remainder of 1917. Operational history The D.V entered service in May 1917 and structural failures of the lower wing immediately occurred. In 2009, Guttman wrote that "Within the month was doing belated stress testing and concluding, to its dismay, that the D.V’s sesquiplane wing layout was even more vulnerable than that of its predecessor". The outboard sections of the D.V upper wing also suffered failures, requiring additional wire bracing and the fuselage sometimes cracked during rough landings. Against these problems, the D.V offered very little improvement in performance. Front line pilots were considerably dismayed and many preferred the older D.III; Manfred von Richthofen was critical of the new aircraft. In a July 1917 letter, he described the D.V as "so obsolete and so ridiculously inferior to the English that one can't do anything with this aircraft". British tests of a captured D.V revealed that the aircraft was slow to manoeuvre, heavy on the controls and tiring to fly. Albatros responded with the D.Va, which featured stronger wing spars, heavier wing ribs and a reinforced fuselage. The modified D.Va was heavier than the D.III but the structural problems were not entirely cured. Use of the high-compression 130 kW (180 hp) Mercedes D.IIIaü engine offset the increased weight of the D.Va. The D.Va also reverted to the D.III aileron cable linkage, running outwards through the lower wing, then upwards to the ailerons - much the same as the earlier Albatros B.I unarmed two-seater had used before 1914 - to provide a more positive control response. The wings of the D.III and D.Va were interchangeable. To further strengthen the wing, the D.Va added a small diagonal brace connecting the forward interplane strut to the leading edge of the lower wing; the brace was also retrofitted to some D.Vs. placed orders for 262 D.Va aircraft in August 1917, followed by orders for another 250 in September and 550 in October. , which had been engaged in production of the D.III, received orders for 600 D.Va aircraft in October. Deliveries of the D.Va commenced in October 1917. The structural problems of the Fokker Dr.I and the mediocre performance of the Pfalz D.III left the with no alternative to the D.Va until the Fokker D.VII entered service in mid-1918. Production of the D.Va ceased in April 1918. In May 1918, 131 D.V and 928 D.Va aircraft were in service on the Western Front; the numbers declined