O.Thetford, P.Gray German Aircraft of the First World War (Putnam)
Albatros D VII
Another experimental fighter from the Albatros stable was the D VII, which flew in August 1917. It was fitted with wings of parallel chord, with ailerons at all four tips linked with a strut. Conventional Albatros constructional practice was followed, but for the first time a vee-eight type engine was installed. Engine, 195 h.p. Benz Bz IIIb . Span, 9.32 m. (30 ft. 7 in.). Length, 6.615 m. (21 ft. 8 1/2 in.). Height, 2.68 m. (8 ft. 9 1/2 in.). Weights: Empty, 630 kg. (1,386 lb.). Loaded, 885 kg. (1,947 lb.). Speed, 204 km.hr. (127.5 m.p.h.). Climb, 2,000 m. (6,560 ft.) in 7 min. Duration, 2 hr. Armament, twin Spandau machine-guns.
W.Green, G.Swanborough The Complete Book of Fighters
ALBATROS D VII Germany
Flown in August 1917, the D VII was powered by a 195 hp Benz Bz IIIb eight-cylinder water-cooled Vee engine. Strut-linked ailerons were carried by all wings and armament comprised two 7,92-mm machine guns. The characteristics of the D VII offered an insufficient advance to warrant development beyond prototype status.
Max speed, 127 mph (204 km/h).
Time to 6,560 ft (2 000 m), 7 min.
Endurance, 2 hrs.
Empty weight, 1,389 lb (630kg).
Loaded weight, 1,951 lb (885 kg).
Span, 30 ft 6 7/8 in (9,32 m).
Length, 21 ft 8 1/4 in (6,61 m).
J.Herris Albatros Aircraft of WWI. Vol.4: Fighters (A Centennial Perspective on Great War Airplanes 27)
The success of the SE.5a and Spad fighters powered by the Hispano-Suiza V8 finally alerted Idflieg to the potential of this engine configuration and Idflieg ordered V8 engine programs at Benz and Daimler (Mercedes), the two biggest German engine suppliers, although the projects were not driven with enough vigor to bring these engines to production status in time to power warplanes in combat.
However, pre-production engines for development of suitable prototype aircraft were made available in small numbers starting in September 1917. Idflieg ordered two fighter prototypes to evaluate the Benz Bz.IIIbo V8 engines, the LVG D.IV and the Albatros D.VII.
There were two versions of the Benz V8, the Bz.IIIbo, the 'o' suffix indicating 'ohne', or without reduction gear, and the Bz.IIIbm, the 'm' suffix indicating 'mit', or with reduction gear. The 'b' suffix in the designation indicates the second Benz engine in the 'III" power category, which stood for an engine of more than 150 hp to 200 hp, the Bz.IIIa being a 185 hp six-cylinder engine that was used in small numbers only in the Roland D.VIb fighter of 1918.
The Albatros D.VII retained the plywood fuselage construction common to the earlier production Albatros fighters and reverted to a wing cellule similar to the earlier D.I and D.II with two-spar upper and lower wings and single-bay bracing. However, unlike earlier Albatros fighters all four wings had ailerons, the upper and lower ailerons on each side being connected by an actuating strut. The shorter, wider V8 engine gave the D.VII bulky nose contours and the horizontal and vertical tailplane had a higher aspect ratio then the D.I through D.V.
Flight testing of the LVG D.IV was characterized by smooth, trouble-free engine operation. That was not the case with the Albatros D.VII, which experienced in flight resonance so severe the wood wing and fuselage structure was damaged. Since the LVG competitor was not experience these problems, it was decided to modify the D.VII airframe to change its resonance frequency to detune it from the sympathetic vibrations created by the engine. This effort was successful but during renewed flight testing in November 1917 the D.VII was not found to have especially good performance. In December the engine was removed and the aircraft set aside and no further development was undertaken of that airframe.
However, a second D.VII prototype with revised wing cellule with ailerons on the top wing only since the first prototype with ailerons on all wings had not exhibited good roll performance. Again powered by a Benz Bz.IIIbo, the second D.VII prototype flew in May 1918. The next month it was grounded for severe nose heaviness. Despite its mediocre flight characteristics, the second prototype was load tested during the first half of July at Adlershof. Provided the wing spars were strengthened this D.VII prototype was cleared for flight by military pilots, but no acceptance tests took place and further work was cancelled. Simultaneously the Aviatik D.III program, which used the same engine, was progressing smoothly and this apparently eliminated the need for the Albatros D.VII.
Just as the D.VII was ordered as a flying testbed for the Bz.IIIbo V8 engine, the Albatros D.VIII was ordered as a flying testbed for the Adler Ad.IV two-row, eight cylinder engine. The D.VIII airframe, similar to that of the D.VII, was completed in May 1918 and stored awaiting the Adler engine it was supposed to test. The Adler was delayed by development problems and did not pass its duration test until too late in the war for the D.VIII ever to be completed. No photographs of the airframe have been discovered, although a contemporary sketch indicates similarity to the D.VII second version.
Albatros Fighter Specifications
D.VI D.VII/1 D.VII/2 D.IX D.X
Engine 160 hp Mercedes D.III 195 hp Benz Bz.IIIbo 195 hp Benz Bz.IIIbo 170 hp Mercedes D.IIIa 195 hp Benz Bz.IIIbm
Span (Upper) 9.80 m 9.30 m 9.32 m 10.40 m 9.90 m
Span (Lower) - 8.20 m 8.32 m 10.20 m 9.15 m
Chord (Upper) 1.6 m 1.3 m 1.3 m 1.3 m 1.3 m
Chord (Lower) - 1.3 m 1.3 m 1.3 m 1.3 m
Gap - 1.32 m 1.33 m 1.32 m 1.37 m
Stagger - 0.18 m 0.18 m 0.17m 0.30 m
Wing Area - 20.5 m2 20.9 m2 24.0 m2 22.9 m2
Length 7.75 m 6.62 m - 6.66 m 6.18 m
Height 2.79 m 2.68 m - 2.75 m 2.74 m
Empty Weight 638 kg 630 kg 750 kg 647 kg 667 kg
Useful Load 242 kg 255 kg 190 kg 220 kg 239 kg
Loaded Weight 880 kg 885 kg 940 kg 897 kg 906 kg
Wing Loading - 43.2 kg/m2 45.0 kg/m2 37.4 kg/m2 39.6 kg/m2
Power Loading 5.50 kg/hp 4.54 kg/hp 4.82 kg/hp 5.28 kg/hp 4.65 kg/hp
Max. Speed - - - 165 km/h 170 km/h
Climb, 1,000 m - - - 4 minutes -
Climb, 2,000 m - - - 8.8 minutes -
Climb, 3,000 m - - - 14.8 minutes -
Climb, 4,000 m - - - 22.8 minutes -
Climb, 5,000 m - - - 35 minutes -
Climb, 6,000 m - - - - -
Notes: All were armed with two machine guns. D.VI track 2.72 m.