In spring 1916, German fighter aircraft quickly began to lose air superiority, guaranteed for months by the Fokker monoplane. The Allies had developed new much more manoeuvrable biplane fighters and brought them to the front. Initially, little could be done to combat these new aircraft. The only solution to this problem was for Germany to develop its own lightweight biplane fighters, known as D-aircraft. The first official tenders followed as soon as March 1916.
The Albatros-Werke had previously been very successful manufacturers of reconnaissance aircraft. Under the leadership of chief design engineer Robert Thelen, it began to develop the fighter aircraft D I. The fabric-covered biplane had a single strut, with upper and lower wing having the same depth and wingspan, and a semi-monocoque, plywood-skinned fuselage. The plane proved to have a very advanced aerodynamic design for the time. This design combined with the rounded rudder to give the plane its characteristic streamlined profile. The plane was initially powered by a Benz Bz III engine delivering power of 110 kW or a Daimler D III engine with 120 kW. As far as possible, the two engines were integrated within the fuselage structure and this brought about a further improvement in the aerodynamic qualities of the aircraft. Only the radiator was mounted to project significantly on the left-hand side of the fuselage.
The Albatros D I was first deployed on active service in September 1916 and proved successful in action. Some 50 aircraft were manufactured. The only problem was caused by the upper wing mounted slightly too high so that the visibility of the pilot was in part too restricted.
This version was therefore replaced from autumn 1916 by the improved Albatros D II. The problem was solved by modifying the design of the struts and lowering the height of the upper wing by more than 40 cm so that it was mounted at the eye level of the pilot. A further aerodynamic improvement was achieved by repositioning the radiator from the right-hand side of the fuselage to the centre of upper wing where it was mounted flat. 275 Albatros D II aircraft, fitted with 120 kW Daimler D III engines, were ultimately built. The aircraft was built under license in Austria-Hungary equipped with an Austro-Daimler 120 kW engine, with the designation Oeffag D II.
While the D II was being mass produced, an improved prototype was already being developed at the Albatros-Werke for a successor, D III. The main difference between the two predecessors was the significantly smaller area and depth of the lower wing, and the substantially increased size of the upper wing. These design features were based on the French Nieuport 11. The performance and design of this plane had made a big impression on German pilots and engineers. This was particularly the case when the first captured aircraft were inspected in detail. The main secret of the Nieuport 11 appeared to lie in the design of its wings: a large upper wing and a significantly smaller lower wing that almost turned the aircraft into a sesquiplane. The main benefit of this wing configuration was to make the aileron of the D III more effective, although the performance enhancement achieved compared with the previous two prototypes was less than expected. Only the rate of climb was significantly higher. The pilot’s downward visibility was also significantly improved – and it’s likely that this was the original reason for making the lower wing smaller. Other improvements on the D I and D II affected the external bracing of the wings. Again, the designers copied the configuration of the Nieuport 11 and replaced the parallel interplane I struts by a V-strut.
The Daimler D III delivering power of 120 kW again served as the power unit. Work on the first prototype started at the end of July / beginning of August 1916, although the date of the maiden flight is unknown. This probably took place at the end of August / beginning of September of 1916. The first aircraft were used in action at the front at the beginning of December in the same year.
More than 1300 Albatros D III had been built at the main Berlin plant in Johannisthal and the Albatros-Werke in Schneidemühl in eastern Germany by the close of 1917 / beginning of 1918. Indeed, the aircraft continued in production when its successor, the Albatros D V, had long since been rolling off the production line in Johannisthal. Austria-Hungary also showed rapid interest in the aircraft and manufactured large numbers of the D III under license at Oeffag as D III (Oef). The engines mounted in these Austrian-built aircraft were generally much more powerful because they tended to be fitted with Austro-Daimler engines delivering power of 136 kW or even 165 kW. However, their armament was much less reliable for a considerable period of time. A special feature of the Oeffag aircraft was the option of fully integrating the engine in the fuselage through the use of additional cowling. However, these supplementary cowlings were often abandoned in hot weather to prevent the engine from overheating.
Overall, the Albatros D III had extremely appealing flight characteristics, although the efficiency of the aileron was not regarded as ideal. However, the aircraft was manoeuvrable, climbed well and was fast enough to regain German air superiority on the Western Front for a considerable period of time. Until the summer of 1917, the D III in the hands of experienced pilots was at least evenly matched with its opponents and was generally popular as a very effective fighter aircraft. On the other hand, Allied aircraft pilots assessed the aerodynamic properties and performance of the aircraft much less favourably and were generally at a loss as to how their German counterparts were able to achieve the phenomenal number of successes.
The Albatros D III remained the most common German fighter aircraft to be deployed until the end of the war and saw action on virtually all front, even in Palestine. However, this apparent success cannot disguise the fact that the Albatros D III was continually beset by some serious technical problems. The aircraft was unable to perform steep or prolonged dives, which was often absolutely essential in aerial combat. It was an important manoeuvre for escaping from opponents and coming home safely and was also crucial when pursuing other planes or attacking from the advantage of a higher altitude. This was precisely the point at which the two wings rapidly started to flutter, i.e. they were subject to continuous bending and torsional vibrations. The engineers were powerless to do anything about this phenomenon. The wing had always demonstrated adequate strength in static load tests and there appeared to be no genuine solution to this problem. The only advice that could be given to pilots was to avoid steep dives with the D III if possible. Moreover, a large number of German fighter pilots lost their lives as a result of the wing’s structural failure. Ultimately, the unknown cause of this defect was found to lie in the design of the lower wing with the single main spar taken over directly from the Nieuport 11 being located too far aft. The Albatros III was almost twice the weight of the Nieuport 11 and its engines were much more powerful. This meant that the design of wing caused it to twist under aerodynamic loads. The Austrian aircraft were fitted with a completely new lower wing possessing adequate torsional stiffness. The company’s own engineers at Oeffag had even made this design of wing a condition for production under license in Austria. Why the lower wing designed in Austria never went into production at the German parent company will always remain a mystery – unsolved to this day.
Albatros D III (Oef) (1918)
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Type: |
Single-seater fighter aircraft |
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Engine: |
A liquid-cooled Austro-Daimler with 165 kW power |
