D III engine, the J 9 flew for the first time in late April 1918. Concurrently, the Idflieg awarded Junkers und Compagnie and the Junkers-Fokker Werke AG each a contract for 10 pre-series J 9s as D.Is. The first D.I prototype was entered in the 2nd D-type contest held at Adlershof in May-June 1918, but combat pilots adjudged it totally unsuited for fighter tactics then current.
It was suggested that, in view of the comparative invulnerability of its metal structure, it should be produced as a specialized "balloon attack" aircraft. Accordingly, further contracts were issued for the D.I for this role between May and November 1918, bringing the total ordered to 60 machines. Of these, Junkers delivered about 27 and Junkers-Fokker delivered 13 through February 1919. There is no record of the D.I having been used in combat during WW I, but a few were active with the Geschwader Sachsenberg in Kurland against Bolshevik insurgents.
One D.I was test flown with an 185 hp Benz Bz IIIb eight-cylinder V-engine, and another, powered by an 185 hp BMW IIIa engine, participated in the 3rd D-type contest in October 1918. View also photo 4831.
Span: 29 ft 6.33 in (7.20 m)
Length: 23 ft 9.375 in (6.20 m)
Height: 8 ft 6.33 in (2.33 m)
Wing area: 159.31 sq.ft (14.80 sq.m)
Weight empty: 1,442 lb (654 kg)
Loaded weight: 1,839 lb (834 kg)
Max speed: 140 mph (225 kmh)
Climb: to 16,405 ft (5,000 m) 24 min
Service ceiling: 9,842 ft (3,000 m)
Endurance: 1 hr 30 min