaining 24 were at training bases.
Engine: Mercedes D.III inline engine
Span: 31ft 2in
Length: 27ft 10.75in
Height: 11ft 11.75in
Empty weight: 1,742lb
Maximum take-off weight: 2,359lb
Max speed: 99mph
Service ceiling: 9,840ft
Climb to 3,280ft: 5 minutes
Endurance: 3 hours
Armament: Two 7.92mm LMG 08/15 machine guns